Meteorology Presentation PPL for ncat.pptx

met course for pilots in ppl phase

1. 5/10/2018 Kalu 2015 PPT 1. 1 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA METEOROLOGY FOR AERONAUTICAL OPERATION COURSE. (AO) BATCH 25

2. The Atmosphere Temperature Humidity Atmospheric Pressure Altimetry Winds 5/10/2018 Kalu 2015 PPT 1. 2 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA MODULE OUTLINE

3. Wind shear and Turbulence Air in Vertical Motion and Atmospheric Stability Cloud and Precipitation Thunderstorm Visibility and fog 5/10/2018 Kalu 2015 PPT 1. 3 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA MODULE OUTLINE CONT`D

4. Air masses and Fronts Aircraft Icing Meteorological information for Air traffic Services and Search and Rescue Aviation Weather Reports- METAR; - SPECI and - TAF CODES 5/10/2018 Kalu 2015 PPT 1. 4 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA MODULE OUTLINE CONT`D

5. Kalu 2015 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 5 At the training centre, given the NCAT Meteorology Training Manual for Aeronautical operations course ,the trainee will be able to describe the fundamental forces that drive the weather systems so as to understand and predict what the weather will do at any time or place, given the basic data, In accordance with the ICAO Annex 3, the NCAT Training Manual FSTM 002 Chapter 4, and Nig. CARs 2015. End –of – Module Objective:

6. Describe the Atmosphere Explain Temperature Explain Humidity Describe Atmospheric Pressure Explain Altimetry Describe the Winds 5/10/2018 PPT 1. 6 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA INTERMEDIATE OBJECTIVES

7. Describe Wind shear and Turbulence Explain Air in Vertical Motion and Atmospheric Stability Describe Cloud and Precipitation Explain Thunderstorm Describe Visibility and fog 5/10/2018 PPT 1. 7 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA INTERMEDIATE OBJECTIVES CONT`D

8. Describe Air masses and Fronts Explain Aircraft Icing Meteorological information for Air traffic service and Search and Rescue Describe Aviation Weather Reports- METAR; - SPECI and - TAF CODES 5/10/2018 PPT 1. 8 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA INTERMEDIATE OBJECTIVES CONT`D

9. Kalu 2015 …..to the World of Weather 5/10/2018 PPT 1. 9 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

10. 5/10/2018 PPT 1. 10 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

11. 5/10/2018 PPT 1. 11 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

12. 5/10/2018 PPT 1. 12 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

13. 5/10/2018 PPT 1. 13 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

14. WEATHER INFLUENCED ACCIDENTS 1975 - 1994 Total WI Per cent 499 104 20.84 5/10/2018 PPT 1. 14 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

15. ELEMENT OF WEATHER INVOLVED All % Fatal % Visibility 22 21.1 10 66.7 Icing/Snow 22 21.1 3 20 Wind/Turbulence 45 43.3 2 13.3 Rain/Wet runway 12 11.5 Lightning 3 2.9 Total 104 100 15 100 5/10/2018 PPT 1. 15 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

16. Meteorology is the branch of science dealing with the earth’s atmosphere and the physical processes occurring in it WHAT IS METEOROLOGY Simply stated: The atmosphere can be seen as a giant weather engine driven by the sun 5/10/2018 PPT 1. 16 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

17. WHAT IS METEOROLOGY CONT’D The study of meteorology is important for the pilot because the atmosphere is the medium through which the aircraft moves. All weather occurs within the atmosphere. The weather is one factor in modern aviation over which man has no control; 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 17

18. WHAT IS METEOROLOGY CONT`D knowledge of meteorology will at least enable the pilot to anticipate some of the difficulties which weather may cause. To avoid hazardous flight conditions therefore, it is essential to know the conditions present along a route. Knowledge of the processes in which weather forms is useful for predicting the conditions that may occur during flight. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 18

19. WHAT IS METEOROLOGY CONT`D 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 19 Meteorology therefore, is the science that studies atmospheric phenomena, especially those that relate to weather. Meteorologists who forecast the weather rely on thousands of weather stations located around the world, both on land and at sea.

20. BRANCHES OF METEOROLOGY 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 20

21. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 21 AVIATION METEOROLOGY Aviation meteorology deals with the impact of weather on air traffic management. It is important for air crews to understand the implications of weather on their flight plan as well as their aircraft

22. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 22 AGRICULTURAL METEOROLOGY involves the integration of climatological and meteorological data and techniques into agricultural problems, such as crop production, soil moisture, moisture stress, and migration of pests. A good background in basic math and sciences is required.

23. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 23 HYDRO-METEOROLOGY Is a branch of meteorology and hydrology that studies the transfer of water and energy between the land surface and the lower atmosphere.

24. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 24 NUCLEAR METEOROLOGY Nuclear meteorology investigates the distribution of radioactive aerosols and gases in the atmosphere

25. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 25 MARITIME METEOROLOGY deals with air and wave forecasts for ships operating at sea.

26. THE ATMOSPHERE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 26

27. When we say it is hot, or wet, or cloudy, we are saying something about the weather. Weather refers to the state of the atmosphere in relation to its temperature, pressure and humidity for a short period of time. The atmosphere plays a very important role in flying as this is the “medium” in which pilots are required to operate. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 27 THE ATMOSPHERE CONT`D

28. THE ATMOSPHERE The term atmosphere refers to the spheroidal gaseous envelope of air that surrounds the Earth. It is held to the Earth by the force of gravity. This gaseous envelope moves with the rotation of the earth and extends from the surface of the planet up to the boundary of space. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 28

29. Kalu 2015 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 29 In the structure of the weather formation, three major elements can be identified. These elements are: Temperature Pressure Humidity These three elements can work individually or in conjunction with each other GASES IN THE ATMOSPHERE CONT`D

30. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 30 COMPOSITION OF THE ATMOSPHERE: Air is a mixture of gases and water. It is about 78 percent Nitrogen, 21 percent Oxygen and 1 percent other gases by volume . Air always contains some water. Water vapour is a variable gas, up to 4 percent over the ocean, while almost not existent over deserts or at high altitudes. However, it is an important material for weather prediction as it can exist in the atmosphere as a gas, liquid or solid.

31. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 31 The Atmosphere

32. GASES IN THE ATMOSPHERE CONT`D 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 32

33. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 33 GASES IN THE ATMOSPHERE THESE ARE THE IMPORTANT ONES AS FAR AS METEOROLOGY IS CONCERNED

34. The principal properties of the atmosphere are: mobility capacity for expansion and capacity for compression.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 34 PROPERTIES OF THE EARTH’S ATMOSPHERE

35. Kalu 2015 There is no specific upper limit to the atmosphere. It simply thins to a point where it fades away. As you progress outward from the earth, the atmosphere displays different properties, including a change in temperature distribution. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 35 LAYERS OF THE ATMOSPHERE AND THEIR PROPERTIES:

36. Kalu 2015 These temperature variances are the most common basis for classifying the four layers of the atmosphere. In ascending order, they are: Troposphere Stratosphere Mesosphere and Thermosphere 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 36

37. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 37 STRUCTURE OF THE ATMOSPHERE

38. Flying takes place in a layer of space above the surface of the earth. Since the normal operational altitude for modem Jet transports, do not as yet, exceed some 50,000 ft, we shall therefore be concerned with the first two layers of the atmosphere namely, Troposphere and Stratosphere . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 38

39. Kalu 2015 THE TROPOSPHERE: The word Trope means change or turning, and this layer is characterised by stability. This is the lowest layer of the atmosphere which extends from the earth’s surface to an average height of 11km (7 miles ). In this layer, temperature decreases with height at an average rate of 2°C per 1000ft ( or 6.5°C per km or 0.65°C / 100 m ) and stops decreasing at a certain level called the TROPOPAUSE . Majority of the weather occurs here and 75% of the total weight of the atmosphere is in this layer. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 39

40. Kalu 2015 THE TROPOSPHERE CONT`D: The tropopause is the upper limit of troposphere where temperature ceases to fall with an increase in height This level is often is characterised by an abrupt change in temperature lapse rate.(Note that it is not a layer ) It can also act as a lid that traps water vapour in the troposphere There is large scale vertical motion of air in this layer. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 40

41. Kalu 2015 THE TROPOSPHERE CONT`D: Wind speed increases with height and reaching a maximum near the tropopause. The tropopause slopes from the Equator to the Pole being about 16km (52,000ft) over Equator and about 8km (26,000ft) over the Pole. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 41

42. THE TROPOSPHERE CONT`D: The tropopause is higher over warm regions (Tropical air mass) than over cold region (polar air mass) and on average, higher in summer than winter. In general, the lower the tropopause, the higher its temperature. The temperature at the tropopause level therefore is higher over the pole than over the equator. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 42

43. TROPOSPHERE The height of this layer varies with the latitude and season. It is higher in summer than in winter and higher over the lower latitudes than over the higher latitudes. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 43

44. Kalu 2015 THE STRATOSPHERE: The stratosphere is the layer immediately above the tropopause. It extends from about 11km to 50km . The temperature of the air tends to remain constant with an increase in height and no weather occurs .The top of the layer is called STRATOPAUSE . Temperature remains relatively constant with height though there may be slight increase at the top due to the presence of ozone. In general, flying conditions in the stratosphere will be smooth and above weather. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 44

45. THE STRATOSPHERE Air in this layer, as evidenced by its root word “strata” tends to move in a generally horizontal direction. It is not uncommon, however, for large cumulonimbus(CB) clouds to penetrate into this layer. 5/10/2018 Kalu 2015 PPT1. 45 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA

46. MESOSPHERE The mesosphere is characterized by noctilucent clouds within the mesosphere. There is a decrease in temperature with increased height. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 46

47. THERMOSPHERE The thermosphere is the last layer and is characterised by layers having a largely electrical nature . The Aurora Borealis and the Aurora Australis are as the result of the ionization that occurs within the thermosphere . Within the thermosphere there is an increase in temperature with height. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 47

48. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 48 Vertical Divisions

49. The international standard atmosphere (ISA), also called the standard atmosphere is an idealized atmosphere with specific vertical distribution of temperature pressure, and density prescribed by international agreement. The ISA values are used for: Calibrating flight instruments Forecasting aircraft performance, and Obtaining QNH from QFE . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 49 THE INTERNATIONAL STANDARD ATMOSPHERE (I.S.A)

50. Kalu 2015 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 50 Measured at mean sea level Temperature is 15°C Density is 1225 gm/m 3 Pressure is 1013,25 hPa or: 29,92 inches of mercury (Hg) or: 760 millimetres of Hg or: 14,7 pounds per square inch (psi) International Standard Atmosphere

51. Kalu 2015 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 51 International Standard Atmosphere Measured at mean sea level Temp Lapse Rate is 1,98°C/1000 ft , up to 36090 ft , then remains at –56,5°C This derives from 6.5°C/1km or 0.65°/100m, and the strange height is 11 km above mean sea level Gravity is 9,81 m/s 2 , or 32,2 ft /s 2 Air is dry and uniform throughout

52. Tropopause height of 11 km (36,090 ft); Pressure and density to decrease with height. Note:- Atmospheric conditions vary from place to place I.S.A defines conditions for one latitude only. Hence average tropopause temperature will be considerably higher than -56.5 C over the Poles, and considerably lower than -56.5 C over the Equator.  5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 52

53. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 53 International Standard Atmosphere

54. ISA TEMPERTAURE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 54

55. ISA STRUCTURE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 55

56. ALTITUDE/PRESSURE RELATIONSHIP 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 56

57. TEMPERATURE: Temperature affects every aspect of weather. The primary cause for temperature differences is unequal solar heating of the earth’s surface. This unequal heating causes temperature differences, which in turn cause pressure differences that result in change in weather Temperature also plays a major role in aircraft performance. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 57

58. Temperature is the degree of heat of a body , measured with a thermometer. It measures the hotness or coldness of a substance. Temperature is really a means of measuring the amount of thermal energy present in a given object or volume of fluid. Meteorological thermometer is normally housed in Stevenson's Screen made of wooden slatted box, painted white and mounted so that the bulb of the thermometer is 4 feet (1.25m) above the ground level (AGL) in an open location. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 58 TEMPERATURE CONT`D:

59. SCALES OF MEASUREMENT:-   There are three temperature scales used in meteorology. They are: Celsius or Centigrade Scale Fahrenheit Scale and Kelvin or Absolute Scale 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 59

60. The  sunshine recorder  records the duration of sunshine at a place for a day. A glass ball with a 10 cm diameter is mounted on a metal frame. This glass ball focuses the sunshine a sensitised card that is placed below it on the metal frame. The sunrays make burn marks on the card. Continuous burn marks show continuous sunshine. Broken marks show otherwise. At the end of the day, the card is removed and the burn marks are totalled to get the total duration of sunshine for the day in hours and minutes. Lines drawn through places having the same amount of sunshine are called isohels. SUNSHINE RECORDER 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 60

61. Maximum Thermometer contains mercury with a high boiling point and it measures the maximum temperature of the day. The mercury in the thermometer expands and pushes the index up the tube when the day temperature increases. However, when the temperature drops, the mercury contracts, the index remains in position. The maximum temperature is thus recorded and the reading is taken at the end of the index closer to the mercury. The instrument is reset by using a magnet to draw the index back to the mercury. Minimum Thermometer contains alcohol with a low freezing point and it records the minimum temperature of the day. The alcohol contracts and menicus of the alcohol pushes the index down when the temperature drops. When the temperature increases, the alcohol in the tube expands, flows past the index but does not move it.The minimum temperature is obtained by reading the scale at the end of the index which is near the minicus . The instrument is reset using a magnet to draw the index up to the menicus . THERMOMETER 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 61

62. In meteorological reports, the Celsius or Centigrade scale is generally used. The temperature scale are: Freezing pt of Water Boiling pt of Water Celsius or Centigrade ( o C ) - O o C 100°C Fahrenheit (°F) - 32°F 212°F Kelvin (°K or °A) - 273°A 373 o A To convert: °F to °C Subtract 32 then multiply by 5/9 °C to o F Multiply by 9/5 then add 32 °C to o A Add 273 °A to °C Subtract 273 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 62

63. CONVERSION EXCERCISES; CONVERT THE FOLLOWING:-   o F into °C:- i) 86°F, ii) 59°F, (iii) - 40°F. °C into °F:- i) 20°C, ii) O°C. °A into °C:- i) 290 A, ii) 263 A 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 63

64. Heat energy can be transferred from one place to another in three ways. The principal mechanism of heat transfer includes: Radiation Conduction and Convection To practically demonstrate how each of these processes take place, Let us consider for a moment, an object given to first person in a Line of people, to be given to the last person in the Line. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 64 TRANSFER OF HEAT .

65. We can simply throw this object to the last person in which case no one else is involved. This would be RADIATION. We can pass the object from one person to the next in the Line (i.e. by contact ). This would be CONDUCTION. We can walk over and hand the object to the Last person. This would be CONVECTION . The Lower Layer’s of the atmosphere is heated by the application of the above three processes and is discussed below. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 65

66. The earth is heated by short wave radiation from the Sun called INSOLATION. Hence, the sun is the primary source of heat for the atmosphere. Radiation includes harmful ultraviolet and cosmic rays. Radiation from the sun is of short wave length (0.6 x 10 -4 cm ) and passes through the atmosphere almost without heating it at all. But the lower atmosphere receives most of it’s heat from the surface on which it rest in the form of long wave (terrestrial ) radiation . It’s wave – length is about 12 x 10 -4 cm. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 66 HEATING OF THE EARTH AND IT’S ATMOSPHERE RADIATION

67. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 67 RADIATION CONT`D The ozone layer in the stratosphere absorb small amounts of insolation primarily, the harmful ultraviolet radiations . Further small amount of this short wave radiations are absorbed by water vapour in the atmosphere, carbon dioxide within the atmosphere and by solid particles in suspension in the air. Aside absorbing solar radiation, clouds also reflect some of the radiation back to space.

68. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 68 INCOMING SOLAR RADIATION

69. Terrestrial or Earth radiation on the other hand, is readily absorbed by water vapour in the air thus retaining heat in the lower atmosphere. The earth’s radiation is also absorbed and re – radiated by the clouds. CONDUCTION   The air lying in contact with the earth’s surface by day will be heated by conduction. At night the air in contact with earth’s surface will also be cooled by conduction. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 69

70. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 70 CONVECTION Convection refers primarily to atmospheric motions in the vertical direction. The air heated by conduction will be less dense and will therefore rise. This will produce up currents called THERMALS OR CONVECTION CURRENTS . Through this method, heat is transferred to upper levels and other areas in the atmosphere. Of the three main methods of heat transfer discussed above therefore, the most efficient mechanism for transferring heat aloft is by Convection.

71. EFFECT OF WATER AND LAND ON HEATING OF THE ATMOSPHERE WATER : Water has a high specific heat ( i.e. 1 or unity ) and as such acts as a storage reservoir for solar energy and its temperature changes very slowly. Hence, air in contact with the water surface will change very little from day to night. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 71

72. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 72 LAND Land in contrast has lower specific heat ( i.e. 1 or unity) and high heat capacity . Bare rock, Sand, dry soil, tarred roads and concrete runways heat up fast and cools fast hence, attaining a higher temperature than woods, Lakes, grasslands and wet soi l. Higher temperature surfaces provide strong up currents called thermals or convection currents. The differences in diurnal variation values between land and sea is the cause of SEA BREEZE.

73. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 73 Effect of Latitude on Insolation

74. DIURNAL VARIATION OF AIR TEMPERATURE The Sun is at it’s highest elevation at noon, but for two to three hours after this time, the earth is receiving more Solar radiation than it is giving up a terrestrial radiation. As a result temperature is highest at about 1500hours (i.e. mid –afternoon ( Tmax . ) From 1500 hours onwards, the temperature falls continuously until sunrise. The lowest temperature is at about sunrise plus ½ to 1 hr ( 0500 hours ) ( Tmin ). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 74

75. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 75 The diagram below shows an idealized diurnal curve of temperature variation.

76. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 76 Diurnal Variation

77. FACTORS AFFECTING THE DAILY (DIURNAL) RANGE OF AIR TEMPERATURE . Several factors play an important role on the diurnal Variation of air temperature. The most common factors include:  Cloud Cover, and  Wind effect. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 77

78. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 78 CLOUD COVER By day, some of the Solar radiation is reflected back by the cloud tops thereby reducing the expected day time temperatures. By night, terrestrial radiation is absorbed and re- radiated back to the earth by the clouds thereby giving higher night temperatures. Cloud therefore, will generally cause a reduction in the value of diurnal temperature Variation.

79. WIND EFFECT By day, wind will cause turbulent mixing of the warm air at the surface with cold air above thereby reducing the expected day time temperatures. Wind will also reduce the time the air is in contact with the warm ground. By night, there will normally be an inversion in the lower layers of the atmosphere. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 79

80. WIND EFFECT CONT`D With light or calm wind condition diurnal variation of air temperature is greatest while with strong wind, the daily variation is very small. Hence, wind and cloud cover will cause temperature maximum to be reduced and temperature minimum to be increased . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 80

81. VARIATION OF TEMPERATURE WITH HEIGHT . It was observed that temperature decreases with height in the troposphere. The rate of change of temperature with height is called LAPSE RATE, and the average Lapse rate in the troposphere is about 2°c per 1000ft. If however, there is an increase of temperature with increase of height in the atmosphere, this is called temperature INVERSION . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 81

82. VARIATION OF TEMPERATURE WITH HEIGHT CONT`D . In this case, warmer air lies over colder air. An important feature of an inversion is that it prevents convection totally . It is also a feature of anticyclone (High pressure centres ). If there is a layer in the atmosphere where the temperature is constant with increase of height, this is called an ISOTHERMAL LAYER . The stratosphere could be regarded to as an Isothermal Layer in a wide sense. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 82

83. Temperature Lapse Rates 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 83

84. TEMPERATURE INVERSION Air in contact with the surface also cools by conduction This cool air sinks and does not mix with the air higher up. The air at ground level is thus cooler and this results in a temperature inversion An inversion may also occur when a warm air mass passes over a cold air or sea surface A pilot will experience a slight “bump” when passing through the inversion layer 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 84

85. TEMPERATURE INVERSION This is the increase of temperature with increased height. It may occur at the earth’s surface or at altitudes far above Surface inversions are commonly observed in hollows and valleys, especially in winter when nights are clear Heat is lost through terrestrial radiation and the surface cools 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 85

86. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 86 Surface Inversion

87. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 87 Stratospheric Inversion

88. TEMPERATURE DEVIATION Temperature deviation is a statement of the deviation of the ambient (actual ) condition from the standard condition. It is often convenient to express the actual (ambient) temperature at a point in the atmosphere by comparing it with the temperature which would exist at the same point in either the international Standard Atmosphere (ISA) or the Jet Standard Atmosphere (JSA). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 88

89. TEMPERATURE DEVIATION The JSA supposes a temperature at MSL of +15°C a Lapse rate of 2°C per 1000ft infinitum, so there is no tropopause. The JSA is commonly used by engine manufacturers. For calculation purposes, it is accurate and convenient to use a temperature Lapse rate of 2°C/1000ft (instead of 1.98 o C/ 1000ft ) when working with the ISA. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 89

90. CALCULATING TEMPERATURE DEVIATION Example: An aircraft is flying at Flight Level 250 (25,000ft) The ambient temperature is -37°C. What is the temperature deviation from ISA? Solution: Step 1: Calculate the temperature that would exist at 25,000ft in the ISA  15 - (2x 25) ( i.e. 2°C/1000ft } 15 – 50 = - 35°C Step 2 : Using the Formular : Temperature deviation from ISA = Ambient - ISA = -37°C – ( - 35 } = -37°C + 35°C = -2°C 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 90

91. EFFECT OF TEMPERATURE ON FLIGHT When air is heated, it expands and therefore becomes less dense. This decrease in air density (increase in density altitude ) brought about by an increase in temperature, has a pronounced effect on flight. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 91

92. EFFECT OF TEMPERATURE ON FLIGHT CONT`D Since an increase in temperature makes the air less dense ( ie . increase density altitude ) Therefore: The take – off run of the aircraft will be longer, The rate of climb slower, and The Landing speed (ground speed ) faster on a hot day than on a cold day. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 92

93. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 93 An aircraft which requires a ground run of 1000ft on a winter day when the temperature is – 18 o C (0 o F); but will require a much longer run on a summer day when the temperature is 38 o C (100 o F ). Hence, an aircraft that requires the greater portion of a short runway for take off on a cold winter day; but may be unable to take – off on the same runway during a hot summer day.

94. HUMIDITY Humidity is the measurement of the water vapour content in the atmosphere. As water evaporates from lakes, seas and oceans and vegetation loses water through transpiration, the humidity of the air increases. The relative humidity of the air (ratio of the amount of water vapour in the air to the maximum amount of water vapour the air can contain expressed as a percentage) is measured using a  hygrometer .

95.   HUMIDITY CONT’D Reference was made in chapter 1 to the presence in the atmosphere of the invisible gas, water vapour mixed with the permanent gases of dry air. Most of the water vapour in the air is concentrated in the Lower levels of the atmosphere – troposphere. The water vapour content in the air is variable and relatively small but it has a significant effect in the study of meteorology. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 95

96.   HUMIDITY CONT`D Oceans, Seas, Lakes etc are the sources of water vapour (moisture) into the atmosphere. Water exists in the atmosphere in :- Gaseous state (Water Vapour ). Liquid State (Water). Solid State (Ice). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 96

97. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 97 HYDROSPHERE

98. These states frequently change with exchange of heat to or from the atmosphere without change in temperature This heat is referred to as LATENT HEAT . Latent heat differs according to the state of the substance. When a change of state occurs, heat is either absorbed (added) or released. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 98

99. Latent heat is released in the change from: Water vapour water droplet (i.e. condensation) Water vapour Ice (i.e. sublimation, a process also known as deposition ) Water droplet Ice (i.e. freezing) Latent heat is added/absorbed in the reverse process of: Water droplet water vapour (i.e. evaporation) Ice Water vapour (i.e. sublimation) Ice Water (Melting) 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 99

100. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 100 Changes of State of Water

101. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 101 The Hydrological Cycle

102. EVAPORATION Evaporation is the change of state from LIQUID to VAPOUR. Latent heat is ABSORBED. Cooling occurs during evaporation . CONDENSATION. It is the change of state of water vapour to water or liquid. In this case, latent heat is released. Condensation occurs when air is cooled below its dew point temperature. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 102

103. In the atmosphere, condensation is brought about by:  radiational cooling adiabatic cooling as air is lifted to higher levels ( e.g. convection ), and cooling by conduction to or advection of warm air over a cold surface 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 103

104. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 104 SUBLIMATION   Sublimation is the change of state directly from WATER VAPOUR to ICE without water droplets being formed. Latent heat is RELEASED. This process is also known as DEPOSITION. The change of state from ICE directly to WATER VAPOUR is also called SUBLIMATION .

105. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 105 SATURATION Air becomes saturated by adding more water vapour into it. Alternatively, as warm air can hold more water vapour than cold air, saturation can be achieved by cooling the air. Air is saturated if it contains the maximum amount of water vapour that it can hold at that temperature . Hence, air is said to be saturated when it’s relative humidity is 100%. If saturated air is cooled , condensation will occur.

106. EFFECTS OF HUMIDITY Animals and plants Humidity is one of the fundamental abiotic factors that defines any habitat, and is a determinant of which animals and plants can thrive in a given environment. Human comfort Humans are sensitive to humid air because the human body uses evaporative cooling as the primary mechanism to regulate temperature.  5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 106

107. EFFECTS OF HUMIDITY CONT`D Electronics Many electronic devices have humidity specifications, for example, 5% to 95%. At the top end of the range, moisture may increase the conductivity of permeable insulators leading to malfunction.  Building construction Traditional building designs typically had weak insulation, and it allowed air moisture to flow freely between the interior and exterior 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 107

108. TERMS USED FOR HUMIDITY MEASUREMENT. (a) ABSOLUTE HUMIDITY. Absolute humidity is the weight of water vapour in Unit Volume of air, Usually expressed in g /m 3 . (b) RELATIVE HUMIDITY. Relative humidity is the amount of water vapour present in a volume of air divided by the maximum amount of water vapour which that volume could hold at that temperature expressed as a percentage R.H 100% = SATURATION . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 108

109. (c) DEW POINT TEMPERATURE Dew point temperature is the temperature to which air must be cooled at constant pressure for saturation to occur. It is never higher than the air temperature.   (d) WET BULB TEMPERATURE The lowest temperature to which air may be cooled by the evaporation of water is known as the WET- BULB TEMPERATURE . In conjunction with the DRY BULB TEMPERATURE, this forms the standard method of measuring humidity at the earth’s surface. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 109

110. DAILY (DIURNAL) VARIATION OF HUMIDITY . By day, as the temperature increases, R.H. will DECREASE because the maximum amount of water vapour the air can hold increases as the temperature rises. After 1500 hours , the temperature will start to fall and the maximum amount of water vapour the air can hold will fall and thus, the R.H. will INCREASE . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 110

111. DAILY (DIURNAL) VARIATION OF HUMIDITY CONT`D . Relative humidity varies inversely with the air temperature without change in water vapour content. Hence lowest value is at 1500 hours and highest value at 0500 hours. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 111

112. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 112 MEASUREMENT OF HUMIDITY Hygrometers are instruments that measures humidity. In the meteorological office, the Wet bulb thermometer together with the Dry bulb thermometer ( termed wet and dry bulb hygrometer or psychrometer ) is the commonly used method of measuring humidity at the earth’s surface. The instrument makes use of evaporation (i.e. Cooling Process ).  

113. The wet – bulb is a modified thermometer, the bulb of which is wrapped in a muslin bag and kept moist by a cotton – wick which draws pure water from the container. If the air is dry, water will evaporate from the muslin covering the wet bulb and Latent heat will Lower the temperature. If air is saturated, no evaporation will occur and the two thermometers will read the same value. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 113

114. EFFECT OF HUMIDITY ON AIRCRAFT OPERATIONS:- Humidity generally has a small effect on density. Humidity reduces density but must be taken into account at moist tropical air fields. High humidity implies Low density and this affects both the aerodynamic and engine performances of the aircraft. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 114

115. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 115 Therefore low density decreases the aircraft performances in the following ways :-. It reduces power by decreasing the weight of the air / air mixture in the engine cylinders. It reduces thrust – ie forward movement of the aircraft. It also reduces lift. It increases the take – off run required, and It reduces the take – off weight of the aircraft

116. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 116 Relative Humidity vs Temperature

117.   ATMOSPHERIC PRESSURE: Atmospheric pressure and its variation plays a very important role in the prediction of winds and weather. Atmospheric pressure therefore is the force per unit area exerted by the atmosphere on any surface in contact with it. The pressure that the atmosphere exerts on a given surface on the earth is a result of the weight of a column of air above that surface. Pressure decreases with an increase in height. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 117

118. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 118

119. Units of Pressure :­ In meteorology, the unit of pressure is the hectopascal ( hpa ). In addition, pressure is expressed in inches or millimeters of mercury. The conversion is 1 hpa equals approximately 0.03 inches of mercury. For actual value use the formula :- Y / 1013.25 = X / 29.92 where X is in inches; and Y in hpa . Example :- Given 1000 hpa , you have 1000 / 1013.25 = X / 29.92 Therefore X = 29.53 ins. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 119

120. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 120 The Mercury Barometer

121. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 121 The Aneroid Barometer

122. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 122 Barograph

123. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 123 Barograph Reading

124. Measurement of Atmospheric Pressure : It is measured by means of a mercury barometer. The type often used is called Kew Pattern Barometer. The pressure at station level is termed QFE (after the usual small corrections are applied for the following errors - index, temperature and gravity). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 124

125. Barometer  a class of instruments used to measure atmospheric pressure. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 125

126. HYGROMETER 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 126 A hygrometer is made up of a dry bulb thermometer and a wet bulb thermometer. The dry bulb thermometer is an ordinary liquid-in-glass thermometer which measures the actual temperature of the air. The wet bulb thermometer is the same as the dry bulb thermometer, except that it is wrapped with a piece of muslin cloth which is kept moist by a piece of wick dipped in water.

127. PRESSURE DATUMS The sub-scale of an altimeter is normally set to one of three datums. QFE -Barometric pressure observed at the airfield datum point . QNH -The pressure setting which causes the altimeter to read the height above MSL of the touch down on Landing plus the height of the altimeter above ground.    5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 127

128. PRESSURE DATUMS CONT`D 1013hpa - When flying above the transition altitude, it is normal to set 1013hpa on the altimeter subscale and maintain a flight level. - when 1013 is set on the subscale , the height shown on the altimeter when the aircraft is on the ground is known as the QNE value.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 128

129. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 129 Meteorologists determine a MSL pressure ( QFF ) which is more accurate than the QNH; by reducing the QFE to mean sea level using ambient (actual ) rather than standard atmosphere temperature lapse rate. The MSL pressure thus obtained is termed QFF.

130. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 130 ISOBARS Isobars are lines joining places of equal atmospheric pressure. Surface Isobars actually join points of equal mean sea level pressure ( QFF ). In order words, surface Isobars join points of equal QFF The Isobars usually make definite shapes on the charts and these are:

131. ANTICYCLONES OR HIGHS (H) It is an area of closed Isobars usually oval or circular in shape with the highest pressure at the center. In mid Latitudes (e.g. N.W Europe) high pressure usually means g ood weather. High pressure centers is indicated on a weather map by a blue H . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 131

132. RIDGE (R) An elongated extension of the high is called a ridge of high pressure with highest pressure values along the ridge line. The Isobars in a ridge are always smoothly rounded – “U” shaped . Strong ridges are accompanied by warm and dry weather condition at the surface LOWS (‘L’) Low pressure areas also called a Depression, have their center pressure value surrounded on all sides by higher pressure values. In mid-Latitudes, low pressure usually means bad weather. A Low Pressure center is indicated in a weather map by a “red” “L”. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 132

133.   TROUGHS (T) An elongated extension of the Low is called a trough with the lowest pressure values along the trough line. Sometimes, the Isobars at a trough have a pronounced V – shaped . Strong troughs are typically preceded by stormy weather and colder air at the airfield. The trough axis is denoted by the purple line. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 133

134. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 134 COL (C) A Col is an area of almost uniform (constant) pressure between two highs and two lows. Sometimes, it is referred to as a “Saddle – back” shape . It does not have any one Isobar defining it’s boundary. The pressure in a col is almost level . It is an area of stagnation . It is also the intersection of a trough and ridge SECONDARY LOW (S.L.) A secondary Low (or depression) is a subsidiary area of low pressure within a bigger (or main Low or depression.).

135. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 135 H H H L L COL Ridge Ridge Trough Trough 1018 1018 1018 1020 1020 1022 1022

136. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 136 Sea Level Synoptic Chart

137. DIURNAL VARIATION OF ATMOSPHERIC PRESSURE The atmospheric pressure at a particular place continually vary daily. A look at the day’s pressure record shows a definite trend as a double wave traveling round the earth following the Sun, having minima at 0400hours and 1600hours with intermediate maxima at 1000hours and 2200hours. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 137

138. PRESSURE GRADIENT Pressure gradient is defined as the rate of change of pressure per unit distance measured along a line perpendicular to the isobars . The nature of the existing Isobar spacing determines the type of pressure gradient. Pressure Gradients are referred to as “STEEP ” when the Isobars are close together (crowded) and “SLACK ” when the Isobars are far apart.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 138

139. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 139 VARIATION OF PRESSURE WITH HEIGHT. Pressure decreases with increasing altitude. Although pressure will decrease with an increase in height, density will also decrease and therefore the reduction in weight of air above a surface will vary Linearly . Most of the air are held close to the earth’s surface by gravity and hence, air pressure decreases rapidly at first, then more slowly at higher levels . Therefore, the rate of pressure decrease is more rapid in Cold air than warm air.

140. In the ISA a reduction in pressure of I hpa would give a height difference of 27 feet at msl ; 36 feet at 10,000ft , and 73 feet at 30,000ft. Pressure distribution at altitude is represented by the use of Constant Pressure or Contour Charts. Constant Pressure Levels and their corresponding heights above mean sea level are as follows 850 hpa 5,000ft 1500meters 700 10,000 3,000 500 18,000 5,000 300 30,000 9,000 200 38,000 11,000 100 53,000 15,000 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 140

141. Like the surface weather charts, lines drawn on a Constant Pressure Chart are termed CONTOURS joining places of equal pressure altitudes and showing areas of Lows and Highs In the upper Air Chart, a HIGH refers to the highest altitude / Point (i.e. a warm air area) and a LOW refers to lowest altitude / Point (i.e. a cold air area). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 141

142. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 142 ISALLOBARS Stations measuring and reporting barometer pressure do so regularly at fixed times. It is often convenient to determine the rate of change of pressure in hectopascal ( hpa ) per hour. If we compare the rate of change of pressure, and join points of equal rate of change of pressure, the lines drawn are known as Isallobars. Isallobars are useful to the forecasters to assist in predicting the future path of pressure system (i.e. pressure tendency).

143. EFFECT OF ATMOSPHERIC PRESSURE ON FLIGHT As altitude increases, pressure reduces as the weight of the air column decreases. This decrease in pressure (meaning increase in density altitude) has pronounced effect on flight. The most noticeable effect of a decrease in pressure due to an altitude increase becomes evident at take – off , rate of climbing and landing. With an increase in altitude hence a decrease in pressure will result to the following. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 143

144. EFFECT OF ATMOSPHERIC PRESSURE ON FLIGHT CONT`D More speed is required to obtain lift for take – off thus, a longer ground run and more fuel burnt. The aircraft engine is less efficient hence, less engine power output. The thrust of the propeller is less effective. The aircrafts rate of climb is slower.  Kalu 2015

145. DENSITY Density may be defined as mass per unit volume and may be expressed as Grams per cubic metre . The value of I.S.A density is 1225gm/ m3. Effect of changes of pressure on density. Density is directly proportional to pressure. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 145

146. DENSITY CONT`D Effect of change of temperature on density. Density is inversely proportional to temperature. Effect of change of humidity on density. Density is inversely proportional to water vapour content. Effect of change of altitude on density. Density decreases as altitude increases. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 146

147. DENSITY CONT`D Effect of change of latitude on density. At the surface, density increases as latitude increases. At about 26,000ft (8km) density remains constant with an increase in latitude. About 26,000ft, density decreases with an increase In latitude. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 147

148. DENSITY CONT`D Effect of change in density on aircraft operations. Accuracy of aircraft instruments – machmeter ASI. Aircraft and engine performance- low density will reduce life, increase take off run, reduce maximum take off weight. Humidity generally has a small effect on density (humidity reduces density), but must be taken into account at moist tropical airfields. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 148

149. Density summary Density can be defined as the mass per unit volume Air density will DECREASE with an INCREASE in temperature. Air density will INCREASE with an INCREASE in pressure Air density will DECREASE with an INCREASE in humidity 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 149

150. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 150 World Pressure Distribution

151. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 151 Mean Global Winds Due To Pressure

152.  ALTIMETRY  An altimeter is a pressure instrument, which is calibrated to indicate the vertical distance between the pressure level indicated on its subscale and the pressure level at which the aircraft is flying. The altimeter is essentially the same instrument as the barograph except that the scale is calibrated to indicate height instead of pressure. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 152

153. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 153 The altimeter reading is meant for the following purposes: Safe height separation Safe terrain clearance Obtaining True elevation or height above airfield reference point

154. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 154 The height indication is referenced to International Standard Atmosphere which assumes at mean sea level: ­   pressure of 1013.25 Hpa temperature of + 15°C or 288°A temperature lapse rate of 1.98°C/ l 000 ft

155. Hence the altimeter will read correctly only if actual conditions are the same as those in the standard atmosphere. Thus if the MSL pressure, temperature and the lapse rate are other than those specified above, the altimeter will not read correctly. The altimeter reading therefore requires correction before TRUE altitude is known . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 155

156. Altimetry discusses the meteorological causes of these errors and asses their magnitude by calculation. The altimeter follows the fundamental relationship that pressure decreases with height. As pressure decreases ( i.e. on ascending ), the altimeter will show an increase in height and a reverse when descending. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 156

157. ALTIMETER ERRORS Barometric Errors :- Errors caused by setting a pressure on the subscale other than the correct one.  When an aircraft flies from a region of HIGH pressure to a region of LOW pressure, the reading of the altimeter is high (i.e. It over reads) H- L- H, but the true altitude will decrease. When the flight is from LOW pressure to HIGH pressure, the altimeter 'reads low (i.e. it under-reads)L-H-L, but the true altitude will increase. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 157

158. Temperature Error  A flight from a column of warm air (HIGH temperature) to a column of cold air (LOW temperature) will make the altimeter to over-read .  From a column of cold air (LOW temperature) to a column of warm air(High temperature ) causes the altimeter to under- read 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 158

159. Drift Error:- When an aircraft is flying across isobars, and experiencing:- A STARBOARD drift ( a drift to the right, i.e. from H to L ),the altimeter over-reads . A PORT drift ( a drift to the left, i.e. from L to H ), the altimeter under-reads . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 159

160. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 160 Altimetry: QNH

161. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 161 Altimetry: QNE (Standard Setting)

162. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 162 Altimetry: QFE

163. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 163 Altimetry: QNH < 1013 hPa

164. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 164 Altimetry: QNH > 1013 hPa

165. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 165 Typical Error Made By Pilots

166. ALTIMETER SETTINGS The various altimeter settings are listed below:- QFE. – Airfield pressure with this pressure set on the altimeter, the instrument will read Zero on the ground, or the height of aircraft above the airfield .  This is the ideal altimeter setting for aircraft taking – off or landing. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 166

167. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 167 QNH. – This is the airfield pressure reduced to MSL in accordance with the ICAO ISA. The altimeter will then read the height of the airfield above MSL or the Aircraft’s height AMSL. This setting is ideal for terrain clearance.

168. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 168 REGIONAL OR FORECAST QNH This is the Lowest forecast value of the QNH expected within a flight information region (FIR). This setting is used by all aircrafts flying 3,000ft above MSL around UK to provide en -route terrain clearance. It is valid for 1 hour.

169. STANDARD PRESSURE SETTING (SPS) If the standard pressure of 1013.25 hpa is set on the altimeter, the instrument will read what is known as PRESSURE ALTITUDE, or height in the standard atmosphere. This is the altimeter setting used when flying above the transition altitude. This setting is used for en-rote portion of a flight to provide vertical separation by specified pressure intervals (usually 500 or 1000ft). It is measured in hundreds of feet. E.g. FL 350 = 35,000ft.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 169

170. ALTIMETER HEIGHT INDICATIONS Indicated Altitude : Height read directly from the altimeter Absolute Altitude : . Absolute altitude is the height or vertical distance above the surface. True Altitude : True altitude is the actual vertical distance above mean sea level and is equal to pressure altitude and indicated altitude. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 170

171. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 171   Pressure Altitude : Pressure altitude is the height above the standard datum plane when 1013. 25hpa (29.92 inches) is set in the altimeter scale.   Density Altitude Density altitude is the pressure altitude corrected for nonstandard temperature. Density altitude increases as ambient temperature increase. Density altitude is used to determine aircraft performance and many aircraft performance charts are based on density altitude.

172.   WIND: A major characteristics of the atmosphere is its mobility. A measure of this motion is wind. Wind therefore defines the horizontal movement of air. It is a vector quantity and therefore has direction and speed. For air to be motion a pressure gradient must exist, in which case air will move from high pressure center to low pressure center. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 172

173. Wind CONT’D Therefore wind is: air in motion. It usually the natural horizontal motion of the atmosphere. Winds are produced by differences in atmospheric pressure,. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 173

174. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 174 WIND DIRECTION AND SPEED Wind direction is always given as the direction from which the wind is blowing. A north wind blows from the North and a South wind blows from the south. Wind direction is normally given in degrees TRUE but wind direction given to a pilot by Air Traffic Controllers, will be given in degrees MAGNETIC.

175. Wind speed is the rate at which the air moves past a stationary object. Wind speed is usually given in KNOT (KT ), 1 knot is equal to 0.5 metres per second. The prevailing wind is the wind direction most often observed during a given time period eg North East wind/South West wind etc. The terms veer and back are used to indicate direction changes. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 175

176. A VEER is a change in wind direction in a clockwise direction (e.g. 120° to 170°). A BACK is a change in wind direction in an anticlockwise direction ( eg 300° to 260°) 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 176

177. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 177

178. MEASUREMENT OF WINDS A variety of instruments measure surface wind. A wind sock, wind tee or wind vane, all measures wind direction. Most wind vanes consist of a long arrow with a tail that moves freely on a vertical shaft. The arrow points into the wind and gives the wind direction. Anemometers measure wind speed . Most anemometers consist of three or more cups that spin horizontally on a vertical post. The rate at which the cups rotate is related to the speed of the wind.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 178

179. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 179 Anemometer

180. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 180 Wind Direction

181. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 181 Both wind vane and anemometer are positioned 33ft (10 meters) above ground level (AGL) and they are located clear of buildings and obstructions which could affect the airflow and accuracy. UPPER WINDS are measured by means of RADIOSONDE , Pilot Balloon and satellite imagery.

182. INSTRUMENT 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 182 The  anemometer  measures the wind speed. It has three or four horizontal arms pivoted on a vertical shaft. Metal cups are fixed to the end of the arms so that when there is wind, the arms rotate. The movements are transmitted to the meter which records the wind speed in meters per second or km per hour or in knots (1.85km/h).

183. The  wind vane  consists of a pointer that moves freely on a vertical shaft. The four cardinal points are tied to the shaft beneath the pointer. When the wind blows, the pointer moves and its head shows the direction from which the wind is blowing. The arrow of the wind vane always points in the direction from the wind blows and the wind is named after this direction. WIND VANE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 183

184. RELATIONSHIP BETWEEN WIND AND PRESSURE A careful assessment of any diagram illustrating pressure distribution reveals that there obviously exist a relationship between wind direction and pressure. This correlation between winds and pressure was first identified (noticed) in the 19 th Century by a Dutch Meteorologist - Buys-Ballot based on his observation of wind direction and pressure systems. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 184

185. RELATIONSHIP BETWEEN WIND AND PRESSURE CONT`D Buys – Ballots Law States that. “If an observer Stands with his Back to the Wind, the Low pressure is to his Left in the Northern hemisphere and to his right in the Southern hemisphere.” Hence, in the Northern Hemisphere, air flows Anticlockwise , around a Low Pressure system and Clockwise around a HIGH pressure systems. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 185

186. FORCES PRODUCING WIND IN A FREE ATMOSPHERE . The wind at level above friction is primarily the result of three forces and these are viz: Pressure Gradient force. Geostrophic (or Coriolis force ). Cyclostrophic (or Centripetal force). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 186

187. FORCES PRODUCING WIND IN A FREE ATMOSPHERE CONT`D . PRESSURE GRADIENT FORCE (PGF). The pressure gradient force is the force arising as a result of the fact that pressure differs between any two places. The force tries to push the air across the isobars from high pressure to low pressure at right angles to the isobars. Hence, the P.G.F. acts at 90° to the isobars . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 187

188. GEOSTROPHIC OR CORIOLIS FORCES (GF) The Geostrophic Force (GF) is the force caused by the rotation of the earth. It causes all free moving objects to deflect to the RIGHT in the NORTHERN Hemisphere and to the LEFT in the SOUTHERN Hemisphere. The Geostrophic force is maximum at the Poles and minimum at the EQUATOR. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 188

189. CYCLOSTROPHIC OR CENTRIPETAL FORCE This is the force that acts on air that is moving along curved isobars. It is also called centripetal force. The isobars are usually curved around pressure centers. The effect of this force is to increase the speed of wind in High pressure area and to decrease it in Low pressure area. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 189

190. GEOSTROPHIC WIND The geostrophic wind is the wind which blows when the Geostrophic Force is balanced by the pressure gradient force. This balance can only occur when it is not affected by other forces and therefore, the geostrophic wind can only blow above the friction layer at about 2000ft. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 190

191. GEOSTROPHIC WIND CONT`D The balance between the two forces is such that the wind direction is PARALLEL to the isobars in accordance with Buys – Ballots law, Hence, if you stand with your back to the wind in the Northern hemisphere, the low pressure is to your left. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 191

192. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 192 Coriolis Effect

193. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 193 Geostrophic Wind

194. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 194 Basic Pressure Patterns

195. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 195 General Upper Winds Due to Coriolis

196. THE GRADIENT WIND The gradient wind applies when the isobars are CURVED . This brings into play a force which makes the wind follow curved path along the isobars. Therefore the gradient wind is the wind which blows parallel to curved isobars due to a combination (balance) of three (3) forces: Pressure gradient force (P.G.F.) Geostrophic force (G F) Cyclostrophic force. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 196

197. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 197 Surface Friction

198. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 198 Convergence : Divergence

199. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 199 Pressure Gradients vs Wind Speed

200. Effect of Friction on Surface Wind: The primary effect of friction with the earth's surface is to reduce the rate of flow of air in the lowest layers. This reduction has two effects on the surface wind. It reduces its speed and changes its direction at a slant angle across the isobars towards the lower pressure. This angle is averagely about 10° over the sea and about 30° or more over the land. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 200

201. Effect of Friction on Surface Wind CONT`D: The change in direction is backed in the northern hemisphere, but veered in southern hemisphere . In general, the effect of surface friction is felt in the lowest 2,000 ft. At 2,000 ft , the wind is geostrophic and the air tends to flow parallel to the isobars. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 201

202. Change in Wind Direction As earlier mentioned, a veer of wind is a change of wind direction in a clockwise manner; while a back of wind is an anticlockwise change in the direction of the wind. The wind is never entirely steady. It is made up of a series of gusts and lulls caused by obstruction to the free flow of the air. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 202

203. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 203 Gust is temporary increase in wind speed lasting for only a few seconds . Lull is a temporary decrease in wind speed, but may last much longer than a gust.

204. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 204 Squall is a very large increase in the average wind speed often lasting many minutes and usually associated with a change of wind direction. It is often due to thunderstorms or rapidly moving cold fronts. Gale warning is issued or is said to occur when the mean surface wind is 34 kt or more or is gusting to 43 kt or more .

205. Diurnal Variation of Surface Wind Due to turbulence and convection, surface wind veers and increases in speed by day , but backs and decrease in speed at night . In coastal areas, we have sea breeze by day and land breeze at night . In valley areas, anabatic by day and katabatic at night. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 205

206. Local Variation of Winds with Topography  Anabatic Wind - It is a flow of warm air up a slope of a hill during the day caused by surface heating. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 206

207. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 207 Katabatic Wind - It is a flow of cold dense air down the slope of a hill at night caused by surface cooling.

208. Anabatic and Katabatic Flow Anabatic daytime flow Katabatic night-time flow Land surface is heated by the sun’s rays Land surface is cooled by Terrestrial radiation Heated air rises Cooled air sinks 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 208

209. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 209 The Föhn Effect Fohn Wind : - It is a warm, dry wind on the leeward side of a mountain.

210. Local Variation of Winds with Topography CONT`D Sea Breeze: It is a flow of air from sea to land during the day. It is caused by differential heating between the sea and the adjacent land. Land Breeze: It is the opposite effect to sea breeze and is a flow from land to sea at night. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 210

211. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 211 The Sea Breeze

212. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 212 The Sea Breeze

213. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 213 The Land Breeze

214. EFFECTS OF WIND ON FLIGHT OPERATIONS Wind play an important role in the performance of aircraft. The Pilot needs to know both the direction and speed of the surface wind in order to make suitable choice of runway to use during the approach phase of the aircraft. He also need to know the direction and speed of upper air in order to chose suitable track to reach destination. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 214

215. EFFECTS OF WIND ON FLIGHT OPERATIONS CONTD For light aircrafts like Tampico (TB-9 and TB-20) and Beach Baron-58 in use in the College, knowledge of the variations in wind are important in determining the stability of an aircraft during take-off and landing phases. However, large aircrafts are less susceptible to these variations but respond more slowly to control changes. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 215

216. EFFECT OF WIND ON AIRCRAFT PARCKED ON GROUND Wind exerts pressure in all directions of the aircraft, hence, the aircraft is regarded to be in a state of equilibrium. However, in a squall, the equilibrium is distorted and this could cause considerable damage to the body frame of the aircraft (fuselage) and the main planes (wings) as well as affect the accuracy of some flight instruments like the compass. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 216

217. EFFECT OF WIND DURING TAKE-OFF PHASE A head wind reduces the aircrafts ground run and take-off distance. A head wind also enables the aircraft to generate lift thus requiring increased power to generate lift. The aircrafts fuel consumption rate will therefore be high. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 217

218. A cross wind will cause the aircraft to drift either to the starboard (right) or port (left) and more fuel will likely be burnt since the pilot will have to apply track error correction in order to reach his destination. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 218

219. EFFECT OF WIND DURING CRUISE (STRAIGHT AND LEVEL FLIGHT) During a cruise in the “ en -route phase of a flight, a head wind is a disadvantage hence reduce range over the ground A tailwind is an advantage hence, will increase range. Consequently, a head wind will increase flight time and fuel consumption requiring increased power. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 219

220. A tail wind will decrease flight time and fuel consumption. A cross wind will cause the aircraft to drift either to the starboard (right) or port (left) and more fuel will likely be burnt since the pilot will have to apply track error correction in order to reach his destination. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 220

221. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 221 EFFECT OF WIND DURING APPROACH (DESCENT) A head wind during the final approach of an aircraft will act as a wind break hence reduces the aircrafts Landing ground run and Landing distance (or emergency distance available).  A tail wind on the other hand, will increase the aircrafts Landing ground run and Landing distance available leading to a possible over – shooting of the run way to the stop way. This could thus cause an incident or accident.

222. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 222 A cross wind in the final approach of an aircraft will cause drift either to the starboard or port. This drift will cause the aircraft to land outside the runway resulting to an incident or accident.

223.   WINDSHEAR AND TURBULENCE  WINDSHEAR. Wind shear is defined as variations in vector wind (i.e. wind direction and/ or speed ) along flight path which causes abrupt displacement from the intended flight path such that substantial control action is required . Low level wind shear is: 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 223

224. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 224  Wind shear encountered during final approach, Along the runway, Along take – off flight path Along the initial climb out flight path. The Low level wind shear is, therefore a significant contributor to major aircraft accidents.

225. MAIN CAUSES OF WIND SHEAR . The most prominent causes of Low level wind shear are; A. Strong (marked) temperature inversion; B. Passage of thunderstorm and fronts, C. Mountain wave system, D. Land/sea breeze front, E. Turbulence boundary layer. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 225

226. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 226 WIND SHEAR WARNINGS AND REPORTING.  Wind shear warnings are reported through the following ways: Met warning , ATS warning Departure/ Approach ATIS Pilot warning , On – board equipment. Note : Pilots encountering wind shear on approach or climb – out are required to make a report to ATC as soon as possible even if previously encountered or forecast.

227. T U R B U LEN C E: Turbulence is simply defined as “bumpiness in flight ”. A turbulent atmosphere therefore is one in which air currents vary greatly over short distances. The effects of turbulence can vary from occasional light bumps to severe jolts. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 227

228. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 228 As an aircraft moves through turbulent air, it experiences changing accelerations which shear the aircraft and cause stress on the airframe. An aircrafts reaction to turbulence varies depending on: Air current size Size of the aircraft Wing Loading Airspeed, and Aircraft attitude

229. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 229 It is highly recommended that an aircraft should reduce its speed when flying through turbulence. There is a recommended turbulence penetration speed for each aircraft in the aircraft flight manual.

230. TURBULENCE INTENSITY CLASSIFICATIONS Light - The occupants of the aircraft feels slight strain against seats Moderate - The occupants of the aircraft feels definite strains against seat belts. Severe - The occupants of the aircraft are forced violently against seat belts. Extreme - The aircraft is violently tossed about. Extreme turbulence can also cause structural damage. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 230

231. TYPE OF TURBULENCE The main types of turbulence are: Low Level turbulence including mechanical, convective (thermal) and frontal. Clear air turbulence Wake turbulence Mountain wave turbulence 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 231

232. LOW- LEVEL TURBULENCE The Low-Level turbulence typically occurs below 15,000ft. Mechanical turbulence – is created when buildings or rough terrain interfere with the normal wind flow. Mechanical turbulence increases on altitude and intensity, as surface winds increase. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 232

233. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 233 Convective turbulence – also called thermal turbulence, is typically a daytime occurrence caused by rising air currents that develop in air heated by contact with warn surfaces below. Frontal turbulence – occurs in a narrow zone ahead of a fast moving cold front where updrafts can reach 1000 fpm. Generally over flat ground, any front moving at a speed of 30kt or more will generate moderate or greater Low Level turbulence.

234. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 234 Mechanical Turbulence

235. WAKE TUBULENCE Wake turbulence is created whenever an airplane generates lift. Air spills over the Wingtips from the high pressure areas below the wing to the Low pressure area above them. This flow causes rapidly rotating whirlpools of air called wing tip vortices or wake turbulence. The strongest vortex occurs when an aircraft is heavy, slow and with flaps up 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 235

236. Wingtip vortices tend to sink below the aircraft flight path. Flight crews with smaller aircraft therefore need to avoid wake turbulence produced by Larger aircrafts. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 236

237. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 237 Wake Turbulence

238. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 238 Wake Turbulence

239. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 239 Wake Turbulence

240. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 240 Wake Turbulence

241. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 241 Wake Turbulence

242. CLEAR AIR TURBULENCE Clear air turbulence, (CAT) implies turbulence in an area devoid of clouds. Its name is derived from early experiences of pilots who encountered significant high level turbulence in clear skies. Clear air-turbulence is usually encountered above 15,000ft. It maybe caused by the interaction of two different air masses ( cold and warm air), or obstructions to normal wind flow. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 242

243. CLEAR AIR TURBULENCE CONT`D The CAT can occur at any level where there is strong wind shear especially near the tropopause close to Jet-stream. If a pilot encounters severe turbulence, it is almost impossible to hold a constant altitude. Instead of chasing the altitude it is recommended to hold a constant attitude as this will put less stress on the aircraft. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 243

244. MOUNTAIN WAVE TURBULENCE : It is caused when air flows over a mountain range or a low line of hills, inducing a wave-like oscillation over and to the leeward side (downstream) of themselves. The motion may be up to heights at least as high as the tropopause in certain circumstances. The waves develop when there is strong surface wind of not less than 15 kt , which increases with height, and there is a marked stable layer just above the ridge. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 244

245. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 245 When the waves are forecast and your flight takes you across the ridge into the wind, you should consider planning to fly at a higher level than usual so that height loss in the down currents will not be disastrous. Indication of the presence of standing or mountain wave is sometimes given by typical cloud form - Lenticular Cloud. It provides the most unmistakable evidence of the existence of standing or mountain wave.

246. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 246 Effects of Downdraught

247. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 247 Mountain Waves

248. AMERICAN HAILSTONE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 248

249. HAILSTONE (SCALE IN INCES) 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 249

250. IMPACT CARTER 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 250

251. HAIL DAMAGE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 251

252. HAIL DAMAGE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 252

253. HAIL DAMAGE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 253

254. HAIL DAMAGE TO HARRIER 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 254

255. ACTION TO AVOID WORST EFFECTS OF MOUNTAIN WAVE. Arrange to cross mountain range at right angles (i.e. 90° degrees). Fly at aircraft recommended turbulence speed. Do not fly parallel to and just down wind of the range. Avoid flight through or near the rotor zone. Avoid flight levels within 5000ft of stable Layer (where severe turbulence is most likely: Allow a height clearance of at least 4000ft above the wave. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 255

256. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 256 Avoid low altitude flight towards the mountain range UPWIND. Aircraft height variations will be out of phase with waves and down draughts will be hazardous. Avoid high altitude flight towards the mountain range DOWN WIND. Buffet margin at high level may be small, and speed of approaching standing waves will be high, with subsequently greater Loads applied to the air frame.

257. SUMMARY OF THE HAZARDS OF TURBULENCE Turbulence can cause: Stress on the aircraft Instrument error Difficulty in reading, the instruments Problem in maintaining altitude Problem in maintaining airspeed Crew and passenger fatigue Aircrew and passenger sickness. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 257

258. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 258 Cap Cloud on Table Mountain

259. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 259 Cap Cloud

260. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 260 Mountain (Lee) Wave Clouds

261. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 261 Lenticular Cloud

262. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 262 Lenticular Cloud

263. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 263 Lenticular Cloud, or UFO?

264. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 264 Mammatus

265. Adiabatic Temperature Changes: When a gas is compressed (e.g. in a bicycle pump) it becomes warmer, even though no heat has been added. In the reverse process, when the pressure on a gas has been reduced (e.g. when air is allowed to escape from a bicycle valve) it becomes cooler.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 265 AIR IN VERTICAL MOTION AND ATMOSPHERIC STABILITY AIR IN VERTICAL MOTION:

266. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 266 These changes in temperature, which are entirely due to variation in pressure, are called Adiabatic changes because no heat has been added to or taken from the surrounding air in the process. In the atmosphere, pressure always decreases with height. Any air parcel, therefore, that rises in the atmosphere will expand and cool adiabatically . This occurs even if the surrounding air has an inversion of temperature.

267. Dry Adiabatic Lapse Rate (DALR): This is the rate of cooling with ascent of rising unsaturated air due to its expansion only and with no loss or gain of heat from its surroundings. This lapse rate applies to any air whose relative humidity is less than 100%. The DALR has a constant value of 3°C per 1,000 feet ( or 1°C./ 100 m) . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 267

268. Saturated Adiabatic Lapse Rate (SALR ): This is the rate of cooling with ascent of rising saturated air due its expansion and partly offset by the latent heat of condensation and with no loss or gain of heat to or from its surroundings. The SALR has a varying value but it averages 1.5°C per 1,000 ft (or 0.6°C /100 m). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 268

269. ATMOSPHERIC STABILITY: The general temperature change with height of the atmosphere as a whole is the Environmental Lapse Rate (ELR). Any air parcel which is rising in the atmosphere, changes temperature at either the DALR or the SALR depending whether or not it is saturated. It can happen that some rising air will have temperature different from that of its surrounding or environment. Depending on these two temperatures is the stability or instability of the air . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 269

270. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 270 Stable Atmosphere: It is that state of the atmosphere in which any parcel of air that is displaced vertically will tend to return to its original level when the displacing force is removed (i.e. rising air will always find itself colder and denser than its surrounding or environment. This will only occur with both saturated and unsaturated air if the ELR is less than the SALR (i.e. also less than DALR ). Examples being inversion layers and isothermal layers. Hence absolute stability is said to exist when the E.L.R is less than S.A.L.R.

271. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 271

272. Unstable Atmosphere: It is that state of the atmosphere in which any parcel of air that is displaced vertically will tend to become more displaced even if the displacing force is removed (i.e. rising air will always find itself warmer and lighter than its environment or surrounding). This will only occur with both saturated and unsaturated air if the ELR is greater than the DALR (i.e. a steeper ELR larger than 3°C per 1,000 ft ). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 272

273. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 273

274. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 274 Hence absolute instability exists when the E.L.R is greater than the D.A.L.R Conditional Unstable Atmosphere It is that state, of the atmosphere in which any parcel of air, which is displaced vertically, will tend to return to its original level if unsaturated, but will become more displaced if saturated when the displacing force is removed. This occurs when the E.L.R. is between the S.A.L.R. and the D.A.L.R. This means a state of the atmosphere that will be unstable provided that the condition of the air is saturated.

275. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 275

276. Stability Stable Conditionally Stable Unstable

277. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 277 Absolute Stability

278. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 278 Tendency of Rising Air: Stable

279. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 279 Absolute Instability

280. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 280 Tendency of Rising Air: Unstable

281. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 281 Conditional Instability

282. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 282 ELR < SALR = Absolute Stability ELR > DALR = Absolute Instability DALR > ELR > SALR = Conditional Instability

283. SOME CHARACATERISTICS OF A STABLE AND UNSTABLE AIR MASSES:   Cloud Stable Air Mass: Unstable Air Mass: Stratus or Stratoculumus . Cumulus or Cumulonimbus Weather Fog, drizzle or light rain. Showers, Thunderstorms, or Hail Visibility , Poor or moderate. Good except in precipitation. Flying Condition Generally smooth, little turbulence. Bumpy, moderate or severe turbulence. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 283

284.  CLOUDS A cloud is a visible aggregate of tiny water droplets and/ or ice crystals suspended in the atmosphere and can exists in a variety of shapes, and sizes. To an experienced pilot, clouds are meteorological sign posts in the sky, that indicate the forces at work in the atmosphere. Their location and appearance (Size, Shape and colour) can show a weather – wise aviator where turbulence might be found, whether a frontal system is approaching or where hail might be encountered. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 284 CLOUDS AND PRECIPITATION

285. The cloudy part of the atmosphere therefore lies below an invisible ‘lid’ called the tropopause. Clouds cannot penetrate this top that is put on the weather and about the only time when we actually can see its effect is when thunderclouds spread their anvils under it. The layer below the tropopause is called the troposphere and all weather processes of interest to us occur in the troposphere. CLOUDS CONT’D 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 285

286. CLOUD FORMATION Cloud form when moist air is cooled below its dew point temperature and water vapour thereby changes into water droplets by condensation or into ice crystals by sublimation. As for cloud formation, the main cause of cooling is the adiabatic changes connected with vertical motion of the atmosphere.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 286

287. The requirements for clouds formation are: adequate water vapour in the air; presence of condensation nuclei; lifting agency for the air to cool to and below its dew points temperature 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 287

288. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 288 Condensation Nucleii

289. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 289 Coalescence/Collision

290. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 290 The Adiabatic Process

291. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 291 Convective Lifting

292. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 292 Convergent Lifting

293. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 293 Orographic Lifting

294. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 294 Frontal Lifting

295. CLOUD CLASSIFICATION The TEN (10) main cloud types can be divided into two ; Stratiform or layered clouds – These are characterized by a layered appearance (formed in a stable atmosphere). Cumuliform or heap clouds – These are characterized by a heap appearance (formed in an unstable atmosphere). The two main categories may be grouped into four (4) families according to height bands. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 295

296. High Clouds Cirrus - Ci Cirrocumulus - Cc Cirrostratus - Cs 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 296

297. Middle Clouds Altocumulus - Ac Altocumulus Altostratus - As 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 297

298. Low Clouds Stratocumulus - Sc Nimbostratus - Ns 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 298

299. Vertical Development Cumulus - Cu Cumulonimbus - Cb 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 299

300. Family Cloud Type Abbreviation Height Range   High Clouds Cirrus CI 16,500 ft to 45,000 ft Cirrostratus CS Cirrocumulus CC     Medium Clouds Altostratus AS   6,500 ft to 23,000 ft Altocumulus AC   Low Clouds Stratus ST   Near ground level to 6,500 ft Stratocumulus SC Nimbostratus NS Heap Clouds of vertical development Cumulus CU Near ground level to 25,00 ft Cumulonimbus CB Near ground level to 45,000 ft 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 300

301. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 301 The Major Cloud Types

302. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 302

303. Cloud Amount Cloud amount is estimated as the coverage of the celestial dome, as it appears to the observer, and expressed in OKTAS (8 th ). Cloud amount is also reported in ranges: Sky Clear No cloud. FEW – Few: 1 – 2 Oktas SCT – Scattered: 3 – 4 Oktas BKN – Broken: 5 – 7 Oktas OVC – Overcast: 8 Oktas 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 303

304. CLOUD BASE This is the height of the base of the cloud above ground (aerodrome) level. In forecast and significant weather charts, heights are given above mean sea level (MSL) 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 304

305. MEASUREMENT OF CLOUD BASE Cloud base is estimated by competent meteorological observers and trained ATC Personnel. BY DAY. A balloon with a known rate of ascent is released and the time between release and the disappearance of the balloon into cloud is noted. From this, cloud base can be calculated. BY NIGHT. An ALIDADE, positioned at known distance from a search light is used to measure the angle above horizontal of the search light glow on the base of the cloud. Height of the cloud base is then calculated by trigonometry. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 305

306. THE CLOUD BASE RECORDER The cloud base recorder gives a continuous readout of cloud base by day and night. It is used at major airports. The system has a transmitter with a arrow beam of light which swings from 8 degrees above the horizontal to the vertical and back again continuously. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 306

307. There is a shrouded photo – electric cell receiver which will only accept light from the vertical for any cloud base, there will be only one angle of the transmitter (TX) beam which will provide vertical light into the receiver (RX). The angle will be known because of the position of the beam at the time an electrical current is received at the RX. The information is then sent by Land line to a recorder display in A.T.C. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 307

308. PRECIPITATION Precipitation is any form of moisture (either Liquid or Solid) that falls from cloud and reaches the ground, such as rain, snow or hail. TYPES OF PRECIPITATION:- DRIZZLE:- Drizzle has very small rain drops i.e. less than 0.5mm diameter. It provides no noticeable impact on a water surface. STRATUS CLOUD ( ST ) is associated with drizzle. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 308

309. LIGHT RAIN:- The water drop is larger in size than a drizzle it’s impact with a water surface is seen. Light rain is associated with STRATOCUMULUS CLOUD ( SC ) . CONTINUOUS MODERATE RAIN:- The water drop is larger in size than that of the light rain (i.e. greater than 0.5mm). Continuous moderate rain is associated with Nimbostratus or Dense Altostratus clouds ( NS or AS ). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 309

310. SHOWERS:- In showers, the commencement of the precipitation is sudden and the duration is short. The water droplets are larger in size than that of the continuous moderate rain. It is associated with towering cumulus cloud ( CU ) . SNOW:- This is precipitation in the form of ICE CRYSTALS. It can be in form of grains, needles or snow flakes. The surface temperature has to be 4 degrees or lower for snow to reach the ground. Largest snow flakes occur at temperatures close to zero degrees. It is associated with SC and NS. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 310

311. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 311 Sig Wx Chart Symbols

312. PRECIPITATION AND FLIGHT OPERATIONS In addition to possible damage by hail and the dangers of icing precipitation may be accompanied by low ceilings and in heavy precipitation visibility may suddenly be reduced to Zero. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 312

313. It is obvious that aircraft which may have accumulated snow while on the ground should never be flown until all traces of snow have been removed including the hard crust that frequently adheres to the surfaces. An aircraft which has been exposed to rain, followed by freezing temperature, should be carefully cleared of Ice and checked before take – off to make certain that the controls operate freely. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 313

314. Types of rainfall What are the different types of rain and where do they happen? 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 314

315. How it rains 1. Warm air rises 2. Air cools 3. Condensation 4. Clouds form 5. Rain 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 315

316. 1. Relief Rain 2. Forced to rise over the mountains 1. Warm moist air from the sea 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 316

317. 3. Air cools as it is forced to rise 4. Condensation 5. Clouds form 6. Rain 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 317

318. 2. Convectional Rain 1. The sun heats the ground which heats the air 2. Warm air rises 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 318

319. 4. Air cools as it is forced to rise 5. Condensation 6. Clouds form 7. Rain 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 319

320. 3. Frontal Rain 1. Mass of warm air meets a mass of colder air 2. Lighter warm air rises over heavier cold air 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 320

321. 3. Warm air cools 4. Condensation 5. Clouds form 6. Rain 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 321

322. A rain gauge consists of an outer 13cm diameter cylinder and an inner cylinder with a jar. Rain is collected in the jar by means of a funnel which has a tapered end so that rain cannot easily evaporate. The rain gauge is sited in open space to receive rain from all angles. It must be located away from buildings and trees that may shelter the raindrops. It is sunk into the ground for stability and its rim is 30cm from the ground to prevent water from splashing into it from the ground. Rainfall collected in the rain gauge is then measured using a measuring cylinder. RAIN GAUGE 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 322

323. THUNDERSTORM A thunderstorm has been defined as one or more sudden electrical discharges, manifested by a flash of light (lightning) and a sharp or rumbling sound (thunder) . Thunderstorms are associated with cumulonimbus Clouds (CB) and they may be several thunderstorm “Cells” within one cloud. They constitute a severe hazard to the aviator. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 323

324. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 324 THUNDERSTORM EFFECT

325. CONDITIONS FOR THUNDERSTORM DEVELOPMENT Thunderstorms occur in a well developed CB cloud, though not all CB produce thunderstorms. They are most likely to occur when there is: Sufficient water vapour to form and maintain the cloud. Conditional instability through a deep layer well above the freezing level. Trigger action to produce early saturation, thus enhancing instability. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 325

326. TYPES OF THUNDERSTORM . Thunderstorms are classified as: Heat or Air mass thunderstorm Frontal thunderstorm. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 326

327. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 327 HEAT OR AIR MASS THUNDERSTORM. Heat type of thunderstorm are: Isolated - all triggers except frontal. Most frequent over land in summer. Form by day, and clear by night. Occur in cols or weak lows.

328. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 328 FRONTAL THUNDERSTORM Frontal thunderstorms are: Most frequent in winter. Form over land or sea, day or night. Usually form in a line at a cold front or occlusion. Occur in active Depressions or Troughs. Can be accompanied by a line squall.

329. THE LIFE CYCLE OF A THUNDERSTORM CUMULUS OR BUILDING STAGE. The cumulus stage begins when one or more cumulus cloud (CU) begin to grow into a towering cumulus (TCU). This stage is characterized mainly by updraft or up current with an inflow of air at the bottom and at the sides at all levels. There is no precipitation at this stage. It’s average life span is 15 to 20minutes. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 329

330. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 330 Cumulus Stage Updraughts only

331. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 331 MATURE STAGE. The mature stage begins with the onset of first down – draughts indicated by rain shafts. The cloud now extends well above the freezing level. The tops of the clouds are now glaciated (containing mostly of ice crystals).

332. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 332 Mature Stage Warm, moist air Gust front Cold air Updraughts and downdraughts Direction of storm movement Wind shear Wind shear Roll cloud Rain Hail Overshooting top

333. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 333 Down draughts associated with increasing volume of precipitation accelerate and produce gust fronts which spread out from the base. The mature stage lasts for a further 15 – 20minutes and maximum vertical development is reached.

334. DISSIPATING STAGE  The dissipating stage of thunderstorm cell is reached when the local supply of moist air is used up. Anvil top begins to spread – out. The anvil indicates the direction of movement of the storm. The core consists mostly of down – draughts which kill off the up – draughts and rain spreads right across the base of the storm towards the end. The cloud structure now tends to stratify and spread out . An individual storm cell may last for LESS THAN ONE (1) hour but a system may persist for several hours. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 334

335. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 335 The Dissipating Stage Predominately downdraughts Light rain Some updraughts Cloud anvil

336. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 336 Thunderstorm Stages of Development

337. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 337 Dissipating Cb

338. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 338 THE HAZARDS' OF THUNDERSTORMS TURBULENCE Turbulence can be violent in cloud and at the sides. Below the cloud, turbulence can be dangerous during take – off and Landing and there can be wind shear. It is possible for a pilot to overstress the airframe in these conditions. Loose articles in the cabins can injure passengers Pressure instruments can be in error due to Lag.

339. AIRFRAME ICING  Icing can occur at all heights in the cloud where the temperature is between Zero and – 45 degrees.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 339

340. HAIL Hail can be met at any height in the cloud, also below the cloud and below the anvil. Severe skin damage to the air frame can occur when hailstones are large.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 340 HAIL Hail can be met at any height in the cloud, also below the cloud and below the anvil. Severe skin damage to the air frame can occur when hailstones are large.  

341. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 341   Hail Damage

342. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 342   Hail Damage

343. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 343   Hail Damage to Harrier

344. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 344  

345. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 345  

346. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 346  

347. LIGHTNING Lightning is most likely to occur within 5,000ft of the freezing level. There are three (3) effects viz: It can cause a pilot to be temporarily blinded. Compasses can become totally unreliable. Light airframe damage can be caused). It can cause damage to light airframe. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 347

348. PRESSURE VARIATIONS Local pressure variations covering only a very small region in or close to a storm can occur causing QFE/ QNH to be in error so that altimeter readings can be inaccurate by as much as ± 1000ft at all heights. These together with gust effects, can cause heights errors at low level which can be dangerous. Pressure can fall several hectopascals behind a storm due to sinking air. This can cause a surface temperature rise. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 348

349. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 349 HEAVY RAIN Ingestion of large quantities of water may cause flameout and possible damage in gas turbine engines. Severe up draughts as well as water may induce compressor stalling. This is indicated by Loud bangs from the engines.

350. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 350 LOW LEVEL WINDSHEAR Severe thunderstorm can cause rapid changes in wind speed and direction. Microbursts or strong down draughts can produce catastrophic loss of height during take – off and landing. Typical micro bursts are less than 5km across, Lasting 1-5 minutes with vertical speeds as high as 60kt or more. A Speed of 350kt in a microburst is possible but rare

351. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 351 Landing in a Microburst

352. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 352 Take-off into a Microburst

353. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 353 Microburst from Mature Cb

354. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 354 Dry Microburst

355. VISIBILTY AND FOG:  VISIBILITY : Visibility is a measure of the transparency of the atmosphere. Meteorological Daylight Visibility is defined as the maximum horizontal distance in a particular direction at which a dark object of suitable size can be seen and identified by an observer with normal sight. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 355

356. When visibility varies with direction, the lowest value is observed or reported. Ideally, day light and night values of visibility should be the same. The horizontal ground visibility as measured by Met. Observer is given in 100's of metres up to 5,000m (5 km) and then in whole kilometers. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 356

357. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 357 RUNWAY VISUAL RANGE (RVR) It is defined as the maximum distance at which the pilot may expect to see the runway lights, runway markers, during a take-off or landing ground roll, from a point 5 metres (15 feet) above the touchdown point. It is assessed and passed to the pilot whenever the Meteorological visibility is 1500 metres or less or the visibility along the runway falls below 1500 metres

358. VISIBILITY PROBLEMS DURING TAKE-OFF AND LANDING For aviation purposes, Meteorological visibility has limited usefulness, because it is made horizontally on the ground, therefore gives little or no information about visibility above the ground. That is, it does not provide a very good indication of the distance at which the ground can be seen from an aircraft in flight (i.e. pilot's oblique visibility). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 358

359. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 359 Oblique Visibility Through Fog, Mist or Haze

360. In general, where mist or haze layer lies well below an aircraft, the distance at which the ground will be visible will increase with height. Conversely, as the aircraft descends into the top of the layer of mist or fog or haze, this distance will decrease markedly.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 360

361.   CAUSES OF REDUCED VISIBILITY: VISIBILITY CAN BE REDUCED BY: Fog and Mist, Cloud and precipitation, Wind-blown spray from the sea, Smoke and haze, Dust and Sand (a) to (c) above are caused by water droplets and (d) to (e) are caused by solid impurities. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 361

362. FOG Fog is a low cloud that has its base within 50 feet of the ground Fog is the most frequent cause of reduced surface visibility. There is fog if the visibility is less than 1000 meters and water droplets are the obscuring agent. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 362

363. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 363 F0G. MIST AND HAZE AND THEIR DIFFERENCES : When visibility due to water droplets becomes less than 1,000 metres (1 km), Fog is said to exist. When the visibility is between 1,000 metres ( 1 km) and 5 km, it is called Mist if the obscurity is caused by water droplets, and Haze, if it is caused by solid particles.

364. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 364 The meteorological practice is that: In Mist, the relative humidity (RH) is more than 80% or the difference between the air temperature and dew point temperature is usually less than 3°C). In Haze, the relative humidity is less than 80% (or the difference between the air temperature and dew temperature is more than 3°C).

365. TYPES OF F0G: RADIATION F0G : It is formed when the ground is cooled by radiation at night to a temperature below the dew point temperature of the air. It occurs only over land. The conditions favourable for its formation are: A high relative humidity (requiring little cooling to reach saturation). A clear sky to allow free and maximum radiative cooling. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 365

366. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 366 A light wind of 2 to 8 k t (to allow for just enough turbulence). If there is no turbulence ( i.e wind is less than 2kt), only dew forms on the ground. Too much turbulence (i.e. wind in excess of 8 kt ), results in the formation of low stratus cloud.

367. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 367 Radiation Fog

368. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 368 Radiation Fog

369. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 369 The likeliest time for the fog to form is about an hour after sunrise especially after a calm night. The fog tends to be most frequent and dense in autum and winter. The pressure systems favourable for its formation are high pressure (or anticyclones), ridge of high pressure, and cols.

370. RADIATION FOG IS DISPERSED BY: solar heating of the ground; increase in 'the surface wind speed to lift the fog into low stratus cloud; a change to a drier air mass. Radiation fog is usually between 300ft and 800ft in depth, and occasionally may reach 1,000 ft deep. It forms more frequently in valleys than over high grounds. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 370

371. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 371 Radiation Fog

372. ADVECTION FOG: This occurs over land and sea when air flows over a cooled surface so that its temperature is reduced below the dew point by conduction. It can form during the day or night. It is not associated with any particular pressure system. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 372

373. The conditions favourable for its formation are:­ Moist air, so that little cooling is needed to saturate it; Wind up to 15 kts to move the ai r ( may be stronger over sea areas)  A cold surface with temperature lower than the dew point of the moving air to ensure condensation. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 373

374. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 374 Advection Fog

375. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 375 Upslope Fog

376. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 376 Valley Fog

377. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 377 Precipitation Fog – “Steam Fog”

378. SUMMARY OF VISIBILITY EFFECTS By DAY visibility is generally poor looking up sun. By NIGHT, visibility is usually better looking up moon, because of light reflections from water surfaces, railway lines, etc. Night visibility is improved if the pilot does not look at bright cockpit lights. In precipitation, visibility is usually worst in DRIVING SNOW and very poor in DRIZZLE because of the large number of small droplets 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 378

379. AIR MASSES AND FRONTS   AIR MASSES. (UNIFORM BODIES OF AIR). An air mass is a large body of air whose properties are horizontally uniform with regard to temperature and humidity and vertically uniform with regard to lapse rates. It’s characteristics are dependent on it’s origin. The temperature and humidity properties are obtained by the air remaining roughly stationary over a surface where conditions are generally constant for some length of time – a high pressure area. Therefore at source, all air masses must be stable. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 379

380. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 380 SOURCE REGIONS OF AIR MASSES. The best source regions for air masses are large areas where air can be stagnant long enough to take on the characteristics of the surface below. The world’s stable high pressure regions constitutes the source of most air masses. The source regions of air masses are classified chiefly on the basis of two primary factors.  

381. TEMPERATURE. Tropical Air mass :- Are quite warm and they are formed in the regions of 20°N Latitude to 50°N Latitude.   Polar Air Mass :- Are relatively Cold and are formed in the area of 60°N Latitude and towards the North Pole. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 381

382. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 382 SURFACE OF ORIGIN.  Continental Air Mass :- Are relatively dry and develop over Land. E.g. PC, TC .   Maritime Air Mass :- Are formed over water where they acquire moisture, e.g. PM. And TM. MAIN AIR MASSES  The main air masses include  Polar Maritime (PM) Polar Continental (PC) Tropical Maritime (TM) Tropical Continental (TC)

383. AIR MASS MODIFICATION As air masses move away from their source region, they are affected by moisture and heat exchanges from the surface. An air mass is said to be COLD if the air is moving over a surface which is warmer than itself hence there is heating from below causing instability. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 383

384. The following characteristics are typical of cold air mass. Unstable Turbulent and Rough air. Good Visibility Rain showers and sometimes Thunderstorms. Convective Clouds. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 384

385. An air mass is said to be warm if the air is moving over a surface which is colder than itself hence there is cooling from below causing stability. Warm air have the following characteristics. Stable Smooth Poor Visibility Stratiform Clouds and Fog. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 385

386. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 386 CIRCULATION OVER WEST AFRICA West Africa is a very Large region, stretching over about 15 of Latitude, from around 5°N to 20° North of equator and from the Atlantic Ocean in the west to the Ethiopian highlands in the East. The seasonal movement of the inter-tropical Discontinuity (ITD) causes the two season’s experienced in the area annually.

387. THE INTERTROPICAL DISCONTINUITY (ITD) The ITD is defined as a thermal Low pressure belt where the trade winds from the Northern Hemisphere (North East) and Southern Hemisphere (S.W.) converge and ascend. These trade winds are the Harmattan air to the North of the ITD and the South West Monsoon to the south of the ITD. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 387

388. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 388 The ITD oscilliates North and South of the Equator . Over West Africa, it’s extreme Northern position is in Summer (August) at about 22°N to 23°N , while the extreme Southern position is in Winter (February) at about 4°N to 5°N. Hence the ITD over West Africa is confined to the North of the Equator throughout the year.

389. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 389 The surface winds are the North East to the North of the ITD which brings Harmattan and the South – West to the South which also brings rains to West Africa. At the upper levels, the mean direction of winds is mainly WESTERLY in January but EASTERLY in July.

390. AIR MASSES OVER WEST AFRICA There are two main air masses which affect West Africa. They include. Harmattan air South West monsoon air 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 390

391. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 391 THE HARMATTAN AIR. Harmattan is the name of a wind which blows towards the coast of West Africa from North Africa particularly North and Central Sudan. The air is very dry, dust Laden and very warm. Hardly any rainfall is received during this period. The harmattan is pre – dominant within the months of November to February every year.

392. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 392 Temperatures are generally increasing from South to North because of more intensive insolation near the equator and relative humidity is generally Low. Dusty Conditions are frequent especially in the Northern Parts of the region, close to the desert. This necessitates flights to either be delayed, diverted or cancelled.

393. THE SOUTH WEST MONSOON AIR The South West monsoon air originates from the Subtropical high pressure over the Southern Atlantic Ocean and reaches West Africa through the Guinea Coast. The air mass is very moist, Unstable and potentially cooler than the harmattan air mass. It produces towering CU, CB, showers, thunderstorms and Squalls. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 393

394. Visibility is usually good except in showers and flights could occasionally be turbulent. Over West Africa, The South – West monsoon air pre – dominates in the months of April and October . However, in the Southern parts of the region it starts in march but in the North, it commences not until May/ June . 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 394

395. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 395

396. WEATHER ZONES OVER WEST AFRICA West Africa has been classified into five (5) Weather Zones namely; Zone A,B,C,D, and E . Here under are the weather zones and associated weather features. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 396

397. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 397 Weather Zones: Associated Weather Features Zones 'A ' Harmattan Zones 'B' If positioned inland - generally fine, but hazy at times; If positioned along the coast (especially from November to Feb February, early morning fog or mist Z one ‘C’ Line Squalls . Zone ‘D’ Monsoon rain Zone É’ Little dry season or August Break .

398. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 398 Certain geographical location in Nigeria frequently favours local line squall formation. These local areas are: (a) Jos Plateau, and (b) Oshogbo Hills.

399. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 399 Global Airmasses

400. FRONTS A front is a zone or surface of interaction between two air masses of different properties ( temperature and moisture ). When the two air masses meet, the warmer air will rise over the top of the colder air because of the difference in density. The frontal surface where they meet is frequently active with much cloud and precipitations. The ground position of the frontal surface is shown by a line on a synoptic charts though it may be many miles across.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 400

401.   The main global fronts are; The polar front The Arctic front The Mediterranean front, and The Inter Tropical Convergence Zone. (ITCZ) and ITD which affect most tropical regions and West African. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 401

402. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 402 A Cold Front

403. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 403 A Warm Front

404. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 404 Frontal Symbols

405. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 405 Warm and Cold Fronts

406. TYPES/ STRUCTURE OF FRONTS WARM FRONT A warm front is defined as the transition Zone where a warm air mass is displacing (or replacing) a cold air mass. When a warm front passes through, the air becomes noticeably warmer and more humid than it was before. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 406

407. A warm front has a gentle slope of about 1 in 150. A warm front is represented by a solid line with semicircles pointing towards the colder air and in the direction of movement On coloured weather maps, a warm front is drawn with a solid Red 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 407

408. An observer to the north of an advancing front will notice Clouds appearing in the following order:- Cirrus (CI), Cirrostratus (CS), (i.e. high Clouds), followed by Altostratus (AS) ( i.e medium Cloud) which thickens into Nimbostratus (NS) and reaches the Low cloud levels. Stratus (ST ) may appear beneath the Nimbostratus. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 408

409. WITH THE PASSAGE OF WARM FRONT AT THE SURFACE Wind Veers and Increases slightly. Temperature and Dew point rises. Pressure Steadies. Precipitation changes from Rain (RA) to Drizzle (DZ) or Drizzle Rain (DZRA) Cloud changes from Nimbostratus (NS) to Stratus (ST) or Stratocumulus (SC). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 409

410. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 410 COLD FRONT A cold front is defined as the transition zone where a cold air mass is displacing or replacing a warmer air mass. The air behind a cold front is noticeably colder and drier than the air ahead of it. When a cold front passes through, temperature can drop more than 15 degrees within the first hour.

411. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 411 A cold front is represented by a solid line with triangles along the front pointing towards the warmer air and in the direction of movement. On coloured maps, a cold front is drawn with a solid BLUE line.

412. As a result of the steep slope (about 1 in 50) the lifted warm air produces unstable type of cloud hence, at the front, there are layers of Altocumulus (AC) and Altostratus (AS) frequently with Cumulonimbus (CB ). Precipitation is usually heavy but the belt is narrow (about 50 miles). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 412 A Cold Front

413. WITH THE PASSAGE OF A COLD FRONT AT THE SURFACE Wind veers and decreases slightly. Temperature and Dew point falls. Pressure rises rapidly. Visibility improves. Intermittent rain or heavy shower begins from Nimbostratus or embedded cumulonimbus (CB). 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 413

414. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 414 WARM AND COLD SECTOR The region between the warm front and cold front where the tropical air mass occupies is called WARM SECTOR , while the remaining larger portion is called the COLD SECTOR .

415. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 415 OCCLUSION. An occlusion occurs when the COLD FRONT in a depression catches up with or over takes the WARM FRONT. An occlusion forms because the Cold Front normally moves faster than the warm front. It usually forms when the pressure in the depression stops falling ( Frontolysis ).

416. TYPES OF OCCLUSION WARM TYPE OCCLUSION . If the air ahead of the warm front is COLDER than the air behind the COLD FRONT, then a warm type occlusion will be formed. The warm sector is lifted above the surface ground and only the warm front will be apparent on the ground. There will be a wide rain belt, with mainly stable type of precipitation. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 416

417. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 417 COLD TYPE OCCLUSION. If the air behind the Cold Front is COLDER than the air ahead of the Warm Front, then a cold type occlusion will be formed. The warm sector will be lifted above the surface and only a COLD FRONT will be apparent on the ground. There will be a narrow rain belt with CB and NS the most likely clouds.

418. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 418

419. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 419 Weather Conditions

420. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 420 Cold Occlusion

421. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 421 Warm Occlusion

422. WEATHERASSOCIATED WITH PRESSURE SYSTEMS DEPRESSION OR LOWS. A depression is a region of comparatively low pressure shown by more or less circular and concentric isobars surrounding the centre , where pressure is lowest. It is sometimes called a low or cyclone. Depression Weather. Cloud – Overcast extending to tropopause and with a low base. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 422

423. Precipitation – Can be continuous, light to moderate and also heavy showers and thunderstorms. Visibility – Usually poor. Temperature – Mild. Winds – Strong.   5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 423

424. ANTICYCLONES An anticyclone or high is a region of relatively high pressure shown by more or less circular isobars similar to a depression but with higher pressure at the centre . Anticyclone Weather; Cloud – None except on the edge of the anticyclone. Precipitation – None. Visibility – Autumn / Winter, Fog early morning and night. Summer – Haze is possible / otherwise good. Temperature – Winter – Cold, Summer – Warm. Winds – Light. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 424

425. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 425 TROUGHS Troughs of low pressure are indicated by isobars extending outwards from an area of low pressure so that the pressure is lower in the trough than on either side. Trough Weather: Cloud – Heap type – CU or CB. Precipitation – Showers can be heavy with thunderstorms and hail. Visibility – Good except in showers. Temperature – Colder than expected. Winds – Moderate with Dusts and Squalls.

426. RIDGE Ridges of high pressure are indicated by isobars extending outwards from an anticyclone and always rounded, never V – shaped as seen in a trough. Ridge Weather: It is similar to anticyclone weather. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 426

427. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 427 COLS: Cols are regions of almost constant pressure between two highs and two lows. Cols Weather: Normally settled, but dependent on changing pressure. In autumn and winter, cols produce poor visibility and fog, whilst in summer, thunderstorms are common.

428. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 428 SECONDARY DEPRESSION. When a small depression is enclosed within the circulation of a larger depression, it is called a secondary depression. Secondary Depression Weather: Secondary depression weather if active can produce strong winds and GALES and can give low cloud and copious rainfall. Heavy CU, CB and thunderstorms are also possible.

429. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 429 AIRCRAFT ICING

430. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 430

431. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 431 Temperature Ranges: Icing

432. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 432 Icing Intensity

433. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 433 Carburettor Icing

434. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 434 Carburettor Icing Intensity

435. 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT 1. 435 AVIATION WEATHER REPORTS

436. Data Collecting and Relay Records: Air Pressure Relative Humidity Precipitation Solar Radiation Wind Velocity Air Temperature 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 436

437. Automated Weather Station This one is set up to transmit to GOES 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 437

438. Global Weather Satellites 5/10/2018 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA PPT1. 438

439. METEROLOGICAL INFORMATION FOR AIR TRAFFIC SERVICES AND FOR SEARCH AND RESCUE SERVICES : The objective of Meteorological Service for air Navigation is to contribute towards the safety, regularity and efficiency of Air Navigation. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 439

440. This is achieved by supplying operators, fight crew members, air traffic services units, airport management and others concerned with the conduct or development of Air Navigation with meteorological information necessary for the performance of their respective functions. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 440

441. In Nigeria, the Authority for the dissemination of meteorological and climatological information is the Nigerian Meteorological Agency (NIMET) who supply the information, which are mainly in the form of forecasts, warnings, observations and or reports. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 441

442. METEOROLOGICAL INFORMATION FOR AIR TRAFFIC SERVICES UNIT . Meteorological offices are to supply ATS Units with up-to-date meteorological reports, forecasts, SIGMET information and appropriate air-reports . FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 442

443. A summary of the type of information most frequently supplied to ATS units and the associated aeronautical communication stations, the meteorological units responsible for providing the information. The frequency with which it is provided and the communications means normally used for this purpose is given in the table below. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 443

444. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 444

445. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 445

446. Note 1 – Communications by closed-circuit TV, video display unit, or similar. If none of these are available, or during unserviceability periods, communications by phone, followed if possible by confirmation by other means. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 446

447. The Meteorological information required by ATS units are provided by their associated meteorological offices. These information include up-to-date meteorological report, forecasts, SIGMET and appropriate air-reports. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 447

448. Tabulated below are the ATS unit and the associated meteorological office.   ATS UNIT ASSOCIATED METEOROLOGICAL OFFICE Aerodrome Control Tower (TWR) Aerodrome Meteorological Office Approach Control Office (APP) Aerodrome Meteorological Office Area Control Centre (ACC) Meteorological Watch Office (MWO) Flight Information Centre (FIC) Meteorological Watch Office (MWO) Rescue Co-ordination Centre (RCC) As designated by regional air navigation Agreement (usually an MWO) FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 448

449. AREAS OF APPLICATION OF METEOROLOGY Weather forecasting Aviation meteorology Agricultural meteorology Hydrometeorology Nuclear meteorology Maritime meteorology FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 449

450. BASIC STEPS FOR MAKING AVIATION WEATHER REPORTS FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 450

451. 1st Step: Observation FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 451

452. 2nd step: collection and transmission of weather data FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 452

453. 3rd Step: Plotting Of Weather Data FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 453

454. 4th Step: Analysis Of Weather Maps, Satellite And Radar Imageries And Other Data FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 454

455. 5th Step: Formulation Of The Forecast FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 455

456. Aviation Weather Reports/Forecasts ( METAR / SPECI / TAF ): AERODROME REPORTS ( METAR AND SPECI CODES ) : METAR (MET Aerodrome Report) is a routine meteorological aerodrome report, and contains information concerning actual conditions at the time of observation. METAR’S are issued every half hour during aerodrome operating hours. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 456

457. A variation in the METAR is the special report SPECI is a special aviation weather report. It is issued when a significant change in weather occurs between two routine reports. A SPECI can be issued to either an improvement or a deterioration in the weather FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 457

458. Aviation weather reports (METAR and SPECI) form part of the VOLMET broadcasts (A VHF plain language, continuous broadcast of selected aerodrome reports for aircraft in flight). FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 458

459. The elements reported are in the following sequence:- REPORT TYPE LOCATION DATE/TIME SURFACE WIND and significant VARIATIONS VISIBILITY RUNWAY VISUAL RANGE (RVR) when applicable and significant variations FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 459

460. WEATHER CLOUD TEMPERATURE AND DEW POINT QNH SUPPLEMENTARY INFORMATION TREND FORECAST RUNWAY STATE FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 460

461. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 461

462. METAR and SPECI FORMAT DECODE : LOCATION : (CCCC) - ICAO four letter aerodrome indicator DATE&TIME: ( GGggz ) – Time of observation in hours and minutes UTC 0800Z = 0800 UTC, 0755Z = 0755 UTC FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 462

463. SURFACE WIND dddff ( Gf m f n ) KT d n d n d n V d X d X d X ddd - direction in degrees from True North ff - wind speed G - gust indicator (if necessary) A gust is a variation of 10 kt or more between peaks and lulls. Fmfm :- maximum wind speed observed (if necessary) wind speed units used are : KT, KMH , MPS FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 463

464. d n d n d n V d x d x d x :- variation in wind direction measured in clockwise when there is change in: direction of 60° or more; and wind speed of more than 3 kt FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 464

465. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 465 Note:- 1. If the surface wind h as a variable direction, it is indicated thus: VRB03 . Calm is indicated thus: 00000. It is defined as wind speed of less than 3 kt .

466. Examples: 31015G27 kt = 310 o T at 15 kt , gusting 27 kt . 280V350 = variation between 280 o T and 350 o T 00000 = Calm A SPECI will be issued if wind direction changes by 45 degree or more in less than 15 minutes and the sustained winds are 10 kt or more throughout the wind shift. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 466

467. VISIBILITY : VVVV( Dv )( VxVxVxVxDv ) or CAVOK - minimum horizontal visibility in metres and direction (eight points of Compass) where required; followed by significant variations at different directions when: FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 467

468. minimum visibility is less than 1500m, and maximum visibility is more than 5000 m. Examples: 4000 decodes as 4000 m 9999 “ “ 10 km or more 1400SW 6000N – Min. vis. = 1400 M to Southwest Max. vis. = 6 km to North FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 468

469. RUNWAY VISUAL RANGE (RVR): RDrDr / VrVrVrVri , or RDrDr / VrVrVrVr V VrVrVrVr Runway Visual Range with direction or location, and significant changes upwards or downwards in RVR during the previous 10 minutes . FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 469

470. Example: R24/P1500 - On RWY 24, RVR is more than 1500 m R24/M0050- On RWY 24, RVR is less than 50 m FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 470

471. PRESENT WEATHER w’w ’ - See Table below  w’w ’ - SIGNIFICANT PRESENT, FORECAST AND RECENT WEATHER FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 471

472. Note :- Code , 50 - 51 DZ ) 52 - 53 ) ) ) • 60 - 61 RA ) 62 - 63 ) ) ) * 70 - 71 SN ) - Light 72 - 73 ) Moderate ) ) ▼ 80 SH ) 81 ) XX + Heavy ; 58 DZRA ) FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 472

473. CLOUDS: N s N s N s h s h s h s (CC) or VVh s h s h s N s N s N s - Cloud amount expressed as:- FEW – few for 1 to 2 oktas ; SCT - scattered for 3 to 4 oktas BKN - broken for 5 to 7 oktas ; OVC - overcast for 8 oktas h s h s h s - Height of base of clouds in units 30 metres or 100 ft   FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 473

474. (CC) - Cloud types; only CB (cumulonimbus) and TCU (towering cumulus) are indicated. VV hshshs -When sky is obscured, vertical visibility is reported Examples: VV002 = Vertical vis = 60m or 200ft VV/// = Vertical vis. = unavailable Cloud cover and ceiling are given above ground level (AGL). FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 474

475. Ceiling is defined as height above ground level of the lowest broken or overcast ( BKN or OVC ) layer aloft or vertical visibility into a surface based obscuration. A layer is defined as clouds or obscuring phenomena aloft when the base is approximately the same level. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 475

476. Note:- When there are no clouds and CAVOK is not appropriate, the cloud group is replaced by SKC = Sky Clear. CAVOK = Cloud and Visibility OK. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 476

477. replaces visibility, RVR, present weather and cloud if:- Visibility is 10 km or more; No CB or no cloud below 1500 m or 5000 ft; or below the highest minimum sector altitude ( MSA ), which ever is greater; No precipitation, thunderstorm, sandstorm, dust storm, shallow fog or low drifting dust, sand or snow. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 477

478. AIR TEMPERATURE AND DEW POINT : TT/ T d T d Air temperature and dew point temperature in whole (if below 0 o C preceded by M). Example: 10 / 03 - Air tempt. 10ºC / Dew point tempt. 3ºC M01 / M03 - Air tempt. Minus 1 o C /Dew point tempt. = Minus 3 o C. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 478

479. ALTIMETER SETTING PRESSURE : QP H P H P H P H QNH in whole hectopascals (HPA) and rounded down or inches, tenths and hundred ths of an inch depending on indicator. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 479

480. If the indicator is: Q then QNH is in HPA A then QNH is in inches   Examples: Q0995 - QNH is 995 hpa   Q1014 - QNH is 1014 hpa   A2994 - QNH is 29.94 ins. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 480

481. SUPLEMENTARY INFORMATION : RE w’w ’ WS TKOF RWYD r D r Or WS LDG RWYD r D r   This information is added at the end of the METAR and it is limited to information on:- Recent weather since last routine report of operational significance, but not occurring at the time if this report.   FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 481

482. Low level Wind Shear along Take-Off and/or Landing runway Runway condition. It is added to the METAR or SPECI if snow or other runway contamination is present .   Example: RETS WS TKOF RW 24   Recent weather (RE) - Thunderstorm   WS TKOF RW 24 – Wind Shear along take-off runway 24. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 482

483. TREND FORECAST: A short term forecast of significant changes expected . Valid not more than 2 Hrs from time of Observation : This group covers changes in Surface Wind, Visibility, Weather and Cloud. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 483

484. These are described by:-   The change indicators: BECMG = Becoming TEMPO = Temporary NOSIG = No significant change of weathering the 2 hours after the time of observation The time indicator for the change: FM - From AT - At TL - till FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 484

485. Example: BECMG TL 1200 9999 NSW = Becoming Till 1200 UTC Visibility = 10 km or more NSW – No significant weather FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 485

486. TEMPO FM0730 TL0810 3000 SHRA - Temporarily from 0730Z until 0810Z expect Visibility of 3000m in rain showers Note :- NSC - No Significant Cloud. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 486

487. An equal sign (=) appears at the end of the MEtAR to denote that the message is complete Pilots should consult METARS for departure and destination aerodrome and also for other aerodromes along the planned route. If the aerodrome of destination does not issue a METAR , consult a METAR from an aerodrome in the vicinity of your destination FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 487

488. SPECIAL AERODROME REPORT ( SPECI ) A variation on the METAR is the special report. A special report which is denoted by the abbreviation, SPECI has the same format as a METAR except that the code SPECI will replace METAR at the beginning of the report FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 488

489. A SPECI will be issued when the weather conditions significantly change in the period between routine observations A SPECI can be issued to indicate either an improvement or a deterioration in the weather. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 489

490. Example SPECI DNAA 231025Z 26012G25KT 220V300 9999 + RA OvC010 5/ MO2 Q0991 RETS WS ALL RWY NOSIG = = denotes the end of the message FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 490

491. TERMINAL AERODROME FORECAST ( TAF ) DECODE : A TAF is a terminal aerodrome forecast and contains an estimate of the conditions which are expected to prevail during the period of the forecast ( usually cover a period of 9 to 24 hours or as specified ) A TAF is actually a forecast of the weather for a specified aerodrome over a defined period of time FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 491

492. TAFs are written in the METAR code with minor differences. The Temperature, Dew Point, QNH and supplementary information are omitted. The validity period is in hours The change indicators is limited to two ( BECMG and TEMPO) FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 492

493. Example of TAF : FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 493

494. Validity Period :- The time group covers a period, using the standard 9 hrs. or the extended period of 18 to 24 hrs. (i.e.0615 means 0600 UTC to 1500 UTC not 0615 UTC ) . FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 494

495. Visibility :- Same as METAR with only minimum value forecast . Weather :- If no significant weather is expected, the group is omitted. After a change group, ( i.e. a Variant ) if the weather becomes insignificant, the NSW ( No Significant Weather ) is used . FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 495

496. Cloud :- If clear sky is forecast, the cloud group is replaced by SKC ( Sky Clear ) . If CAVOK and SKC are not appropriate, then NSC ( No Significant Cloud ) is used . Significant Changes ( Variant ) :- As in TREND Forecast . FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 496

497. Note :- They introduce new self – contained part of forecast in which the conditions quoted supersede the equivalent conditions given in the main part . Indicators for changes are only limited to two terms only:- BECMG , and TEMPO . FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 497

498. The code BECMG marks a permanent change in the forecast weather, but which will establish itself more gradually than weather conditions introduced by the code FM The FM indicator introduces what is effectively a new forecast The code TEMPO indicates a temporary change in weather conditions expected to last for less than hour FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 498

499. The code PROB (meaning probability) in a TAF indicates the probability of the occurrence of specified weather phenomenon PROB 30 indicates a low probability of a change occurring PROB 40 indicates a high probability for change occurring The code PROB can be followed by a time group of its own and/or by an indicator such as BECMG or TEMPO FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 499

500. Note:- In order to distinguish METAR and TAFs in the Bulletin print-outs, prefix letters are used as follows:- SA - indicate METARs , and these are normally re-issued every ½ hour SP – Indicate selected or special aerodrome weather report issued when a significant change in weather occurs that is of operational significance FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 500

501. FC - indicate standard 9 hours TAF’s and they are normally re-issued every 3 hours FT - indicate extended TAF’s covering a period of 18 hours in UK, and 24 hours in the USA They are re-issued every 6 hours. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 501

502. GRADU/BECMG - Constant or irregular rate of change. TEMPO - Infrequent change of less than 1 Hour As a temporary nature, it may occur at any time during the period . INTER - Frequent change of less than 1 Hour. RAPID - Change of less than ½ Hour ( used mainly with passage of Cold Front ). FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 502

503. There are other types of aeronautical forecasts designed to meet requirements for the various stages of flight These include: Forecast for take-off Landing forecast Area forecast Flight forecast and Route forecast FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 503

504. DECODING OF METAR AND TAF : Decode the following Weather Reports :- METAR DNMM 050800Z 27010KT 6000 BR SCT011 SCT020CB ( N – E ) BKN100 26/25 Q1013 NSW = FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 504

505. METAR LSZH 0720Z 21006KT 5000 RA SCT008 BKN020 OVC060 12/11 Q1014 NOSIG = METAR EGKK 1650Z 30005KT 9999 SCT012TCU BKN050 11/10 Q1011 NOSIG FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 505

506. Decode the following Aerodrome Weather Forecasts from :- Nancy/ Essey (France) ( LFSN ); Quipes (France) ( LFRQ ); Gander(Canada) ( CYQX ); Cairo ( HECA ); FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 506

507. TAF LFSN 030800Z 0918 20006KT 9999 SCT020 BKN040 BKN100 BECMG 1214 18015KT BKN020 BKN04 OVC100 TEMPO 1318 20015G30KT 7000 -RA BKN008 BKN020 OVC080 = FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 507

508. TAF LFRQ 030800Z 0918 24020G40KT 9999 SCT012 BKN100 TEMPO 6000 -DZ BKN009 BECMG 1214 29015G30KT 9999 SCT013 SCT025 TEMPO 1518 -SHRA BKN012 = FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 508

509. TAF CYQX 041042Z 1111 VRB03KT 9999 SCT025 BKN100 TEMPO 0104 4800 -SHRA BKN010 OVC025 FM04 20015KT 3200 -SHRA OVC010 TEMPO 0409 1200 BR OVC006 FM09 27010KT 9999 NSW OVC008 = FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 509

510. TAF HECA 151140Z 1212 34008KT CAVOK FM01 VRB03KT 2000 HZ SCT020 BECMG 0305 1200 BR FM10 32005K 9999 NSW SCT030 These forecast defer in respect of area or airspace covered and in respect of the offices preparing and issuing them (see below) FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 510

511. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 511

512. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 512

513. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 513

514. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 514

515. AIRCRAFT OBSERVATIONS AND REPORTS : The following aircraft observations are made: routine aircraft observations; special aircraft observations; aircraft observations during climb-out and approach; other aircraft observations on request. These observations are made and reported by registered aircrafts and operating on International Air Routes. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 515

516. ROUTINE AIRCRAFT OBSERVATIONS : Routine observations are made in relation to those air traffic services reporting points or intervals: At which the applicable air traffic services procedures require routine position reports; and Which are those separated by distance corresponding most closely to intervals of one hour of flying time. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 516

517. An aircraft is exempted from making routine observations when: The flight duration is 2 hours or less; or The aircraft is at a distance equivalent to less than one hour flying time from the next intended point of landing The altitude of the flight path is below 1,500 metres (5,000ft). FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 517

518. SPECIAL AIRCRAFT OBSERVATIONS : Special observations are made by all aircraft operating on international air routes whenever: severe turbulence or severe icing is encountered; or moderate turbulence, hail or cumulonimbus clouds are encountered during transonic or supersonic flight; FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 518

519. Other meteorological conditions, for example, the other en-route weather phenomena specified for SIGMET message are encountered which, in the opinion of the pilot-in-command, may affect the safety or markedly affect the efficiency of other aircraft operations. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 519

520. AIRCRAFT OBSERVATIONS DURING CLIMB-OUT AND APPROACH All aircraft should make observations of meteorological conditions encountered during climb-out or approach phases of flight, not previously reported to the pilot-in-command which in his opinion are likely to affect the safety of other aircraft operations. These are mainly turbulence, wind shear and icing. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 520

521. OTHER AIRCRAFT OBSERVATIONS : Additional aircraft observations are made by aircraft operation on international air routes. These include FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 521

522. Air Report (AIREP) Format : There are three major parts to a Routine Air Report Position information Aircraft Identification Position or latitude and longitude Time FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 522

523. Flight level or altitude Next Position and time over Ensuring significant point Part 2 - Operational information Estimated time of arrival Endurance FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 523

524. Part 3 - Meteorological information Air temperature Wind direction Wind speed Turbulence Aircraft Icing Humidity (if available) FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 524

525. For special air-reports, Part 1 and 2 are only considered excluding next position and ensuring time in Part 1. The MWO is designated to provide the aircraft in flight with winds and temperatures for a specific route sector request for this is done through the ATS Unit with which the aircraft is expected to be in contact. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 525

526. When an aircraft diverts, or propose to divert, to an aerodrome along a route for which no forecast has been provided, the Pilot may request the relevant, information from the ATS Unit serving the aircraft at the time, and the necessary forecasts will be provided by the associated forecast office. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 526

527. Air-reports received from aircraft in flight containing meteorological information are to be delivered to the associated meteorological office without delay. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 527

528. SIGMET INFORMATION : The term SIGMET information refers to the occurrence and/or expected occurrence of one of more of the following: at subsonic cruising levels : Active thunderstorm area Tropical revolving storm Severe line squall FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 528

529. Heavy Hail Severe turbulence Severe icing Marked mounting waves Widespread sandstorm/dust storm; Volcanic ash cloud FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 529

530. At transonic levels and supersonic cruising levels : Moderate or severe turbulence Cumulonimbus clouds Hail Volcanic ash cloud FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 530

531. For thunderstorms or hail the following is applicable: ISOL = individual CBs (isolated) OCNL = Well-separated CBs Occasional FRQ = widespread within an area with little or no separation FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 531

532. SQL = along a line with little or no separation EMBD = embedded in cloud layer OBSC = concealed in cloud layer or concealed by haze FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 532

533. Aircraft in flight should be warned by the ACC/FIC of any of the above for the route ahead for up to 500nm or 2 hours’ flying time. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 533

534. SUMMARY The Atmosphere Temperature Humidity Atmospheric Pressure Altimetry Winds FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 534

535. SUMMARY CONT’D Wind shear and Turbulence Air in Vertical Motion and Atmospheric Stability Cloud and Precipitation Thunderstorm Visibility and fog FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 535

536. SUMMARY CONT’D Air masses and Fronts Aircraft Icing Meteorological information for Air traffic Services and Search and Rescue Aviation Weather Reports- METAR; - SPECI and - TAF CODES FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 536

537. MASTERY TEST MT.1.1 FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 3. 537

538. DO YOU KNOW THAT I n Bible times - "˜You are able to interpret the appearance of the sky but the sign of the times you cannot interpret.” Book of Matthew 1441 -King  Sejong’s son, Prince Munjong , invented the first standardized rain gauge  1450 -  Leone Battista Alberti developed a swinging-plate anemometer, and is known as the first  anemometer . 1643 -Evangelista Torricelli invented the barometer, Torricelli noticed that air pressure changes in accordance with changes in the weather. In fact a drop in pressure would often signal that a storm was coming.  FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 538

539. DO YOU KNOW THAT CONT’D 1644 - hygrometer was invented 1662 - Sir Christopher Wren invented the mechanical, self-emptying, tipping bucket rain gauge. 1714 – Daniel Gabriel Fahrenheit invented the mercury thermometer 1742 - Anders Celsius, a Swedish astronomer, proposed the 'centigrade' temperature scale, the predecessor of the current Celsius scale 1607 -  Galileo Galilei constructs a  thermoscope FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 539

540. DO YOU KNOW THAT CONT’D 1765 - daily measurements of air pressure, moisture content, wind speed and direction began to be made. This was first done by French scientist Laurent Lavoisier who stated, “ With all of this information it is almost always possible to predict the weather one or two days ahead with reasonable accuracy.” 1783 - the first hair hygrometer is demonstrated by Horace- Bénédict de Saussure. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 540

541. DO YOU KNOW THAT CONT’D 1806 -  Francis Beaufort introduced his system for classifying wind speeds 1854 -  French warship and 38 merchant vessels sank in a fierce storm off the Crimean port of Balaklava April 1960 - launch of the first successful weather satellite, TIROS-1, marked the beginning of the age where weather information became available globally. FS NIGERIAN COLLEGE OF AVIATION TECHNOLOGY, ZARIA 5/10/2018 PPT 1. 541