Agrometeorology: Campbell stokes sunshine recorder & Rain gauge

This presentation covers briefly about two equipments used to record the weather data for Agricultural research...

1. AGROMETEROLOGY AND CLIMATE CHANGE(AGR122) By: MURALI B.L 3 rd Bsc.(Hons) Agriculture University of Agricultural sciences Bengaluru

2. CAMPBELL-STOKES SUNSHINE RECORDER

3. CAMPBELL-STOKES SUNSHINE RECORDER CSSR is defined as a type of sunshine recorder which is used to measure duration and intensity of solar radiation. CSSR was invented by John Francis Campbell in 1853 , which was modified by George Gabriel stokes in 1879 .

4. PARTS OF CSSR GLASS SPHERE METALLIC FRAME HEMISPHERICAL BOWL CHEMICAL CARDS

5. GLASS SPHERE A glass sphere of diameter 10cm and refractive index of 1.5micron. It is fixed centrally to a frame. It acts as a converging lens.

6. DIFFERENCE CAMPBLL’S RECORDER STROKES MODIFICATION 1. Glass sphere set into wooden bowl 1.Wooden bowl was replaced by metallic hemispherical bowl in both of these working principle remains same

7. METALLIC FRAME A metallic frame to which glass sphere and hemispherical bowl is attached The frame is mounted on a base with 3 leveling screws, which is kept on a platform of height of 10 feet from ground surface.

8. HEMISPHERICAL BOWL Below the glass sphere, a metallic hemispherical bowl is rigidly fixed to frame. The bowl has 3 slots/grooves through which chemically treated cards are inserted

9. TYPES OF CARDS LOND CURVED CARDS SHORT CURVED CARDS STRAIGHT CARDS Also called as “ summer cards ”. Also called as “ winter cards ”. Also called as “ equinox cards ”, where day and night lengths are equal. These are used from 13 th April to 31 st August. These are used from 13 th October to end of February. These are used from 1 st March to 12 th April and 1 st September to 12 th October Introduced through bottom slot in concave plate. Introduced through top slot. Introduced through middle slot.

10. PRINCIPLE Sunrays are concentrated on a chemically sensitized card by spherical lens. This card produces a trace as sunrays fall during the hours of bright sunshine. As the card is graduated in hours and tenths, the daily duration of sunshine can be easily determined.

11. BURNING TRACES ON CARDS

12. Measurement and inference Duration of bright sunshine hours can be analysed by measuring length of burnt trace. Intensity of solar radiation will be measure based on width of burnt trace. If there is a continuous burnt symptom it indicates a bright day. If there is intermittent burnt symptom it indicates cloudy day.

13. Precaution Care should be taken to use appropriate cards according to the season. The sunshine recorder is kept on a platform at a height of 10 feet from the ground surface. Sunshine recorder is kept on perfectly horizontal plane by leveling screws to adjust it. Spherical ball should be placed in such a way that the solar radiation should fall on spherical ball without any interruption i.e from East to West direction.

14. Disadvantage It requires manual observation of burnt marks on record cards and manual change of cards.

15. RAIN GUAGES INTRODUCTION ON RAIN GAUGES A rain gauge is a type of instrument used by meteorologists and hydrologist to gather and measure amount of rainfall over a period of time .

16. TYPES OF RAIN GAUGES Ordinary type of rain gauge or symon’s rain gauge Siphon rain gauge Bucket tipping type of rain gauge

17. ORDINARY TYPE OR SYMON’S RAIN GAUGE

18. DEFENITION AND INTRODUCTION Definition : It is a type of rain gauge which is used to measure the amount of rain fall . Introduction : It is a non automated observatories. With this device the observer takes measurements using rain measuring glass in regular interval. It is an completely sealed instrument .

19. PARTS OF ORDINARY TYPE OF RAIN GAUGE Funnel Outer jacket Receiver Base Measuring cylinder

20. PARTS OF RAIN GAUGES

21. PARTS EXPLAINATION OUTER JACKET : it is the outer most covering of Receiver, It is made of galvanized iron sheet of 12 gauge thickness, or fiber ,glass or plastic. It houses the collecting jar and also receives the overflow of rain water from it.

22. FUNNEL It is a receptacle of Rainwater, it is 30cm height with 15.9cm diameter . Where Base area is wider than top because to reduce surface tension .

23. RECEIVER OR COLLECTING JAR Collecting jar is storage vessel which is placed 30cm depth from ground surface .

24. BASE It is completely sealed concrete structure which avoid runoff or leakage of water .

25. MEASURING CYLINDER it is a transparent cylindrical structure with graduations to measure amount of precipitation It ranges from 0.1 mm to 20 mm It is 10 times reduced than collecting jar

26. WORKING PRINCIPLE When it rains, water enter the gauge from top of the rim of funnel which is lead to receiver. The rain water thus collected is measured with the help of measuring cylinder

27. PRECAUTIONS Rain gauge should be kept on a hard compact levelled platform partially buried grant. It should be buried in such A way that rim should be at height of 80cm above the ground level. Rain gauge should be checked for leaks and dust particles. Measuring cylinder should be clean .

28. TIPPING BUCKET RAIN GUAGE

29. BUCKET TIPPING TYPE OF RAIN GUAGE IT IS TYPE OF RAIN GUAGE WHICH IS USED TO MEASURE BOTH INTENSITY AND AMOUNT OF RAIN FALL Generally installed in AUTOMATIC WEATHER STATION A type of rain guage generates an electric signal or pulse for each unit of precipitation

30. PARTS OF RAIN GUAGE FUNNEL RECEIVER FILTER TIPPING BUCKET SENSORS DRAIN CYLINDER

31. pRINCIPLE 1. The reservoir or bucket is so small that It houses only 0.5mm of rain fall 2.When the exact volume has been collected, bucket automatically tips the sensor and water is emptied 3.This tipping action is sensitized by sensor

32. OPERATION AND MEASURMENT This is an automated device in which water enters through the funnel and is accumulated in the bucket of certain volume When exact volume of water is filled in bucket ,tipping mechanism is sensitized by sensors Then it is recorded in the computer automatically

33. NOTE :- 1 tipping action = 0.5mm of rainfall PRECAUTIONS : - The rim of rain guage collector should be sharp and durable There should not be any kind if damage or bending of bucket , it causes error in readings Depending upon the maximium intensity of rainfall for a given location the tipping bucket rainguage with sutiable sensitivity should be selected

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