introduction to Different TYPES OF CLOUDS.pptx

weather and climate

1. MOISTURE IN THE ATMOSPHERE [ FORMS OF PRECIPITATION ] GRD_10_GEO

2. Formation of Clouds Heat received on the ground makes warm and moist air to rise as water vapour The warm, moist rising air cools adiabatically at higher altitudes Further cooling of air results into condensation at dew point temperature Tiny water droplets form around a nuclei such as salt and dust particles The water droplets or ice crystals become suspended above ground surface or float within the atmosphere as clouds

3. How clouds form?

4. Cirroforms – these are high clouds found at very high altitudes of about 12 km above sea level. They are thread-like or feathery clouds that consist of mainly ice crystals. Altoforms – are middle clouds found between 2.1km and 6 km above sea level. There are two types of altoforms being the Altocumulus and Altostratus . The Altocumulus are globular or slightly rounder in shape while the Altostratus are thin layered clouds i.e. occur in layers. Stratoforms – are layered clouds. They may be found at ground level as mist or fog. However, they may also develop into dark grey layered clouds capable of bringing rainfall e.g. the Nimbostratus clouds. Cumuliforms – are globular clouds capable of bringing convectional rainfall associated with thunder and lightning such as the cumulonimbus clouds.

5. Reasons for Cloud Formation

6. Extent of cloud cover presentation

7. HUMIDITY Humidity – the amount of water vapour (moisture) in the atmosphere. Relative humidity (RH)– the amount of moisture in the air compared to what the air can hold at that given temperature (expressed as a percentage) As the air gets warmer, the amount of water vapour it can hold increases. When RH is 100% - the air is said to be saturated i.e. has reached condensation level and can not hold any other moisture therefore it rains. The maximum amount of water vapour that air can hold at a particular temperature is called water vapour capacity RH is used in weather forecasts to predict chances of rain .

8. A rise in RH also increases temperature in humans through prevention of evaporation from sweat (discomfort index) e.g. according to the Heat index, an RH of 75% at 27 degrees Celsius will feel like 29 degrees Celsius in humans. RH = Actual humidity (absolute) ÷ water vapour capacity × 100 If a weather station has a water vapour content of 9g/m 3 and the water vapour capacity is 30g/m 3 . Calculate the relative humidity at that station . Answer 9g/m 3 ÷ 30g/m 3 × 100 = 30% Factors that influence RH capacity to reach 100% Rate of evaporation - Amount of water vapour (WV)/moisture in the air: if the WV content increases, the RH will increase. Increase in evaporation. Temperature: if the air temp drops, the WV capacity will also drop. Decrease in evaporation

9. FORMS OF PRECIPITATION

10. FORMS OF PRECIPITATION FROST DEW

11. FORMS OF PRECIPITATION desublimates

12. Dew and frost

13. FORMS OF PRECIPITATION HAIL SNOW

14. FORMS OF PRECIPITATION

15. TYPES OF RAINFALL

16. RELIEF/OROGRAPHIC RAINFALL

17. CONVECTIONAL RAINFALL

18. CONVECTIONAL RAINFALL

19. FRONTAL/ CYCLONIC RAINFALL

20. RAINFALL DISTRIBUTION