Cloud Formation
Clouds form when damp air is cooled, usually by rising. This may happen in three ways :
1. When a wind rises to cross hills or mountains.
2. When a mass of air rises over, or is pushed up by another mass of denser air.
3. When local heating of the ground causes convection currents.

Cloud Types

Cirrus are detached clouds composed of microscopic ice crystals which gleam white in the sun resembling hair or feathers. They are found at heights of 6 000 to 12 000 meters.
Cirrostratus are a whitish veil of cloud made up of ice crystals through which the Sun can be seen often producing a halo of bright light.
Cirrocumulus is another high altitude cloud formed by turbulence between layers moving in different directions.
Altostratus is a grey or bluish straiated, fibrous or uniform sheet of cloud producing light drizzle.
Altocumulus is a thicker and fluffier version of cirrocumulus, it is white and grey patchy sheet of cloud.
Nimbostratus is a dark grey layer of cloud obscuring the sun and causing almost continuous rain or snow.
Cumulus are detached heaped up, dense low clouds. The sunlit parts are brilliant white while the base is relatively dark and flat.
Stratus forms dull overcast skies associated with depressions and occurs at low altitudes up to 1 500 meters.
Cumulonimbus are heavy and dense clouds associated with storms and rain. They have flat bases and a fluffy outline extending up to great altitudes.

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