Clouds are a visible mass of small water drops or ice crys- tals formed by the condensa- tion of water vapour in the atmosphere, usually at a considerable height above the earth’s surface. Clouds are caused mainly by the adiabatic cooling of air below, its dew point.
Clouds are grouped by whether they are high, medium, or low clouds. There are ten basic cloud types.
These clouds are high, white & thin. They are composed of ice crystals. They form delicate patches and give a fibrous and feathery appearance. Other high clouds include cirrostratus and cirrocumulus.
These low clouds have a flat base and have the appearance of rising domes. These clouds are often described as having cauliflower structure. Other types of low clouds are: stratocumulus, stratus, nimbostratus, and cumulo nimbus.
These low clouds are fairly thin and blanket like. Subdivided into high clouds, medium clouds and low clouds.
Types of medium clouds include: altocumulus, nimbostratus, and altostratus. Alto and Nimbo are the two prefixes which refer to middle level clouds and low clouds of considerable thickness with dark grey appearance respectively.
Precipitation is the formation of water particles or ice within the cloud that falls towards the earth’s surface. It occurs when con densation takes place rapidly within the cloud. Precipitation in the form of ice pellets (hail stones) that develops in and fall from cumulo nimbus clouds, either at a cold front or where intense heating of the surface causes rapidly ascending convection currents called Hails.