Clouds : Definition, types and Importance in water cycle

When we look at the sky , we see clouds of different types based on the seasons.  Do you know clouds have been differentiate based on their shapes, colour and height ?.

So before starting on types of clouds , we should understand "What is cloud?"

Cloud is a mass of minute water droplets or tiny crystals of ice formed by the condensation of the water vapour in free air at considerable elevations. So cloud plays an important role in water cycle on earth. Water is transported from oceans to various parts of earth surfaces in form of  clouds.

As the clouds are formed at some height over the surface of the earth, they take various shapes. According to their height, expanse, density and transparency or opaqueness clouds are grouped under four types : cirrus,cumulus, stratus and  nimbus.

Cirrus clouds 

Cirrus clouds are formed at high altitudes (8,000 - 12,000 m). They are thin and detached clouds having a feathery appearance. They are always white in colour.

Cumulus clouds 

Cumulus clouds look like cotton wool. They are generally formed at a height of 4,000 -7,000 m. They exist in patches and can be seen scattered here and there. They have a flat base.

Stratus clouds

As their name implies, these are layered clouds covering large portions of the sky. These clouds

are generally formed either due to loss of heat or the mixing of air masses with different temperatures.

Nimbus Clouds

Nimbus clouds are black or dark gray. They form at middle levels or very near to the surface of the earth. These are extremely dense and opaque to the rays of the sun. Sometimes, the clouds are so low that they seem to touch the ground. Nimbus clouds are shapeless masses of thick vapour.

A combination of these four basic types can give rise to the following types of clouds: 

high clouds – cirrus, cirrostratus, cirrocumulus;

 middle clouds – altostratus and altocumulus;

low clouds – stratocumulus and nimbostratus

and clouds with extensive vertical development – cumulus and cumulonimbus.

Reference : NCEART Class 11