The classification of the clouds is done on the basis of their shapes and their heights in the sky. The clouds are classified according to height, expanse, density and transparency or opaqueness.
♦ Cirrus (8000-12,000m elevation): formed at high altitude. Thin and detached clouds having feathery appearance. They are white in colour.
♦ Cumulus (4,000-7,000m elevation): they look like cotton wool. They are scattered here and there and have a flat base.
♦ Nimbus: these clouds are formed near the surface of the earth and are extremely dense and opaque. They are shapeless clouds. They are blackish to dark greyish in colour. These are rain clouds.
♦ Stratus: they cover large portion of the sky and appear as layers in the sky. They generally form in combination with other types of clouds, for example: Cirro-stratus, nimbo-stratus.
♦ Cumulus clouds give the sign of upcoming rain.
♦ Cirrus clouds and cumulus clouds are responsible for good weather.
♦ Nimbus clouds create heavy thunderstorm with heavy rain.
