Formation of Clouds

Written by earthfacts.net

Clouds are formed of masses of water droplets (which may remain in a liquid state as supercooled droplets at temperatures as low as -40°C) and ice crystals. They are classified according to their shape and height above ground level.

Generally, there are two main cloud shapes. Cumuliform, or heap, clouds have considerable vertical depth. They form in air that is rising fairly quickly and steeply. The highest cumuliform cloud, the cumulonimbus or thunderstorm cloud, may measure more than 4,000m between its dark, heavy base and its often anvil-shaped top. Stratiform, or layer, clouds, on the other hand, are thin sheets spread across the sky. They generally form when air rises slowly and at relatively gradual gradients.

Temperatures fall at a fairly constant rate (up to altitudes of about 10km) of about 0.65°C for every 100m increase in height. But in fast-rising air, the release of heat associated with condensation may make the rising air much warmer than the surrounding air. This effect reinforces the upward movement, heightening the cloud and creating unstable conditions that lead to precipitation from the clouds.

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