When the rising air cools, its water vapor condenses. The updrafts create tall cumulonimbus clouds. Winds blow the cloud top sideways. This makes the well-known anvil shape of a cloud known as a thunderhead (Figure below).

How are cumulonimbus formed?

Cumulonimbus clouds are born through convection, often growing from small cumulus clouds over a hot surface. ... They can also form along cold fronts as a result of forced convection, where milder air is forced to rise over the incoming cold air.

How does a cumulonimbus cloud form for kids?

A cumulonimbus cloud is made of very tiny drops of water. But because these clouds grow so high in the sky, the drops of water freeze higher in the cloud as the temperatures get colder. This makes the outline of the top of the cloud look a little fuzzy, without clear edges.