Description

Cumulonimbus (Cb) (Cb) clouds, in which Thunderstorms are found, form when three conditions are met:

• There must be a deep layer of unstable air.
• The air must be warm and moist.
• A trigger mechanism must cause the warm moist air to rise:
  • Heating of the layer of air close to the surface.
  • Rising ground forcing the air upwards (orographic uplift).
  • A front forcing the air upwards.

A Cumulonimbus Cloud develops in three distinct phases: