advise or assist a pilot on thunderstorm avoidance. The turbulence within most
thunderstorms is considered one of the worst hazards of flying.
Thunderstorm Stages
The life cycle of a thunderstorm cell consists of three distinct stages: the cumulus stage,
the mature stage, and the anvil or dissipating stage. These stages are depicted in
Figure 1-11.
Figure 1-11 -- Thunderstorm stages.
Cumulus Stage
Although most cumulus clouds do not become thunderstorms, the initial stage of a
thunderstorm is always a cumulus cloud. The chief distinguishing feature of this
cumulus or building stage is an updraft which prevails throughout the entire cell. Such
updrafts vary in speed from a few feet per second to as much as 100 feet per second in
mature cells.
1-27