Most thunderstorms contain three phases: (A) the cumulus stage; (B) the mature stage; (C) dissipating stage.
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Thunderstorm Formation

Most thunderstorms contain three stages: the cumulus stage, the mature stage, and the dissipating stage.

Cumulus Stage
During the first phase, the sun heats the ground during the day, which then heats the air. Since warm air is lighter than cool air, it starts to rise. If the air is moist, then the warm air condenses into a cumulus cloud. The cloud will continue to grow as long as warm air below it continues to rise.

Mature Stage
When the cumulus cloud becomes very large, the water in it becomes large and heavy. Raindrops start to fall through the cloud when the rising air can no longer hold them up. At the same time, cool dry air starts to enter the cloud. Because cool air is heavier than warm air, it starts to go lower in the cloud. This pulls the heavy water downward, which makes rain.

This cloud has become a cumulonimbus cloud. Thunder and lightning start to occur, as well as heavy rain. The cumulonimbus is now a thunderstorm cell.

Dissipating Stage
After about 30 minutes, the thunderstorm begins to break up. The storm dies out with light rain as the cloud disappears from bottom to top.

The whole process takes about one hour for a normal thunderstorm. Supercell thunderstorms are much larger, more powerful, and last for several hours.

Last modified May 27, 2010 by Becca Hatheway.

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