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Key Idea 5
Energy and Phase Changes
Concept Question: What is the role of energy in phase changes?

Few weather phenomena are more dramatic than a thunderstorm. Flashes of lightning, rolls of thunder and torrents of rain combine to produce an awe-inspiring event. Although you may not have carefully thought about it before, a thunderstorm is a rapid and intense release of energy.

An image of a thunderstorm

The massive release of energy that occurs during a thunderstorm is caused by the condensation of huge amounts of water vapor into liquid water. All phase changes involve energy transfers; condensation specifically is accompanied by the release of energy. In a thunderstorm, the energy associated with condensation is released in dramatic fashion, causing strong winds and violent precipitation as rain and sometimes hail (the production of lightning, however, is caused by a different process).

Let us explore the energy transfers associated with phase changes.