Hurricanes get their start over the warm tropical waters of the North
Atlantic Ocean near the equator. Most hurricanes appear in late summer or early
fall, when sea temperatures are at their highest. The warm waters heats the air
above it, and the updrafts of warm, moist air begin to rise. Day after day the
fluffy cumuli form atop the updrafts. But the cloud tops rarely rise higher than
about 6,000 feet. At that height in the tropics, there is usually a layer of
warm, dry air that acts like an invisible ceiling or lid.
Once in a while, something happens in the upper air that destroys this lid.
Scientist don not know how this happens. But when it does, it's the first step
in the birth of a hurricane.
With the lid off, the warm, moist air rises higher and higher. Heat energy,
released as the water vapor in the air condenses. As it condenses it drives the
upper drafts to heights of 50,000 to 60,000 feet. The cumuli become towering