Rick Dalton, age 14, of Indianapolis, Ind., for his question:

HOW IS A FUNNEL CLOUD FORMED?

A funnel cloud is part of a powerful twisting wind storm called a tornado. About 700 of them are sighted  in the United States each year during spring and early summer.

A funnel cloud may form when a front of cool, dry air from the north meets a front of warm, humid air from the Gulf of Mexico. A narrow zone of thunderstorm clouds will often develop. The area is called a squall line and results when the warm air rises extremely rapidly and more warm air rushes in to replace it. The inrushing air also rises and often begins to rotate, thus forming the action of a funnel cloud.

Rounded masses at the bottom of the clouds then start to twist. One of the twisting masses then forms a funnel that extends downward to earth. If the funnel touches the ground, huge dust clouds form and almost everything in its path can be destroyed.