Essay by The ReaperHigh School, 12th gradeA+, May 2005

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Meteorology is the study of the earth's atmosphere and especially the study of weather. A meteorologist is a person who studies the atmosphere.

One of nature's displays of electrical forces is the lightning storm. A lightning stroke is a brief but large current of negative charge that travels from cloud to ground along a "wire" of air molecules that have been ionized or ripped apart. The awesome power of the lightning stroke originates in the thunderstorm cloud where charges somehow become separated. There are several complicated theories that try to explain the actual mechanism of this charge separation, but no one really knows what pulls the charges apart in a thunderstorm cloud.

Since the ground beneath the cloud has far fewer negative charges on it than the bottom of the cloud, there is an attraction between the ground and the bottom of the cloud. As these electrons move, they bash into air molecules that are in their way, breaking the molecules up and creating more charged fragments.

All the new negative fragments are dragged downward along with the original electrons.

This would keep going if there weren't for the heavier and slower positive charges that are left behind. They tend to attract the accelerating electrons back toward the cloud. But more electrons are continually being freed up in the cloud, and they stream to the slowing electrons below, reinforcing their race downward. This process of electrons slowing and then being reinforced repeats itself over and over again. The original electrons make their way in jerky 150-foot steps along a twisting path toward the ground. This forms what is called a "stepped leader." The stepped leader takes about 5/1000 of a second, moving at about 240 miles per second, to reach from cloud to ground. When either the stepped leader reaches...