Freedman, David H. Bolts From the Blue. Discover Magazine. Vol. 11 No. 12. December, 1990.

Abstract: This article explains the physics of lightning. In detail, the article explains how separated positive and negative charges in clouds result in lightning flashes. The article also explains the different types of lightning. A single lightning flash usually consists of several lightning flashes and each one takes about one fiftieth of a second. Another type of lightning has continuous currents that can last one full second. This type of lightning is very dangerous and is usually responsible for starting forest fires. Scientists do not know much about lightning, especially why it occurs. There are conflicting theories, none of which have been proven correct. One theory credits precipitation as the cause of lightning. The other popular theory states that convective updrafts and downdrafts are responsible for the electrical outbursts. The other important question scientists are struggling to answer is how lightning chooses its targets. Experiments are currently underway to explain this mystery.