Around the year 2000, Dr. Hugh Christian and Dr. Richard Blakeslee and their NASA colleagues at the National Space Science and Technology Center in Huntsville, Alabama, used new detector sys tems orbiting Earth in satellites to monitor lightning. They discovered for the first time that the global distribution of lightning depends on the latitude, longitude, and time of the year.

This new technology has provided a more accurate picture of lightning activity. The scientists discovered that lightning occurs half as often as previously estimated. Before their studies, people thought that about one hundred lightning flashes per second struck the planet. But Christian and his colleagues discovered that lightning peaks in the Northern Hemisphere in summer at forty-five flashes per second.

The scientists also discovered that the place where people have the best chance of getting hit by lightning twice is central Africa because...