May 22, 2001
A crash of lightning displays the awesome power of a summer thunderstorm! In central Arizona, such thunderstorms are characteristic of the monsoon -- a seasonal shift in wind direction which brings air from the Gulf of Mexico. Pushed up by desert mountain ranges, this warm, moist air collides with cooler air, producing a violent combination of rain, wind, and lightning. A lightning strike can deliver 100,000 amperes of current at millions of volts, and heats the surrounding air to 50,000 degrees Fahrenheit! Such incredible energy is an obvious danger to people and property. This photograph (a 90-second nighttime exposure during which passing cars made the streaks of light in the foreground) was taken from several miles away with a telephoto lens; before the storm moved nearer, the photographer had already left to find shelter.