About 2000 thunderstorms occur worldwide at any time. Lightning—the visible discharge of atmospheric electricity—strikes Earth 100 times per second, or more than 8 million times a day. The power in a strike can be immense: up to 10 trillion watts. An average bolt carries 20,000 amperes of current, while the most powerful lightning bolts carry more than 300,000 amperes.
Every year, lightning kills hundreds of people and damages or destroys billions of dollars in property. Only 0.2 amperes, or 0.001 percent of the current in the average bolt, is needed to stop a person's heart. Besides direct hits, near misses also prove dangerous. When lightning strikes the ground, the current fans out across the earth. A portion of the current can travel through the body of a person standing nearby, resulting in injury or, in 10 percent of the time, death.
Electronic devices react even more sensitively to lightning than humans, often breaking at currents less than 0.001 amperes, or 0.000005 percent of the strength of the average bolt. Electromagnetic fields emitted from a lightning bolt can damage electronic devices more than a kilometer and a half away.