How Lightning Works

Lightning Safety

Lightning is one of nature's most dramatic, and also one of its deadliest, meteorological events. According to the National Weather Service, in 2020 there were 17 direct lightning fatalities in the U.S., compared with 20 in 2019. From 2010 to 2019, on average, 26 people died each year from lightning strikes in the United States. Most fatalities happen when people venture outside or into the water before the danger of being struck has passed. A good rule for deciding whether it's safe to venture outside is to count the number of seconds between a lightning flash and a roll of thunder. Since it takes the sound of thunder about five seconds to travel a mile, if you hear thunder within 30 seconds of seeing the lightning flash, the storm is close enough to be dangerous. After the storm, remain indoors for at least 30 minutes after hearing the last clap of thunder.

If you are caught outside in a storm, always look for appropriate shelter. Do not take any chances — lightning can use you as a path to earth just as easily as it can use any other object. Appropriate shelter would be a building or a car. If you do not have anywhere to go, then you should make for the lowest possible ground like a valley or ravine. Avoid taking shelter under trees or near metal objects like fences and poles, or huddling up with other people in a group — spread out from your friends as much as you can.

If you are indoors, stay away from plumbing pipes (bath tub, shower). Lightning has the ability to strike a house or near a house and impart an electrical charge to the metal pipes used for plumbing. This threat is not as great as it used to be, because PVC (polyvinyl chloride) is often used for modern indoor plumbing. If you are not sure what your pipes are made of, wait it out.

For more information on lightning and related topics, check out the links on the next page.

Lightning Myth #4

Rubber tires aren't why you're safe in a car during a lightning storm. In strong electric fields, rubber tires actually become more conductive than insulating. You're safe in a car because the lightning will travel around the surface of the vehicle and then go to ground. This occurs because the vehicle acts like a Faraday cage. Michael Faraday, a British physicist, discovered that a metal cage would shield objects within the cage when a high potential discharge hit the cage. The metal, being a good conductor, would direct the current around the objects and discharge it safely to the ground. This process of shielding is widely used today to protect the electrostatic sensitive integrated circuits in the electronics world.