Lightning is a huge electrical discharge, or spark, that results from vigorous motions that occur in thunderstorms. While you can be safe in a car in a lightning storm, it is not because of the tires. Rubber tires do act as an insulator but only at low voltages. For comparison, the current in your house is 120 volts and 15 amps, while a typical lightning bolt is about 300 million volts and about 30,000 amps. The voltage in a lightning bolt is too high to be stopped by tires. A lightning strike can blow out your tires or wreck your car’s electronic control circuits.
Inside a car can be a safe place to wait out a lightning storm. If the car is struck by lightning, its metal frame redirects the electrical current around the sides of the car and into the ground without touching the interior contents, including the people inside.
Don’t lean on the doors. The metal frame acts like a Faraday cage, which is a hollow conducting object that protects its interior from electrical fields and currents. Riding around in a convertible, no matter what kind of tires you have, will not protect you, as you are not in a fully enclosed metal cage.
Lightning is very dangerous. About 300 people in the U.S. are injured by lightning each year, and about 62 people are killed. On average there is about one death caused by lightning in Wisconsin annually.
While your chances of getting hit by lightning are only about one in a million in a given year, it is good to keep some safety tips in mind.
Steve Ackerman and Jonathan Martin, professors in the UW-Madison Department of Atmospheric and Oceanic Sciences, are guests on WHA radio (970 AM) at 11:45 a.m. the last Monday of each month.