What happens if your car's hit by lightning?

Izzie Clarke put this shocking query to the Naked Scientists forum...

Izzie - Alan said that the biggest risk would be reduced visibility in a storm and the likelihood of an uncontrolled skid.

Evan thought that it was all down to the design of the car’s electronics.

So to get to the bottom of this electrifying question, we asked Philip Garsed from the University of Cambridge to strike up an answer…

Philip - A lightning strike last a hundred millionths of a second. Tens of thousand of amps heat the air to 50,000 degrees and make it explode. Your questioner is right to wonder where the safest place to be in a lightning storm is, and the car is a pretty good bet, but you probably don’t really want to be struck whilst you’re driving one.

A car conducts electricity far, far better than the surrounding air and when lightning strikes a metal car with a metal roof, the enormous current flows easily through the body of the vehicle and so it goes around the occupants rather than through them. It’s kind of like the electrical equivalent of building a bypass. Traffic goes around a town rather than through the middle of it.

Izzie - This is what's known as a Faraday cage and you’ll be safe as long as you remain completely inside the vehicle and not disrupt the current flow. So whilst it’s good news for you, the lightning strike won’t be good news for your car…

Philip - Although the worst of a lightning strike will go through the chassis, modern cars use lots of sensitive electronics. In the best case, that sudden burst of interference from the lightning would cause a lot of them to develop faults. But, more likely, those circuits will see currents they were never designed for and be permanently damaged.

Izzie - Ahh. That doesn’t sound good. And, according to Philip, there are a few other threats if you’re on the road at the time…

Philip - The biggest problem is likely to be how you respond. Because we know that you’ll probably be unharmed by the actual strike, but the problem is everything else that might happen. The thunder will make you jump, the lightning will dazzle you, you'll lose your lights, trigger the airbags, or perhaps even have a nice little electrical fire on your dashboard and, also, probably some of your tyres have exploded.

Of course, it’s pretty unlikely that your car will get struck by lightning  in a thunderstorm unless you're in a very exposed place.

Izzie - But, perhaps little a bit of space behind the car in front just in case. Thanks Philip for clearing that up.

Next week we’re picking at this question from Patrick…

Why, oh why, am I unable to stop picking my nose? What is it that makes it so satisfying and addictive? Is there an evolutionary reason behind it? Also, why do some other people eat what comes out?