Science Questions

If lightning strikes a pool you’re in are you fried?

I understand that water’s quite a good insulator. If lightning strikes a pool you’re in are you fried? If that’s the case then how about if you’re in a lake? Bill Gettys

We answered this along with Robert Sullivan's question...

When lightning hits water, it suddenly dumps a huge amount of energy into the bit of water it’s hitting – so very close to where it’s hit it will form steam.  When lightning hits sand it releases so much energy it causes sand to melt and turn into glass.  It would probably vapourise the water near where it’s hit and cause a bubble of steam which probably will cause a splash.

If you’re swimming and lightning hits a lake it is actually very, very dangerous.  If lightning hits the middle of a lake water has got some salts in it so it will conduct electricity a bit.  You would conduct electricity better.  So if you’re swimming in a lake and there’s a big current from the lightning strike flowing through the lake it sees you as a kind of ‘short’ as it can jump 2m to an easy path.  So it will flow through you.  You’d get a big current flowing through you which would be very dangerous.  It can stop your heart which is why I was told in the States that you don’t go swimming in a thunderstorm.

The fish could end up fried as well then!

January 2008