Science Questions

Why does lightning rumble?

Sun, 29th Jul 2007

Listen Now    Download as mp3 from the show Naked Science Question & Answer Show


Andrew asked:

A lightning strike only takes a few thousandths of a second, why do you hear it as a long rumble?


If a lighting strike is very close to you it sounds like a very sharp crack and then a bit of a rumble afterwards, the further away you get the longer the rumble can sound.  So a lightning bolt will make a sharp short noise, but first of all the noise is produced along a line up to a couple of kilometers long (if you live in Arizona), so because sound travels at 330m/s it could take up to 6 seconds for the sound from the top to reach you so the sound will be spread out over several seconds.  The sound is then further spread out as you move further away from the lightning because the sound can get to you directly or by bouncing off things.  This means that the sound will take lots of different times to get to you and therefore be spread out over several seconds as a rumble.


Subscribe Free

Related Content

Not working please enable javascript
Powered by UKfast
Genetics Society