thunder and lightning

[Immortal298]

there was a delicious storm here yesterday and i automatically counted the seconds between the lightning flashes and the thunder.  i was thinking about it and i know that i count cos when i was a kid i was told it could tell u how far away the storm was.  is that right?  and is it one second per mile?

[Sequin]

At 20C, the speed of sound in dry air is 1127 feet per second (343 m/s)

Therefore the sound would take 4.6 seconds to travel a mile (5760 feet).

Sound will travel faster in wet air, so if you approximate 4 seconds for every mile, you won't be far wrong

[Immortal298]

huh, all i understood was that last bit :)  the rest went right over my head.  thanks anyway :)

[mycatis]

lol Immortal298  Thats how I've always done it, still do. Isnt thunder and lightning coooool?

[brassmonkey7]

It is 5 seconds per mile

[jake-the-peg]

Imortal

The point is that the lightning strike generates the noise you hear as thunder.

You see the lightning immediately but it takes some time for the sound of the thunder to reach your ear

The thunder travels at the speed of sound, so in the time it takes you to count 4 seconds the thunder has managed to travel a mile