Thunder & lightning

[stevie-p]

When i was young i was told that you could work out how far away a storm was by counting the time between the above...anyone remember how?

[jenstar]

Sound takes about five seconds to travel a mile, so count the seconds and divide by five to obtain the approximate distance in miles.

[heathfield]

Or (approximately) 345 metres per second

[mibn2cweus]

FLLAASH!!! . . . "One thousan" . . . CRRAACK!!! . . . DAM, That was close.

[dyli795]

jenstar, it's only off the top of my head, I haven't researched it or anything, but at this point in time, I can not believe that sound takes five secconds to cover one mile.
As a little lad my dad told me to count the secconds after a lightning flash and there is the distance in miles.

[dyli795]

Neither do I believe sound covers one mile in a fifth of a seccond. (perhaps if it had a torch beam behind it who knows?)

[mibn2cweus]

speed of sound

[sddsddean]

Speed of sound in air at sea level is (roughly) 700mph =
11 2/3 mp minute = 0.194mp second. So in 5secs it covers 0.972 miles; which is close enough to 1 mile for me.

[tomd]

Yes - taking a speed for sound in air as 330 metres per second, in 5 seconds the sound would travel 1 650 metres, which is 1.025 miles.

Sound travels surprisingly slowly, at large concerts with multiple speakers further back though the crowd they even have to delay the signal fed to them, to co-incide with the arrival time of the sound from stage.