# Does anyone know how to calculate the distance where a lightning has struck?

I remember when I was a child we learned how to calculate the distance where a lightning has struck by counting the seconds between the time we saw the flash until we heard the thunder. I forgot the number that we multiplied the time by ( I think is the speed of sound). I thought about this after we had a nasty thunderstorm. Does anyone know?

7 years ago
Sound travels at 768mph (in dry air at 20o in a storm it'll be a bit different). 1 second = ~1/5th of a mile, so 5 sec = ~a mile.
But be aware that strikes from high altitude are going to throw the ground-contact point off a bit and you can't measure short periods of time very accurately - it's a rough guide.

L

dacruz7 years ago
hey William i think its that when the lightning strikes count the seconds depending on the seconds, that's how many miles the lightning hit away. for example, if lightning strikes and you count 2 seconds that's roughly about 2 miles.
blkhawk (author)  dacruz7 years ago
Thank you dacruz! That is precisely the number I needed to know and I think is more or less five.
Burf7 years ago
Count the number of seconds from the time you see the lightning flash until you hear the first rumble of the thunder. Divide the number of seconds by 5 to calculate the distance in miles (or divide by 3 for kilometers)
The result is a fairly good approximation of the distance away from you.