The Naked Scientists Forum

Author Topic: The sound of Thunder  (Read 3732 times)

paul.fr

• Guest
The sound of Thunder
« on: 08/03/2007 19:19:35 »
It is often said that you can tell how far off a thunder storm is by counting the seconds between the flash of lightening and the sound of thunder.

But how true is this? Does anyone know?

lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
The sound of Thunder
« Reply #1 on: 08/03/2007 19:35:11 »
It is often said that you can tell how far off a thunder storm is by counting the seconds between the flash of lightening and the sound of thunder.
But how true is this? Does anyone know?
You see the flash and you start your chronometer. When you hear the bang, you stop it.
Seconds*340 = distance in metres (sound's speed in the air = 340 m/s). Where is the problem?
« Last Edit: 08/03/2007 19:37:03 by lightarrow »

daveshorts

• Moderator
• Neilep Level Member
• Posts: 2583
• Physics, Experiments
The sound of Thunder
« Reply #2 on: 09/03/2007 10:11:57 »
It is very true, it works because light moves so fast that over the sort of distances yo ucan hear thunder it is essentially instant, but sound travels 1km in about 3 seconds, so if you time the difference in time between when you see the lightning and when you hear the sound it makes from this you know how long the sound took to get to you and therefore how far away the lightning was.

elegantlywasted

• Hero Member
• Posts: 573
The sound of Thunder
« Reply #3 on: 09/03/2007 12:59:47 »
Wait a minute... 3 seconds is equal to 1km???? I worked outdoors on a farm last summer and we weren't allowed to come inside unless there was a 5 second delay... I knew they were hoping we'd fry in those greenhouses

FreeThinker

• First timers
• Posts: 3
The sound of Thunder
« Reply #4 on: 13/03/2007 16:18:26 »
It's 5 seconds per mile.

daveshorts

• Moderator
• Neilep Level Member
• Posts: 2583
• Physics, Experiments
The sound of Thunder
« Reply #5 on: 14/03/2007 16:36:09 »