i was reading a book and it said if theres a thunderstorm when you here thunder start counting 1..2...3....... and when you here it again stop countng and whatever number you land on thats how many miles away the thunderstorm is is that true?
2007-07-13 05:29:17 · 20 answers · asked by vanilla 2 in Science & Mathematics ➔ Weather
The general statment I know is count from when you see lightning to when you hear the thunder (light faster than sound.). I don't think it's 100% scientifically factual, but it is a decent guage to make a guess.
2007-07-13 05:32:16 · answer #1 · answered by pa 5 · 1⤊ 1⤋
Here's the deal, no lie. It is not an urban myth, it's physics. Most of the posters above me are missing the formula.
I learned this in the Navy.
If there are a whole bunch of flashes, it's complicated, because the sound is confused.
But you wait until there is a period of one flash, distinct, then count:
one-thous-and
two-thous-and, (one second each, or look at your watch) etc. until you hear the thunder.
Take the number you got from that.
The speed of sound is the speed at which sound moves through air.
At sea level and standard atmospheric pressure, the speed of sound is 1116.45 feet per second (340.294 meters per second), or 742 miles per hour plus or minus a few, depending on various factors.
There are 5280 feet in a mile.
This means that the sound moves one mile in roughly 4.7 seconds.
Take your number, and divide it by 5. (or 4.7 to be more accurate)
So if it flashes, and you get to 5 thousand, it is pretty close to a mile away.
You do this over a short period, with a few flashes to tell if the general epicenter of the storm and / or lightning are moving closer to your position, or farther away, because sometimes it is not advantageous to move if you are in an exposed position, if the storm will eventually pass by.
(i.e. 75 yards from an enemy position you are observing, you do not want to be around in a tree, or on open ground if lightning is happening on top of you, so it might be better to risk moving, even though random flashes might illuminate you. If it is 2 miles away then 3, it has passed you, so stay put...we used it like that.)
2007-07-13 13:45:28 · answer #2 · answered by A Military Veteran 5 · 0⤊ 0⤋
I was amazed that there could be so many WRONG answers to one question. It just goes to show that you cannot count on Yahoo!Answers for good information. It's best to look it up yourself.
A couple of answers are correct, but they are certainly in the minority.
The flash of light from a lightning strike travels at 186,000 miles per second, and so in practical terms you see the flash at the same instant it happens.
The sound from a thunderclap caused by the same lightning stroke travels at about 1100 feet per second. That is, close to 1/5 of a mile per second. Therefore if you start counting seconds when you see the flash, you can figure it's a mile away for every five seconds. That's an approximation, but it will do for most purposes.
This is fully scientifically based, and real grownups use this idea every day. In the army they also teach it as a good way to estimate the distance to an artillery installation. They call it the "flash-bang" method, and you can call it that, too.
To count seconds, people use various word devices. In the army they teach you to count "One-one-thousand, two-one-thousand, three-one-thousand..." and so on. Some people say, "one-Mississippi, two-Mississippi, three-Mississippi..." and so on, while others say "one chimpanzee, two chimpanzees, three chimpanzees..." and so on. Any word or phrase that takes about a second to pronounce.
Have fun...
2007-07-14 01:22:20 · answer #3 · answered by aviophage 7 · 0⤊ 1⤋
Actually it's when you see lightning you start counting and when you hear the thunder you stop. That does give you an approximate distance of where the lightning occurred. Light travels much faster than sound. So you will see the lightning right away but the thunder takes longer depending on how far you are from the lightning.
2007-07-13 12:33:14 · answer #4 · answered by Gwenilynd 4 · 1⤊ 1⤋
Not quite, you are supposed to start counting when you see a flash of lightning and stop when you hear the thunder. These occur at different times because light travels faster than sound and the difference between the two can be a good estimate of the distance from the storm.
2007-07-13 12:33:04 · answer #5 · answered by Anonymous · 1⤊ 1⤋
Sound travels 345 meters per second.
Not a mile!
If you count till 5 then the thunder is only about 1 mile away!
2007-07-13 12:57:32 · answer #6 · answered by Kinkg 2 · 0⤊ 0⤋
Not sure if it's true. I learned the same thing but it was in kilometers so it might be an urban myth. The accuracy of measurement might be wrong but generally the proximity of the actual thunder storm is closer if you hear the thunder quickly after you see the lightning as they both happen at the same time but light travels faster than sound.
2007-07-13 12:34:34 · answer #7 · answered by sticky 7 · 0⤊ 1⤋
Its actually the time between a flash of lightning and the clap of thunder to determine how far away the lightning strike was. Given the difference between the speed of light and the speed of sound, 1 second per mile is actually a fairly rough estimate, but fairly accurate.
2007-07-13 12:33:58 · answer #8 · answered by jjsocrates 4 · 1⤊ 1⤋
I think what you are referring to is the lightening strike you see and the sound of thunder that comes after it. You see the lightening flash, you count seconds off until you hear the thunder from that flash, that's a rough estimate of how many miles away the lightening was.
2007-07-13 12:34:00 · answer #9 · answered by K 2 · 1⤊ 1⤋
You count from the lightning to the thunder.
And it's about 5 seconds per mile.
I'll find the proof to back that up in a sec...
http://www.wikihow.com/Calculate-the-Distance-from-Lightning
2007-07-13 12:40:02 · answer #10 · answered by Nasubi 7 · 0⤊ 0⤋