How Far Away Is Lightning?
Next time you're stuck in a thunderstorm, try this easy way to calculate how far away you are from lightning strikes.
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00:00How far away is lightning?
00:04Picture it. You're stuck in a thunderstorm and you need to figure out how long you have to take cover.
00:09The last thing you want to do is math.
00:11But here's an easy way to calculate how far away you are from lightning strikes.
00:16When you see a flash of lightning, count the number of seconds that pass between that flash and the crack of thunder that follows it.
00:24Got that number?
00:26Now, divide it by five.
00:29The resulting number will tell you how many miles away you are from where the lightning just struck.
00:35So let's say you see a jagged burst of light and it takes five seconds before you hear the boom.
00:41That means the lightning struck one mile away from you.
00:45A ten second gap means the lightning is two miles away.
00:48This math could keep you safe.
00:51The National Weather Service recommends that you take cover if that time between the flash and the boom is 30 seconds, which means the lightning is six miles away.
01:02There's science behind that calculation, but it's a little complicated.
01:07Light travels 186,291 miles per second, while sound travels just 1,088 feet per second, depending on air temperature.
01:18The gist is that light travels much quicker than sound, so you see the light from the lightning basically in real time.
01:26The sound from the thunder, however, travels much slower.
01:29That's why you can get a distance by knowing how long it took the sound from the thunder to reach your ears.
01:36How far away is lightning? Just another one of life's little mysteries.