Five second delay

Ever since I was a child, whenever I see lightning I start to count. It all has to do with physics.

Sound travels through air at around 1,000 feet per second. So it takes about five seconds for sound to travel a mile (5280 feet).

Since light travels, well, at the speed of light, we see a lightning strike essentially instantaneously. But the accompanying sound of thunder takes longer.

For every mile of the distance between you and lightning, there will be about a five second delay before you hear the thunder. For example, a lightning strike two miles away will be accompanied by a clap of thunder after about ten seconds.

Late last night there was a thunder storm, so I started counting in my bed. Until, that is, I saw a flash of lightning and heard a clap of thunder at pretty much the same time.

That’s when I hid under the covers and wished I didn’t know so much physics.

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