What causes thunder?

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‘Lightning causes thunder! Energy from a lightning channel heats the air briefly to around 50,000 degrees Fahrenheit, much hotter than the surface of the sun. This causes the air to explode outward. The huge pressure in the initial outward shock wave decreases rapidly with increasing distance and within ten yards or so has become small enough to be perceived as the sound we call thunder.

Thunder can be heard up to 25 miles away from the lightning discharge, but the frequency of the sound changes with distance from the lightning channels that produce it, because higher frequencies are more quickly absorbed by the air. Very close to lightning, the first thunder you hear is from the closest channels, which produce a tearing sound, because that thunder contains high frequencies. A few seconds later, you hear a sharp click or loud crack from lightning channels a little farther away, and several tens of seconds later the thunder from the most distant part of a flash has quieted to low frequency rumbling.

Because light travels through the air roughly a million times faster than sound does, you can use thunder to estimate the distance to lightning. Just count the number of seconds from the time you see a flash until you hear lightning. Sound travels approximately one fifth of a mile per second or one third of a kilometer per second, so dividing the number of seconds by 5 gives the number of miles to the flash and dividing by 3 gives the number of kilometers.’ (Source) 

“That is what my father used to tell us about counting,” says Kimmy. “So at least that part is true, but not God bowling.” 

And that’s enough! Kimmy puts her phone down. Now that she knows all about rain that still doesn’t help them to figure out how long it will last or if there is a way to get the rain to stop. Yeti tells Kimmy that they have sat there long enough. So, they pay and walk outside.  

Continue - Time to head home

Story beginning – Rain, rain go away