* The sound of thunder is caused by the rapid heating and cooling of air around a lightning bolt. When lightning strikes, it creates a very hot channel of air that expands rapidly. This expansion creates a shock wave that travels through the air at the speed of sound. The shock wave is what we hear as thunder.
* The distance to the lightning bolt can be estimated by counting the seconds between the lightning flash and the sound of thunder. Sound travels at about 1,100 feet per second, so each second between the flash and the thunder means that the lightning bolt is about 1,100 feet away.
* Thunder can be a different sound depending on the distance from the lightning bolt. Close to the lightning bolt, the thunder will be a sharp crack. Farther away, the thunder will be a low rumble.
* Thunder can also be heard in the mountains, even if the lightning bolt is not visible. This is because the sound waves from the lightning bolt can bounce off the mountains and back down to the ground.
* Thunderstorms can produce a lot of thunder. A single thunderstorm can produce up to 100 lightning bolts, and each lightning bolt can create its own thunderclap. This can lead to a very loud and rumbling thunderstorm.