Thunder. Don’t you just love a good thunderstorm?
Thunder is amazing, though. It’s one of nature’s great phenomena. What causes it? Lighting. It’s the sound of lightning, right? Well, sort of. As your six inch thick bolt of lightning sears from cloud to cloud, or cloud to ground, it’s hotter than the surface of the sun. So the air it passes through gets pretty hot, too. So hot in fact, that it changes its state. It breaks apart the molecules of gas into atoms, and breaks the bonds within them to form a plasma.
Just as when you boil a kettle and change water into steam and it expands, so the plasma expands, too. But it has nowhere to go, there’s all that pesky air in the way. But so dramatic are the heat and expansion, that it pushes the billions of molecules of air out if the way faster than the speed of sound.
And that’s thunder: the sonic boom of the atmosphere as it gets pushed out of the way at supersonic speed.