Although it’s hard to say why, some of nature’s most powerful forces make for some of the most soothing sounds. Lapping ocean waves are, of course, a bedtime classic. As are monstrous thunderstorms.

Look at that mountain! Imagine you are standing at the base of a volcano looking up. You were told that the volcano isn’t going to erupt anytime soon, but you notice a little bit of smoke (or is that ...