Thunder

The actual sound of thunder (as in with lightning, very, very frightening), is the sound of lightning striking the ground. However, thunder also occurs without the electrical discharge into the Earth. In these cases, the noise is referred to as 'black thunder' and is caused by the grinding of ice in the clouds. Think of it like chaffing nylon cycle shorts. The sound is more 'grumbly' than the powerhouse of the lightning strike, more akin to the noise produced when digesting a fillet of beef.