Thunder

Thunder is the sound caused by lightning, ranging from a long low rumble to a sudden loud crack depending on distance and the character of the lightning strike. A lightning bolt heats the air along its path to roughly 20,000 to 30,000 kelvin in a fraction of a second, and this sudden heating makes the surrounding air expand faster than sound can normally travel, producing a shock wave known as a thunderclap. Close to the lightning channel, thunder can reach sound pressure levels of 165 to 180 decibels and occasionally more than 200 decibels. The scientific study of thunder is called brontology, and an irrational fear of it is known as brontophobia.