ABSTRACT
Everyone who has heard thunder has experienced the effect of shock waves. A flash of lightning instantly heats the air to as much as 60,000°F (33,320°C). When air is heated, it expands. When it is heated to such a high temperature so quickly, air expands explosively and forms a shock wave. The shock wave rushes away from the lightning faster than the speed of sound. Within a few feet, it has slowed down and become an ordinary sound wave, which we hear as
thunder. Similarly, the sharp crack of a whip is produced when the tip of the whip goes faster than the speed of sound and sets off a shock wave.
