What Is a Shock Wave?

A moving airplane causes disturbances in the air--waves of pressure--similar to sound waves. These pressure waves move ahead of the airplane, spreading outward in all directions at the speed of sound. When the airplane exceeds the speed of sound, it overtakes its own pressure waves, causing them to "pile up" into a sudden, sharp pressure disturbance--a shock wave.

Shock wave formation in front of the Bell X-1, the first airplane to fly faster than sound; the Concorde, a supersonic airliner; and the Space Shuttle during reentry into the atmosphere.

(Rev. 09/17/96)