Sonic Boom

 A loud, explosive noise heard on the ground when an airplane passes overhead at a speed faster than the speed of sound. Sound-pressure waves build up as the airplane passes through the air, but because the airplane is flying faster than these waves can move out ahead of it, the sound pressure builds up and forms a shock wave. The shock wave radiates out from the airplane in the form of a cone. When this cone passes over the ground, the pressure difference between the pressure inside the wave and the pressure of the surrounding air causes the loud explosion-like sound.