Why do sonic booms come two at a time?

Answer 1

When an object passes through the air, it creates a series of pressure waves in front of it and behind it. These waves travel at the speed of sound, and as the speed of the object increases, the waves are forced together, or compressed, because they cannot "get out of the way" of each other, eventually merging into a single shockwave at the speed of sound. This critical speed is known as Mach 1 and is approximately 1,225 kilometers per hour (761 mph) at sea level at room temperature.

In smooth flight, the shock wave starts at the nose of the aircraft and ends at the tail. Because directions around the aircraft's direction of travel are equivalent, the shock forms a Mach cone with the aircraft at its tip. So the faster it goes, the finer, (more pointed) the cone.

There is a rise in pressure at the nose, decreasing steadily to a negative pressure at the tail, followed by a sudden return to normal pressure after the object passes. This "overpressure profile" is known as an N-wave because of its shape. The "boom" is experienced when there is a sudden change in pressure, so the N-wave causes two booms, one when the initial pressure rise from the nose hits, and another when the tail passes and the pressure suddenly returns to normal. This leads to a distinctive "double boom" from supersonic aircraft.

IN SHORTER WORDS:A separate shock wave is created at both the front and back of the airplane.

Answer 2

Sonic booms typically come in pairs due to the formation of shock waves as an object breaks the sound barrier. The first boom is caused by the initial shock wave generated when an object crosses the speed of sound, and the second boom is caused by the second shock wave trailing behind the object. These two shock waves create the characteristic double boom heard during supersonic flight.