Sonic boom the ground. For example, the speed of sound at is about , but an aircraft must travel at least (Mach 1.12, where Mach 1 equals the speed of sound) for a boom to be heard on the ground. The composition of the atmosphere is also a factor. Temperature variations, humidity, atmospheric pollution, and winds can all have an effect on how a sonic boom is perceived on the ground. Even the ground itself can influence the sound of a sonic boom. Hard surfaces such as concrete, pavement, and large buildings can cause reflections which may amplify the sound of a
Bomb hot gas. Under normal circumstances, this deflagration occurs too slowly to produce a significant pressure wave; low explosives, therefore, must generally be used in large quantities or confined in a container with a high burst pressure to be useful as a bomb. A high explosive bomb is one that employs a process called "detonation" to rapidly go from an initially high energy molecule to a very low energy molecule. Detonation is distinct from deflagration in that the chemical reaction propagates faster than the speed of sound (often many times faster) in an intense shock wave. Therefore, the pressure wave produced