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
Periodic travelling wave calculate the form and stability of periodic travelling wave solutions of partial differential equations, and the regions of parameter space in which waves exist and in which they are stable. Examples of phenomena resembling periodic travelling waves that have been found empirically include the following. Periodic travelling wave In mathematics a periodic travelling wave (or wavetrain) is a periodic function of one-dimensional space that moves with constant speed. Consequently it is a special type of spatiotemporal oscillation that is a periodic function of both space and time. Periodic travelling waves play a fundamental role in many mathematical equations, including self-oscillatory