Compressive waves with sudden changes in stress (or pressure), density and temperature in gas, liquid and solid media are also called shock waves. Shock waves will appear in supersonic flow, explosion and other processes. The shock wave formed during explosion is also called explosion wave. The wave formed by the sudden closing of the valve in the water pipe is also a shock wave. In solid medium, strong impact will form shock wave (see shock wave in solid), and it will also form shock wave in plasma. Only the shock wave in the gas will be introduced below.