Shock wave
![Schlieren photograph of an attached shock on a sharp-nosed supersonic body.](/Images/godic/202501/30/Schlierenfoto_Mach_1-2_Pfeilflügel_-_NASA2423.jpg")
![Pressure-time diagram at an external observation point for the case of a supersonic object propagating past the observer. The leading edge of the object causes a shock (left, in red) and the trailing edge of the object causes an expansion (right, in blue).](/Images/godic/202501/30/Pressure_plot2423.png")
![Shock wave propagating into a stationary medium, ahead of the fireball of an explosion. The shock is made visible by the shadow effect (Trinity explosion.)](/Images/godic/202501/30/Trinity_explosion_film_strip2423.jpg")
![Schlieren photograph of the detached shock on a bullet in supersonic flight, published by Ernst Mach and Peter Salcher in 1887.](/Images/godic/202501/30/Photography_of_bow_shock_waves_around_a_brass_bullet,_18882423.jpg")
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance. When a wave moves faster than the local speed of sound in a fluid it is a shock wave. Like an ordinary wave, a shock wave carries energy, and can propagate through a medium; however it is characterized by an abrupt, nearly discontinuous change in pressure, temperature and density of the medium. In supersonic flows, expansion is achieved through an expansion fan also known as a Prandtl-Meyer expansion fan.