For a given Mach number, M, and corner angle, θ, the oblique shock angle, β, and the downstream Mach number, M, can be calculated. Unlike after a normal shock where M must always be less than 1, in oblique shock M can  be supersonic (weak shock wave) or subsonic (strong shock wave). Weak solutions are often observed in flow geometries open to atmosphere (such as on the outside of a flight vehicle). Strong solutions may be observed in confined geometries (such as inside a nozzle intake). Strong solutions are required when the flow needs to match the downstream high pressure condition. Discontinuous changes also occur in the pressure, density and temperature, which all rise downstream of the oblique shock wave.