Dynamically the same as the hydraulic jump, but in meteorological contexts the equations are applied to a temperature inversion or to a system of two inversions. The phenomenon of a pressure jump is thus a steady-state propagation of a sudden finite change of inversion height, in analogy to the shock wave in a compressible fluid. The prefrontal squall line has been interpreted as a pressure jump, with the cold front providing the initial pistonlike impetus. See also compression wave.