Mach number temperature generally decreases with increasing altitude between sea level and , the speed of sound also decreases. For example, the standard atmosphere model lapses temperature to at altitude, with a corresponding speed of sound (Mach1) of , 86.7% of the sea level value. While the terms "subsonic" and "supersonic", in the purest sense, refer to speeds below and above the local speed of sound respectively, aerodynamicists often use the same terms to talk about particular ranges of Mach values. This occurs because of the presence of a "transonic regime" around M = 1 where approximations of the Navier-Stokes equations used
David Mach David Mach David Mach (born 18 March 1956) is a Scottish sculptor and installation artist. Mach was born in Methil, Fife. His artistic style is based on flowing assemblages of mass-produced objects. Typically these include magazines,vicious teddy bears,newspapers, car tyres, match sticks and coat hangers. Many of his installations are temporary and constructed in public spaces. One example of his early magazine pieces, "Adding Fuel to the Fire", was an installation assembled from an old truck and several cars surrounded and subsumed by about 100 tons of magazines, individually arranged to create the impression that the vehicles were being caught