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
Alexander Mach Alexander Mach Alexander Mach (11 October 1902 in Slovenský Meder (today Palárikovo) – 15 October 1980 in Bratislava) was a Slovak nationalist politician. Mach was associated with the far right wing of Slovak nationalism and became noted for his strong support of Nazism and Germany. Mach joined the Slovak People's Party at an early age and came to prominence within that movement as an aide to Vojtech Tuka. Under Tuka's tutelage Mach served as editor of the party organs "Slovak" and "Slovenska Pravda" and was appointed to the party's political committee in 1924. He belonged to the non-clerical wing of