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
Mach Song population segments not reached by their media partners. On certain issues, Mach Song Media mobilizes local faith and community organizations to reach deep into their constituencies. So far they have worked with over 200 such organizations on various issues and have the capacity to reach 1,000 faith and community organizations in the Vietnamese communities across the US. "Boat People SOS" has invested over 1 million dollars to develop its own network of Vietnamese-language mass media. This network includes Mach Song monthly publication, Mach Song radio programs and Mach Song television programs. If necessary, Mach Song can readily increase the circulation