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 to 100,00 copies, distributed through their vast community networks within and without their areas of physical presence. In the aftermath of Hurricane Katrina (2005), Mach Song monthly printed 50,000 additional copies for six months for distribution to hurricane victims. They similarly increased the circulation of Mach Song monthly after Hurricane Ike (2008). Mach Song Mach Song (, literally "Life Stream") is a national monthly bilingual Vietnamese–English newspaper published in Houston, Texas. The paper has a readership of approximately 75,000 in 15 cities across the United States and is published by "Boat People SOS"—a national Vietnamese American 501(c)(3) nonprofit organization. Working