Mach number a small area around the object's leading edge. (Fig.1b) Fig. 1. "Mach number in transonic airflow around an airfoil; M < 1 (a) and M > 1 (b)." When an aircraft exceeds Mach 1 (i.e. the sound barrier), a large pressure difference is created just in front of the aircraft. This abrupt pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this.
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