Objects move at supersonic speed when the objects move faster than the speed at which sound propagates through the medium. Sounds are traveling vibrations in the form of pressure waves in an elastic medium. This occurs typically somewhere between Mach 0.8 and Mach 1.2. Flights during which only some parts of the air surrounding an object, such as the ends of rotor blades, reach supersonic speeds are called transonic. Speeds greater than five times the speed of sound (Mach 5) are often referred to as hypersonic. For objects traveling in dry air of a temperature of 20 ☌ (68 ☏) at sea level, this speed is approximately 343.2 m/s (1,126 ft/s 768 mph 667.1 kn 1,236 km/h). Supersonic speed is the speed of an object that exceeds the speed of sound ( Mach 1). The white cloud forms as a result of the supersonic expansion fans dropping the air temperature below the dew point. Navy F/A-18 approaching the sound barrier. A United States Navy F/A-18F Super Hornet in transonic flight U.S. For other uses, see Supersonic (disambiguation).
