Breaking the sound barrier!

Prandtl-Glauert singularity. The Prandtl-Glauert singularity (sometimes referred to as a "vapor cone") is the point at which a sudden drop in air pressure occurs, and is generally accepted as the cause of the visible condensation cloud that often surrounds an aircraft traveling at transonic speeds, though there remains some debate. It is an example of a mathematical singularity in aerodynamics. In aerodynamics, the sound barrier usually refers to the point at which an aircraft moves from transonic to supersonic speed. The term came into use during World War II when a number of aircraft started to encounter the effects of compressibility, a grab-bag of unrelated aerodynamic effects. By the 1950s, aircraft started to routinely "break" the sound barrier. The white halo is formed by condensed water droplets which are thought to result from a drop in air pressure around the aircraft...