Can you Say Sonic BOOM

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. One view of this phenomenon is that it exhibits the effect of compressibility and the so-called "N-wave". The N-wave is the time variant pressure profile seen by a static observer when a sonic compression wave passes......


http://en.wikipedia.org/wiki/Prandtl-Glauert_Singularity