livescience.com – Tue Jun 30, 2009 - by Editorial Director Robert Roy Britt. A U.S. Air Force F-22 Raptor executes a supersonic flyby over the flight deck of the aircraft carrier USS John C. Stennis (CVN 74) in the Gulf of Alas.

The breaking of the sound barrier is not just an audible phenomenon. As a new picture from the U.S. military shows, Mach 1 can be quite visual.

This widely circulated new photo shows a Air Force F-22 Raptor aircraft participating in an exercise in the Gulf of Alaska June 22, 2009 as it executes a supersonic flyby over the flight deck of the aircraft carrier USS John C. Stennis.

The visual phenomenon, which sometimes but not always accompanies the breaking of the sound barrier, has also been seen with nuclear blasts and just after space shuttles launches, too. A vapor cone was photographed as the Apollo 11 moon-landing mission rocketed skyward in 1969.

The phenomenon is not well studied. Scientists refer to it as a vapor cone, shock collar, or shock egg, and it's thought to be created by what's called a Prandtl-Glauert singularity.

Here's what scientists think happens:
A layer of water droplets gets trapped between two high-pressure surfaces of air. In humid conditions, condensation can gather in the trough between two crests of the sound waves produced by the jet. This effect does not necessarily coincide with the breaking of the sound barrier, although it can. To learn more, click here.

The aircraft carrier was participating in Northern Edge 2009, an exercise focused on detecting and tracking things at sea, in the air and on land.

Off the coast of Pusan, South Korea, July 7, 1999 -- An F/A-18 Hornet assigned to Strike Fighter Squadron One Five One (VFA-151) breaks the sound barrier in the skies over the Pacific Ocean. VFA-151 is deployed aboard USS Constellation (CVN 64).



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