July 7, 1999 – Off the coast of Pusan, South Korea
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. ~ Wikipedia
The cloud you see is called a vapor cone. These are typically observed as an aircraft approaches transonic velocity. Water in the atmosphere then condenses becoming visible.
You can read much more about vapor cones at wikipedia.
Image Credit
Photo by Ensign John Gay, U.S. Navy is Wikimedia Public Domain
When I was out at sea on the US Navy’s aircraft carrier USS Eisenhower a F-14 from the 103 “Jolly Rogers” Squadron flew screaming by and as it broke the sound barrier it created a vapour cone. It was an awe inspiring sight.
Very cool!
Indeed Shannon!
Another great shot here:
http://en.wikipedia.org/wiki/File:FA-18_going_transonic.JPG