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.
Photo by Ensign John Gay, U.S. Navy is Wikimedia Public Domain