GHS AFJROTC TX20027

Many people have heard a sonic boom but few have seen one. When an airplane travels at a speed faster than sound, density waves of sound emitted by the plane cannot precede the plane so they accumulate in a cone around and behind the plane. When this shock wave passes, a listener hears the accumulated sound waves all at once, causing the phenomenon known as a sonic boom. Sometimes when a plane accelerates just to the point that it breaks the sound barrier, an unusual cloud will form around or behind the plane. The origin of this cloud is still debated but a leading theory is that a drop in air pressure at the plane described by the Prandtl-Glauert Singularity occurs so that moist air condenses there to form water droplets which create the cloud. Above you see a McDonnell Douglas F/A-18 flown by a member of the U.S. Navy Blue Angels Demonstration Team, photographed just as it broke the sound barrier during a show at Pensacola Beach, Florida on July 2, 2005 which was attended by a group of cadets from Gilmer's JROTC program.