-= Krypt0ni4n =-

They show the Prandtl-Glauert condensation cloud phenomenon which accompanies aircrafts when they reach transonic speeds. Transonic is an aeronautics term referring to a range of velocities just below and above the speed of sound (about 741 miles (1185 kilometers) per hour at sea level) - via Robot Wisdom.

http://chamorrobible.org/gpw/gpw-20040817.htm
http://chamorrobible.org/gpw/gpw-20040818.htm
http://chamorrobible.org/gpw/gpw-20041216.htm
http://chamorrobible.org/gpw/gpw-20041217.htm