.jpg)
Credit: John Gay, U.S. Navy
U.S. F/A-18 Hornet flying at transonic speeds. In aerodynamics, the sound barrier is a physical boundary that was once thought to be stopping large objects becoming supersonic. When an aircraft is near to the speed of sound, an unusual cloud sometimes forms. A drop in pressure, in this case due to shock wave formation, causes water droplets to condense and form the cloud.