Birth of an F-18 This plane has just accelerated past the speed of sound. The cloud around the plane is caused by water vapor being forced out of the air by the sonic "boom." Not only were the water vapor, density and temperature just right, but there just happened to be a camera in the vicinity to capture the moment. This is extra ordinary photography, a once in a lifetime photo. Every so often, just the right combination of conditions and events occur to create an unbelievable event - in this case an F-18 passing through the sound barrier. The F-18 is actually in transonic flight, with normal shock waves emanating from behind the canopy and across the wings and fuselage. The condition will last for only an instant, and once supersonic flow exists completely around the aircraft, sharp-angled sonic cones replace the normal shock waves.