The bow shock-wave - very high subsonic flight, just below the speed of sound. Some surfaces of the aircraft are already supersonic - there is local supersonic flow. The mass condensation occurs in the low pressure area directly behind the bow shock-wave.
Skydiver Felix Baumgartner breaking the sound barrier - Red Bull Stratos - 24 miles into space. miles an hour Oct 13 or 14 , The first man to break sound barrier in a plane also went back up to break it again 65 yrs after his success - now he is