That moment when air itself concedes defeat.
 Like waves building at the bow of a moving boat, pressure waves in the atmosphere begin to stack and compress until Mach 1 (approx. 761 mph (1,225 km/h) at sea level, 68°F (20 °C).  As an object travels beyond this speed, the waves compress until they can't get out of their own way, merging into a single shockwave cone, and the results can be spectacular.