In terms of airflow, what does a high Mach number indicate?

A high Mach number indicates that an object is moving faster than the speed of sound in air. The Mach number is a dimensionless unit representing the ratio of the speed of an object to the speed of sound in the surrounding medium. When the Mach number exceeds 1, it signifies supersonic speeds, meaning the object travels faster than the sound waves it generates. This phenomenon leads to various aerodynamic effects, including shock waves and changes in the airflow characteristics around the object.

In contrast, lower Mach numbers reflect subsonic speeds, with a Mach number of 1 being the speed of sound. A constant speed or a measurement that is slower than the speed of sound would not contribute to the dynamics associated with high Mach numbers. Thus, a high Mach number is a clear indicator of supersonic flight, which comes with unique challenges and requirements in aircraft design and operation.