Rocket or jet engines often feature a distinctive pattern of of light and dark patches in their exhaust.
- The bright patches in this formation are called shock diamonds.
- These shock diamonds, also known as Mach diamonds, are formed as result of a pressure imbalance between the exhaust and the surrounding air.
- Because the exhaust gases are moving at supersonic speeds, changing their pressure requires a shock wave (to increase pressure) or an expansion fan (to decrease the pressure).
