According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack or propelling nozzle. It often disperses downwind in a pattern called an exhaust plume.

This is the Nozzle Extension, or bottom part, of the Apollo Service Module Propulsion System (SPS). The top part is the SPS Ring, Strut, and Thrust Chamber Assembly, simply called the SPS Thrust ...