Final answer:
Turbulent smoke filling a compartment signals a possible flashover, a simultaneous ignition of nearly all combustible materials in an area due to high temperatures and gas turbulence.
Step-by-step explanation:
Turbulent smoke that has filled a compartment is a warning sign of impending flashover. A flashover is a dangerous phenomenon in fire dynamics where nearly all combustible materials in an enclosed area ignite almost simultaneously. This can occur as the gas heats up and the turbulence inside the compartment causes friction between the gas and the walls, increasing the temperature to a critical point. Recognizing the signs of a potential flashover, such as turbulent smoke, is vital for fire safety and can be a matter of life and death during firefighting operations.