Which of the following terms refers to the spontaneous ignition of hot gases in the upper levels of a room or compartment?

The term that refers to the spontaneous ignition of hot gases in the upper levels of a room or compartment is rollover. During a rollover, heated gases rise and can ignite suddenly when they reach a certain temperature or come into contact with an ignition source, creating a potential flash of flames. This phenomenon typically occurs when the temperature in the upper layers of the room exceeds the ignition point of the gases present.

Understanding rollover is crucial for firefighters, as it indicates the potential for a rapidly worsening fire situation and can serve as a warning sign for imminent flashover, which is an explosive ignition of all combustibles in the room. Recognizing this can help firefighters take appropriate action to avoid being caught in hazardous conditions.

In this context, thermal layering describes the stratification of heat in different layers of air, while flashover refers to the moment when all combustible contents ignite simultaneously. Backdraft, on the other hand, occurs when oxygen is suddenly reintroduced to a fire that has been smoldering with limited oxygen, resulting in an explosive reaction. Each of these terms represents different fire dynamics and understanding them helps improve safety and effectiveness in firefighting operations.