What is the term for the spontaneous ignition of hot gases in the upper levels of a room or compartment?

The correct answer is the term "rollover" also known as "flameover." This phenomenon occurs when unburned hot gases that have accumulated in the upper levels of a room or compartment ignite spontaneously. Rollover is characterized by the flames spreading across the ceiling or along the upper layers of the room before any significant burning occurs at the lower levels.

Understanding rollover is important for fire fighters as it can indicate that there is a significant amount of heat and flammable gas present, which poses a serious risk to those in the environment. Recognizing this condition can help firefighters to make strategic decisions about how to approach the suppression of the fire and how to ensure their safety while conducting operations.

In contrast, flashover refers to a rapid propagation of fire through a space after it reaches a certain temperature, resulting from the ignition of all combustible materials almost simultaneously. Backdraft involves the explosive ignition of superheated gases when oxygen is introduced into an oxygen-depleted environment. A fireball typically describes a large, bright ball of flame generated by the rapid ignition of gases and is not specific to the behavior of hot gases within a room or compartment.