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. This phenomenon occurs when the accumulated hot gases near the ceiling reach their ignition temperature, igniting in a rapid manner. This often happens in the later stages of a fire when the temperatures are extremely high, and it is characterized by flames moving across the ceiling and can signal that a flashover condition may follow if enough combustible materials are present and in the right conditions.

In contrast, flashover is a more intense and rapid transition where all combustible materials in a space ignite almost simultaneously due to extreme heat, whereas backdraft involves a sudden explosion of fire that occurs when oxygen is introduced to a smoldering fire environment that has not had enough air. Thermal layering refers to the stratification of temperatures within a burning structure, resulting in cooler temperatures near the ground and hotter gases near the ceiling. These concepts are related but distinct from rollover, which specifically describes the ignition of hot gases. Understanding these terms is crucial for firefighting tactics and safety.