What is an indicator of rollover in fire behavior?

Rollover is a specific fire behavior phenomenon that occurs when the hot gases above a fire reach a temperature where they ignite, resulting in visible flames spreading through the upper layers of hot gas. This phenomenon typically occurs in a compartment or room where combustion is taking place, and an accumulation of unburned gases becomes heated to the point of ignition.

The ignition of these gases allows flames to move horizontally through the hot gas layer, effectively indicating that an increase in fire intensity could be imminent. Recognizing this behavior is crucial for firefighters because it signals a rapid change in fire conditions, which may pose a significant hazard.

The phenomenon of rollover can also be associated with other signs of imminent fire behavior changes, but focusing specifically on flames spreading through hot gas layers best captures the essence of what rollover involves. This is why the identification of this behavior is essential for maintaining situational awareness and ensuring proper firefighting strategies are employed.