What does "thermal layering" refer to in fire dynamics?

"Thermal layering" refers to the stratification of temperatures within a burning environment. In a fire scenario, different layers of air can form at various temperatures due to the heat produced by the fire. This phenomenon occurs as hot gases rise to the ceiling while cooler air remains closer to the ground, creating distinct temperature layers. The warmer, less dense layers of gas can lead to an accumulation of smoke and toxic gases in the upper regions, while the cooler layers provide a more breathable atmosphere near the floor.

Understanding thermal layering is crucial for firefighters, as it influences fire behavior and smoke movement, leading to tactical decisions about ventilation, escape routes, and the approach to extinguishing the fire. Identifying these layers can also impact the safety of both firefighters and occupants in a structure, as moving through different thermal layers can affect visibility and the risk of heat exposure.