In fire behavior, what does "thermal layering" refer to?

Thermal layering refers to the stratification of heat and smoke in layers within a structure during a fire incident. As a fire burns, hot gases rise, creating a layering effect where the hottest gases accumulate near the ceiling and cooler air remains closer to the floor. This phenomenon is crucial for firefighters to understand because it affects visibility, temperature, and the potential for flashover, which is an explosive spread of fire when all combustible materials in an area ignite simultaneously. Recognizing thermal layering enables firefighters to make informed decisions about their approach, ensuring their safety and the effective suppression of the fire. Understanding this concept helps in predicting the fire's behavior, as well as planning tactics for ventilation and firefighting operations.