What does thermal layering refer to in fire behavior?

Thermal layering refers to the phenomenon where gases in a fire environment separate into distinct layers based on temperature. As a fire burns, hot gases rise and cooler gases tend to settle lower in the confined space. This stratification occurs because hot air is less dense than cooler air, resulting in a layering effect that can significantly impact the movement of smoke and heat within a structure. Understanding thermal layering is crucial for firefighting strategies, as it helps firefighters predict how smoke and heat will behave in a given environment, informing their tactics and ensuring their safety. Recognizing the existence of these thermal layers allows for appropriate ventilation and tactics when dealing with a fire situation.