What is the burning of heated upper layers in a fire referred to as?

The burning of heated upper layers in a fire is commonly referred to as rollover. During a fire, as combustion occurs, heat rises and warms the upper layers of air. When this superheated air reaches its ignition point, it can ignite volatile gases that have accumulated in that space. This phenomenon is characterized by the visible flames moving along the ceiling and is often seen just before or during a flashover, where the entire room can suddenly ignite.

Rollover is a crucial concept for understanding fire behavior, especially in enclosed spaces, as it can indicate an impending flashover, which is an extremely dangerous situation for firefighters and individuals inside the structure. Recognizing the signs of rollover can help in predicting the fire's progression and in making more informed decisions about safety and attack strategies during firefighting operations.