What is characterized by a fuel-rich atmosphere being pushed in front of a fire due to heat?

The phenomenon characterized by a fuel-rich atmosphere being pushed in front of a fire due to heat is known as rollover. Rollover occurs when the combustible gases produced during a fire reach a temperature that allows them to ignite, creating a flaming layer at the ceiling level. As the fire burns, heat causes unburned fuels in the smoke layer to accumulate above the flames. When enough of these gases concentrate and their temperature threshold is met, they ignite, resulting in a dramatic and potentially dangerous flame front that rolls over the fire and spreads rapidly.

This dynamic is particularly hazardous in confined spaces, where it can lead to rapid fire escalation. Understanding rollover is essential for fire personnel because it can provide critical insights into fire behavior and help them make informed decisions when combating a fire.