occurs when the hot gas layer of a fire ignites. As fuels in a room burn, superheated soot, smoke, gases, and partially burned pyrolysis products rise to the top of the room. This layer of fuel-rich gases grows as the temperature increases. If the fire becomes hot enough, one or more of these gases will reach its ignition temperature, igniting the cloud of fuel. This is flameover, also called rollover, due to the physical manifestation of "rolling" of flame across the ceiling as the gas layer ignites.