What characterizes flameover in a fire scenario?

Flameover is characterized by the accumulation of unburned fuel igniting in the ceiling layer of a fire scenario. This phenomenon occurs when hot gases and smoke rise to the upper portions of a room, creating an environment where flammable materials can accumulate. When the temperature in this upper layer reaches a critical point, any combustible materials present can ignite, resulting in a rapid spread of fire across the ceiling and the potential for flames to travel horizontally.

This ignition process is distinct from other fire characteristics, as it specifically involves the interplay of heat, fuel, and the layering of combustion gases near the ceiling. Understanding flameover is critical for fire investigators, as it helps to determine the intensity and spread of a fire, as well as potential causes and patterns of fire behavior in both commercial and residential settings. The other options describe different fire behavior phenomena, not specifically flameover.