What is flashover in the context of a compartment fire?

Flashover in the context of a compartment fire refers to a critical event where all combustible materials in an enclosed space reach their ignition temperature almost simultaneously, resulting in a rapid spread of fire throughout the compartment. This phenomenon occurs when heat accumulates in a closed area, raising the temperature of all surfaces to a point where they can ignite, leading to a nearly instantaneous transition from the growth stage of a fire to a full involvement of the entire compartment.

Understanding this concept is vital for fire investigation and safety, as it helps identify the potential for rapid fire spread and informs strategies for fire suppression and safety measures. Other options presented do not accurately describe flashover; for instance, the first option refers to an explosion which does not capture the nature of flashover, while the third option describes a fire receding rather than spreading, and the fourth option focuses on smoke characteristics rather than ignition processes.