Smoke inversion is defined as what?

Smoke inversion is defined as what?

• A. The condition in which smoke hangs low to the ground because of the presence of cold air.
• B. A rapid spread of smoke through openings.
• C. Smoke separating into multiple layers.
• D. The process of venting smoke from a structure.

Answer: (A)

Smoke inversion describes a situation where smoke stays close to the ground and hangs low, instead of rising, because cold air near the surface is heavier and forms a stable layer that traps the buoyant smoke above it. This causes smoke to pool at floor level, reducing visibility and increasing exposure risk for anyone inside or near the structure. This behavior is distinct from a rapid spread of smoke through openings, which is about how quickly smoke moves through gaps rather than where it accumulates. It’s also different from smoke separating into multiple layers, which involves different temperature or density gradients creating distinct strata, not specifically the low-hanging effect caused by an inversion. Venting smoke from a structure is an active action to remove smoke, not a description of how smoke naturally behaves under inversion conditions.