Initial 7 Fire and Smoke Practice Exam

Hot gases rise because heat makes air less dense, so the hottest layer forms up near the ceiling where buoyant air can accumulate. This creates a distinct thermal stratification: a hot layer at the top and cooler air closer to the floor. The floor stays cooler because the dense cold air pools there, and unless strong mixing occurs, you don’t get a uniform temperature throughout. The idea of the hottest layer in the middle would imply significant mixing, which isn’t the typical stable state in a layered environment.