In thermal layering, where is the hottest layer located and why?

• A. Near the floor due to cold air pooling.
• B. In the middle due to convection currents.
• C. Near the ceiling due to buoyancy of hot gases rising.
• D. Uniform temperature throughout.

Answer: (C)

When air is heated, it becomes less dense and rises. In a room with a heat source, those buoyant hot gases push upward until they reach the ceiling, where they collect and form the hottest layer. Meanwhile cooler, denser air remains near the floor, creating a vertical temperature difference. This is why you typically see a hot layer at the top with a cooler layer below; strong mixing or ventilation can reduce the gradient, but the basic behavior is hot air rising to the ceiling due to buoyancy.