In the case of smoke that rises to the ceiling and dissipates, what does this mean?

When smoke rises to the ceiling and dissipates, it indicates that the heat and smoke from the fire are moving upwards. This behavior of smoke is typically associated with a fire that is located above the level where the smoke is rising. In a multi-story building, hot smoke will rise due to its lower density compared to cooler air, and as it reaches the ceiling, it can begin to spread horizontally before dissipating.

Therefore, the observation of smoke rising and then dissipating is a clear indicator that the source of heat and combustion is not on the same level or below; instead, it suggests that the fire is positioned above grade. Understanding this can help firefighters determine the most appropriate tactics for suppression and ensure they approach the situation effectively, focusing their efforts on the area where the smoke is originating from.