When an unconfined fire is present, what type of air is drawn in at the bottom?

When an unconfined fire is present, cold air is drawn in at the bottom due to the natural movement of air caused by heat. As the fire burns, it heats the surrounding air, causing it to rise. This process creates a low-pressure area at the base of the fire, which pulls in cooler, denser air from the surrounding environment. This influx of cold air contributes to the combustion process by supplying the oxygen necessary for the fire to sustain itself. Understanding this airflow pattern is crucial for firefighters to predict fire behavior and to effectively manage the situation during operations.