What primarily determines the intensity of fire on a slope?

The intensity of fire on a slope is primarily determined by the slope percentage and steepness due to the physics of fire behavior. Steeper slopes can facilitate the movement of flames and heat upward, allowing the fire to spread more rapidly. As fire moves uphill, it becomes more intense because the flames can preheat the vegetation above and create a larger fire front. Additionally, the heat from the fire rises, and in steep terrain, this can lead to increased rates of spread and intensity as the fire can effectively 'climb' more readily compared to flat or gently sloped surfaces.

While the type of vegetation, rainfall patterns, and the time of day do influence fire behavior, they do not primarily drive the intensity in a way that slope does. Vegetation type impacts fuel quantity and flammability, rainfall patterns affect moisture content, and time of day can influence temperature and humidity levels, but these factors work alongside the steepness and percentage of a slope, which have a more direct impact on how a fire behaves in that specific terrain. Understanding the dynamics of fire spread on slopes is critical for wildfire mitigation strategies and for predicting fire behavior in various landscapes.