Wildland Firefighting Practice Exam

The ability of fire to spread quicker on steeper slopes is primarily due to which factor?

1. Increased humidity

2. Higher available fuel

3. Convection and radiation

4. Lower temperatures

The correct answer is: Convection and radiation

The ability of fire to spread quicker on steeper slopes is primarily influenced by convection and radiation, which are key mechanisms in the spread of fire. When a fire burns, it generates heat, which rises due to convection. This rising heat can pre-heat the fuels above the fire, making them more susceptible to ignition. Additionally, the angle of the slope can enhance the effectiveness of radiation, as the flames can radiate heat to the surrounding area more effectively on an incline. On steeper slopes, the combination of increased heat from the flames rising and greater radiation effects facilitates quicker ignition of fuels both above and in proximity to the fire. This means that as fire spreads upward on a slope, it can ignite new fuels more rapidly because they are being heated directly by the flames and indirectly through the hot air rising. Humidity, available fuel, and temperature do have their impacts on fire behavior, but they do not account for the direct relationship between slope and fire spread as clearly as convection and radiation do. Increased humidity generally slows down fire spread, and while higher available fuel contributes to fire intensity, it doesn't directly account for the influence of slope steepness. Similarly, lower temperatures can hinder combustion rather than enhance it. Thus, convection and radiation provide the most accurate