Intro to Wildland Fire Behavior (S-190) Practice Test

The slopes that tend to have the highest fuel temperatures in the morning and afternoon are south and southwest slopes. This is primarily due to the angle of the sun relative to the Earth's surface. During the day, especially in the afternoon, south and southwest slopes receive direct sunlight for the longest periods, leading to increased temperatures of the fuels present in those areas.

In the morning, these slopes warm up more quickly as the sun rises, since they face the direction of the sun's path across the sky. The accumulation of heat throughout the day on these slopes can significantly influence fire behavior, as higher temperatures can lead to drier fuels, making them more susceptible to ignition and more intense fire spread.

Essentially, the orientation of the slopes plays a critical role in determining how much solar radiation they receive, affecting moisture levels and temperature of the vegetation, which are key factors in wildland fire behavior.