Wildland Firefighting Practice Exam

East facing slopes experience upward air flow first as the sun rises because these slopes receive direct sunlight in the morning as the sun rises in the east. This sunlight causes the surface to warm up more quickly compared to slopes that are shaded, leading to the heating of the air above these slopes. The warm air then starts to rise due to its lower density. In contrast, north and west facing slopes receive sunlight later in the day, while south facing slopes may have morning sunlight depending on the geographical location, but generally not as early as east facing slopes. Thus, the early warming and subsequent upward air flow especially occurs on east facing slopes at sunrise, making this the correct answer.