Wildland Firefighting Practice Exam

What part of the day do winds typically blow down canyon?

1. Morning

2. Midday

3. Evening

4. Night

The correct answer is: Night

Winds blowing down canyons are a phenomenon influenced primarily by the diurnal temperature cycle. During the evening and into the night, the temperature decreases, causing the air in the canyon to cool more quickly than the air at higher elevations. As the cooler, denser air settles, it begins to flow down the slopes of the canyon, creating a downslope wind. This phenomenon is often observed in the context of wildland firefighting because these winds can significantly impact fire behavior by pushing flames and embers in the direction they are blowing, often leading to sudden and unpredictable changes in fire spread. This understanding is crucial for effective firefighting strategy and safety. In contrast, during the morning and midday, the sun heats up both the canyon and surrounding areas, causing the air to rise, which generally results in upslope winds. Recognizing these patterns helps firefighters predict fire behavior according to the time of day and adjust their tactics accordingly.