Wildland Firefighting Practice Exam

What weather phenomenon is indicated by the presence of virga?

1. Precipitation

2. Adverse winds

3. Thunderstorms

4. Fog

The correct answer is: Adverse winds

Virga refers to the phenomenon where precipitation, such as rain or snow, falls from clouds but evaporates or sublimates before it reaches the ground. This occurrence is typically associated with dry air that lies beneath the cloud base. The presence of virga can indicate adverse wind conditions because the downward movement of air associated with the evaporation and the turbulence created can affect local weather patterns. Strong winds can enhance the evaporation process and can lead to unstable atmospheric conditions. This often signals changes in the weather that could potentially include gusty winds, which makes it relevant to the option discussing adverse winds. Understanding virga's role in the weather helps firefighting professionals monitor fire conditions, as the evaporation effectively takes moisture away from the surface, increasing fire risk in areas where firearms are present.