Wildland Firefighting Practice Exam

What shape will a burn likely take if there is a strong wind in one prevailing direction?

1. Rectangular

2. Spherical

3. Wedge-shaped

4. Elliptical

The correct answer is: Elliptical

When a fire encounters strong winds blowing in one prevailing direction, the burn pattern typically takes on a wedge-shaped formation. This occurs because the wind acts as a driving force, pushing the fire forward more aggressively in the direction of the wind. As the fire spreads, it tends to create a narrow front that extends outwards, resembling the shape of a wedge. The wedge shape is characterized by a pointed edge where the flames are most active and intense, while the base of the wedge represents the area of ignition that is broader as the fire spreads outward from the point of origin. This is particularly important for wildland firefighters to understand because it informs their strategy for controlling the fire and protecting at-risk areas. While other shapes like rectangular, spherical, or elliptical can describe burn patterns under different conditions, they do not effectively convey the impact of unidirectional strong winds. For instance, rectangular shapes might suggest a controlled or grid-like burn, whereas spherical and elliptical shapes imply a more uniform spread in all directions, which isn't typically the case when strong winds are consistently funneling fire in one direction. Therefore, it is the dynamics of fire behavior influenced by wind that lead to the distinctive wedge-shaped progression in these circumstances.