More parts of a fire

Flanks are the sides of the fire. A flank fire burns at right or oblique angles with the wind direction. It generally moves slower, has lower intensity and is easier to control than a head fire. Flank fires are more difficult to control than backing fires. Flanking fires are used on prescribed burns to help encircle the burn area before the head fire is lit. They are also used on prescribed burns when the intensity of a head fire would be too great for existing conditions or desired results. The left flank is the left side looking toward the head from the origin of the fire; the right flank is on the right side of the fire.

Perimeter is the total length of the outside edge of the burning or burned area.

Slopovers or breakovers occur when the fire crosses the firebreak. The main fire and slopover are adjacent to each other with no unburned fuel between them.

Fingers are a narrow strip of fire that burns away from the main fire. Fingers are caused by a shift of wind or change in topography. They develop behind the head, extending from the flanks. They may become second heads.

Islands are patches of unburned fuel inside the fire perimeter.

Pockets are deep indentations of unburned fuel along the fire’s perimeter.

Spot fires are burning areas outside the main fire perimeter, usually caused by wind-blown embers or rolling debris. In contrast to slopovers, spot fires have unburned fuel between them and the main fire.