Specially designed tank, generally of fabric or metal, fitted closely to the bottom of a helicopter and used for transporting and dropping suppressants or fire retardants.

Irregular motion of the atmosphere usually produced when air flows over a comparatively uneven surface such as the surface of the earth; or when two currents of air flow past or over each other in different directions or at different speeds.

Standard 24-hour period beginning at 1000 hours, during which most wildfires undergo a predictable speeding up and slowing down of intensity, depending primarily on the influence of weather and fuel factors.

In FireFamily Plus, a day with both a weather observation and at least one large (as defined by the user) fire.

In FireFamily Plus, a day with both a weather observation and a number of fires equal to or greater than that determined by the user to be a significant workload.

The trunk of a tree.

Fire pattern indicators that are generally only visible when viewed within close proximity.

To travel over a given route to prevent, detect, and suppress fires. Includes interaction with the public for wildland fire prevention and educational purposes.

The average distance from the bottom of the litter layer to the top of the layer of fuel, usually the surface fuel.

Average height of surface fuels contained in the combustion zone of a spreading fire front.