A circular-like flow of a fluid (such as air or water) drawing its energy from a flow of much larger scale, and brought about by pressure irregularities as in the downwind (lee) side of a solid obstacle. For example, wind conditions may be erratic and may eddy on the downwind side of large rock outcroppings, buildings, etc. 

A loose limb, top, or piece of bark lodged in a tree, which may fall on anyone working beneath it.

The rate of heat release per unit time per unit length of fire front. Numerically, it is the product of the heat yield, the quantity of fuel consumed in the fire front, and the rate of spread.

Type of shovel specifically designed for use in constructing a fireline; has a tapered blade with both edges sharpened for scraping, digging, grubbing, cutting, and throwing.

Actions taken on a wildfire that has exceeded the initial response.

An incident that exceeds the capability of the initial attack resources and/or organization to successfully manage the incident to conclusion.

A fire edge that crosses a control line or natural barrier intended to confine the fire.

A fire edge that crosses a control line or natural barrier intended to confine the fire.

Winds which are generated over a comparatively small area by local terrain and weather. They differ from those which would be appropriate to the general pressure pattern.

Large scale winds caused by high- and low-pressure systems but generally influenced and modified in the lower atmosphere by terrain.