NWCG Glossary of Wildland Fire, PMS 205

The ground area covered by the crown of a tree as delimited by the vertical projection of its outermost perimeter.

A fire that advances from top to top of trees or shrubs more or less independent of a surface fire. Crown fires are sometimes classed as running or dependent to distinguish the degree of independence from the surface fire.

A theoretical concept that is used to model and classify crown fire. It may be observable after the fact in burn severity assessments.

A fire that rises from ground into the tree crowns and advances from tree top to tree top. To intermittently ignite tree crowns as a surface fire advances.

The ratio of live crown to tree height.

Browning of needles or leaves in the crown of a tree or shrub caused by heating to lethal temperature during a fire. Crown scorch may not be apparent for several weeks after the fire.

The height above the surface of the ground to which a tree canopy is scorched.

A probability that a crown fire may start, calculated from inputs of foliage moisture content and height of the lowest part of the tree crowns above the surface.

The ultimate growth of a cumulus cloud into an anvil-shaped cloud with considerable vertical development, usually with fibrous ice crystal tops, and usually accompanied by lightning, thunder, hail, and strong winds.

A principal low cloud type in the form of individual cauliflower-like cells of sharp non-fibrous outline and less vertical development than cumulonimbus.

A fireline trench on the downhill side of fire burning on steep slopes that is supposed to be built deep enough to catch rolling firebrands that could otherwise start fire below the fireline. A high berm on the outermost downhill side of the trench helps the cup trench catch material.

Weight of a truck empty (without payload and driver) but ready to drive, including a full fuel tank, cooling system, crankcase, tools, spare wheel, and all other equipment specified as standard.

Weight of a vehicle including full fuel tank, cooling system, crankcase, spare wheel, and other standard equipment.

The act of vulcanization. In fire hose, the vulcanization of the tube to the jacket.

In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture falls to 30% or less.

Complete power cycle of an engine—including intake, compression, power, and exhaust strokes.

A synthetic polyester fiber. The first manmade fiber ever used in fire hoses.High-strength, low-stretch material ideally suited for fire hoses.

In fire danger rating, a subjective estimate of the degree of activity of a potential human-caused fire source relative to that which is normally experienced. Five activity levels are defined: none, low, normal, high, and extreme.

Paid on a calendar day basis (0001-2400).

The comparative differences of damage to objects resulting from the fire’s passage.

The amount of fire related destruction to combustible objects determined by comparing opposing sides of an object.

The database from which the polygon originated.

A particular day of a calendar year.

The last edit, update, of this GIS record.

The combination of date and time elements.

The datum associated with the coordinates that identify the point of origin. Point of origin is the location where a competent ignition source came into contact with the material first ignited and sustained combustion occurred.

Fuels with no living tissue in which moisture content is governed almost entirely by absorption or evaporation of atmospheric moisture (relative humidity and precipitation).

In prescribed fire terminology, a fire used to dispose of scattered, piled, or windrowed dead woody fuel, generally in the absence of a merchantable overstory. Its purpose is to reduce unsightly fuel concentrations, or consume unwanted natural fuels to facilitate subsequent resource management or land use actions on the area. 

In fire suppression terminology, a fire spreading from any fire originally ignited to clear land or burn rubbish, garbage, crop stubble, or meadows (excluding incendiary fires).

An event dealing with a fire spreading from any fire originally ignited to clear land or burn rubbish, garbage, crop stubble, or meadows (excluding incendiary fires).

The helibase operational area that includes the touchdown pad, safety circle, hover lanes, and external cargo transport area.

The difference in degrees between true north and magnetic north.

A fire that has gained headway and built up heat in a structure so as to require greater cooling for extinguishment.

A fire burning far below the surface in duff, mulch, peat, or other combustibles as contrasted with a surface fire.

As it refers to atmospheric pressure, a decrease in the central pressure of a low. This is usually accompanied by intensification of the cyclonic circulation (counter-clockwise wind flow around the low).

A burning with great heat and intense light.

Chemical decomposition by burning material in which the reaction is less than sonic velocity, for example, low explosives.

This is an informal session held immediately following the incident, within 24 hours. It is peer support led, and focuses on initial venting of feelings and stress education.

In a discussion of fire retardant slurries, deterioration of viscosity.

A unit of angular measurement equal to one-360th part of the circumference of a circle. The entire globe contains 360 degrees, each degree contains 60 minutes, and each minute contains 60 seconds.

Polystyrene balls, 1.25 inches in diameter, containing potassium permanganate. The balls are fed into a dispenser, generally mounted in a helicopter, where they are injected with a water-glycol solution and then drop through a chute leading out of the helicopter. The chemicals react thermally and ignite in 25-30 seconds. The space between ignition points on the ground is primarily a function of helicopter speed, gear ratio of the dispenser, and the number of chutes used (up to four). 

A statement provided to the incident commander by the agency administrator delegating authority and assigning responsibility. The delegation of authority can include objectives, priorities, expectations, constraints and other considerations or guidelines as needed.

An attribute flag to tell editors to remove a feature added in error.

The resource is no longer assigned to an incident and travel has started, but the resource has not yet arrived home.

The orderly, safe, and efficient return of an incident resource to its original location and status.

Demobilization Unit staff develop an Incident Demobilization Plan that includes specific instructions for all personnel and other resources to be demobilized. They begin their work early in the incident, creating rosters of personnel and resources and obtaining any missing information as check-in proceeds. Once the Incident Commander or Unified Command has approved the Incident Demobilization Plan, Demobilization Unit staff ensure its distribution at the incident and elsewhere, as necessary. For major incidents, demobilization plans are dynamic and the staff in the Demobilization Unit may need to update them frequently.

A unit of weight; used to express the yarn number of polyester and other continuous filament fibers.