NWCG Glossary of Wildland Fire, PMS 205

The net amount of heat that would be given off if fuel burns when it is absolutely dry, noted as Btu per pound of fuel.

An area of low pressure caused by intense heating of the earth's surface. High surface temperature causes air to expand and rise, resulting in low atmospheric pressure and induces a weak inflow of air at the surface. Air which rises in a heat low is very dry so clouds seldom form. Rising air above a heat low produces a warm upper level high and results in a net outflow of air aloft. Heat lows remain practically stationary over areas which produce them. 

The heat energy resulting from the complete combustion of a fuel, expressed as the quantity of heat per unit weight of fuel. The high heat of combustion is the potential available, and the low heat of combustion is the high heat of combustion minus several losses that occur in an open system (primarily heat of vaporization of moisture in the fuel).

Total amount of heat released per unit area as the flaming front of the fire passes, expressed as Btu/square foot; a measure of the total amount of heat released in flames.

Apparatus used to detect heat.

Total amount of heat produced per unit mass of fuel consumed per unit time.

Amount of heat released to the atmosphere from the convective-lift fire phase of a fire per unit time.

Process by which heat is imparted from one body to another, through conduction, convection, and radiation.

A Heat Low which is elongated in shape.

The total heat energy released during combustion, usually published as units of heat energy produced per unit mass of ovendry fuel consumed.

The heat of combustion corrected for various heat losses, mainly the presence of moisture in the fuel. To a very close approximation, the quantity of heat per pound of fuel burned that passes through a cross section of the convection column above a fire that is burning in a neutrally stable atmosphere.

Any ground vehicle capable of transporting a dozer, tractor, or other heavy piece of equipment.

Fuels of large diameter such as snags, logs, large limbwood, which ignite and are consumed more slowly than flash fuels.

That portion of a fire backing directly away from and in relatively close proximity to the ignition area. The slowest spreading portion of a fire edge and generally opposite the head.

The vertical measurement of vegetation from the top of the crown to ground level.

A height measured with respect to the underlying ground surface.

Height above mean sea level in feet.

All control line that still contains the fire when mopup is completed. Excludes lost line, natural barriers not backfired, and unused secondary lines.

The main location within the general incident area for parking, fueling, maintenance, and loading of helicopters. It is usually located at or near the incident base.

A crew of individuals who may be assigned to support helicopter operations.

Specially designed bucket carried by a helicopter like a sling load and used for aerial delivery of water or fire retardants.

A ground service vehicle capable of supplying fuel and support equipment to helicopters.

Largest helicopter type that can use the water source.

A permanent facility for the operation of helicopters which has been built to FAA standards and which is marked on aeronautical charts. Natural resource agencies refer to agency heliports as permanent helibases.

Lightweight portable pump developed for transport by helicopter.

A natural or improved takeoff and landing area intended for temporary or occasional helicopter use.

The utilization of helicopters to transport crews, equipment, and fire retardants or suppressants to the fireline during the initial stages of a fire. The term also refers to the crew that performs helicopter management and attack activities.

A crew of firefighters specially trained and certified in the tactical and logistical use of helicopters for fire suppression.

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.

A helicopter equipped with a fixed tank, Airtanker Board certified, capable of delivering a minimum of 1,100 gallons of water, foam, or retardant.

An aerial ignition device hung from or mounted on a helicopter to disperse ignited lumps of gelled gasoline. Used for backfires, burnouts, or prescribed burns.

Relating to or functioning in the mechanics of blood circulation.

A plant that does not develop woody, persistent tissue but is relatively soft or succulent and sprouts from the base (perennials) or develops from seed (annuals) each year. Includes grasses, forbs and ferns.

In NFDRS, a calculated value representing the approximate moisture content of the live herbaceous vegetation in the rating area expressed as a percentage of the oven dry weight of the sample.

The modeled condition of herbaceous vegetation (pre-green, green-up, transition, cured, frozen) for the 1978 version of NFDRS.

Fire scar in a tree resulting from fire injury to the cambium without destruction of the overlying bark and therefore not readily discernible.

Removal of the first (i.e., outside) thread of a female or male coupling to prevent crossing or mutilation of threads. Dimpled rocker lug on female coupling indicates beginning of Higbee Cut.

Foam with an expansion between 201:1 and 1000:1.

A day when an ignition trigger and/or significant weather trigger and an appropriate fuel dryness level combine to create conditions that historically have resulted in a significant fire event for a particular area.

Small capacity spray jet produced at very high pressures (greater than 250 psi, the normal maximum pressure for standard ground tankers) and discharged through a small hose with a gun-type nozzle.

A naturally occuring mass of earth material whose crest or summit is at a lower elevation than a mountain.

In WIMS, a weather station that is no longer in service for which access to archived observations is still available in NIFMID.

All actions taken to stop the spread of fire.

A predetermined maneuver which keeps an aircraft within a specified airspace while awaiting further orders.

Resources assigned to do all required fire suppression work following fireline construction but generally not including extensive mopup.

A fire that remains dormant for a considerable time.

An adjective that describes a permanent place associated with a resource.

Evaluation of a dwelling and its immediate surrounding to determine its potential to escape damage by an approaching wildland fire. Includes the fuels and vegetation in the yard and adjacent to the structure, roof environment, decking and siding materials, prevailing winds, topography, fire history, etc., with the intent of mitigating fire hazards and risks. 

The NWCG Unit Identifier of the center primarily responsible for dispatching the resource.