NWCG Glossary of Wildland Fire, PMS 205

Any changing characteristic; in statistics, a measurable characteristic of an experimental unit.

A ceiling of less than 3,000 feet (900 m) which rapidly increases or decreases in height by one or more reportable values during the period of observation.

Resultant of all fire danger factors that vary from day to day, month to month, or year to year (e.g., fire weather, fuel moisture content, condition of vegetation, variable risk).

A sky condition that varies between reportable values of sky cover amounts during the period of observation.

A condition when the prevailing visibility is less than 3 miles (5 km) and rapidly increases and decreases by one or more reportable values during the period of observation.

Wind direction which varies by 60 degrees or more during the period of time the wind direction is being determined.

Directions of fire spread as related to rate of spread calculations (in degrees from upslope).

The vegetation departure index is displayed on actuals, and is an index on the FRCC. The vegetation departure percentage is displayed on estimated treatments and activities and is a percentage.

Development of new aboveground plants from surviving plant parts, such as by sprouting from a root crown or rhizomes. Even if plants form their own root system, they are still genetically the same as the parent plant.

Establishment of a new plant from a seed that is a genetically distinct individual.

Fire originating in or on a vehicle or mobile equipment.

An event dealing with a fire originating in or on a vehicle or mobile equipment.

The Vehicle Identification Number (VIN) assigned to a piece of equipment.

The release of enclosed smoke and heat from a structure by creating openings in it, as by hacking a hole in the roof, to allow free passage of air.

A numerical value relating the potential of the atmosphere to disperse airborne pollutants from a stationary source, calculated by multiplying the mixing height by the transport wind speed.

A measure of the volume rate of horizontal transport of air within the mixing layer, per unit distance, normal to the wind. Units are measured in square meters per second or knot-feet.

Fuels above ground and their vertical continuity, which influences fire reaching various levels or vegetation strata.

Plot of the actual dry-bulb temperature against height above the earth's surface, most commonly determined by a RAWINSONDE observation.

Radio frequency range from 30 MHz to 299 MHz. The sub-bands most commonly used by fire are: VHF-FM Lo band: Frequency Modulation 30 MHz - 80 MHz, of which fire frequencies are between 30 MHz and 50 MHz. VHF-FM Hi band: Frequency Modulation 150 MHz - 174 MHz. This is the most widely used band by fire agencies. VHF-AM: Amplitude Modulation. This band is commonly referred to as the "Victor or VHF" band. The frequency range is from 118 MHz to 136 MHz. The only authorized use of this band is for aviation. The FAA controls and assigns all frequencies within this sub-band. 

System of radio navigation in which any magnetic bearing relative to a special radio transmitter on the ground may be chosen and flown by an aircraft pilot.

A subjective assessment of the health of individual plants in similar site and growing conditions; or a more specific measure based upon a specific facet of growth, such as seed stalk or tiller production per plant or per unit area.

Precipitation falling out of a cloud but evaporating before reaching the ground.

Thickness of a liquid, the degree to which it resists flow.

Water that contains a thickening agent to reduce surface runoff; tends to cling to burning fuels and spread in layers that are several times thicker than plain water, thereby having an increased capacity to absorb heat, cool fuel, and exclude oxygen.

The greatest horizontal distance at which selected objects can be seen and identified, or its equivalent derived from instrumental measurements.

Map showing the different classes of visible area covered by a lookout point or points; may differentiate between seen areas, indirectly visible areas, and blind areas, or only between seen areas and blind areas. Also known as seen area map.

Basic weather conditions prescribed for flight under Visual Flight Rules: ceiling above 1,000 feet (300 m) and flight visibility in excess of 3 miles (5 km).

An NDVI-derived image of vegetation greenness compared to a very green reference such as a golf course.

Maximum distance at which a given object can just be seen by an observer with normal vision.

The inventory and planning actions taken to identify visual values and to establish objectives for managing those values; and the management actions taken to achieve the visual management objectives.

The visible physical features on a landscape (e.g., land, water, vegetation, animals, structures and other features).

A systematic and thorough scan of the wildland fire environment for an object or feature as it relates to seeing or sight.  This scan may be aided by magnification when necessary.

Readily changeable into vapor at low temperatures.

Readily vaporized organic materials which, when mixed with oxygen, are easily ignited.

An event dealing with response to volcanic activity.

A fire department company or a response unit, the members of which are not paid.

A fire department of which some or all members are unpaid.

Legally enrolled firefighter under the fire department organization laws who devotes time and energy to community fire service without compensation other than Worker's Compensation or other similar death and injury benefits.

Miniature whirlwinds trailing from the wingtips of any aircraft in flight. Vortex will be in the form of a horizontal whirlwind with velocities up to 25 mph (40 km) per hour or more. Also created by action of rotor blades on helicopters; these whirlwinds tend to move downward toward the ground. If an aircraft flies low over a fire, vortices may reach the ground and suddenly cause violent and erratic fire behavior.

The walk test is designed to determine the ability to carry out light duties. It consists of a one-mile test with no load that approximates an aerobic fitness score of 35. A time of 16 minutes, the passing score for this test, ensures the ability to meet emergency and evacuate to a safety zone. 

The leading edge of a relatively warm air mass which moves in such a way that warm air replaces colder air that moves away from a region. Winds associated with warm frontal activity are usually light and mixing is limited. The atmosphere is relatively stable when compared to cold front activity.

The official delegation of authority to contracting officers and procurement officers establishing the dollar amount and type limits for acquisitions.

A shallow channel or raised barrier, e.g., a ridge of packed earth or a thin pole laid diagonally across the surface of a road or trail so as to lead off water, particularly storm water. (Frequently installed in firelines on steep slopes to prevent erosion.) 

Apparatus utilizing an air compressor and positive displacement pump coupled to the same engine, plumbed to a non-pressurized tank, for producing foam. The operation involves injecting compressed air into a liquid stream containing a suitable foaming agent.

Apparatus utilizing a pressurized tank, hose, and nozzle for producing foam by injection of compressed air or gas into a liquid stream downstream from the pumping source. The liquid stream must contain a suitable foaming agent.

A force created by the rapid acceleration or deceleration of water, commonly created by opening or closing a valve too quickly. Pressures developed in a water hammer, proportional to the mass multiplied by the square of the velocity, can damage a pipe or hose. 

Any strategically located supply of water that is readily available for pumps, tanks, trucks, helicopters, or fire camp use.

The type of water source.

A map showing location of supplies of water readily available for pumps, tanks, trucks, camp use, etc.

Any ground vehicle capable of transporting specified quantities of water.