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Gallons per Minute (GPM)

1. The measure of water flow in firefighting. It is used to measure the output of wildland and structural fire engines, pumps, hose streams, nozzles, hydrants, and water mains.

Gap

1. Weak or missed area in a retardant drop or in a fireline.

Gate Valve

1. A valve with a gate-like disk that moves up and down at right angles to the flow when actuated by a stem screw and hand wheel. Gate valves are best for service that requires infrequent valve operation and where the disk is kept either fully open or closed.

Gear Pump

1. Positive displacement pump which uses closely meshed gears to propel water when high pressures and low volumes are desired; can be used safely only with clear water-- suspended particles of soil or rocks can quickly wear the gears and reduce pressure and volume of water.

General Fire Weather Forecast

1. A forecast, issued daily during the regular fire season to resource management agencies, that is intended for planning of daily fire management activities, including daily staffing levels, prevention programs, and initial attack on wildfires. Also called presuppression forecast.

see also: Incident Weather Forecast ; Spot Weather Forecast

General Origin Area

1. The larger area where the fire started that is readily identifiable based on macro scale indicators and witness statements.

General Services Administration (GSA)

1. An agency of the United States Government that includes the Federal Supply Service, the Automated Data and Telecommunications Service, the Public Buildings Service, and the National Archives and Records Service.

General Staff

1. The group of incident management personnel reporting to the Incident Commander. They may each have a deputy, as needed. The General Staff consists of: Operations Section Chief, Planning Section Chief, Logistics Section Chief, and Finance/Administration Section Chief.

General Winds

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

see also: Local Winds ; Slope Winds

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Geographic Area

1. A boundary designated by governmental agencies (wildland fire protection agencies) within which they work together for the interagency, intergovernmental planning, coordination, and operations leadership for the effective utilization of emergency management resources within their area. There are nine geographic areas. A listing of the areas can be found in the National Interagency Mobilization Guide, Chapter 20, section 21.1 along with listings of the Geographic Coordinating Areas and Geographic Area Coordination Centers.

see also: Geographic Area Coordination Center ; Geographic Coordinating Area

Geographic Area Coordination Center (GACC)

1. The physical location of an interagency, regional operation center for the effective coordination, mobilization and demobilization of emergency management resources. Listings of geographic coordination centers and their respective geographic coordinating areas can be found within the National Interagency Mobilization Guide, Chapter 20, Section 21.1

see also: Geographic Area ; Geographic Coordinating Area

Geographic Coordinating Area

1. A boundary designated by governmental agencies (wildland fire protection agencies), that may coincide with a geographic area boundary or may be a subdivision of a geographic area within which they work together coordinating, for the efffective, mobilization and demobilization of emergency management resources within their area. Listings of geographic coordinating areas and geographic coordination centers can be found in the National Interagency Mobilization Guide, Chapter 20, Section 21.1.

see also: Geographic Area ; Geographic Area Coordination Center

Geographic Information System Specialist (GISS)

1. The incident support position responsible for collecting and maintaining geospatial data and providing geospatial analysis and producing products (maps, etc.) in support of wildland fire incident planning. GISS is utilized in support of incident management, assigned to an ICS organization's Situation Unit.

Geostationary Operational Environmental Satellite (GOES)

1. The satellite used for data relay from NFDRS weather stations to ASCADS.

see also: National Fire Danger Rating System ; Automated Sorting Conversion and Distribution System

Getaway Time

1. Elapsed time from receipt of notification by the personnel charged with initiating suppression action to the departure of the first attack unit.

Global Positioning System (GPS)

1. A system of navigational satellites operated by the U.S. Department of Defense and available for civilian use. The system can track objects anywhere in the world with an accuracy of approximately 40 feet.

Glowing Combustion

1. the process of oxidation of solid fuel accompanied by incandescence. All volatiles have already been driven off, oxygen reaches the combustion surfaces, and there is no visible smoke. This phase follows the smoldering combustion phase and continues until the temperature drops below the combustion threshold value, or until only non-combustible ash remains.

Glowing Combustion Phase

1. The final phase of combustion following flaming and smoldering phases.

see also: Glowing Combustion

Going Fire

1. Any wildfire on which suppression action has not reached an extensive mop up stage.

synonym: Active Fire

Gradient Wind

1. Wind flowing parallel to pressure isobars or contours with low pressure on the left of the observer in the Northern Hemisphere; velocity such that the pressure gradient, Coriolis, and certrifugal force acting in the area are in balance.
2. Wind created by differing barometric pressures between high- and low-pressure systems. Velocity is generally five to 30 miles per hour, and wind shifts are usually gradual as systems move and shift.

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Grass Fire

1. Any fire in which the predominant fuel is grass or grasslike.

Grass Stem Indicators

1. Remains of grass stems having different appearances based on the direction of fire spread.

Grass Type

1. In NFDRS, the two grass types (annual, perennial) determine how seasonal drying of live herbaceous fuels is modeled.

Gravimetric

1. Of, or pertaining to, measurement by weight.

Gravity Tank

1. Water storage tank for fire protection and sometimes community water service that supplies water by gravity pressure.

Greenbelt

1. Landscaped and regularly maintained fuelbreak, usually put to some additional use (e.g., golf course, park, playground).

see also: Fuelbreak

Greenhouse Effect

1. the heating of the earth's surface by both atmospheric infrared radiation and incoming solar radiation.

Greenness Factor

1. In the 1988 version of NFDRS, a code scaled from 0 to 20 representing the greenness of grasses and shrubs from near dead to maximum greenness.

see also: Relative Greenness

Green-up

1. Green-up for the 1978 version of NFDRS model is defined as the beginning of a new cycle of plant growth. Green-up usually occurs once a year, except in desert areas where rainy periods can produce a flush of new growth more than once a year. Green-up may be signaled at different dates for different fuel models. Green-up should not be started when the first flush of green occurs in the area. Instead, the vegetation that will be the fire problem (represented by the NFDRS fuel model associated with the weather station) when it matures and cures should be identified. Green-up should start when the majority of this vegetation starts to grow.

Grid Ignition Technique

1. Method of igniting prescribed fires in which ignition points are set individually at predetermined spacing with predetermined timing throughout the area to be burned. Also called point source ignition technique.

Gridding

1. To search for a small fire by systematically traveling over an area on parallel courses or gridlines.

Gross Axle Weight Rating (GAWR)

1. The value specified by the manufacturer as the maximum allowable weight placed on an axle of a vehicle when fully equipped, including payload, fluids and occupants.

Gross Vehicle Weight (GVW)

1. Actual vehicle weight, including chassis, body, cab, equipment, water, fuel, crew, and all other load.

Gross Vehicle Weight Rating (GVWR)

1. The value specified by the manufacturer as the maximum allowable weight of a vehicle fully equipped, including payload, fluids and occupants.

Gross Weight

1. Total allowable weight of a loaded aircraft for takeoff or landing, adjusted for altitude differences.

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Ground Effect

1. Reaction of a rotor downdraft against the ground surface, forming a "ground cushion" that increases lifting capability of that section of air.

Ground Fire

1. Fire that consumes the organic material beneath the surface litter ground, such as a peat fire.

Ground Fog

1. Fog which extends vertically to less than 20 feet.

Ground Fuel

1. All combustible materials below the surface litter, including duff, tree or shrub roots, punky wood, peat, and sawdust, that normally support a glowing combustion without flame.

Ground Speed

1. Speed with which an aircraft traverses the ground over which it flies.

Ground Support Unit

1. Functional unit within the Logistics Section responsible for the fueling, maintaining and repairing of vehicles, and the transportation of personnel and supplies.

Ground Support Unit Leader (GSUL)

1. The ICS position responsible for supervising the Ground Support Unit. Reports to the Support Branch Director or Logistics Section Chief.

see also: Ground Support Unit

Ground Truth

1. Verification at the site of what has been observed and/or measured from aircraft, satellites, other aerial platforms, aerial photographs, or maps.

Ground Visibility

1. Horizontal visibility observed at the ground.

Group

1. Groups are established to divide the incident into functional areas of operation. Groups are composed of resources assembled to perform a special function not necessarily within a single geographic division. Groups, when activated, are located between branches and resources in the operations section.

see also: Division

Growing Season Burning

1. Prescribed burning or wildland fire use during the photosynthetically-active growing season, where live fuel moistures are relatively high and the dominant vegetation, grasses, forbs, and herbaceous vegetation are fully greened.

Guard Unit

1. Geographic subdivision of a fire-protected area, delimiting the initial attack bounds of a single fire guard or fire crew.

Gum Thickened Sulphate (GTS)

1. A dry chemical product which is mixed with water to form a fire retardant slurry.

Gust

1. Rapid fluctuations in wind speed with a variation of 10 knots (11.5 mph) or more between peaks and lulls.

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