Glossary of Terms

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Radiant Burn:
A burn injury incurred from a radiant heat source.

Radiant Heat Flux:
The amount of heat flowing through a given area in a given time, usually expressed as calories per square centimeter per second.

Rappelling:
Technique of landing specially trained firefighters from hovering helicopters; involves sliding down ropes with the aid of hand-held friction-producing devices called "Genies." Rappellers are often deployed into remote areas where access is difficult (e.g. without roads or helicopter landing spots) or too remote to allow effective deployment of firefighters without extended hiking time.

Rate of Spread:
The relative activity of a fire in extending its horizontal dimensions. It is expressed as a rate of increase of the total perimeter of the fire, as rate of forward spread of the fire front, or as rate of increase in area, depending on the intended use of the information. Usually it is expressed in chains or acres per hour for a specific period in the fire's history.

Reburn:
The burning of an area that has previously burned but that contains flammable fuels that ignite when burning conditions are more conducive to ignition. Can also refer to an area that has reburned.

Red Card:
Fire qualifications card issued to fire-rated persons showing their training needs and their qualifications to fill specified fire suppression and support positions on a fire or other incident.

Red Flag Warning:
Alert issued by fire weather forecasters to warn personnel about an ongoing or imminent critical fire weather situation.

Rehabilitation:
Commonly referred to as "rehab," the work necessary to repair damage or disturbance caused by wildland fire or suppression activities. Often includes restoration of firelines or dozer work, and projects such as erosion control, installation of water bars or culverts, re-seeding or other rehab of fire-damaged areas.

Relative Humidity (RH):
The ratio of the amount of moisture in the air to the maximum amount of moisture that the air would contain if it were saturated -- the ratio of the actual vapor pressure to the saturated vapor pressure.

Remote Automated Weather Station (RAWS):
There are nearly 1,500 interagency Remote Automated Weather Stations (RAWS) strategically located throughout the United States. Weather data assists land management agencies with monitoring air quality, rating fire danger, and providing information for research applications. Most of the stations owned by the wildland fire agencies are located where they can monitor fire danger. RAWS units collect, store, and forward data to a computer system at the National Interagency Fire Center (NIFC) in Boise, Idaho, via the Geostationary Operational Environmental Satellite (GOES). The GOES is operated by the National Oceanic and Atmospheric Administration (NOAA). These data are automatically forwarded to other computer systems including the Weather Information Management System (WIMS) and the Western Regional Climate Center in Reno, Nevada (www.wrcc.dri.edu). Other Automated Weather Stations (AWS) transmit data to the WIMS system via telephone telemetry. Fire managers use RAWS data to predict fire behavior and monitor fuels; resource managers also use data to monitor environmental conditions.

Resource Management Plan (RMP):
A document prepared by field office staff with public participation and then approved by field office managers, providing direction for land management activities at a field office. The RMP identifies the need for fire in a particular area and for a specific benefit.

Resource Order:
An order placed with dispatch for firefighting or support resources, often initiated by the incident management team on a fire.

Resources:
1) Personnel, equipment, services, and supplies available, or potentially available, for assignment to fires or other incidents. 2) The natural resources of an area, such as timber, wildlife habitat, grasslands, watershed values, and recreational and other values.

Retardant:
A substance or chemical agent which reduces the flammability of combustibles. Retardant application is generally via fixed-wing airtankers or helicopters, and is used to slow or retard the flames, often for pre-treatment of fuels prior to ground attack or other suppression activities or for slowing the spread or potential for spread of the fire.

Run of a Fire:
The rapid advance of the head of a fire with a marked change in fireline intensity and rate of spread from that noted before and after the advance. A fire "makes a run" if such conditions are present.

Running:
A fire event including rapidly spreading surface fire with a well-defined head.