Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
NOVA Online (see text links below)
Fire Wars

Lighting a backfire Armed with a drip torch, a wildland firefighter lights a backfire.
Glossary of Fire Terms

backfire—A fire set along the inner edge of a fireline to consume the fuel in the path of a wildfire and/or change the direction of force of the fire's convection column.

blow-up—A sudden increase in fire intensity or rate of spread strong enough to prevent direct control or to upset control plans. Blow-ups are often accompanied by violent convection and may have other characteristics of a firestorm (see flare-up).

brush fire—A fire burning in vegetation that is predominantly shrubs, brush, and scrub growth.

candle or candling—A single tree or a very small clump of trees that is burning from the bottom up.

campfire—As used to classify the cause of a wildland fire, a fire that was started for cooking or warming that spreads sufficiently from its source to require action by a fire control agency.

creeping fire—Fire burning with a low flame and spreading slowly.

crown fire (crowning)—The movement of fire through the crowns of trees or shrubs more or less independently of the surface fire.

debris burning—A fire spreading from any fire originally set for the purpose of clearing land or for rubbish, garbage, range, stubble, or meadow burning.

escaped fire—A fire that has exceeded or is expected to exceed initial attack capabilities or prescription.

extreme fire behavior—"Extreme" implies a level of fire behavior characteristics that ordinarily precludes methods of direct control action. One or more of the following is usually involved: high rate of spread, prolific crowning and/or spotting, presence of fire whirls, strong convection column. Predictability is difficult because such fires often exercise some degree of influence on their environment and behave erratically, sometimes dangerously.

fingers of a fire—The long narrow extensions of a fire projecting from the main body.

firestorm—Violent convection caused by a large, continuous area of intense fire. Often characterized by destructively violent surface indrafts, near and beyond the perimeter, and sometimes by tornado-like fire whirls.

fire whirl—Spinning vortex column of ascending hot air and gases rising from a fire and carrying aloft smoke, debris, and flame. Fire whirls range in size from less than one foot to more than 500 feet in diameter. Large fire whirls have the intensity of a small tornado.

Crownfire A fire whirl (center) shoots up from a crown fire.
flaming front—The zone of a moving fire where the combustion is primarily flaming. Behind this flaming zone combustion is primarily glowing. Light fuels typically have a shallow flaming front, whereas heavy fuels have a deeper front. Also called fire front.

flanks of a fire—The parts of a fire's perimeter that are roughly parallel to the main direction of spread.

flare-up—Any sudden acceleration of fire spread or intensification of a fire. Unlike a blow-up, a flare-up lasts a relatively short time and does not radically change control plans.

head of a fire—The side of the fire having the fastest rate of spread.

hotspot—A particularly active part of a fire.

large fire—1) For statistical purposes, a fire burning more than a specific area of land, e.g., 300 acres. 2) A fire burning with a size and intensity such that its behavior is determined by interactions between its own convection column and weather conditions above the surface.

prescribed fire—Any fire ignited by management actions under certain predetermined conditions to meet specific objectives related to hazardous fuels or habitat improvement. A written, approved prescribed fire plan must exist, and Environmental Protection Agency requirements must be met prior to ignition.

project fire—A fire of such size or complexity that a large organization and prolonged activity is required to suppress it.

run (of a fire)—The rapid advance of the head of a fire with a marked change in fire line intensity and rate of spread from that noted before and after the advance.

running—A rapidly spreading surface fire with a well-defined head.

slop-over—A fire edge that crosses over a control line or natural barrier intended to contain the fire.

smoldering fire—A fire burning without flame and barely spreading.

spot fire—A fire ignited outside the perimeter of the main fire by flying sparks or embers.

structure fire—Fire originating in and burning any part or all of any building, shelter, or other structure.

test fire—A small fire ignited within the planned burn unit to determine the characteristics of the prescribed fire, such as fire behavior, detection performance, and control measures.

torching—The ignition and flare-up of a tree or small group of trees, usually from bottom to top.

uncontrolled fire—Any fire which threatens to destroy life, property, or natural resources.

underburn—A fire that consumes surface fuels but not trees or shrubs.

wildland fire—Any nonstructure fire, other than prescribed fire, that occurs in the wildland.

Excerpted with permission from the National Interagency Fire Center Web site, at www.nifc.gov/fireinfo/glossary.html

Photo credits



Printer-Friendly Format   Feedback

The Producer's Story | The World on Fire | Outfitting Wildland Firefighters
How Plants Use Fire | Glossary of Fire Terms | Wildfire Simulator | On Fire
Resources | Transcript | Site Map | Fire Wars Home

Search | Site Map | Previously Featured | Schedule | Feedback | Teachers | Shop
Join Us/E-Mail | About NOVA | Editor's Picks | Watch NOVAs Online | To Print
PBS Online | NOVA Online | WGBH

© | Updated June 2002

 

Support provided by

For new content
visit the redesigned
NOVA site

Shop Teachers Feedback Schedule Previously Featured Site Map Search NOVA Online Fire Wars Site Map