Technical glossary

Fire –

• (1) Simultaneous release of heat, light, and flame, generated by the combustion of flammable material.
• (2) In a wider sense, any outbreak of fire.

  Note Forest Fire and Wildfire.

Fire Analysis – Review of fire management actions taken with respect to a specific fire, group of fires, or fire season in order to identify reasons for effective and ineffective actions and to recommend or prescribe ways and means of doing a more efficient job.

Fire Behaviour – The manner in which fuel ignites, flame develops, and fire spreads and exhibits other related phenomena as determined by the interaction of fuels, weather, and topography. Some common terms used to describe fire behaviour include the following:

• Smouldering – A fire burning without flame and barely spreading.
• Creeping – A fire spreading slowly over the ground, generally with a low flame.
• Running – A fire rapidly spreading and with a well-defined head.
• Torch or Torching – A single tree or a small clump of trees is said to "torch" when its foliage ignites and flares up, usually from bottom to top. Synonym - Candle or Candling.
• Spotting – A fire producing firebrands carried by the surface wind, a fire whirl, and/or convection column that fall beyond the main fire perimeter and result in spot fires. Note Solid Mass or Ember Transport under Heat Transfer.
• Crowning – A fire ascending into the crowns of trees and spreading from crown to crown. Note the three classes of Crown Fire under Forest Fire (1).

  Note Forest Fire (1).

Fire Behaviour Officer – A specialist position under the plans function of a fire overhead team (assigned to a campaign fire) responsible for making predictions of probable fire behaviour based on an analysis of the current and forecasted state of the fire environment.

Fire Behaviour Triangle – An instructional aid in which the sides of an equilateral triangle represent the three interacting components of the fire environment that are responsible for fire behaviour (i.e. fire weather, fuels, and topography). Note Fire Triangle.

Fire Bombing – An air attack operation involving the use of aircraft to drop suppressants or retardants to suppress or retard the spread of forest fires.

Firebrand – A piece of flaming or smouldering material capable of acting as an ignition source.

Firebreak – See Fuelbreak.

Top of page

Fire Cause Class – The assignment of a wildfire to a category according to the causative agent responsible for starting the fire. The following classifications, adopted in 1980, are used for reporting national wildfire statistics:

• Lightning – A wildfire caused directly or indirectly by lightning.
• Recreation – A wildfire caused by people or equipment engaged in a recreational activity (e.g. vacationing, fishing, picnicking, non-commercial berry picking, hiking).
• Resident – A wildfire resulting from activity performed by people or machines for the purpose of agriculture or an accidental fire caused by activity associated with normal living in a forested area.
• Forest Industry – A wildfire caused by people or machines engaged in any activity associated with forest products production.
• Other Industry – A wildfire caused by industrial operations other than forest industry or railroads. Includes municipal, provincial, or federal works projects whether employees, agents, or contractors.
• Railroads – A wildfire caused by any machine, employee, agent, or contractor performing work associated with a railway operation, or a passenger on a train.
• Incendiary – A wildfire willfully started for the purpose of mischief, grudge, or gain.
• Miscellaneous – A wildfire of known cause that cannot be properly classified under any of the other standard classes listed above.

Fire Cycle – The number of years required to burn over an area equal to the entire area of interest. Note Fire Frequency and Fire Interval.

Fire Damage(s) – Any effect(s) of fire that are detrimental or damaging in terms of the attainment of forest management and other land use objectives. Note Fire Effect(s) and Fire Impact(s).

Fire Danger – A general term used to express an assessment of both fixed and variable factors of the fire environment that determine the ease of ignition, rate of spread, difficulty of control, and fire impact. Note Fire Hazard and Burning Conditions.

Fire Danger Rating – The process of systematically evaluating and integrating the individual and combined factors influencing fire danger represented in the form of fire danger indexes.

Fire Detection – A system for or the act of discovering, locating, and reporting wildfires.

Fire Edge – Any part of the boundary of a going fire at any given moment. May apply to any portion of the fire perimeter as distinct from the different segments defined under forest fire (2). The entire boundary is termed the fire perimeter.

Fire Effect(s) – Any change(s) on an area attributable to a fire, whether immediate or long-term, and on-site or off-site. May be detrimental, beneficial, or benign from the standpoint of forest management and other land use objectives. Note Fire Damage(s) and Fire Impact(s).

Fire Effects Value Appraisal – Determination of the net gains or losses resulting directly or indirectly from forest fires, expressed in monetary or other terms, based on a systematic assessment of fire benefit(s) and fire damage(s). Note Damage Appraisal.

Fire equipment cache – A supply of fire fighting tools and equipment in planned quantities or standard units at a strategic point for exclusive use in fire suppression.

Fire Frequency – The average number of fires that occur per unit time at a given point. Note Fire Cycle and Fire Interval.

Fireguard – A strategically planned barrier, either manually or mechanically constructed, intended to stop or retard the rate of spread of a fire, and from which suppression action is carried out to control a fire. The constructed portion of a control line. Note Fireline and Fuelbreak.

Top of page

Fire Hazard – A general term to describe the potential fire behaviour, without regard to the state of weather-influenced fuel moisture content, and/or resistance to fireguard construction for a given fuel type. This may be expressed in either the absolute (e.g. "cured grass is a fire hazard") or comparative (e.g. "clear-cut logging slash is a greater fire hazard than a deciduous cover type") sense. Such an assessment is based on physical fuel characteristics (e.g. fuel arrangement, fuel load, condition of herbaceous vegetation, presence of ladder fuels). Note Fire Danger.

Fire History – The study and/or compilation of evidence (e.g. historical documents, fire reports, fire scars, tree growth rings, charcoal deposits) that records the occurrence and effects of past wildfires for an area. Note Fire Cycle, Fire Frequency, Fire Interval and Fire Occurrence.

Fire Impact(s) – The immediately evident effect of fire on the ecosystem in terms of biophysical alterations (e.g. crown scorch, mineral soil exposure, depth of burn, fuel consumption). Note Fire Damage(s) and Fire Effect(s).

Fire Intensity – Note Frontal Fire Intensity.

Fire Interval – The average number of years between the occurrence of fires at a given point. Note Fire Cycle and Fire Frequency.

Fireline –

• (1) That portion of the fire upon which resources are deployed ad are actively engaged in suppression action. In a general sense, the working area around a fire. Note Control Line and Fireguard.
• (2) Any cleared strip used to control a fire. Loosely synonymous with fireguard.

Fire Logistics – The assembly, organization, and movement of personnel, equipment, and supplies to and from fires.

Fire Management – The activities concerned with the protection of people, property, and forest areas from wildfire and the use of prescribed burning for the attainment of forest management and other land use objectives, all conducted in a manner that considers environmental, social, and economic criteria.

Note: Fire management represents both a land management philosophy and a land management activity. It involves the strategic integration of such factors as knowledge of fire regimes, probable fire effects, values-at-risk, level of forest protection required, cost of fire-related activities, and prescribed fire technology into multiple-use planning, decision making, and day-to-day activities to accomplish stated resource management objectives. Successful fire management depends on effective fire prevention, detection, and presuppression, having an adequate fire suppression capability, and consideration of fire ecology relationships.

Fire Management Decision Support System – A generic term for the various systems used by fire management agencies in Canada that employ computer software designed to facilitate the storage, compilation, analysis and display of fire intelligence data and other related information on the fire environment, fire suppression resources, fire occurrences, values-at-risk, etc. in support of planning and daily operational decision making with respect to wildfires and prescribed fires.

Fire Management Plan – A statement of policy and prescribed actions with respect to forest fires (prescribed fires and wildfires) for a specific area (may include maps, charts, and statistical data). Note Fire Suppression Plan.

Fire Management Planning – The systematic, technological, and administrative management process of determining the organization, facilities, resources, and procedures required to protect people, property, and forest areas from fire and to use fire to accomplish forest management and other land use objectives.

Top of page

Fire Occurrence – The number of fires started in a given area over a given period of time. Note Fire Frequency.

Fire Overhead – A collective term for all fire supervisory positions. The following is a summary of the key fireline positions used in the Canadian Interagency Forest Fire Centre's National Fire Command System. (Some agencies use a slightly different fire overhead organization or use synonymous terms for some positions). Note that specialist and support positions have not been defined; instead, general descriptions of the main support functions are given.

Fire Boss – The person responsible and accountable for conducting all direct suppression and logistical activities consistent with an agency policy, given fire, or zone of fires. Depending on the size of the fire and the complexity of operations the fire boss may carry out all duties directly or may assign line and staff duties to subordinates. Synonyms - Fire Foreman and (in British Columbia) Fire Superintendent.

• Suppression Boss – The person responsible to the fire boss for supervising, directing, and auditing the suppression effort on the entire fireline. Synonyms - Line Boss and Line Foreman.
• Division Boss – A person responsible to the fire boss or suppression boss, depending upon the degree of organization required, for the conduct of all suppression work on a division. Supervises two or more sector bosses. Synonym – Division Foreman.
• Sector Boss – A first line supervisor responsible and accountable to a division boss, suppression boss, or fire boss, depending upon the degree of organization required, for directing and controlling the total suppression effort on one sector of a fire. Generally supervises two or more crew bosses.
• Crew Boss – A person responsible to a sector boss or fire boss, depending upon the degree of organization required, for the supervision of fire fighting crews on the fireline. Synonym -Crew Foreman.

Fire Perimeter – The entire outer edge boundary of a fire. Recommended SI units are metres (m) or kilometres (km) (1000 m is equivalent to 1.0 km). Note Fire Edge.

Fire Prevention – Activities directed at reducing fire occurrence; includes public education, law enforcement, personal contact, and reduction of fire hazards and risks.

Fireproofing – A procedure aimed at reducing the flammability of fuels. Note - Hazard Reduction.

Fire Pump – An engine driven pump, usually gasoline powered, specifically designed for use in fire suppression. Synonym - Power Pump.

Fire Regime – The kind of fire activity or pattern of fires that generally characterize a given area. Some important elements of the characteristic pattern include fire cycle or fire interval, fire season, and the number, type, and intensity of fires.

Fire Report – An official report of a fire, generally including information on cause, location, action taken, damage, and costs from start of the fire until completion of suppression action. The report is usually accompanied by a map of the burn. These reports vary in form and detail from agency to agency.

Fire Retardant – A substance that by chemical or physical action reduces flammability of combustibles. Note Long-term and Short-term Retardant.

Fire Scar –

• (1) An injury or wound on a tree caused or accentuated by fire.
• (2) A scar on the landscape made by fire. (Somewhat archaic).

Fire Scouting – Reconnaissance of a fire and its surroundings by any means to obtain fire intelligence information.

Fire Season – The period(s) of the year during which fires are likely to start, spread, and do damage to values-at-risk sufficient to warrant organized fire suppression; a period of the year set out and commonly referred to in fire prevention legislation. The fire season is usually further divided on the basis of the seasonal flammability of fuel types (e.g. spring, summer, and fall).

Top of page

Fire Severity – A general term most commonly describe the combined affects of both flaming combustion and smouldering combustion on either a wildfire or prescribed fire site as manifested in various fire behaviour characteristics (e.g. fire intensity, flame height and length, residence and burn-out times, etc.); this is quite inferred after-the-fact from the fire impact(s).

Fire Shovel – Note Tools, Hand, Fire.

Fire Simulator – A training device that imposes simulated fire and smoke and depictions of fire suppression measures on a projected landscape scene to instruct fire management personnel in different fire situations and fire suppression techniques.

Fire Size Class – The assignment of a wildfire to a category according to its size (i.e. from the smallest fire to a very large fire). Recommended SI unit is hectares (ha). The following classification, adopted in 1986, is used for reporting national wildfire statistics:

No.	Letter	Area (ha)
1	A	up to 0.1
2	B	0.11 - 1.0
3	C	1.1 - 10
4	D	10.1 - 100
5	E	100.1 - 1000
6	F	1000.1 - 10 000
7	G	10 000.1 - 100 000
8	H	over 100 000

Either the number or letter can be used to designate a fire size class. Prior to the adoption of the above classes, the following classifications were used; in some cases the conversion from acres (ac) to hectares (ha) was not exact:

No.	Area (ac)	Area (ha)
A	up to 0.25	up to 0.09
B	0.26 - 10.0	0.1 - 4.0
C	10.1 - 100.0	4.1 - 40.0
D	100.1 - 500.0	40.1 - 200.0
E	over 500	over 200

Fire Storm – A large continuous area of intense burning characterized by violent fire-induced convection resulting in gale-force indraft surface winds near and beyond the fire perimeter, a towering convection column, and the occurrence of large fire whirls. Note Extreme Fire Behaviour.

Fire Suppression – All activities concerned with controlling and extinguishing a fire following its detection. Synonym - Fire Control. Note Control a Fire.

Methods of suppression are:

Direct Attack – A method whereby the fire is attacked immediately adjacent to the burning fuel.

Parallel Attack – A method whereby a fireguard is constructed as close to the fire as heat and flame permit, and burning out the fuel between the fire and the fireguard.

Indirect Attack – A method whereby the control line is strategically located to take advantage of favourable terrain and natural breaks in advance of the fire perimeter and the intervening strip is usually burned out or backfired.

Hot Spotting – A method to check the spread and intensity of a fire at those points that exhibit the most rapid spread or that otherwise pose some special threat to control of the situation. This is in contrast to systematically working all parts of the fire at the same time, or progressively, in a step-by-step manner.

Cold Trailing – A method of determining whether or not a fire is still burning, involving careful inspection and feeling with the hand, or by use of a hand-held infrared scanner, to detect any heat source.

Mop-up – The act of extinguishing a fire after it has been brought under control.

Fire Suppression Plan – A document containing the essential elements of actions necessary to save human life and property, and minimize fire damage(s). May apply to an overall fire suppression program for a broad area but most often if is for site-specific situations. Synonyms - Fire Control Plan and Fire Protection Plan. Note Fire Management Plan.

Top of page

Fire Triangle – An instructional aid in which the sides of an equilateral triangle represent the three factors necessary for combustion and flame production (i.e. oxygen, heat, and fuel). When any one of these factors is removed, flame production is not possible or ceases.

Fire Whirl or Fire Whirlwind – A spinning, moving column of hot air and gases rising up from a fire and carrying aloft smoke, debris, flame and firebrands. These range from less than one metre to several hundred metres in diameter. They may involve the entire fire area or only hot spots within or outside the fire perimeter.

Flame Angle – The angle formed between the flame at the fire front and the ground surface, expressed in degrees.

Flame Depth – The width of the zone within which continuous flaming occurs behind the edge of a fire front. Recommended SI unit is metres (m).

Flame Height – The average maximum vertical extension of flames at the fire front; occasional flashes that rise above the general level of flames are not considered. Recommended SI unit is metres (m).

Flame Length – The length of flames measured along their axis at the fire front; the distance between the flame height tip and the midpoint of the flame depth at the ground surface. Flame length is an approximate indicator of frontal fire intensity. Recommended SI unit is metres (m).

Flammability – The relative ease with which a substance ignites and sustains combustion.

Flareup – A sudden, localized increase in frontal fire intensity within or along the fire perimeter requiring a temporary adjustment in suppression action in order to avoid a possible blowup condition. Unlike a blowup, a flareup is of relatively short duration and does not radically change existing control plans.

Flash-over – The rapid combustion and/or explosion of trapped, unburned gases; usually occurs in poorly ventilated areas. The flash-over phenomenon is normally associated with structural or urban fires. However, it can occur in forest fires (although rare) when gases are trapped in topographic pockets or accumulate over a broad area when there is a temporary lull in air movement.

Foam – The collection of a mass of bubbles which are formed by forcing air into a solution of water and foam concentrate by means of suitably designed equipment or by cascading it through the air at a high velocity.

Common terms and definitions associated with foam include -

• Aspirate – To draw in air by suction. The aspirating nozzle draws air into the nozzle to mix with foam solution.
• Batch Mix (Batching) – Manually adding one ingredient to another to develop the final product. Batching can involve a powder and a liquid or two liquids. For foams it is the process of manually pouring foam concentrate into water to make a foam solution. Foam is produced when the solution is pumped down a hose and out an aspirating nozzle. For fire retardants it is the process of adding powder to a measured amount of water and mechanically agitating it to produce fire retardant.
• Batch Mixer – The container in which batching is done. In retardant mixing operations, it is a tank, usually 1,000 gallons in which powdered retardant and water are mixed together by mechanical means to produce the final product.
• Class A Foam – Foam intended for use on woody fuels. Made from hydrocarbon-based surfactants possessing excellent wetting properties and is biodegradable.
• Class B Foam – Foam designed for use on flammable liquid fires.
• Combination Nozzle – Also called an "adjustable fog nozzle". Used for applying water, wet water, or foam solution as either a solid stream or a fixed spray pattern.
• "Dripping" Foam – Characteristics: The bubbles of "DRIPPING" foams are mostly spherical. There is less separation of bubbles by the solution than wet foam. Some of the bubbles walls may be touching. Dripping foams have medium to fast drainage rates. Synonym - Fluid Foam.
• Dry Foam – Characteristics: The bubbles of "dry" foams are polyhedral in shape. The bubble walls are very thin with only small amounts of solution between the bubbles. These types of foams have very slow drainage rates.
• Eductor – A proportioning device using vacuum created by a liquid moving through a hose line to draw another liquid into the stream. In foam operations, foam concentrate is educted into the main water stream through a venturi. The venturi create a vacuum in the water stream causing foam concentrate to be drawn into the stream. Educting can take place on the suction or discharge side of the pump. When using an eductor, mixing takes place either when the solution passes through the pump or in the turbulence as the solution travels down the hose line.
  Foam Blanket - A layer of foam which forms an insulating and reflective barrier from heat and is used for fuel protection and property.
• Foam Concentrate – The concentrated foaming agent as received from the manufacturer, containing a surfactant, corrosion inhibitor, and stabilizers.
• Foam Solution – A homogeneous mixture of water and foam concentrate to which air is added to produce foam. Characteristics: Foam "SOLUTION" has no real bubble structure but some bubble formation may occur due to agitation and impact.
• Low Expansion – Foam having an expansion between 1:1 and 20:1.
• Medium Expansion – Foam having an expansion between 21:1 and 200:1.
• Proportioner – A device that adds a predetermined amount of liquid foam or retardant concentrate to water to form a solution.
• Surface Tension – The elastic-like force at the surface of a liquid, which tends to minimize the surface area, causing drops to form.
• Wet Foam – Characteristics: The bubbles of "wet" foams are spherical masses of air which are enclosed on solution. The bubble walls are separated by a large amount of solution, relative to other types of foams. Wet foams have very fast drainage rates.

Top of page

Forest Closure – An official order by a designated authority to close a specified forest area. Usually provided for in fire prevention legislation. Note Closed Area.

Forest Fire – Any wildfire or prescribed fire that is burning in forested areas, grass, or alpine/tundra vegetation.

• (1) The main types of forest fire are:
  • Ground Fire – A fire that burns in the ground fuel layer. Synonym - Subsurface Fire.
  • Surface Fire – A fire that burns in the surface fuel layer, excluding the crowns of the trees, as either a head fire, flank fire, or backfire.
  • Crown Fire – A fire that advances through the crown fuel layer, usually in conjunction with the surface fire. Crown fires can be classified according to the degree of dependence on the surface fire phase:
    • (i) Intermittent Crown Fire – A fire in which trees discontinuously torch, but rate of spread is controlled by the surface fire phase. Synonym - Passive Crown Fire.

      (ii) Active Crown Fire – A fire that advances with a well-defined wall of flame extending from the ground surface to above the crown fuel layer. Probably most crown fires are of this class. Development of an active crown fire requires a substantial surface fire, and thereafter the surface and crown phases spread as a linked unit. Synonym - Dependent Crown Fire.

      (iii) Independent Crown Fire – A fire that advances in the crown fuel layer only. Synonym - Running Crown Fire.

      (iv) Continuous Crow fire – A fire that burns in the crowns of trees in a continuous manner.

• (2) The anatomical parts of a forest fire are:
  • Bay(s) – A marked indentation(s) in the fire perimeter, usually located between two fingers. Synonym - Pocket(s).
  • Finger(s) – An elongated burned area(s) projecting from the main body of the fire resulting in an irregular fire perimeter.
  • Flanks – Those portions of the fire perimeter that are between the head and the back of the fire which are roughly parallel to the main direction of spread. Synonym - Sides.
  • Head – That portion of the fire perimeter having the greatest rate of spread and frontal fire intensity which is generally on the downwind and/or upslope part of the fire. Synonym - Front.
  • Back – That portion of the fire perimeter opposite the head; the slowest spreading part of the fire. Synonyms - Base, Heel, and Rear.
  • Island(s) – An area(s) of unburned fuels located within the fire perimeter.
  • Point(s) of Origin – The location(s) within the fire perimeter where ignition(s) first occurred. Synonym - Origin(s) of a Fire.
• Note Spot Fire (1).

Forest Floor – The organic surface component of the soil supporting forest vegetation; the combined duff (if present) and litter layers.

Free-burning – A general term to describe the condition of a fire or portion of a fire perimeter that is unaffected by natural or man-made barriers to fire growth and/or any suppression measures taken.

Front – In meteorology, the boundary between two air masses of different density. A cold front represents the leading edge of colder air replacing warmer air; the reverse of this is a warm front.

Frontal Fire Intensity – The rate of heat energy release per unit time per unit length of fire front. Flame size is its main visual manifestation. Frontal fire intensity is a major determinant of certain fire effects and difficulty of control. Numerically, it is equal to the product of the net heat of combustion, quantity of fuel consumed in the flaming front, and linear rate of spread. Recommended SI unit is kilowatts per metre (kW/m). Synonyms - Byram's Fireline Intensity (used mainly in the United States) and Line-fire Intensity. Note Flame Length.

Front of a Fire – See Head of a Fire under Forest Fire (2).

Fuelbreak – An existing barrier or change in fuel type (to one that is less flammable than that surrounding it), or a wide strip of land on which the native vegetation has been modified or cleared, that act as a buffer to fire spread so that fires burning into them can be more readily controlled. Often selected or constructed to protect a high value area from fire. In the event of fire, may serve as a control line from which to carry out suppression operations. Synonym - Firebreak. Also note Control Line and Fireguard.

Fuel – Material capable of burning.

Fuel Management – The planned manipulation and/or reduction of living or dead forest fuels for forest management and other land use objectives (e.g. hazard reduction, silvicultural purposes, wildlife habitat improvement) by: prescribed fire; mechanical, chemical, or biological means; and/or changing stand structure and species composition.

Fuel Moisture Content – The amount of water present in fuel generally expressed as a percentage of the substance's weight when thoroughly dried at 100 degrees Celsius (o C).

Fuel Treatment – See Hazard Reduction.

Fuel Type – An identifiable association of fuel elements of distinctive species, form, size, arrangement, and continuity that will exhibit characteristic fire behaviour under defined burning conditions. Synonym - Fuel Complex.

Full Response Fire – A wildfire which requires immediate, aggressive initial attack and/or sustained suppression action until the fire is declared out.