NWCG Glossary of Wildland Fire, PMS 205

This glossary provides the wildland fire community a single source for wildland fire and incident management terminology commonly used by the NWCG and its subgroups.

Glossary entries related to Organizations, IT Applications, and NWCG Positions have been removed from the glossary based on term inclusion criteria. For more information about the glossary and the criteria, see the About the NWCG Glossary page or the NWCG User Guide for the Glossary of Wildland Fire, PMS 937.

Reference Definitions

Some of the terms within this glossary will be followed by initials or will have references or comments at the end of the definition to help broaden the recognition and understanding of the term. An explanation of those references is as follows:

Also called: Means there is another term that may sometimes be in use, but is not defined in this glossary.
Acronym: An abbreviation formed from the initial letters of other words and pronounced as a word. An acronym appears in parentheses following the term.
Initialism: An abbreviation consisting of initial letters pronounced separately. An initialism appears in parentheses following the term.
See: Means there is another, preferred term that should be used instead. In such a case only the preferred term is defined in this glossary.
See Also: Means there are one or more related terms that may also be of interest to the glossary user. The related terms are also defined in this glossary.
Synonym: Means the term is synonymous with another. The terms have the same, or essentially the same, definition and the terms are interchangeable in their use.
Definition Extension: An example, further explanation, or usage guidance in support of the definition.

Glossary Acronyms/Initialisms

6 (1) | A (126) | B (94) | C (160) | D (102) | E (67) | F (261) | G (48) | H (90) | I (83) | J (10) | K (4) | L (74) | M (92) | N (31) | O (47) | P (133) | Q (6) | R (100) | S (221) | T (71) | U (28) | V (37) | W (60) | Z (1)
  • A pre-determined complement of tools, equipment and/or supplies stored in a designated location, available for incident use. 
Calculation of Probabilities
  • Evaluation of all factors pertinent to probable future behavior of a going fire and of the potential ability of available forces to perform fire suppression operations on a specified time schedule. 
Calibrated Airspeed
  • Indicated airspeed of an aircraft, corrected for position and instrument error. Equal to true airspeed in standard atmosphere at sea level. 
  • A geographical site(s), within the general incident area, separate from the incident base, equipped and staffed to provide sleeping, food, water, and sanitary services to incident personnel. 
  • The burning of the foliage of a single tree or a small group of trees, from the bottom up. 
  • The stratum containing the crowns of the tallest vegetation present (living or dead), usually above 20 feet. 
Carbon Dioxide (CO2)
  • A colorless, odorless, nonpoisonous gas, which results from fuel combustion and is normally a part of the ambient air. 
Carbon Monoxide (CO)
  • A colorless, odorless, poisonous gas produced by incomplete fuel combustion. 
  • Any substance that can cause or contribute to the production of cancer. 
Cardinal Altitudes
  • Odd or "even" thousand-foot (305 m) altitudes or flight levels. E.g., 5,000, 6,000, 7,000; FL 250, FL 260, and FL 270.
Cardinal Directions
  • North, south, east, west; used for giving directions and information from the ground or air in describing the fire (e.g., the west flank or east flank, not right flank or left flank). 
Cargo Chute
  • A parachute designed and rigged for dropping equipment and supplies from an aircraft. 
Cargo Compartment
  • An internal area of an aircraft specifically designed to carry baggage or cargo. 
Cargo Drop
  • Dropping of equipment or supplies, with or without a parachute, from an aircraft in flight. 
Cargo Hook
  • Mechanically and electrically operated hook attached to the bottom of a helicopter to which a sling load is attached. 
Cargo Net
  • Net attached to the cargo hook of a helicopter, used to carry cargo. Also called cargo sling. 
Cargo Rack
  • Externally mounted rack for transporting supplies or cargo aboard a helicopter. 
Carousel Hook
  • A remote hook attached to the end of a longline. It has four or more individual hooks which can be independently released, allowing the pilot to fly cargo loads to different locations without landing. 
Carrier Fuels
  • The fuels that support the flaming front of the moving fire. 
Category Day
  • A numerical index related to the ability of the atmosphere to disperse smoke. Different agencies use different scales [e.g., in South Carolina, the current scale is based on ventilation factor and ranges from 1 (poor) to 5 (excellent)]. 
  • According to the American Meteorological Society, the height ascribed to the lowest layer of clouds or obscuring phenomena when it is reported as broken, overcast, or obscuration and not classified "thin" or "partial." The ceiling is termed unlimited when the foregoing conditions are not satisfied. Source: http://glossary.ametsoc.org/wiki/Ceiling
  • According to the American Meteorological Society, same as centigrade temperature scale, by convention. Centigrade temperature scale is a temperature scale with the ice point of water at 0 degrees and the boiling point at 100 degrees. Source: http://glossary.ametsoc.org/wiki/Centigrade_temperature_scale
Center Firing
  • Method of broadcast burning in which fire is ignited in the center of the area to create a strong draft; additional fires are then ignited progressively nearer the outer control lines (sometimes in one step) as indraft increases so as to draw the flames and smoke toward the center. 
Centrifugal Pump
  • Pump which expels water by centrifugal force through the ports of a circular impeller rotating at high speed. With this type of pump, the discharge line may be shut off while the pump is running without damaging the pump or hose. 
Certifying Official
  • The agency official at the home unit who is responsible for authorizing and granting position certification per agency policy. The agency official is responsible for completing the agency certification block located on the inside front cover of a Position Task Book. 
  • Unit of measure in land survey, equal to 66 feet (20 M) (80 chains equal 1 mile). Commonly used to report fire perimeters and other fireline distances, this unit is popular in fire management because of its convenience in calculating acreage (e.g., 10 square chains equal one acre). 
Chain Lightning
  • Lightning in a long zigzag or apparently broken line. 
Chain of Command
  • A series of management positions in order of authority. 
  1. Carbonaceous material formed by incomplete combustion of an organic material, most commonly wood; remains of burned materials.
  2. In fire simulation, a darkened area within the fire perimeter; usually indicates fire has already passed through; usually created by an opaque material blocking out a selected portion of basic scene illumination. 
Char Height
  • The vertical distance above ground scorched or blackened on a tree bole. 
Charged Line
  • Hose filled with water under pressure and ready to use. 
Chase Truck
  • Vehicle that carries crew gear, supplies, and operational equipment for initial/extended attack. 
Check Line
  • A temporary fireline constructed at right angles to the control line and used to hold a backfire in check as a means of regulating the heat or intensity of the backfire. 
Check Valve
  • A valve that permits flow of liquid through a hose or pipe in one direction but prevents a return flow. Uses include the prevention of backflow on uphill hose lays, loss of prime with centrifugal pumps and chemical contamination in fire chemical mixing systems. 
  • The process whereby resources first report to an incident. Check-in locations include incident command post (ICP), base or camps, staging areas, helibases, or direct to a tactical assignment. 
Chevron Burn
  • Burning technique in which lines of fire are started simultaneously from the apex of a ridge point, and progress downhill, maintaining position along the contour; used in hilly areas to ignite ridge points or ridge ends. 
  • The ICS title for individuals responsible for command of functional sections: Operations, Planning, Logistics, and Finance/Administration. 
Chief of Party
  • The chief of party is responsible to the sending unit dispatcher until destination is reached. Chief of party is responsible for all traveling personnel assigned on the manifest list. 
Circumstantial Evidence
  • Testimony or information not based on actual personal knowledge or observation, but dependent on inference of other facts or experience. For example, testimony that defendant?s cigarette lighter was found in ashes of a fire. 
  • A form of high cloud, composed of ice crystals, which seldom obscures the sun. 
  • A written demand for a specific amount of money or other objects of value, other than ordinary obligations incurred for services, supplies, or things.
  • An individual, partnership, association, corporation, country, the federal government, state, or other political subdivision asserting a right, demand, or claim against another entity.
Class A Foam
  • Foam intended for use on Class A or woody fuels; made from hydrocarbon-based surfactant, therefore lacking the strong filming properties of Class B foam, but possessing excellent wetting properties. 
Class B Foam
  • Foam designed for use on Class B or flammable liquid fires; made from fluorocarbon-based surfactants, therefore capable of strong filming action, but incapable of efficient wetting of Class A fuels. 
Class I Areas (Air Quality)
  • Geographic areas designed by the Clean Air Act subject to the most stringent restrictions on allowable increment of air quality deterioration. Class I areas include Forest Service wildernesses and nation memorial parks over 5,000 acres, National Parks exceeding 6,000 acres, international parks, as well as other designated lands. 
Class II Areas (Air Quality)
  • All areas of the country not designated Class I, including everything from non-Class I areas to urban areas. A greater amount of air pollution can be added to these areas than Class I. 
Clean Air Act
  • A federal law enacted to ensure that air quality standards are attained and maintained. Initially passed by Congress in 1963, it has been amended several times. 
Clear Text
  • The use of plain English in radio communications transmissions. No Ten Codes or agency specific codes are used when using Clear Text. 
  • The prevalent or characteristic meteorological conditions of any place or region, and their extremes. 
Climate Class
  • In NFDRS, one of four classifications of general climate of an area. 
Climatological Breakpoint
  • Points on the cumulative distribution of one fire weather/fire danger index without regard to associated fire occurrence/business. 
Clock Method
  • Means of establishing a flight path to a target on a fire by referring to clock directions from the aircraft's present location, with the nose of the aircraft pointing at 12:00. 
Closed Area
  • An area in which specified activities or entry are temporarily restricted to reduce risk of human-caused fires or to mitigate the risk to human health or safety by potential or on-going wildland fires. 
  • An administrative action limiting or prohibiting access to a specific geographic or jurisdictional area for the purposes of reducing wildfire or the risk it poses to life, property, and/or resources. Example of use: "Pursuant to 36 C.F.R. 261.50 (a) and (b), it is hereby ordered that the prohibitions hereinafter set forth apply to the general forest area of the Ozark-St. Francis National Forests until further notice."
  • A visible cluster of minute water/ice particles in the atmosphere. 
  • Adjective class representing the degree to which the sky is obscured by clouds. In weather forecast terminology, expected cloud cover of about 0.7 or more warrants use of this term. In the National Fire Danger Rating System, 0.6 or more cloud cover is termed "cloudy."
Co-op Fire
  • Refers to federal, state, and local cooperative fire programs. 
Cold Front
  • The leading edge of a relatively cold air mass which displaces warmer air, causing it to rise. If the lifted air contains enough moisture, cloudiness, precipitation and even thunderstorms may result. As fronts move through a region, in the Northern Hemisphere, the winds at a given location will experience a marked shift in direction. Ahead of an approaching cold front, winds will usually shift gradually from southeast to south, and on to southwest. As a cold front passes, winds shift rapidly to west, then northwest. Typical cold front windspeeds range between 15 and 30 mph but can be much higher. 
Cold Line
  • Fireline that has been controlled. The fire has been mopped up for a safe distance inside the line and can be considered safe to leave unattended. 
Cold Trailing
  • A method of controlling a partly dead fire edge by carefully inspecting and feeling with the hand for heat to detect any fire, digging out every live spot, and trenching any live edge. 
Collective Control
  • Controls the pitch angle of the main (helicopter) rotor blades. Used as primary altitude control. 
  • Species of vegetation that establish on a burned (or otherwise denuded) site from seed. 
Combination Nozzle
  • A nozzle is designed to provide either a solid stream or a fixed spray pattern suitable for applying water, wet water or foam solution. Also called: Adjustable Fog Nozzle. 
Combination Nozzle Tip
  • Two attached straight stream nozzle tips of different orifice size used to increase or restrict water flow. 
  • The rapid oxidation of fuel in which heat and usually flame are produced. Combustion can be divided into four phases: preignition, flaming, smoldering, and glowing. 
Combustion Efficiency
  • The relative amount of time a fire burns in the flaming phase of combustion, as compared to smoldering combustion. A ratio of the amount of fuel that is consumed in flaming combustion compared to the amount of fuel consumed during the smoldering phase, in which more of the fuel material is emitted as smoke particles because it is not turned into carbon dioxide and water. 
Combustion Period
  • Total time required for a specified fuel component to be completely consumed. 
Combustion Rate
  • Rate of heat release per unit of burning area per unit of time. 
  • The act of directing, and/or controlling resources by virtue of explicit legal, agency, or delegated authority. 
Command Climate
  • The working environment within the influence of a particular leader or chain of command. The command climate is based on the subordinates' understanding of how they are expected to perform, how they are treated, and how they must conform to the leader's style. 
Command Presence
  • How leaders present themselves to others. The personal attributes and traits that determine whether leaders are worthy of trust and respect from their subordinates. 
Command Staff
  • The command staff consists of the information officer, safety officer and liaison officer. They report directly to the incident commander and may have an assistant or assistants, as needed. 
Communications Unit
  • An organizational unit in the Logistics Section responsible for providing and maintaining communication services at an incident. May also be a facility (e.g., a trailer or mobile van) used to provide the major part of an incident communications center. 
Community Wildfire Protection Plan (CWPP)
  • A plan developed in the collaborative framework established by the Wildland Fire Leadership Council and agreed to by state, tribal, and local government, local fire department, other stakeholders and federal land management agencies managing land in the vicinity of the planning area. A Community Wildfire Protection Plan (CWPP) identifies and prioritizes areas for hazardous fuel reduction treatments and recommends the types and methods of treatment on Federal and non-Federal land that will protect one or more at-risk communities and essential infrastructure and recommends measures to reduce structural ignitability throughout the at-risk community. A CWPP may address issues such as wildfire response, hazard mitigation, community preparedness, or structure protection - or all of the above. 
  • A formal working agreement among agencies to obtain mutual aid. 
  • Spacing between fuel particles.
Compare and Contrast
  1. An investigative technique that involves comparing same sized indicators within an indicator category at separate locations; looking for either differences or similarities in appearance.
    • Definition Extension:  Includes the comparison of overall patterns and pattern clusters.
  2. The practice of comparing and contrasting the fire damage on different surfaces of an object that has been subjected to the oncoming fire.
    • Definition Extension: Typically, the exposed side has more fire effects present than the contrasting protected side that normally has less fire effects visible.

Source: Guide to Wildland Fire Origin and Cause Determination, PMS 412.

Compensation-for-Injury Manager
  • Person responsible to the Compensation/Claims Unit Leader for administrative matters arising from serious injuries and fatalities occurring on the incident. 
Compensation/Claims Unit
  • Functional unit within the Finance/Administration Section responsible for the overall management and direction of all Compensation-for-Injury and Claims Specialists assigned to the incident. 
  • A broad description that groups core behaviors necessary to perform a specific function. 
Competent Ignition Source
Compressed Air Foam Systems (CAFS)
  • A generic term used to describe foam systems consisting of an air compressor (or air source), a water pump, and foam solution. 
Computed Gross Weight
  • Term used in calculating from performance charts the permissible helicopter payload at which a helicopter is capable of hovering in ground effect or hovering out of ground effect, based on pressure altitude and air temperature. 
  • A substance that has been concentrated; specifically, a liquid that has been made denser, as by the removal of some of its water. 
Conceptual Model
  • A model that is a diagram or description of a set of relationships between factors that describe how a system works, such as an ecological model. 
  • The process by which a gas becomes a liquid. 
Condition Class
  • Depiction of the degree of departure from historical fire regimes, possibly resulting in alterations of key ecosystem components. These classes categorize and describe vegetation composition and structure conditions that currently exist inside the Fire Regime Groups. Based on the coarse-scale national data, they serve as generalized wildfire rankings. The risk of loss of key ecosystem components from wildfires increases from Condition Class 1 (lowest risk) to Condition Class 3 (highest risk).
Condition of Vegetation
  • Stage of growth or degree of flammability of vegetation that forms part of a fuel complex. Herbaceous stage is at times used when referring to herbaceous vegetation alone. In grass areas minimum qualitative distinctions for stages of annual growth are usually green, curing, and dry or cured. 
  • Heat transfer through a material from a region of higher temperature to a region of lower temperature. 
  • A wildfire response strategy of restricting a wildfire to a defined area, primarily using natural barriers that are expected to restrict the spread of the wildfire under the prevailing and forecasted weather conditions.
  • The strategy employed in appropriate management responses where a fire perimeter is managed by a combination of direct and indirect actions and use of natural topographic features, fuel, and weather factors. 
  • A raging, destructive fire. Often used to connote such a fire with a moving front as distinguished from a fire storm. 
Conflagration Threat
  • Likelihood that a wildfire capable of causing considerable damage will occur. 
Consistency (Foam)
  • Uniformity and size of bubbles. 
Constant Danger
  • Resultant of all fire danger factors that are relatively unchanging in a specific area (e.g., resource values at risk, topography, fuel type, exposure to prevailing wind). 
  • The amount of a specified fuel type or strata that is removed through the fire process, often expressed as a percentage of the preburn weight. 
  • The status of a wildfire suppression action signifying that a control line has been completed around the fire, and any associated spot fires, which can reasonably be expected to stop the fire's spread. 
  1. The status of a wildfire suppression action signifying that a control line has been completed around the fire, and any associated spot fires, which can reasonably be expected to stop the fire's spread.
  2. The act of controlling hazardous spilled or leaking materials. 
Continental Climate
  • Climate that is characteristic of the interior of a land mass of continental size, marked by large annual diurnal and day-to-day ranges of temperature, low relative humidity and irregular precipitation. 
Contingency Actions
  • A back-up plan of action when actions described in the primary plan are no longer appropriate. Contingency actions are required to be taken when the result exceeds its intent. Actions are taken to return the project to its intended design. 
Contingency Plan
  • The portion of a prescribed fire plan, incident action plan, or implementation plan that identifies possible but unlikely events and the contingency resources needed to mitigate those events. 
Contingency Resources
  • Planned and identified fire suppression personnel and equipment that mitigate possible but unlikely events that exceed or are expected to exceed holding resource capabilities. 
  • Any written agreement giving one party a right, a service, or a commodity in exchange for a right, a service, or a commodity. Contracts include land use permits, purchase orders, equipment rental agreements, leases, etc.
Contracted Resource Vendor
  • The name of the company who, through a contract, provides resources to support incident management activities.
Contracting Officer (CO)
  • Agency personnel with specific delegation of procurement authority, also known as warranted Contracting Officer.
Contracting Officer’s Technical Representative (COTR) / Contracting Officer’s Representative (COR)
  • An individual designated by the Contracting Officer to provide technical support for the contract within specific authority and limitations as specified in the delegation. The COTR/COR must be agency certified.
  • Private sector personnel, vendor or business contracted to provide goods and services to a government agency.
Control Force
  • Personnel and equipment used to control a fire. 
Control Line
  • An inclusive term for all constructed or natural barriers and treated fire edges used to control a fire. 
Control Time
  • The time a fire is declared controlled. 
  • The completion of control line around a fire, any spot fires therefrom, and any interior islands to be saved; burned out any unburned area adjacent to the fire side of the control lines; and cool down all hotspots that are immediate threats to the control line, until the lines can reasonably be expected to hold under the foreseeable conditions. 
Controlled Airspace
  • Airspace of defined dimensions within which air traffic control service is provided to IFR and VFR flights in accordance with the airspace classification. 
Controlling Nozzle
  • Shut-off nozzle that permits the nozzle operator to open or close the nozzle or adjust the pattern of the stream. 
  1. The transfer of heat by the movement of a gas or liquid; convection, conduction, and radiation are the principal means of energy transfer.
  2. As specialized in meteorology, atmospheric motions that are predominantly vertical in the absence of wind (which distinguishes this process from advection), resulting in vertical transport and mixing of atmospheric properties. 
Convection Column
  • The rising column of gases, smoke, fly ash, particulates, and other debris produced by a fire. The column has a strong vertical component indicating that buoyant forces override the ambient surface wind. 
Convective Activity
  • General term for manifestations of convection in the atmosphere, alluding particularly to the development of convective clouds and resulting weather phenomena, such as showers, thunderstorms, squalls, hail, tornadoes, etc. 
Convective-lift Fire Phase
  • The phase of a fire when most of the emissions are entrained into a definite convection column. 
  • The term for horizontal air currents merging together or approaching a single point, such as at the center of a low pressure area producing a net inflow of air. When this occurs in the lower atmosphere, the excess air is removed by rising air currents. Expansion of the rising air above a convergence zone results in cooling, which in turn often gives condensation (clouds) and sometimes precipitation. 
Convergence Zone
  1. The area of increased flame height and fire intensity produced when two or more fire fronts burn together.
  2. In fire weather, that area where two winds come together from opposite directions and are forced upwards often creating clouds and precipitation. 
Conversion Burning
  • Burning an area where brush has excluded forest reproduction to prepare the area for tree planting. 
Cooperating Agency
  • An agency supplying assistance including but not limited to direct tactical or support functions or resources to the incident control effort (e.g. Red Cross, law enforcement agency, telephone company, etc).
  • The process of systematically analyzing a situation, developing relevant information, and informing appropriate command authority of viable alternatives for selection of the most effective combination of available resources to meet specific objectives. The coordination process (which can be either intra- or interagency) does not involve dispatch actions. However, personnel responsible for coordination may perform command or dispatch functions within limits established by specific agency delegations, procedures, legal authority, etc. 
Coordination Center
  • Term used to describe any facility that is used for the coordination of agency or jurisdictional resources in support of one or more incidents. 
Coriolis Force
  • An apparent force due to the rotation of the earth that causes a deflection of air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This force maximizes at the poles and is essentially zero at the equator. 
  • Result of chemical reaction between a metal and its environment (i.e., air, water, and impurities in same). 
Cost Sharing Agreements
  • Agreements that document the financial responsibility for incident resource costs, possibly identifying requirements of other party payments. 
Cost Unit
  • Functional unit within the Finance/Administration Section responsible for collecting all cost data, performing cost effectiveness analyses, and providing cost estimates and cost saving advice. 
Council Tool
  • Long-handled combination rake and cutting tool, the blade of which is constructed of a single row of three or four sharpened teeth. Also called fire rake, council rake. 
Counter Fire
  1. Fire set between main fire and backfire to hasten spread of backfire. 
  2. Emergency firing to stop, delay, or split a fire front, or to steer a fire.
  • Device that connects the ends of adjacent hoses or other components of hose. 
  • In aviation, the intended direction of horizontal flight. 
  • The area on the ground covered by the combined aerial parts of plants expressed as a percent of the total area. 
Cover Type
  • The designation of a vegetation complex described by dominant species, age, and form. 
Coverage Level
  • Recommended amount of aerially applied retardant keyed to the NFDRS fuel models and/or fire behavior models. Coverage level 2 represents 2 gallons of retardant per hundred square feet. Levels range from 1 to 6 for most fuel models. A coverage level of greater than 6 is for heavy fuels. The levels can be adjusted for fire behavior. 
Coyote Tactics
  • A progressive line construction duty involving self-sufficient crews which build fire line until the end of the operational period, remain at or near the point while off duty, and begin building fireline the next operational period where they left off. 
  • Fine cracking of glass, usually from heat of fire. 
Creeping Fire
  • Fire burning with a low flame and spreading slowly. 
  • An organized group of firefighters under the leadership of a crew boss or other designated official. 
Crew Shuttle
  • Transportation of fireline personnel to and/or from assigned fireline locations. 
Crew Transport
  • Any vehicle capable of transporting a specified number of personnel in a specified manner. 
Criteria Pollutants
  • Pollutants deemed most harmful to public health and welfare and that can be monitored effectively. They include carbon monoxide (CO), lead (Pb), nitrogen oxides (Nox), sulfur dioxide (SO2), ozone (O3), particulate matter (PM) of aerodynamic diameter less than or equal to 10 micrometers (PM10) and particulate matter of aerodynamic diameter less than or equal to 2.5 micrometers (PM2.5). 
Critical Burnout Time
  • Total time a fuel can burn and continue to feed energy to the base of a forward-traveling convection column. 
Critical Incident Stress Debriefing (CISD)
  • The process in which teams of professional and peer counselors provide emotional and psychological support to incident personnel who are or have been involved in a critical (highly stressful) incident. 
Cross Shot
  • Intersecting lines of sight from two points to the same object, frequently used to determine location of a fire from lookouts. Also called cross bearing. 
Crown Consumption
  • Combustion of the twigs, and needles or leaves of a tree during a fire. 
Crown Cover
  • The ground area covered by the crown of a tree as delimited by the vertical projection of its outermost perimeter. 
Crown Fire
  • A fire that advances from top to top of trees or shrubs more or less independent of a surface fire. Crown fires are sometimes classed as running or dependent to distinguish the degree of independence from the surface fire. 
Crown Out
  • A fire that rises from ground into the tree crowns and advances from tree top to tree top. To intermittently ignite tree crowns as a surface fire advances. 
Crown Ratio
  • The ratio of live crown to tree height. 
Crown Scorch
  • Browning of needles or leaves in the crown of a tree or shrub caused by heating to lethal temperature during a fire. Crown scorch may not be apparent for several weeks after the fire. 
Crown Scorch Height
  • The height above the surface of the ground to which a tree canopy is scorched. 
Crowning Potential
  • A probability that a crown fire may start, calculated from inputs of foliage moisture content and height of the lowest part of the tree crowns above the surface. 
  • The ultimate growth of a cumulus cloud into an anvil-shaped cloud with considerable vertical development, usually with fibrous ice crystal tops, and usually accompanied by lightning, thunder, hail, and strong winds. 
  • A principal low cloud type in the form of individual cauliflower-like cells of sharp non-fibrous outline and less vertical development than cumulonimbus. 
Cup Trench
  • A fireline trench on the downhill side of fire burning on steep slopes that is supposed to be built deep enough to catch rolling firebrands that could otherwise start fire below the fireline. A high berm on the outermost downhill side of the trench helps the cup trench catch material. Also known as gutter trench. 
Curb Weight
  • Weight of a truck empty (without payload and driver) but ready to drive, including a full fuel tank, cooling system, crankcase, tools, spare wheel, and all other equipment specified as standard. 
  • In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture falls to 30% or less.