Module 1: Basic Concepts of Wildland Fire
Crowning
A dangerous form of fire which more or less moves independent of the main fire by spreading from treetop to treetop - classed as running or dependent based on the degree of independence it has from the surface fire.
Containment
A fire suppression action that can reasonably be expected to stop the fire spread under current and predicted conditions.
Islands
Unburned areas inside the fire perimeter.
Spot fires
Fires burning outside the fire perimeter caused from sparks, embers, and burning twigs carried upward and outward by convection columns. Also caused by burning material running down a slope, passing control and fire lines.
Flaming/fire front
Leading edge of the fire perimeter
Fingers
Long, narrow strips of fire extending from the main body of the fire. This is due to a variation in terrain and wind, mixed fuels (heavy and light), or when the head is split by natural features (rocks, water, etc).
Control line
Refers to all natural and constructed fire barriers including treated fire edges used to contain the fire.
Spotting fire
Type of fire where wind or convection columns carry embers and burning material produced by the main fire, causing fires beyond the main fire perimeter.
Firewhirl
Essentially a fire tornado.
Creeping fire
A fire that burns with a low flame and spreads slowly.
Smoldering fire
A fire that burns without a flame and is barely spreading.
Torching
A fire that periodically ignites the crown of a single or group of trees before returning to the surface. Not as serious as a crowning fire.
Running fire
A fire that spreads rapidly with a well-defined head.
Backing fire
Also referred to as a heel fire - portion of the fire with a low ROS and burns with less intensity.
The green
Any area that isn't burnt, but is adjacent to the involved fire area.
Fire line
Any cleared strip or portion of a control line that has been dug by hand, stripping the area down to mineral soil.
Anchor Point
Any good place where you can start constructing a fire line. This is typically a fire barrier.
Flare-up
Any sudden increase in intensity and or ROS. Relatively short in duration and does not radically change existing control plans. Potentially caused by low-flying helicopters and air tankers.
Any unburned areas between fire fingers and the main body of the fire (think the area between fingers on your hand).
The black
Area that has already been burnt by the fire and contains blackened fuels. Can be, but isn't always safe; can be reburnt by adjacent fuels, potentially holds residual heat and smoke, has logs with the potential to roll downhill, has hot spots, and has smoldering snags (dead trees with the potential to fall).
The way in which you measure ROS
Chains per hour: 1 feet./minute = 1 chain an hour. An area that burns 10 by 10 chains is a 1 acre fire. 1 chain is 66 feet. or 20 meters. (Since there are 60 minutes in an hour, if the fire burns at one foot per minute that fire will burn 60 feet in an hour, or roughly one chain.)
Blowup
Occurs when ROS and intensity of the fire sufficiently increases to prevent direct control of the fire. Often accompanied with violent convection and will most likely pushback existing suppression plans.
Slopover, otherwise referred to as breakover
Occurs when a fire crosses any control line or natural barrier intended to contain the fire.
Perimeter, sometimes known as the fire edge
Outer boundary of a fire.
Head
Part of a wildland fire with the greatest rate of spread (ROS). Typically on the edge of a fire opposite the direction from which the wind is blowing (if the wind is blowing from the northeast then the greatest ROS would be the southwest edge, and or the upper part of a slope..
Rear or heel of a fire
Part of the fire opposite the head. Typically has a slow ROS, lesser intensity, and is burning and moving into the wind.
Control
Point in time when the perimeter spread of a fire has been halted and may reasonably hold for the foreseeable future.
Flanks
The sides of a wildland fire. Fire fingers often extend from these and should be controlled as soon as possible.
Mop-up
This marks the final stage of a fire suppression plan - Involves felling snags, trenching logs with the potential to roll, as well as check and extinguish any residual hot spots.
Origin
Where the fire started and the point from which it spreads