S-190 Basic Concepts of Wildland Fire
Perimeter - answer- the outer boundary or the distance around the outside edge of the
burning or burned area
- also called the fire edge
- continues to grow until you get it controlled and extinguished
Control Line - answeran inclusive term for all constructed or natural barriers and treated
fire edges used to control a fire
Fire Line - answerpart of the control line that is constructed by firefighters
Rear - answer- or called heel, of a wildland fire is the end opposite the head, that is
relatively closer to the point of origin than to the head
- burns with low intensity
- has a low rate of spead
- is generally easier to control than the head
Flanks - answer- are the sides of wildland fire, roughly parallel to the main direction of
fire spread
- are identified as either left or right as you are looking from the heel of the fire toward
the head
- shift in wind direction may quickly change a flank into a head
- fingers often extend from flanks
Islands - answer- are unburned areas inside the fire perimeter
- because they are unburned potential fuels, patrol them frequently and check for spot
fires
- close to a control line may flare up later and start spot fires across the control line
- you may consider burning out islands to consume fuels between the perimeter and the
control line
Spot Fires - answer- as gases rise from a fire into the convection column, sparks,
embers, and burning twigs are carried aloft
- as these items fall back to the ground a spot fire occurs
- can also result from being blown across a fireline by winds
- items can roll downhill across the fire line into unburned fuels beyond the main fire
occurs some distance from the control line
Convection Column - answerrising column of heated air or gases above a continuing
heat or fire source
, Fuel - answerflammable and combustible substances available for a wildland fire to
consume
Slopover - answer- also known as breakover
- occurs when fire crosses a control line or natural barrier intended to contain the fire
- occurs immediately across and adjacent to the control line
The Green - answer- any area that's not burnt but is adjacent to an involved area
- live fuels can include:
- vegetation with high moisture content
- vegetation with lower moisture content and highly flammable
- dense, golden yellow annual grasses and other similar fuels with low moisture content
that may burn vigorously
Live Fuels - answerliving plants, such as trees, grasses, and shrubs, in which the
seasonal moisture content cycle is controlled largely by internal physiological
mechanisms rather than by external weather influences
Dead Fuels - answerfuels with no living tissue in which the moisture content is governed
almost entirely by atmospheric moisture, dry bulb temperature, and solar radiation
The Black - answer- the black or the burn, is the area in which the fire has consumed or
"blackened" the fuels
- whether it is safe or not depends on:
- if it is completely burned over and little if any unburned fuel remains, the black is
relatively safe area during a fire. however, the black is not always safe
Surface Fuel - answerfuel that contacts the surface of the ground; consists of duff, leaf
and needle litter, dead branch material, downed logs, bark, tree cones, and low stature
living plants. these are the materials normally scraped away to construct a fireline.
sometimes called Ground Fuel
Aerial Fuels - answerstanding and supported live and dead combustibles not in direct
contact with the ground and consisting mainly of foliage, twigs, branches, stems, cones,
bark, and vines
Hazards of the Black - answer- in steep terrain, exposure from adjacent unburned fuels
can cause reburn
- residual heat and smoke
- hot spots and smoldering snags, stumps, and downed trees
- falling snags
Snags - answerstanding dead trees
Reburns - answerif a surface fire leaves aerial fuels more or less intact in the black, or
vice versa, a reburn can occur when burning conditions are more favorable
Perimeter - answer- the outer boundary or the distance around the outside edge of the
burning or burned area
- also called the fire edge
- continues to grow until you get it controlled and extinguished
Control Line - answeran inclusive term for all constructed or natural barriers and treated
fire edges used to control a fire
Fire Line - answerpart of the control line that is constructed by firefighters
Rear - answer- or called heel, of a wildland fire is the end opposite the head, that is
relatively closer to the point of origin than to the head
- burns with low intensity
- has a low rate of spead
- is generally easier to control than the head
Flanks - answer- are the sides of wildland fire, roughly parallel to the main direction of
fire spread
- are identified as either left or right as you are looking from the heel of the fire toward
the head
- shift in wind direction may quickly change a flank into a head
- fingers often extend from flanks
Islands - answer- are unburned areas inside the fire perimeter
- because they are unburned potential fuels, patrol them frequently and check for spot
fires
- close to a control line may flare up later and start spot fires across the control line
- you may consider burning out islands to consume fuels between the perimeter and the
control line
Spot Fires - answer- as gases rise from a fire into the convection column, sparks,
embers, and burning twigs are carried aloft
- as these items fall back to the ground a spot fire occurs
- can also result from being blown across a fireline by winds
- items can roll downhill across the fire line into unburned fuels beyond the main fire
occurs some distance from the control line
Convection Column - answerrising column of heated air or gases above a continuing
heat or fire source
, Fuel - answerflammable and combustible substances available for a wildland fire to
consume
Slopover - answer- also known as breakover
- occurs when fire crosses a control line or natural barrier intended to contain the fire
- occurs immediately across and adjacent to the control line
The Green - answer- any area that's not burnt but is adjacent to an involved area
- live fuels can include:
- vegetation with high moisture content
- vegetation with lower moisture content and highly flammable
- dense, golden yellow annual grasses and other similar fuels with low moisture content
that may burn vigorously
Live Fuels - answerliving plants, such as trees, grasses, and shrubs, in which the
seasonal moisture content cycle is controlled largely by internal physiological
mechanisms rather than by external weather influences
Dead Fuels - answerfuels with no living tissue in which the moisture content is governed
almost entirely by atmospheric moisture, dry bulb temperature, and solar radiation
The Black - answer- the black or the burn, is the area in which the fire has consumed or
"blackened" the fuels
- whether it is safe or not depends on:
- if it is completely burned over and little if any unburned fuel remains, the black is
relatively safe area during a fire. however, the black is not always safe
Surface Fuel - answerfuel that contacts the surface of the ground; consists of duff, leaf
and needle litter, dead branch material, downed logs, bark, tree cones, and low stature
living plants. these are the materials normally scraped away to construct a fireline.
sometimes called Ground Fuel
Aerial Fuels - answerstanding and supported live and dead combustibles not in direct
contact with the ground and consisting mainly of foliage, twigs, branches, stems, cones,
bark, and vines
Hazards of the Black - answer- in steep terrain, exposure from adjacent unburned fuels
can cause reburn
- residual heat and smoke
- hot spots and smoldering snags, stumps, and downed trees
- falling snags
Snags - answerstanding dead trees
Reburns - answerif a surface fire leaves aerial fuels more or less intact in the black, or
vice versa, a reburn can occur when burning conditions are more favorable
