Chapter 4 "Wildland Fire Behavior"
Torching
Fire burning on the surface, but periodically igniting the crown of a single or small group of trees or shrubs before returning to the surface. Although sometimes confused with crowning this behavior is not as serious as a crown fire.
Creeping
Fire burning with a low flame and spreading slowly
Smoldering
Fire burning without flame and spreading very slowly
What 3 factors influence the intensity of vertical dimension?
Fire intensity, stability of air, winds aloft
Backing
Fire moving away from the head, downhill, against wind.
crowning
Fire that advances across tops of trees/shrubs more/less independent of surface fire.
Flanks
Sides of fire
Spotting
Sparks or embers produced by the main fire are carried by winds or convection column.
What is the most common form of firing?
Strip burning is the most common firing technique. It allows for fast ignition and the regulation of intensity. The width of the strips can vary.
Dew point
Temp at which air is 100% saturated w/ water vapor
Burning out
To remove fuels between the fire and the Fireline. Can reduce mop up. Can create a safety zone
As a general rule, construct Fireline moving in what direction?
Uphill
Three primary factors that influences the direction of a fire
Wind, slope, condition of fuel
General winds
Winds blowing over large areas reported daily
Running
fire spreading rapidly with a well defined head
Indraft winds
move in to replace heated air that is lifted by the convective action of the fire. Indrafts provide oxygen to the flame front, increasing convective heating and preheating the fuels
blowup
A sudden increase in fire intensity or rate of spread sufficient to preclude direct control or to upset existing control plans
Area Ignition
Area "peppered" with spot fires, most energy release is vertical not horizontal
Fingers
Caused by shift of winds
Slopovers
Crosses fireline
Plume driven
Direction of travel and rate of spread are harder to predict
Burning Out operations shall have the approval of the ______
Division/Group Supervisor
Who can make the decision to backfire? ***tes t question
Except in extreme emergencies, the decision and timing to backfire lies with the incident commander or operations section chief
Identify several ways fire can cross a Fireline ***test question
Radiant & convective heat, roll downs, burning snags, gusts of wind, whirlwinds, Fire whirls
As a general rule, the Fireline should be at least ____ times as wide as the predominant fuel is tall. Where extreme Fire Behavior is expected, the width of Fireline should be ____times the fuel height.
1 1/2 & 2
Pockets
Fuel indentations of unburned fuel along the fires perimeter
Backfiring
Indirect attack tactic used to slow a fast burning fire. A back fire is set ahead of the main fire
Ring firing ***test question
Is used when you need to protect a structure or other significant sites.
Why is speed and direction so important?
It is most influential factor when it comes to the fires rate & spread
Wind driven fire
Large fire, you usually have an idea what direction it will it will burn in
Two types of fuel moisture
Living, dead
spread
Movement of fire measures by rate of speed
Downdrafts
Occur below the convective column. When the heated air is lifted by the convection column, & subsequently cooled in the upper atmosphere it rushes back toward the surface of the earth.
Islands
Patches of unburned fuels inside fires perimeter