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