S-190 Intro to Wildland Fire Behavior
what are the hazards of a thunderstorm?
Hazards Include: Change in wind speed and direction (downdraft winds), rising heat, and dangerous lightning pg.2c.26
Indicator of increased fire behavior
Unstable Atmosphere: encourages upward motion of air. pg. 2c.13
When is a fire controlled?
when control lines can reasonably be expected to hold under the forseesable conditions pg. 1.9
What has the greatest effect on fire spread?
wind pg. 2c.15
Running Fire
fire spreading rapidly with a well defined head pg. 1.6
Spotting
process of convection starting new fires beyond the zone of direct ignition by main fire pg. 1.6
What are the components of the fire triangle?
1) Fuel: to burn 2) Air: oxygen for flame 3) Heat: to start and continue combustion process. *remove any single one, there can be no fire* pg. 1.10
Vertical Arrangement
1) Gr-ound Fuels: all combustible material lying beneath the surface (ex: deep duff, tree roots, rotten buried material, other organic material) 2) Surface Fuels: all combustible materials lying on or immediately above the ground (ex: needles, leaves, duff, grass, stumps ect.) 3)Ladder Fuels: combustible materials that aid the spread of fire from the surface little, shrubs, and other moderate height vegetation 4) Aerial Fuels: All green and dead materials located in the upper canopy (ex: tree branches, crowns, snags ect.) pg. 2b.9-10
6 Basic Fuel Types
1) Grass 2) Grass-Shrub 3) Shrub 4) Timber- Understory 5) Timber Litter 6) Slash- Blowdown pg. 2b.3
What are the 3 processes of heat transfer, which is most important?
1) Radiation: dries surrounding fuels and sometimes ignites them 2) Convection: occurs when lighter warm air moves upward 3) Conduction: heat transferred by from one fuel particle to another * convection is the most important while conduction is least important because of woods low conduction rate*
Horizontal Continuity
1) Uniform fuels: all fuels distributed continuously over an area. (network of fuels providing continuous path of fire spread) 2) Patchy fuels: all fuels ditributed unevenly over an area (ex: patches of rock outcroppings, bare ground, and areas where another dominant type of fuel is much less flammable) pg. 2b.8-9
Canyons (2 types)
1)Narrow Canyons: fire in a steep narrow canyon can easily spread to fuels on the adjacent side by radiation and spotting. 2) Box canyon: Fires starting near the base of box canyons may react similarly to fire in a wood burning stove or fireplace pg. 2a.5
Barrier (2 types)
Any obstruction to the spread of fire 1) Natural Barriers: rocks, rivers, lakes, slides. 2) Man-Made Barries: roads, highways, reservoirs, fireline constructed by fire resources pg. 2a.7
what weather factor leads to increased fire behavior
Battling or Shifting (Foehn) winds lead to increased fire behavior. pg. 2c.25
what wind indication is a sign of increased fire behavior
Dust Devils and Fire whirls are clear signs of increased fire behavior. pg. 2c.28
What are the hazards of a narrow canyon
Wind eddies and strong up-slope air movement, spreading fuels to adjacent sides by radiation and spotting pg. 2a.5
What fuel type reacts the fastest?
Grass: burns the hottest and fastest pg. 2b.4
Relative Humidity
amount of moisture in the air divided by the amount of air held when saturated at the same air temperature *typically reaches its lowest point at mid to late afternoon (when temperature reaches its max)** pg. 2b.8
Smoldering
also known as "punking around" is a fire with out flame and barely spreading pg. 1.6
As relative humidity increases, temperature _______.
decreases pg. 2c.6
