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Unit 1: The Changing Fire Environment

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Environment   ::   Heat Transfer   ::   Behavior   ::   Predictions   ::   Summary   ::  Exercises

Exercise 1

Describing Fire Behavior

Match the fire behavior terms on the right to the definitions on the left

Term Definition
1. Spotting a. Fire moving from surface fuels into the crowns of individual trees, but not necessarily from one crown to another.
2. Surface Fire b. Sudden acceleration of fire spread or intensity, but of relatively short duration.
3. Running c. Fire spreading rapidly with a well defined head.
4. Creeping d. Fire burning with a low flame and spreading slowly.
5. Smoldering e. Fire that advances from top to top of trees or shrubs more or less independently of the surface fire.
6. Crown Fire f. Fire that burns surface litter, debris, and small vegetation.
7. Ground Fire g. A spinning, moving column of ascending air rising within a vortex and carrying aloft smoke, debris and flames.
8. Blowup h. Fire producing sparks or embers that are carried by the wind and start new fires beyond main fire.
9. Flareup i. Fire burning without flame and barely spreading.
10. Flaming Front j. That zone of a moving fire within which the combustion is primarily flaming.
11. Firewhirl k. Fire that consumes the organic material beneath the surface litter, i.e., peat.
12. Torching l. Sudden increase in fire intensity or rate of spread which defies control or forces changes in plans.

Exercise 2

Describing Fires

Answer the following questions about the fire illustrated below

  1. In what type of environment is the fire burning?
  2. Which of the three major components making up the fire environment is likely to change the most in time? Why?
  3. State the processes by which the fire is spreading.
  4. Describe the rate of spread and fire intensity of the fire.
  5. In what type of fuels is the fire burning?
  6. Does a crown fire appear likely to occur? Explain.
  7. What changes in environmental factors could cause this fire to grow larger in size and intensity?

Exercise 2

  1. Considered as a closed environment, however, if fire intensity should increase substantially, it could become open.
  2. Weather is the most likely to change. Slope is uniformly level and large dead fuels change very slowly.
  3. Fire is spreading primarily by radiation and convection, but also by conduction. Spotting could occur with torching.
  4. Fire appears to be creeping with a low fire intensity.
  5. Fire is burning in surface litter, needles, and logs.
  6. Crown fire is not likely. Although individual trees might torch out, the canopy is not continuous.
  7. Increase in wind would have the greatest effect. Also increase in temperature, decrease in relative humidity, and increase in atmospheric instability could all increase fire intensity and size.

Copyright 2008, Michael Jenkins. Cite/attribute Resource . admin. (2005, October 05). Unit 1: The Changing Fire Environment. Retrieved January 07, 2011, from Free Online Course Materials — USU OpenCourseWare Web site: This work is licensed under a Creative Commons License Creative Commons License