The elliptical shape and size of wind-driven crown fires
Document Type: Journal
Author(s): Martin E. Alexander ; Miguel G. Cruz
Publication Year: 2014

Cataloging Information

  • crown fire
  • ellipse perimeter
  • fire growth
  • wind-driven wildland fire
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Record Maintained By:
Record Last Modified: December 13, 2016
FRAMES Record Number: 17773


Typically, for wildfires in conifer forests to become large, some degree of crowning must occur. A common axiom in wildland fire management is that approximately 95 percent of area burned is generally caused by less than about 5 percent of the fires. A forest fire at the very minimum doubles its spread rate after the onset of crowning, and the area burned for a given period will be at least four times what would have been covered by a surface fire. In other words: the area burned is proportional to the rate of spread increase (following the transition to crowning) to the power of 2. Thus, if a fire triples its rate of advance after crowning, the area burned will be nine times greater than had it remained as a surface fire.

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Alexander, Martin E.; Cruz, Miguel G. 2014. The elliptical shape and size of wind-driven crown fires. Fire Management Today 73(4):28-33.