He found that even the most intense " crown fires, " sending flames 120 feet into the air, will not ignite a plywood-sided building when the flames are 65 feet away.
32.
A crown fire also can throw embers up to a mile away, VanDriel said, " and then you could have a fire ahead of you that you don't even know about ."
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Scientists from around the world are gathering this month in Canada's Northwest Territory to study crown fires, the most dangerous fires that light the tops of trees and allow wildfires to move quickly.
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And there are so many trees in the forest understory that they form a ladder of fuel that guarantees the killing crown fires that leap into the top of the oldest and tallest trees.
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Less than 20 miles west of the Crown fire, the Foothill fire forced the temporary closing on Saturday afternoon of part of the Antelope Valley Freeway, a major artery just south of Santa Clarita.
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And while a high Haines index might mean flames are more likely to leap into the tree tops, starting a rapidly proliferating " crown fire, " the vertical motion also helps keep smoke away from settlements.
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"Leaving that many trees ( 50 percent ) leaves the forest in a condition where it will still support crown fires, " the devastating fires that can wipe out sections of the forest for decades, Covington said.
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The dominant fire regime in the boreal forest is high-intensity crown fires or severe surface fires of very large size, often more than 10, 000 ha, and sometimes more than 400, 000 ha ( Heinselman 1981 ).
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On Monday, Pasinato said, he and a group of firefighters and reporters were caught by surprise when a wall of fire raced up a mountainside toward them as they watched the Crown fire from a ridge overlooking Placerita Canyon.
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At this level, the models encounter limits in knowledge about the composition of pyrolysis products and reaction pathways, in addition to gaps in basic understanding about some aspects of fire behavior such as fire spread in live fuels and surface-to-crown fire transition.
