While forest fire incident commanders and crew leaders have developed thick manuals of fire behavior they rely on to keep themselves safe, it turns out the actual physics of flame still has a lot of unknowns. The fire wall sends up a sheet of flame that cools as it rises, but also becomes more turbulent. Finney uses it to learn how different intensities of flame ignite unburned trees and shrubs. Eventually, that will help firefighters predict how fast a blaze might move through different kinds of forests.

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The whirl chamber studies a more pernicious kind of fire effect. Under certain wind or geographic conditions, forest fires can produce tornadolike plumes that move much faster than ordinary flame fronts. Sometimes these plumes don’t even burn, but deliver winds strong enough to flip a truck or lift a house. They can also fling burning embers half a mile ahead of the main fire.

“There’s been a lot of research on fire whirls’ velocity and structure,” said mechanical engineer Jason Forthofer. “But there’s almost no work done on how they get started. And we know these can be really hazardous to firefighters. We got this apparatus built about two weeks ago.”