Fire fighters hate winds. They can make a fire fall to a puff or explode to a roar; they can make it jink to the left or right, or halt and spin in a circle. Nature's winds are fickle and unpredictable, and they can be a fire fighter's worst enemy. What's more, when conditions are right, fires spawn their own winds as the flames gobble up oxygen, sucking it in from all sides. These winds in turn can create a bizarre natural phenomenon: microweather, born of fire. Odd little weather systems, occurring within the larger system, can give rise to tornadoes filled with fire and noxious gases. They can cause huge thunderheads to form in a cloudless sky; they can make rain fall and lightning flash.
All these wonders start with the plume that is formed as the heated air rises from the fire in a column. Usually a strong prevailing wind quashes such a plume before it can grow. But when the fire is especially hot and the wind is weak, the plume can prevail. "Wind is the most critical weather component for fires," says Margaret Gross, a meteorologist for the National Weather Service in Riverside, California. "It determines more than anything else how fast a fire will spread. But when the power of the fire is greater than the wind, these large plumes can rise high into the atmosphere. Those are the fires that usually generate weather."
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