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A fire whirl – also colloquially known as a fire devil, fire tornado, firenado, or fire twister – is a whirlwind induced by a fire and often made up of flame or ash. Fire whirls may occur when intense rising heat and turbulent wind conditions combine to form whirling eddies of air. These eddies can contract into a tornado-like structure that sucks in burning debris and combustible gases. Rarely, however, do fire whirls grow to become actual tornadoes, which are violently rotating vortices connecting the surface to a cumuliform (such as pyrocumulus or pyrocumulonimbus) cloud base. ==Formation== A fire whirl consists of a core – the part that is actually on fire – and an invisible rotating pocket of air. A fire whirl can reach up to – hot enough to potentially reignite ashes sucked up from the ground. Often, fire whirls are created when a wildfire or firestorm creates its own wind, which can turn into a spinning vortex of flame. Combustible, carbon-rich gases released by burning vegetation on the ground are fuel for most fire whirls. When sucked up by a whirl of air, this unburned gas travels up the core until it reaches a region where there is enough fresh, heated oxygen to set it ablaze. This causes the tall and skinny appearance of a fire whirl's core. Real-world fire whirls usually move fairly slowly. Fire whirls can set objects in their paths ablaze and can hurl burning debris out into their surroundings. The winds generated by a fire whirl can also be dangerous. Large fire whirls can create wind speeds of more than – strong enough to knock down trees – and people who get caught by a fire whirl can be burned alive. Fire whirls can last for an hour or more, and they cannot be extinguished directly.〔Fortofer, Jason (20 September 2012) ("New Fire Tornado Spotted in Australia" ) ''National Geographic''〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「fire whirl」の詳細全文を読む スポンサード リンク
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