Firenado: a twister of flame

Fire whirls, also known as fire devils, fire tornadoes or firenadoes, are whirlwinds of flame that may occur when intense heat and turbulent wind conditions combine to form whirling eddies of air. These eddies can tighten into a tornado-like structure that sucks in burning debris and combustible gases.

A fire whirl consists of a core—the part that is actually on fire—and an invisible pocket of rotating air that feeds fresh oxygen to the core. The core of a typical fire whirl is 1 to 3 feet (0.30 to 0.91 m) wide and 50 to 100 feet (15 to 30 m) tall. Under the right conditions, large fire whirls, severalfirestorm tens of feet wide and more than 1,000 feet (300 m) tall, can form. The temperature inside the core of a fire whirl can reach up to 2,000 °F (1,090 °C)—hot enough to potentially reignite ashes sucked up from the ground. Often, fire whirls are created when a wildfire or creates its own wind, which can turn into a spinning vortex of flame. A CLOSER LOOK:

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 100 miles per hour (160 km/h)—strong enough to knock down trees.

Fire whirls can last for an hour or more, and they cannot be extinguished directly.

 In 1923, events Kanto earthquake in Japan, triggering a firestorm that burned to produce a tornado struck the town and a giant fire that killed 38,000 people in 15 minutes in the area Hifukusho-Ato in Tokyo. This event was considered the deadliest fire whirl on record.

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Source: WIKIPEDIA