FIRE TORNADO

A tornado just might be nature's greatest spectacle. A small one inspires awe and wonder. A larger one drives people into shelters and basements. And a monster tornado, a storm that earns an EF-5 rating on the enhanced Fujita scale, well, there's a reason why it's sometimes referred to as "the finger of God." When such a storm strikes, it leaves behind complete and total devastation, the way an angry deity might if he wanted to punish mortals for their sins.

A fire whirl consists of a core—the part that is actually on fire—and an invisible core of a fire whirl can reach up to 2,000 °F (1,090 °C)—hot enough to potentially reignite ashessucked 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 100 mph (160 km/h)—strong enough to knock down trees.

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

Now inject heat, ash and fire into a spinning mass of air. Watch as a funnel of flames leaps from the ground, reaches for the heavens and then races forward to consume everything in its path. Is such a phenomenon possible? And if so, could such a storm rage with the same intensity as an EF-5, becoming, if you will, "the finger of the devil"?

During the 2003 Canberra bushfires, a fire whirl with a diameter of nearly 500 metres (1,600 ft) with horizontal winds exceeding 250 km/h (160 mph) was documented. Further research into the fires confirmed this in 2012.^[2] In Canberra, wind damage consistent with an F2 tornado on the Fujita Scale was observed, in addition to the fire damage.^[3] New research released in 2013 showed that the supercell thunderstorm that caused the tornado originated from the converging winds of firestorm itself, one of the first confirmed observations of an intense thunderstorm forming from a Pyrocumulonimbus cloud.

Another extreme example of a fire tornado from other than a vegetation fire is the 1923 Great Kantō earthquake in Japan which ignited a large city-sized firestorm and produced a gigantic fire whirl that killed 38,000 in fifteen minutes in the Hifukusho-Ato region of Tokyo.

Another example is the numerous large fire whirls (some tornadic) that developed after lightning struck an oil storage facility near San Luis Obispo, California on 7 April 1926, several of which produced significant structural damage well away from the fire, killing two. Many whirlwinds were produced by the four-day-long firestorm coincident with conditions that produced severe thunderstorms, in which the larger fire whirls carried debris 5 kilometers away.

You might be surprised to find out that the answer to both questions is yes, and the storm responsible is typically known as afire tornado, a fire whirl or a fire devil. If the latter two terms sound familiar, it's because they echo the colloquial names we give to similar meteorological phenomena – whirlwinds and dust devils. In fact, fire tornadoes are more closely related to whirlwinds than they are to full-fledged tornadoes. But all such storms are related in that they involve a mass of air rotating rapidly around a central axis.

So why haven't we heard more about fire tornadoes? It's not because they're uncommon, but because they form in situations most of us try to avoid. These situations include wildfires, large fires spawned by natural disasters and, in some cases, house fires. As you might expect, firefighters have seen their share of fire tornadoes. And scientists who want to study the characteristics of these strange storms must venture into infernos or bring the inferno into their labs. Think of it as storm chasing, with an incendiary twist.

REFERENCE :WIKIPEDIA,HOWSTUFF WORKS