FIRE WHIRL

 Tornadoes are terrifying events, but add fire and they become spectacularly terrifying. Fire whirls occur when the heat from a fire drive the air above it in such a way as to form a vortex with the cooler air outside. If this vortex acquires a vertical spin then a fire whirl, a vortex sucking flames upwards, will form. Fire whirls can be incredibly dangerous as they may pick up burning debris and so spread the flames.

When Tokyo was struck by an earthquake in 1923 an enormous fire whirl was created by the massive numbers of burning wooden buildings. The whirl was a major factor in the burning to death of 38,000 people. Smaller whirls are commonly seen at the front of fires in grasslands.

 A fire tornado 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 tornado 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, very large fire tornadoes—several tens of feet wide and more than a thousand feet (300 meters) tall—can form. The temperature inside the core of a fire tornado can reach up to 2,000 °F (1,090 °C)—hot enough to potentially reignite ashes sucked up from the ground. Often, fire tornadoes are created when a wildfire or firestorm creates its own wind, which can turn into a spinning vortex of flame.


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. Thousands of whirlwinds were produced by the four-day-long[dubious – discuss] firestorm[citation needed] coincident with conditions that produced severe thunderstorms, in which the larger fire whirls carried debris 5 kilometers away.

 There are currently three known types of fire whirls:
    Type 1: Stable and centered over burning area.
    Type 2: Stable or transient, downwind of burning area.
    Type 3: Steady or transient, centered over an open area adjacent to an asymmetric burning area with wind.