Global warming? Fuggedaboutit — we’re in the age of global heating! This firenado (aka fire tornado, fire devil, or fire whirl), filmed recently in California, is a rare breed, but I have a feeling it’s going to be a lot less rare in the
Here’s Wikipedia’s current writeup on firenado formation:
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, several 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 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 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.