Wildfires: Beyond the Basics
Wildfires are nightmarish scenarios that have become a reality for many people not only in California but also across the globe. These catastrophic events not only threaten life and property but also within a blink of an eye can grow out of control. Bringing about new dangers outside of the fire itself.
An example of bizarre behavior within a wildfire was brought to public attention via a home recording from Portugal. The short clip depicts a scene that has seemingly been taken out of the newest Hollywood disaster flick. An out of control wildfire is seen ravaging the countryside coupled with what appears to be a tornado that is on fire. The title of the video was “Portugal Fire tornado”. But what exactly is a “Fire Tornado”? Further research into the subject reveals that the so-called ‘Fire Tornado’, is a misnomer. The video from Portugal captured what is actually known as a fire whirl. A fire whirl is defined as a cyclone, or whirlwind induced by fire and is comprised of flame debris or ash. The fire whirl, commonly dubbed fire tornado, fire devil, or firenado, results when air at the surface is heated, loses density and begins to rise. The rising air leaves an open space for cooler air to rush in. The newer cooler air becomes heated and rises, and the cycle continues and each rising thermal contains a combination of ash, fire, and debris. The vorticity or spin of the rising air will “tighten up” into the recognizable funnel shape, similar to when you drain a bathtub. These fire whirls are unpredictable and extremely dangerous for first responders attempting to extinguish the inferno.
However, fire whirls are not technically considered to be a meteorological event. Conversely, some wildfires can become so expansive and release enough energy that they generate their own wind systems and form what is known as a firestorm. Firestorms are not exclusively produced from wildfires, but can also result from aerial bombings and explosives. Because these firestorms have their own wind systems, they can manufacture weather systems. When the heat and moisture from the fire rise into the atmosphere a pyro-cumulonimbus cloud can form. These marvels behave the same as regular cumulonimbus clouds but the fact that pyro-cumulonimbus clouds do not exist outside of the above conditions is a key distinction between the two.
Pyro-cumulonimbus clouds have been known to yield thunder, lightning, hail, and rain. In January of 2003, a severe bushfire had spread in Canberra, Australia and decimated the area. After the bushfire was contained, locals were left with nothing but the task of cleaning up the devastation. While surveying the area, a puzzling discovery was revealed. Along with typical destruction associated with bushfires, there was extraordinary amount of damage that was not consistent with fire. Cars had been tossed and scattered about like toys and rooftops had sustained severe damage associated with high winds. Later, a local resident released video footage he had taken of what appeared to be a funnel within the out of control bushfire. It was later discovered a pyro-cumulonimbus cloud spawned a fire tornado that reached wind speeds of 111 to 135 miles per hours, measuring an EF-2 on the Enhanced-Fujita scale. Because of the unpredictability and sporadic nature of wildfires, fire tornados are a rare occurrence and are difficult for scientists to study. In fact, fire tornados were only recently discovered.
One can hope that amidst all the devastation and destruction plaguing California, it will allow scientists the opportunity to learn more about these destructive events and provide the public with new techniques regarding fire prevention and safety.
To learn more about this and other high-impact fire weather events, be sure to click here!
©2017 Weather Forecaster Ali Van Fleet
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