Abstract Fire whirls and tornadoes are separate atmospheric phenomena that look similar but occur under different conditions. Fire whirls require calm air surrounding a large fire where the rising heat of the fire creates a convection cell which pulls fuel, fire and oxygen into a vertical vortex. Tornadoes often occur on the trailing edge of thunderstorms and are created when warm wet air rises over cool dry air creating a strong low pressure system which sucks air and debris from the ground level up into the storm cloud. These phenomena have different life cycles, and since they have different causes, they are not the same atmospheric phenomena despite their similar appearance. However, a fire tornado is possible when a large enough fire …show more content…
A fire whirl on the other hand is a whirlwind caused by a fire and is made up of flame and ash. Tornadoes occur when a warm, wet air mass comes into contact with a cold, dry air mass with winds rotating along a horizontal axis at ground level. The warm moist air is less dense than the cold, dry air, so it rises over the colder air, which reduces pressure at ground level. An updraft is caused by the lower pressure from the rising warm air mass, which can catch the winds rotating along a horizontal axis at ground level. These rotating winds are carried up and get tangled, eventually turning into a cyclone following the low pressure corridor created by the rising hot air into the cloud. Tornadoes are the most violent of all atmospheric storms on Earth. The strength of a tornado is rated using the Enhanced Fujita Scale (EF scale). The EF scale attempts to determine the speed of 3-second wind gusts based on 28 factors that can be observed via ground based observations of the damage caused by the storm. The reason that the wind speeds are determined by damage is because anemometers are often destroyed at tornado strength wind speeds. The scale rates tornadoes on a strength of 0 to 5 (Table 1) based on the speeds determined by these ground based …show more content…
Tornadoes and fire whirls generally do not last longer than 10 – 15 minutes, though the Tri-State Tornado was on the ground for over 7 hours (Maddox, et al., 2013), and fire whirls have been observed that last up to an hour. If a fire becomes large enough, and conditions are just right, it is possible for a pyrocumulonimbus cloud to form above the fire, and a tornado can form in this cloud, and pull burning fuel and oxygen from ground level into the vortex of the tornado. The 2003 Canberra Australia wildfires produced a pyrocumulonimbus cloud that produced an EF-2 fire tornado (Geoscience Australia,