What are tornadoes really? The simple explanation is that they are a very powerful rotating column of air. But where does that power come from, and how does the spiral form? A select few factors need to be present in the right place at the right time for a tornado to form. It takes just a current of low, warm moist tropical air foiled with cold polar air to create the perfect storm. It is the combination of these factors that incentivize tornado-forming supercells to come out and play. Supercells are giant thunderstorms that often precede tornadoes. These thunder clouds rival your typical angry rain cloud as they can get grow up to 50,000 feet in height.
To better understand how tornadoes form, you must first understand how weather works. Weather is formed when there are changes in temperature and pressure in the atmosphere. Tornadoes specifically are formed when high pressure meets low pressure. Low pressure will draw in higher pressure, resulting in a vortex.
The tornado is the most intense of the atmospheric circulation. The wind speeds of a tornado are measured on the Fujita-Pearson scale, or the F scale. The lowest wind speed range on this scale is 40-72mph (F0), the highest range is 261-318 mph (F5). Most tornadoes have wind speeds less than 112 mph, however. It is odd to think a swirling vortex of terror is actually going slower than some of the motorcycles on the interstate currently. The vortex of a tornado generally varies between a few feet and a mile wide.
Damage paths from tornadoes range from 1 mile wide and 50 miles wide. About half of all tornadoes fall into the F1 category, the second mildest on the Fujita-Pearson scale at 73-112 mph. Only about one percent of tornadoes have wind speeds high enough to fall under the F5 category of 261-318 mph winds. F5 tornadoes have Wizard of Oz capabilities, strong enough to rip houses from their foundations and hurl them a good distance.
Tornadoes occur all over the world, but are most common in the United States. On average, the US gets about 1,000 tornadoes per year. Most of the tornadoes in the US take place in the central plains and southeast states, this region is called “tornado alley”. Tornadoes tend to form in these areas as these places provide the perfect atmosphere. The warm air from the humid Gulf of Mexico clashes with the cool, dry air from both the Rocky Mountains and Canada to create tornado spawning supercells. In the central plains, tornadoes occur most frequently in spring time during the late afternoon.
Although tornadoes are usually visible as a funnel cloud, as we are used to seeing in movies, they are not always. “Invisible” tornadoes, though rare, form when the funnel cloud does not quite extend to the earth’s surface. Invisible tornadoes can only really be identified by the debris that it will create around it. Do not think that just because you don’t see a vortex a tornado cannot be present, look scan for debris as well.
Do you live in a region that is prone to tornadoes? Food Insurance® has put together a Disaster Bug-Out-Bag that is ideal for tornado preparation.