Tornadoes typically result in damage to vegetation and property, and often people and animals being killed or injured.
Much like the nature of tornadoes themselves, the results are unpredictable, and those observed have yielded a variety of results, sometimes ones regarded as fantastic, from two tornadoes combining into one both (or more) tornadoes dissipating, to one dissipating the other, to much more varied effects.
No. Cyclones can produce tornadoes, but not the other way around. A cyclone is a large scale system that can produce smaller storm cells. A tornado is a small scale vortex that results from such a cell.
The most common sorts of damage include downed trees, damaged roofs, and collapsed sheds and garages. Only a small percent of tornadoes cause catastrophic damage.
Yes. Tornadoes have hit airports. When this happens it often results in heavy damage to airplanes.
Tornadoes, particularly strong ones, can cause a lot of damage which must be repaired. This is expensive, sometimes extremely. The cost of damage from the Joplin, Missouri tornado, for example, is $2.8 billion, more than 20 times the city budget. Businesses and parks can be destroyed or have to close down, which results in lost revenue. This results partly from destroyed infrastructure as tornadoes can take out power lines and, in some cases, bridges and roads.
In short, thunderstorm forms from masses of warm, moist air rising high into the atmosphere, which results in the formation of towering cumulonimbus clouds. Tornadoes are a product of rotating air currents in violent thunderstorms.
In the U.S. hail rarely results in fatalities, while fatalities due to wind and tornadoes are more common. So the SPC probably regards wind and tornadoes as a more serious threat.
Tornadoes in the U.S. are called tornadoes.
The Tornado History Project has a number of good maps for tornadoes in the Unites States from the years 1950-2010 including Alabama. However, in that time period Alabama has had nearly 1700 tornadoes. Trying to view them all at once results in an unreadable map. You may want to try more specific search parameters, such as a specific set of years.
That is difficult to determine. Since individual towns are small targets tornado activity tends to be sporadic. Since records began in 1950 there have been 4 recorded tornadoes in Thornton, all in a period running from the early '80s to the mid '90s This results in a frequency of tornadoes somewhere between once every 4 years and once every 15 years.
Tornadoes are sometimes divided into "weak" tornadoes "strong" and "violent" tornadoes. Weak tornadoes are those rated EF0 and EF1. Most tornadoes are weak. Strong tornadoes are those rated EF2 and EF3. Violent tornadoes are those rated EF4 and EF5. They are the rarest of tornadoes, only about 1% of tornadoes are this strong.
It depends on what you mean by extreme. Tornadoes of EF4 and EF5 tornadoes, however are often referred to as violent tornadoes. These account for about 1% of all tornadoes.