Why do 75% of tornadoes occur in the USA?

Answer 1

Tornadoes usually result from large, rotating storms called supercells, although there are such things as non-mesocyclone tornadoes. In either case, rotating storms usually result along boundaries, the more extreme the better. The United States is a hotbed for tornadoes, especially the central United States, because cool, dry air originating in Canada clashes with warm, moist air originating from the Gulf of Mexico. Most other world locations do not have this ideal setup of cool/dry versus warm/moist because there is not a large, cool, continental area to develop the former air mass along with a large, warm, moist area to develop the latter air mass.
Additionally, the US has a large surface area which adds to absolute numbers. Florida also has many tornadoes resulting from convergence from sea breezes and the Great Lakes develop many non-mesocyclone tornadoes from sea breeze boundaries.

Answer 2

I would need some evidence that 75% of tornadoes occur in the USA. Russia and China get their fair share too and tornadoes are seen all over the world. The country with the most tornadoes per unit area every year is the United Kingdom. The USA might get a lot but the USA is big while the UK is small.

Answer 3

Outstanding answer from mandos, but I can't let it go unsaid that I don't believe that 75% figure for a second.

Tornadoes do occur all over the world, and Tornado Alley probably represents about 1% of the earth's surface. There's no way that 75% number is correct. I might believe 10 or 15%....

...but I'm just guessing.

But 75%?? No way.

Answer 4

Most tornadoes in the northern hemisphere create winds that blow counterclockwise around a center of extremely low atmospheric pressure. In the southern hemisphere the winds generally blow clockwise. Peak wind speeds can range from near 120 km/h (75 mph) to almost 500 km/h (300 mph). The forward motion of a tornado can range from a near standstill to almost 110 km/h (70 mph).

A tornado becomes visible when a condensation funnel made of water vapor (a funnel cloud) forms in extreme low pressures, or when the tornado lofts dust, dirt, and debris upward from the ground. A mature tornado may be columnar or tilted, narrow or broad—sometimes so broad that it appears as if the parent thundercloud itself had descended to ground level. Some tornadoes resemble a swaying elephant's trunk. Others, especially very violent ones, may break into several intense suction vortices—intense swirling masses of air—each of which rotates near the parent tornado. A suction vortex may be only a few meters in diameter, and thus can destroy one house while leaving a neighboring house relatively unscathed.

Answer 5

The United States, particularly the midwest and central US, is known to see more tornadoes than other locations because cold Canadian air interacts with moisture from the Gulf of Mexico. When these two airmasses meet, warm air rises into surrounding cool air, forming intense thunderstorms. This is common in spring and fall.

Answer 6

Tornado Alley which includes the states of, TN, KS, OK, TX, MS, NE, South and Western IL, Western TN, and AR>

Answer 7

Because in other countries they are called cyclones