Tornadoes occur in many parts of the world. There is a correlation between the location of agricultural areas and the occurrence of tornadoes. They are also more numerous in some areas humid subtropical climate . Because moisture is an important factor in the development of severe storms that cause tornadoes, this relationship is easily understood. However, they occur only where the conditions of wind shear are favorable which means that the most powerful are not necessarily in the most humid environments. Rural areas as well as cities can undergo this phenomenon. The United States suffered the largest number of tornadoes and they tend to be a very intensive . 800 to 1,200 tornadoes are observed each year in this country and twenty reach the F4 or F5 level .
The largest absolute density of tornadoes in the world is in Florida , although these are generally low to medium. However, the most active area is the area of the river basin Mississippi and Great Plains . Tornadoes are usually very powerful. The states of Texas , the Oklahoma , the Kansas and Nebraska have also acquired the nickname " Tornado Alley "with a third of tornadoes in the United States .
This area is particularly exposed because warm moist air from the Gulf of Mexico , near the ground, meets the cool dry air aloft from the Rocky Mountains and Canada . The whole gives birth (see explanation of the phenomenon , below) to severe thunderstorms comprising traffic mésocyclonique . This area actually extends to the Canadian Prairies .
Other parts of the world often report tornadoes, these include: South Africa, some parts of Argentina, Paraguay and southern Brazil, the great plain of northern Europe , including Germany and Poland , Australia and New Zealand and the delta of the Ganges . On the right image, the reader can see this distribution and its relationship with agricultural areas and thus with moisture availability.
- Bangladesh
- India
- Argentina
- Italy
- Australian
- New Zealand
- South Africa
- Germany
- Estonia
- Uruguay