Monday, May 05, 2003

About - Tornadoes - Why They Are Primarily an American Phenomena

About - Tornadoes
Tornadoes can occur almost anywhere on earth, but in most places, their frequency is very low... However, in North America, tornadoes occur with a relatively high frequency, as the conditions there in spring and summer are often just right for supercell storms to develop. Down the middle of North America runs a strip of land, roughly from Arkansas to Colorado and all the way from Texas to North Dakota, which is called Tornado Alley, due to the high number of tornadoes striking there. It is the unique situation by which upper-level winds are partially blocked by the Rocky Mountains, and low-level air can flow unobstructed from the Gulf of Mexico to the north, creating enough windshear with the upper-level westerlies and having enough moisture to feed supercell storms.

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