Image: Tornado Map (1973)

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Tornado Countries

Though outdated and far from comprehensive, Ted Fujita's 1973 map of tornadoes expected to occur over a four-year period gives a rough idea of where they are known to occur around the globe. Not surprisingly, the planet does have other tornado seedbeds, and some occasionally germinate twisters to rival the nastiest the U.S. has to dole out. In raw numbers, Canada probably comes in second to the U.S. The same climatological regime that brings tornadoes to the southern Great Plains in early spring moves north through the year to unleash more of the same on western Canada in July.

After the U.S. and Canada, Bangladesh and East India probably get the most violent tornadoes; they certainly suffer the deadliest. On April 26, 1989, the most lethal tornado on record swept Bangladesh, killing about 1,300 people, injuring 12,000, and leaving 80,000 homeless. High population density, flimsy housing, and a nonexistent tornado warning system mean killer tornadoes are all too common there, says Jonathan Finch, a meteorologist at the National Weather Service in Dodge City, Kansas, who is an expert on that region's tornado climatology.

Europe may come next in sheer number and intensity. Tornadoes have been reported across the continent, from Scandinavia south to Italy and from Spain east to European Russia. The United Kingdom gets more than 30 tornadoes a year, which per unit area compares with the Great Plains. But as in Florida, they're sired by nonsupercell storms and thus pack a much softer punch.

The Southern Hemisphere has several hotspots, including southeastern and southwestern Australia; the region encompassing northern Argentina, Uruguay, and southern Brazil; and southeastern South Africa. Records show that more than 200 tornadoes hit South Africa in the 20th century, including one in 1999 that knocked down part of a pharmacy in which President Nelson Mandela was shopping at the time (he was uninjured).

Virtually all areas that regularly see tornadoes share one thing in common: they lie 20° to 50° on either side of the equator, in the mid-latitudes. "You could probably get a tornado anywhere on the planet, but there are places where they are far less frequent," says John Snow, a tornado expert at the University of Oklahoma. "For good meteorological reasons, these tend to be in the tropics and the very high latitudes." The only continent where tornadoes have not been reported is Antarctica.

In 1973, the year his Fujita Scale went into effect, tornado expert Theodore Fujita called for the creation of an international tornado reporting system. Such a system would help in better understanding and preparing for potentially devastating tornadoes. Yet 30 years later, no such thing exists. International reports remain so incomplete that rather than rely on them, Brooks has taken to studying environmental conditions worldwide to make estimates of the frequency of the severe thunderstorms that give rise to tornadoes.

The situation is improving. This November representatives from across Europe will meet about creating a Europe-wide tornado database. A similar database for Bangladesh tornadoes is in the works. Perhaps even Russia and China—two nations notorious for keeping mum about their tornadoes—will begin to collect and share reliable data. Both countries are thought to get their share of deadly tornadoes: one tornado north of Moscow in 1984 may have been an F5—the most destructive type of funnel—and southeastern China is regularly pounded by typhoons that likely trigger tornadoes. Perhaps it's just a matter of time before we have a truly accurate notion of how many tornadoes are not American-made.

That won't change where the most and worst tornadoes occur, however. The Great Plains, as my dreaming mind knows, will always hold that distinction. Incidentally, a mea culpa: I did describe my dream. For the very moment I realized I was surrounded, I got so spooked I woke up.

Source: PBS

Views: 4,458
Added: 11 years ago.
Topic: 5. Atmospheric sciences



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