(CNN Student News) -- Since the 19th century, damage surveys have included reports of tornadoes moving entire houses while keeping them intact, driving pieces of straw into tree trunks in high-speed winds, and tearing asphalt pavement away from the road like an orange peel. The following facts can help distinguish between myth and reality concerning tornadoes.
MYTH: TORNADOES ALWAYS ROTATE COUNTER-CLOCKWISE
FACT: Most tornadoes rotate cyclonically, meaning that they spin counter-clockwise north of the equator and clockwise south of the equator. However, although such cases are extremely rare, some tornadoes rotate anti-cyclonically: clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere.
MYTH: THE LARGER THE TORNADO, THE STRONGER
FACT: A thin funnel cloud called a "rope tornado" may not look as devastating as some of the massive, computer-generated tornadoes seen in the movies, but don't be fooled. A tornado's size and shape does not signal its strength. Some rope tornadoes can wreak F5 levels of damage, whereas some extremely wide twisters, called "wedge tornadoes," only reach F0, the weakest level on the Fujita Scale.
MYTH: MOBILE HOMES ATTRACT TORNADOES
FACT: Although many reports describe tornadoes striking in or near mobile home communities, the structures themselves do not attract tornadoes. The temperature, moisture and rotation of the thunderstorm that spawns a tornado determines its path. Mobile homes are fragile and susceptible to even weak tornadoes, but they have no effect on the twister's direction.
MYTH: OPENING WINDOWS WILL MINIMIZE DESTRUCTION
FACT: Although authorities once encouraged people to open windows to equalize air pressure, experts now say that doing so only lets in high-speed winds and the prospect of flying debris.
MYTH: BRIDGES AND OVERPASSES OFFER SAFE SHELTERS FROM TORNADOES
FACT: On April 26, 1991, a TV news crew hid from a weak tornado under a Kansas Turnpike overpass. The crew survived unharmed, filming the twister as it moved northeast. Millions saw the video, spawning the myth that an overpass serves as a shield. In fact, bridges cannot protect shelter-seekers from flying debris or high winds. Experts recommend getting indoors or, if that's impossible, lying flat in a low, remote place.
MYTH: THE SOUTHWEST CORNER OF THE BASEMENT IS THE SAFEST SPOT TO STAY
FACT: Because many U.S. tornadoes travel northeast from the southwest, this myth assumes that debris will be blown in a northwesterly direction, avoiding the southwest corner of the basement. However, tornadoes can travel in any direction -- not necessarily from the southwest. The safest place to be in a basement is under sturdy or cushiony protection, as parts of a house can collapse or be blown into the basement.
MYTH: EL NIÑO CAUSES TORNADOES
FACT: The weather cycle El Niño and its counter-phase La Niña both stem from long-term, sea surface temperature changes in the Pacific Ocean. Those temperature changes can affect weather patterns in the United States, but it is not proven that they directly trigger tornado-causing thunderstorms.
MYTH: THE HILL, RIVER OR GIANT ROCK NEAR MY TOWN PROTECTS IT
FACT: Just because a town has not been hit by a tornado in the last several hundred years does not mean that it is impervious to such twisters. Strong tornadoes can easily cross rivers, mountains and canyons.
MYTH: TORNADOES AVOID DOWNTOWN AREAS
FACT: Tornadoes do not avoid anything, just like they are not attracted by mobile homes or deflected by rivers. Tornadoes have hit downtown areas of major cities, such as Atlanta, Georgia; St. Louis, Missouri; Little Rock, Arkansas; and Fort Worth and Waco, Texas. If you think that skyscrapers and large buildings may break up or deter a tornado, think again. A twister's circulating winds are many times longer, wider and stronger than any high-rise.
Source: CNN.com E-mail to a friend
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