Tornado, violently
rotating column of air extending from within a
thundercloud down to ground level. The strongest tornadoes
may sweep houses from their foundations, destroy brick
buildings, toss cars and school buses through the air, and
even lift railroad cars from their tracks. Tornadoes vary
in diameter from tens of meters to nearly 2 km (1 mi),
with an average diameter of about 50 m (160 ft). 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.
Scientists study tornadoes to gain a better understanding of their
formation, behavior, and structure. Scientists who study tornadoes
have a variety of powerful research tools at their disposal. Advances
in computer technology make it possible to simulate the thunderstorms
that spawn tornadoes using computer models running on desktop computers.
Doppler radars, which detect the rain in clouds, allow meteorologists,
scientists who study weather, to "see" the winds inside
the storms that spawn tornadoes. Modern video camera footage and
reports from trained storm-spotters provide an unprecedented amount
of high-quality tornado documentation. These tools all contribute
greatly to the scientific understanding of tornadoes. This information
may eventually lead to increased tornado warning times, better guidelines
for building construction (especially schools), and improved safety
tips.
| Photos |
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This photo was taken on a turnpike
~ 10-20 miles north of Norman, OK. USA in April of 1991. (Photo
by Bryan Patrick)
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These tornadoes were spawned
by a cyclic supercell in the United States on the 29th May 2001
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| A large land
spout type tornado NW of McLeans Ridges on 29th
January 2001
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| This information has brought
it to you from Encarta |
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