What is a Tornado?
A tornado is
an etremely intense windstorm known
by a twisting, funnel-shaped cloud. The word "tornado" comes from the
Spanish or Portuguese verb tornar, meaning "to turn." The event appears
in storms all around the world, though they most commonly occur in a
broad area of the American Midwest and South known as Tornado Alley,
but some other countries see the storms occur in even higher densities.
Tornadoes form from severe thunderstorms, usually spawned from squall
lines and supercell thunderstorms, though they sometimes happen as a
result of a hurricane.
They are believed
to be produced when cool air
over takes a layer of warm air, forcing the warm air to rise rapidly.
How big can a Tornado get?
The
method for measuring tornadoes is known
as the Fujita scale. The Fujita scale rates a tornado's intensity by
the damage it inflicts on human-built structures and if measurable -
it's wind speed. It was introduced in 1971 by T. Theodore Fujita of the
University of Chicago. Here's how it works.
- F-0 - Wind speeds up to 73
miles per hour (<115 km/h). Light damage. Some
damage to chimneys; branches broken off trees; shallow-rooted trees
pushed over; sign boards damaged.
- F-1 - Wind speeds 73 to 112
miles per hour (116-180 km/h). Moderate damage. Peels surface off
roofs; mobile homes pushed off foundations or overturned; moving autos
blown off roads.
- F-2 - Wind speeds 113 to 157
miles per hour (181-250 km/h). Considerable damage. Roofs torn off
frame houses; mobile homes demolished; boxcars overturned; large trees
snapped or uprooted; light-object missiles generated; cars lifted off
ground.
- F-3 - Wind speeds 158 to 206
miles per hour. 251-330 km/h). Severe damage. Roofs and some walls torn
off well-constructed houses; trains overturned; most trees in forest
uprooted; heavy cars lifted off the ground and thrown.
- F-4 - Wind speeds 207 to 260
miles per hour. (331-415 km/h). Devastating damage. Well-constructed
houses leveled; structures with weak foundations blown away some
distance; cars thrown and large missiles generated.
- F-5 - Wind speeds 261 to 318
miles per hour. (416-510 km/h). Incredible damage. Strong frame houses
leveled off foundations and swept away; automobile-sized missiles fly
through the air in excess of 100 meters (109 yds); trees debarked;
incredible phenomena will occur. The movie"Twister" refers to an F5 as
"The Finger of God", referring to the mental imagery of God draging a
finger across the Earth, wiping out everything that was in its path.
Of all tornadoes
formed in the US, F0
and F1 tornadoes account for a large percentage of
occurrences. On the other end of the scale, the massively destructive F5
tornadoes account for less than 2% of all tornadoes in the US.
How often do Tornadoes occur?
The United States experiences by far the
most tornadoes of any country, and has also suffered the most intense
ones. However, tornadoes do occur throughout the world; the most
tornado-prone region of the world, as measured by number of tornadoes
per unit area, is the United Kingdom, especially England. In Canada, an
average of 80 tornadoes occur annually, killing 2, injuring 20 and
causing tens of millions of dollars in damage. On average, the United
States experiences 100,000 thunderstorms each year, resulting in over
1,000 tornadoes and approximately 50 deaths per year.
What is the worst recorded Tornado in US history?
The Tri-State
Tornado as it is known. At About 1:00 PM on March 18, 1925, trees began
to snap north-northwest of Ellington, Missouri, and for the next three
and a half hours more people would die, more schools would be
destroyed, more students and farm owners would be killed, and more
deaths would occur in a single city than from any other tornado in U.S.
history. Records would be set for speed, path length, and probably for
other categories that can't be measured so far in the past.
Without todays
modern weather surveilence
equipment, these people were totally blindsided by the storm. The
aftermath was devestating. 695 dead, and over 2000 injured. Millions in
total damage, and thousands of homes completely destroyed. More than
six tornadoes in one day is considered a tornado outbreak. The biggest
tornado outbreak on record—with 148 tornadoes, including six F5 and 30
F4 tornado's - occurred on April 3, 1974
What is protecting us from "the dark side of
nature"?
Modern science, early detection, and advanced
warning.
Each time tornado
season comes around, schools and
media outlets in tornado-prone areas spend time educating the public
about the dangers and what can be done to improve the chances of
surviving a storm. In the United States, citizens are often advised to
purchase NOAA Weather Radios. They are relatively inexpensive devices
costing as little as US$20 which will activate whenever the National
Weather Service issues severe weather warnings. Warnings are also
carried on radio and television, and most communities have civil
defense sirens that will activate when severe weather is believed to be
approaching.
There is no way to
be sure how many lives have
been saved due to all the advances in weather technology, but it
numbers in the thousands per year.
According to
Environment Canada, the chances of
being killed by a tornado are 12 million to 1 (12,000,000:1). One may
revise this yearly and/or regionally, but the probability may be
factually stated to be low. Tornadoes do cause millions of dollars in
damage, both economic and physical, displacement, and many injuries
every year.
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