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The Cruel Mysteries of Tornadoes
- Analysis by John D. Cox
Tue May 24, 2011 - FROM>> Discovery news
There is a mean randomness to tornadoes that continues to puzzle
storm researchers. Why do they form out of one severe thunderstorm but
not another? On one day but not the next? Why is one more powerful than
another? And most particularly, perhaps -- why is one tornado 200 feet
wide and another a mile or more in diameter?
Tornadoes: Wide Angle
Forecasters and researchers can't really answer these questions. They
can tell you the basic ingredients for a tornado outbreak -- the
collision of cold dry air aloft with warm moist air at the surface --
but they can't say if the tornadoes are going to be narrow or wide or
weak or powerful.
"This is one of the great mysteries," observes meteorologist Greg
Carbin at the National Weather Service's Storm Prediction Center in
Norman, Oklahoma. Carbin recalls a 2003 outbreak when a rash of intense
tornadoes 50-75 yards wide was followed by a monster with a girth of a
mile and a half wide that totally wrecked Greensburg, Kansas. "How can
nature do this?"
BLOG: Tracking the Birth of a Hurricane
As Earth sciences go, the subject of weather is young, and the
science of tornadoes is a newborn babe. Until 1950, in fact, government
forecasters couldn't even mention the word "tornado" in a forecast for
fear of sewing public panic with a rash of false alarms.
Even now, unlike other weather phenomena, basic information about
wind speed inside a tornado is not measured instrumentally but rather is
estimated by the extent of the damage it does. This is weather at the
edge of chaos -- forces so powerful that most instruments can't survive
them.
The widest tornado ever observed -- two and a half miles in diameter
-- struck May 22, 2004 in Hallam, Nebraska. A recent study draws a
statistical link between tornado size and damage, but that's at least
partly because a bigger, wider storm covers more ground.
STORMCHASERS: Episode and Real-Time Weather Tracker
Carbin notes that the width of a tornado has "something to do with
intensity and the environment of the updraft" but researchers can't yet
say exactly how these conditions work together to alter the size and
shape of a tornado or the intensity of its winds. "Vortices in the
atmosphere can range in size from something very, very small to
something very, very large," said Carbin.
Among all the mysteries, cruelest is the serendipity of their
location -- exactly where tornadoes strike. "Yesterday in Joplin, a very
intense tornado moved through a populated area," Carbin noted. "If it
had happened just a few miles to the south, we probably wouldn't be
talking about it."
IMAGE: Storm debris from a tornado that struck May 22, 2011,
litters whole neighborhoods in Joplin, Missouri. The mile-wide tornado
ripped through the densely populated town of Joplin killing at least 116
people. (Photo by Julie Denesha/Getty Images)