The storm that never was: Why the weatherman is often wrong
Mark A. Philbrick/BYU |
Have
you ever woken up to a sunny forecast only to get soaked on your way to the
office? On days like that it's easy to blame the weatherman. But BYU mechanical
engineering professor Julie Crockett doesn't get mad at meteorologists. She
understands something that very few people know: it's not the weatherman's
fault he's wrong so often.
According
to Crockett, forecasters make mistakes because the models they use for
predicting weather can't accurately track highly influential elements called
internal waves.
Atmospheric
internal waves are waves that propagate between layers of low-density and
high-density air. Although hard to describe, almost everyone has seen or felt
these waves. Cloud patterns made up of repeating lines are the result of
internal waves, and airplane turbulence happens when internal waves run into
each other and break.
"Internal
waves are difficult to capture and quantify as they propagate, deposit energy
and move energy around," Crockett said. "When forecasters don't
account for them on a small scale, then the large scale picture becomes a
little bit off, and sometimes being just a bit off is enough to be completely
wrong about the weather."
One
such example may have happened in 2011, when Utah meteorologists predicted an
enormous winter storm prior to Thanksgiving. Schools across the state cancelled
classes and sent people home early to avoid the storm. Though it's impossible
to say for sure, internal waves may have been driving stronger circulations,
breaking up the storm and causing it to never materialize.
"When
internal waves deposit their energy it can force the wind faster or slow the wind
down such that it can enhance large scale weather patterns or extreme kinds of
events," Crockett said. "We are trying to get a better feel for where
that wave energy is going."
Mark A. Philbrick/BYU |
Jaren Wilkey/BYU |
Internal
waves also exist in oceans between layers of low-density and high-density
water. These waves, often visible from space, affect the general circulation of
the ocean and phenomena like the Gulf Stream and Jet Stream.
Both
oceanic and atmospheric internal waves carry a significant amount of energy
that can alter climates.
Crockett's latest wave research, which appears in a recent issue
of theInternational
Journal of Geophysics, details how the relationship between
large-scale and small-scale internal waves influences the altitude where wave
energy is ultimately deposited.
To
track wave energy, Crockett and her students generate waves in a tank in her
lab and study every aspect of their behavior. She and her colleagues are trying
to pinpoint exactly how climate changes affect waves and how those waves then
affect weather.
Based
on this, Crockett can then develop a better linear wave model with both 3D and
2D modeling that will allow forecasters to improve their weather forecasting.
"Understanding
how waves move energy around is very important to large scale climate
events," Crockett said. "Our research is very important to this
problem, but it hasn't solved it completely."
Source: Brigham
Young University
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Posted by Unknown
on Friday, January 25, 2013.
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