Earth Science: Geology, the Environment, and the UniverseChapter 13:
The Nature of StormsProblem of the WeekDoppler Radar: A Key to Tracking Severe Weather The Perfect Storm In the 2000 blockbuster movie, "The Perfect Storm," the captain of the
swordfish ship, Andrea Gail, received regular weather reports via
a type of onboard FAX system. The captain monitored weather factors, such
as barometric pressure, temperature, wind speed, and radar images that
showed the converging paths of three storm systems. In this true story,
the three weather systems met head on, out in the North Atlantic, to produce
one of the most intense storms in recorded history. Receiving meteorological
reports allows ship captains to keep their ship and crew out of harms
way, and in good fishing waters. You'll have to rent the movie to see
how this captain used the information he had about the storm.
Severe or Clear? Severe or Clear? When the weather is clear, we don't pay much attention
to the weather reports given by the local meteorologists. But in the event
of a severe weather system, such as a blizzard, thunderstorm, hurricane,
or tornado we look to them to give us the most current, precise information
possible. We expect them to predict the path of these storms, to tell
us how fast the winds will blow, when to expect them in our area, and
when the storms will be over. One of the most important tools used by
the meteorologist to provide us with this information is Doppler radar.
Doppler radar works by using the reflective nature of water in the atmosphere.
Radar waves are sent out from a transmitter. These waves bounce off of,
and are scattered by, raindrops, hail, and other things like large flocks
of birds and buildings. As the scattered radar beam returns to the radar
station, a receiver collects and measures the intensity of the beam. An
image is produced from the returned radar beams giving information about
a storm's intensity. The image is usually color enhanced by computers
to clearly show the intensity of the weather activity within a storm system.
(0.0K) Look at the Doppler radar image below. You can see that various colors
are used to represent the different intensities of precipitation within
a storm. Using the key beside the radar image, determine where the centers
of heaviest precipitation are located. If you were a weather forecaster,
how would you describe this storm that is affecting the state of Texas?
(1.0K) (6.0K)
NOAA http://www.srh.noaa.gov/oun/wxdata/radarindex.html
(image source page)
(0.0K) Doppler radar is also used to detect the relative velocity of storm movement,
that is, the motion of winds toward and away from the radar location.
In a relative storm velocity image, blues and greens represent parts of
the storm system where winds are moving toward the radar, and reds and
yellows represent winds blowing away from the radar. A combination of
these two colors extremely close to each other in a very small area of
the radar image, is often the signature of a tornado. Take a look at the
Doppler radar images below. Locate the tornado signatures.
Take a look at the Doppler radar images below. Can you find the tornado
signatures? 1. (17.0K) 2. (47.0K)
(1.0K) NOAA - http://www.nssl.noaa.gov/noaastory/book.html
- http://www.spc.noaa.gov/coolimg/cape_may.htm
Websites to Visit: - IMAX
Film - Storm Chasers: Streaming Video of Tornado formation
- The
Franklin Institute Online: Radar-ology
- Radar
Meteorology: Online Remote Sensing Guide
- Severe
Storms: Online Meteorology Guide
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