Physics Photo of the Week
April
17, 2009
2 Storms
Friday, April
10, 2009 was a stromy day in the southeastern United States. The
satellite photo for 16:45 UTC (12:45 pm EDT) shows two storms in N.
Carolina and Tennessee - the dense yellow parts of the image.
These images were made by an infrared sensor on a geostationary NASA
satellite. The infrared sensor has two advantages: 1) cloud
images can be made at night in the absence of sunlight; 2) the false
colors indicate the temperatures of the cloud tops. Yellow
regions are very high altitude extreme cold cloud tops. The
presence of the high altitude cloud tops indicate extreme convection
that forms thunderstorms and the accompanying severe weather.
Warren Wilson College in western North Carolina had just experienced a
strong thunderstorm a few hours earlier as the first of these two
storms swept by. The second storm (west-central Tenessee in the
satellite image above), however proved very bad for parts of northern
Alabama and Tennessee later 
in the day
forming highly destructive tornadoes in parts of Alabama. The
second storm swept through western North Carolina later that night,
bringing over an inch of rain to Warren Wilson College - but no severe
weather. The animation at right shows the passage of the two
storms through the area. The animation is a 5 hour time lapse
beginning about 11:30 am. Notice how the second storm rapidly
grew in size to cover a much larger area as it rampaged through.
These two storms were part of a complex weather pattern centered in
southern Illinois. The weather pattern circulated around a low
pressure center. The circulation brought moist air from the Gulf
of Mexico and cold artic area from the northest plains. The
meeting of the warm humid gulf air and the cold air formed much
precipitation, generated massive cumulus clouds and thunderstorms, and
produced the violent destructive tornadoes. The central US has
more tornadoes than any other part of the world - hence the name
"Tornado Alley".
The images were downloaded at the NASA interactive satellite center: http://wwwghcc.msfc.nasa.gov/GOES/
which displays the current satellite images (visible, infrared, and
water vapor) for any place on the Earth. The weather satellite
service provided by NASA for public use is much appreciated.
Physics
Photo of the
Week is
published weekly during the academic year on Fridays by the Warren
Wilson College Physics
Department. These photos feature interesting phenomena in
the world around us. Students, faculty, and others are invited to
submit digital (or film) photographs for publication and
explanation. Atmospheric phenomena are especially welcome.
Please send any photos to dcollins@warren-wilson.edu.
All photos and discussions are copyright by Donald
Collins or by the person credited for the photo and/or
discussion. These photos and discussions may be used for private
individual use or educational use. Any commercial use without
written permission of the photoprovider is forbidden.
Click
here to see the Physics Photo
of
the Week Archive.
Observers are invited to submit
digital photos to:
