|
|
|
|
The Upper Atmosphere
Wed Jan 21, 2004
Listen in RealAudio 
When Space Shuttle Columbia met its tragic end a year ago, it broke apart in a little-known
region of the atmosphere some meteorologists call the "Ignorosphere." Hi, I'm Bryan Yeaton for
The Weather Notebook.
We may know more about Jupiter's atmosphere than the upper reaches of our own, regions
technically known as the Mesosphere and Thermosphere. It's seldom studied: too high for
research balloons, but too low for satellites, whose orbits quickly decay under the drag of
the tenuous high atmosphere.
In this realm above 30 miles, aurora shimmer and falling stars fall. But even stranger
denizens haunt the Ignorosphere: wispy transparent clouds, strange red flashes, and blue
upward-striking lightning bolts.
Noctilucent clouds are silvery-blue, cirrus-like clouds that float over 50 miles high. They
are so thin, they only become visible during summer twilight at high latitudes. Believed to be
made of ice crystals forming on meteor dust, they were first noticed following the great 1883
eruption of Krakatoa.
Red Sprites are massive electrical discharges flashing over thunderstorms simultaneously with
cloud lightning strokes. These weakly luminous red flashes extend from the cloud top to
altitudes above 60 miles. In contrast, Blue Jets are narrow cones of lightning that shoot
upward through the stratosphere from the cloud tops.
The Ignorosphere may also contain patches of relatively dense air that can jolt a shuttle
during reentry. Two missions in the 1990s hit such patches, forcing extensive use of the
thrusters to realign the shuttle on descent.
Thanks to our contributing writer, Keith Heidorn. Our high-altitude supporters are Subaru of
America and the National Science Foundation. Check out how our tour is going through
www.davisnet.com.
Today's Links
USA Today: Upper atmosphere may hold clues in Columbia mystery
http://www.usatoday.com/news/nation/2003-02-06-atmosphere_x.htm
Making Sense of the Upper Atmosphere
http://www.ucar.edu/communications/staffnotes/9601/time.html
|
|
