Weather Notebook
Bryan Yeaton
 


 
The Upper Atmosphere
Wed Jan 21, 2004

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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

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