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August 27, 2008
Clouds at the Edge of Space
Posted by jennifer, at 09:37 AM
Two years after the 1883 eruption of Krakatoa, the Indonesian supervolcano, Robert Leslie published a note in the journal Nature describing wispy blue filaments in the night sky. He is now credited with the discovery of noctilucent clouds (NLCs).
Photograph from the International Space Station, positioned 340 km over western Mongolia on July 22, 2008. Clouds estimated to be 83km above earth (at the edge of space). Credit to NASA at http://science.nasa.gov/headlines/y2008/25aug_nlc.htm
According to Gary Thomas, atmospheric scientists at the University of Colorado, the clouds are thought to be spreading and their first sightings coincide with the Industrial Revolution.
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Thanks to Willem for the link.
Posted by jennifer at August 27, 2008 09:37 AM
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Comments
Lovely word 'noctilucent'
Equally fascinating are the noctilucent zones in the oceans seen by ships and photographed by orbiting satellites.
http://www.pnas.org/content/102/40/14181.full.pdf
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1448986
Posted by: Steve Short at August 27, 2008 11:01 AM
Noctilucent clouds - first sightings coincide with the Industrial Revolution.....hmmm
Bit skeptical here. Elves and sprites were only noticed first by aircraft pilots at high altitude. Their initial sighting reports of these phenomena were pooh poohed by "scientists". Up until recently these were not understood, even now a lot to learn about them.
Posted by: Beano at August 27, 2008 02:45 PM
I think these are similar to the polar stratospheric clouds also known in Scandanavia a "Perlan clouds"
http://www.smh.com.au/news/science/extreme-weather-makes-rare-cloud/2006/08/01/1154198117951.html
Neil
Posted by: Neil Ayrey at August 27, 2008 07:45 PM
Watts also has a post up with a reader supplied ppt that graphs recent changes in noctilucent cloud frequencies.
The graphs are, to my eye, perfect inverses of the solar sunspot cycles, or negatively correlated with solar activity, as far as sunspots are a proxy of that activity.
Watts conjectured that there is a geomagnetic connection with GCRs and the solar wind via their nucleation of these ice clouds.
As the geomagnetic field has been declining by 0.5% per decade since the clouds were discovered, he may be onto something. At solar minimum, the magnetopause collapses and the solar wind, though diminished in pressure and velocity can have free as well as freer entry.
Accuweather's GW blog reported on a paper estimating a 2-3 degree C Arctic temperature anomaly this summer, due to this effect.
Posted by: Gary Gulrud at August 28, 2008 05:36 AM
From the stark black of space
through wrenching shades of blue
and onto the ground
through sad shades of brown.
Posted by: Steve Stip at August 28, 2008 01:15 PM