Onyma Report This Comment
Date: July 20, 2009 08:13AM
Mysterious, glowing clouds previously seen almost exclusively in Earth’s
polar regions have appeared in the skies over the United States and Europe over
the past several days.
Photographers and other sky watchers in Omaha, Paris, Seattle, and other
locations have run outside to capture images of what scientists call noctilucent
(”night shining”) clouds. Formed by ice literally at the boundary where the
earth’s atmosphere meets space 50 miles up, they shine because they are so
high that they remain lit by the sun even after our star is below the
The clouds might be beautiful, but they could portend global changes caused by
global warming. Noctilucent clouds are a fundamentally new phenomenon in the
temperate mid-latitude sky, and it’s not clear why they’ve migrated down
from the poles. Or why, over the last 25 years, more of them are appearing in
the polar regions, too, and shining more brightly.
“That’s a real concern and question,” said James Russell, an atmospheric
scientist at Hampton University and the principal investigator of an ongoing
NASA satellite mission to study the clouds. “Why are they getting more
numerous? Why are they getting brighter? Why are they appearing at lower
Nobody knows for sure, but most of the answers seem to point to human-caused
global atmospheric change.
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