PICTURES: "Night Shining" Clouds Getting Brighter

PICTURES:
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Shimmering noctilucent, or "night shining," clouds (seen above in Finland in an undated photograph) have long graced high-latitude sunsets around the globe.

But recently, the clouds have been mysteriously appearing as far south as the U.S. states of Colorado and Utah.

"They are becoming brighter and seem to be coming to lower latitudes than in the past," James Russell, principal investigator for NASA's Aeronomy of Ice in the Mesosphere (AIM) satellite, said last week at an American Geophysical Union meeting in San Francisco.

Scientists suspect that the increase in night-shining clouds may be due to climate change: Even as surface temperatures rise, the upper atmosphere is getting colder due to the buildup of carbon dioxide, creating perfect conditions for cloud formation, experts say.

(Related: "Mysterious 'Night-Shining Clouds' Sighted.")

--Richard A. Lovett
— Photograph by Pekka Parviainen, TWAN
 
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