BEAUTIFUL VIDEO OF ELECTRIC-BLUE NOCTILUCENT CLOUDS OVER SCOTLAND

 

Noctilucent clouds are like a great "geophysical light bulb." They turn on every year in late spring.

 

It is summer in Antarctica now, and experiencing this noctilucent cloud event

As December unfolds, a vast bank of noctilucent clouds is blanketing Antarctica. It started on Nov. 20th as a tiny puff of electric-blue and quickly expanded to overlie nearly the entire continent.

So why do these clouds appear in the summer?

 

The answer has to do with wind patterns and the flow of humidity in our atmosphere.

 

Summer happens to be the time when the greatest number of water molecules are wafted up from the lower atmosphere to mix with "meteor smoke" at the edge of space. Ironically, summer is also the time when the upper atmosphere is coldest, allowing the ice crystals of NLCs to form.

 

In recent years NLCs have intensified and spread. When noctilucent clouds first appeared in the 19th century, you had to travel to polar regions to see them. Since the turn of the century, however, they have been sighted as close to the equator as Colorado and Utah.

Some researchers believe this is a sign of climate change. One of the greenhouse gases that has become more abundant in Earth's atmosphere since the 19th century is methane.

"When methane makes its way into the upper atmosphere, it is oxidized by a complex series of reactions to form water vapor," explains Hampton University Professor James Russell, the principal investigator of AIM. "This extra water vapor is then available to grow ice crystals for NLCs." If this idea, one of several, is correct, noctilucent clouds are a sort of "canary in a coal mine" for one of the most important greenhouse gases. And that, says Russell, is a great reason to study them.

Read more - http://www.spacedaily.com/reports/Electric_Blue_Clouds_Appear_over_Antarctica_999.html

And watch beautiful time lapse NASA video by Maciej Winiarczyk of noctilucent clouds over Scotland here:
http://apod.nasa.gov/apod/ap130819.html

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