Mysterious, Glowing Clouds Appear Across America’s Night Skies

By Alexis Madrigal on July 16, 2009

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. 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.

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