Weather Blog

Glowing 'noctilucent' clouds make inaugural appearance

Glowing 'noctilucent' clouds make inaugural appearance
Noctilucent clouds over Shelton, July 1, 2011. (Photo: Steven Rosenow, Fire Mountain Photography.)

 It's another sign of summer: The clouds that glow at night.

Glowing clouds you say? Yes, they're something called "noctilucent" -- the word originating from nocti for night and lucent for glowing. And they're usually only spotted in the summer time.

Steven Rosenow of Fire Mountain Photography captured these clouds over Shelton Friday night -- part of a big display that spanned a large part of southern Canada and the northern U.S.

The clouds are at the very edge of space, hundreds of thousands of feet in the air. The air is very cold and very dry at that level of the atmosphere, but in the summer time, the rising air from the hotter surface can gradually push a little water moisture to those space-high altitudes (that's why they're seen only in the summer).

Scientists are still not quite sure of all the details that cause the clouds to form, although the glow is from simple sunlight -- the clouds are so high they reflect sunlight even after the sun appears well below the horizon from the ground.

Here are more photos more from Steve's submissions on YouNews and here are other photos from around the world courtesy of spaceweather.com.