Photo of noctilucent clouds by Robert and Jennifer More in Seattle, taken early the morning of July 15, 2009.By Scott Sistek
The heavens have been really showing off these past few weeks -- what with volcanic clouds, blue moons, rainbow clouds, and UW-shaped lightning.
Tuesday night was no different.
Astute observers from around the northern latitudes of the world noticed a dazzling display of "noctilucent" clouds.
They are clouds 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. CONTINUE
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