Above is a picture taken after sunset at Seattle's Shilshole Bay Marina by Joseph Marsh on Tuesday evening. Just clouds? Not quite...these are very special clouds that are the highest clouds on earth...noctilucent clouds.
These clouds are most commonly seen on clear nights north of roughly 50N during the summer months. They are located in the mesosphere at heights of roughly 50 miles above the surface. (Remember...the layers of the atmosphere are troposphere, stratosphere, mesosphere). These are ice clouds that form on dust, probably produced by meteors. Such clouds often have a silvery or bluish color, and a ragged look.
Want to see the clouds in the department time lapse imagery? Check out the following and wait until the very end, after sunset:
http://www.atmos.washington.edu/images/webcam0/movies/20090714.mov
So on the next few clear nights take a look during twilight and see if you can spot them.
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