In this photo by Kelly Speelman of the National Science Federation, we see Nacreous clouds observed on January 6, 2011. These polar stratospheric clouds at 80,000 feet (24,384 m) are the highest of all clouds. They only occur in the polar regions when the stratospheric temperature dips below 100 degrees below zero Fahrenheit (-73 C). They are also the site of chemical reactions that break down ozone in the upper atmosphere and contribute to the creation of the ozone hole above Antarctica.

Due to their high altitude and the curvature of the surface of the Earth, these clouds will receive sunlight from below the horizon and reflect it to the ground, shining brightly well before dawn or after dusk. [Source]

This is one in a series of 37-photos published by The Atlantic’s In Focus entitled Scenes from Antarctica.

If you’re intrigued by cloud formations, check out this post the Sifter did earlier this year.