The pictures you're looking at are actually classes of clouds. They're called noctilucent clouds, and they are some of the most poorly understood meteorological phenomena on Earth. They are notoriously difficult to view from ground, and the they are only visible once the Sun has dipped below the horizon.

So to get a good view of them you'll have to be in outer space.

This particular image was captured from aboard the International Space Station as it passed over the Tibetan Plateau on June 13.

Beautiful and breathtaking.



NASA says that "the exact cause for the formation of polar mesospheric clouds is still debated," though rocket exhaust, dust from meteors and volcanic activity have all been fingered as potential explanations.

[NASA Earth Observatory]

Top image via NASA, noctilucent clouds from Earth photographed via Wikimedia Commons