Crystal-colored cloudscapes

"A rare and spectacular cloud formation has been seen at the end of the polar night on 25 July at Australia's Mawson Station in Antarctica.

"These so-called nacreous clouds were situated high in the stratosphere, some 20km above the ground, and reveal very cold temperatures in the rarefied atmosphere... The delicate colours were produced when the fading light at sunset passed through tiny water-ice crystals blown along on a strong jet of stratospheric air."


"This particular cloud formation appeared over Iceland at an altitude of about 22 km on February 4, 2003."

By way of The Knight Science Journalism Tracker