rare photos of Antarctic nacreous clouds

Spectacular images of "nacreous clouds" have been posted here at the Australian Antarctic Division. Here is an excerpt:

Beauty and mystery in rare Antarctic clouds

Tuesday 1 August 2006

A rare and spectacular cloud formation has been seen at the end of the polar night 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.

Photographs taken by Renae Baker, a meteorological officer with the Australian Bureau of Meteorology at Mawson, on July 25 show delicate colours produced when the fading light at sunset passed through tiny water-ice crystals blown along on a strong jet of stratospheric air.

"Spectacular is an understatement. The clouds were such a special and welcoming sight now that the sun has just started to return near the end of winter. I am keeping my eyes towards the celestial dome and camera at the ready in the hope of some more."

Atmospheric layers in the Antarctic winter. Dr. Andrew Klekociuk, Australian Antarctic Division
Nacreous clouds show colours similar to those on the inside of a Mother-of-Pearl shell. The clouds only occur at high polar latitudes in winter, requiring temperatures less than approximately -80ºC to form...