As December draws to a close, the first polar stratospheric clouds (PSCs) of northern winter are forming around the Arctic Circle. Anders Gjørwad Hagen of Vinstra, Norway, photographed this specimen on Dec. 27th:

© Anders Gjørwad Hagen
Also known as "nacreous" or "mother of pearl" clouds, icy PSCs form in the lower stratosphere when temperatures drop to around minus 85ºC. Sunlight shining through tiny ice particles ~10µm across produce the characteristic bright iridescent colors by diffraction and interference.

The display Hagen witnessed formed in the wake of "Dagmar," a storm that "hit the coast of Norway with hurricane strength on Dec. 25th and 26th," says Hagen. "Record breaking winds up to 145 mph were recorded. While people on the coast dealt with the aftermath, photo enthusiasts inland saw the effects of high altitude winds in these colorful clouds. It was a beautiful display, but not comfortable to think of all the suffering lying behind it."

More images: from Bjarki Mikkelsen of Jokkmokk Lapland, Sweden; from P-M Hedén of Tänndalen, Sweden; from Krystian Rosa of Brandbu, MNorway; from Patricia Cowern of Porjus,Sweden