Extremely rare 'rainbow clouds' light up Arctic skies for 3 days in a row

Iridescent, rainbow-colored clouds, known as polar stratospheric clouds, have been spotted across the Arctic for days on end.  (Image credit: Ramunė Šapailaitė)

"Spectacular" rainbow-colored clouds have been shimmering in the skies over and around the Arctic for more than three days thanks to an unusual cold snap in the upper atmosphere. And even more of these technicolor treats could appear during the next few months, experts say.

The colorful clouds, known as polar stratospheric clouds (PSCs), were spotted floating high in the sky above parts of Norway, Sweden, Finland and Alaska, and even as far south as Scotland. They began to emerge on Dec. 18 and continued to appear clearly until Dec. 20, according to Spaceweather.com. Some smaller, less distinct clouds were also spotted on Dec. 21, but in general they seem to be disappearing.