Also called « Polar stratospheric clouds », the nacreous clouds get their brilliant, rainbow colours from sunlight that’s reflected from below the horizon. The clouds are so high above the earth -82,000 feet- that they continue to glow in these incredible hues long after the sun has gone down.

These clouds are extremely rare but unmistakeable! The lower stratosphere, where nacreous clouds live, is so dry that it often prevents cloud formation, but the extreme cold of polar winters creates nacreous clouds. They are best captured during winter at high latitudes. They have been spotted in Iceland, Alaska, Northern Canada and on rare occasions, farther south in England and Scotland where they appear during colder winters.

 Nacreous clouds are one of the most beautiful cloud formations but are also the most destructive to our atmosphere. Indeed, they encourage the chemical reactions that break down the ozone layer because of their high acid nitric concentration. Scientists believe that the general increase in observations of theses clouds is linked directly to man’s contribution to global warming.

Antarctic Nacreous, Deven Stross, (CC BY-NC-ND 3.0)

Nacreous Clouds, Alan Light, http://flic.kr/p/9ZNeVG,(CC BY 2.0)

Nacreous Clouds, Alan Light, http://flic.kr/p/9ZNY33,(CC BY 2.0)

Nacreous Clouds, Alan Light, http://flic.kr/p/9ZNeij,(CC BY 2.0)