The very pretty Nacreous clouds also called Polar stratospheric clouds (PSC), are appearing in the winter polar stratosphere. This image shot a few days ago, over NASA’s Radome at McMurdo Station in Antarctica. Image © Deven Stross
These Nacreous clouds are getting their rainbow colors from reflected sunlight from below the horizon.
Nacreous Clouds have a short season in Antarctica so you grab photos when you can. This was out the back door of my work center at McMurdo Station.
A type II (water) PSC showing iridescence
Polar stratospheric clouds or PSCs, also known as nacreous clouds, from nacre, or mother of pearl, due to its iridescence), are clouds in the winter polar stratosphere at altitudes of 15,000–25,000 meters (49,000–82,000 ft). They are best observed during civil twilight when the sun is between 1 and 6 degrees below the horizon.They are implicated in the formation of ozone holes. The effects on ozone depletion arise because they support chemical reactions that produce active chlorine which catalyzes ozone destruction, and also because they remove gaseous nitric acid, perturbing nitrogen and chlorine cycles in a way which increases ozone destruction.