Polar stratospheric clouds over Norway on December 20, 2017. By Fredrik Broms / www.northernlightsphotography.no
The stratosphere above the Arctic Circle is getting cold … very cold. That’s one way – the only way for space weather scientists – to explain these colorful clouds – polar stratospheric clouds (PSCs) – which require temperatures around -85ºC to form and appeared over Norway and Sweden on Dec. 20th:
This absolutely stunning display of stratospheric clouds appeared high above the ordinary gray rainclouds. It’s very seldom to see PSCs with such vivid colours as today.