Rare colorful ‘cloudships’ appear above the Arctic Circle

This week, sky watchers are reporting an outbreak of rare colorful ‘cloudships’ in the skies above the Arctic Circle.

Strange looking clouds with straight edges and matching angled corners forming rectangles?

Aliens are hiding their spacecraft in colorful clouds these days?

According to Spaceweather, the clouds are polar stratospheric clouds (PSCs). Unlike normal grey-white clouds, which hug Earth's surface at altitudes of only 5 to 10 km, PSCs float through the stratosphere (25 km) and they are fantastically colorful.

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

Credit: Truls Tiller photographed these beautiful clouds over Tromsø, Norway, on December 16, 2015.