Dr. Phillips at Spaceweather.com keeps looking up and seeing … polar stratospheric clouds:
Normally, polar stratospheric clouds (PSCs) are confined inside the Arctic Circle. Only above the poles can the stratosphere become cold enough to create these rare clouds. However, during this week’s outbreak of PSCs, the clouds have spilled out of the Arctic to places they are seldom seen. This morning, Ian Carstairs photographed them over Harleston, Norfolk, UK:
[picture omitted, go follow the link, above]
“The display has spread south all the way to +52N,” says Nock. That’s more than 14 degrees below the Arctic Circle.
Widely considered to be the most beautiful clouds on Earth, polar stratospheric clouds are a sign of extreme cold. PSCs form when the temperature in the Arctic stratosphere drops to a staggeringly-low -85 C. Then, and only then, can widely-spaced water molecules in the dry stratosphere coalesce into tiny ice crystals. High-altitude sunlight shining through the crystals creates intense iridescent colors that rival auroras.
A later update reports sightings as far south as Liverpool in the UK. Recalling that latitude’s definition is …
In geography, latitude is a coordinate that specifies the north–south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pole, with 0° at the Equator. Lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude and longitude are used together as a coordinate pair to specify a location on the surface of the Earth.
Liverpool’s latitude is 53°. For comparison and future cloud observations, Minneapolis’s latitude is 45°, or rather to the south of Liverpool. Still, I’ll try to keep an eye on the sky[1], and maybe get lucky. They look … almost clownish. A reminder that unusual conditions sometimes lead to unusual results.
1 Which incidentally was a tagline of the local WCCO weather service at one time.
