· ·

Nacreous clouds appear around the Arctic Circle

strange-clouds-appear-around-the-arctic-circle

Sky watchers are observing an outbreak of polar stratospheric clouds or PSCs around the Arctic Circle, SpaceWeather reports. Unlike normal grey-white clouds, which hug Earth's surface at altitudes of only 5 to 10 km (3.1 – 6.2 miles), PSCs float through the stratosphere (25 km/15.5 miles) and are fantastically colorful.

Polar stratospheric clouds, also known as nacreous clouds (from nacre, or mother of pearl), are icy structures that form in the lower stratosphere (15 – 25 km) when temperatures drop to around -85 ºC (-121 ºF). They are best observed when the Sun is between 1 and 6 degrees below the horizon.

"High-altitude sunlight shining through tiny ice particles ~10µm across produce the characteristic bright iridescent colors by diffraction and interference. Once thought to be mere curiosities, some PSCs are now known to be associated with the destruction of ozone," Dr. Tony Phillips of the SpaceWeather.com explains.

Truls Tiller photographed these over Tromsø city, Norway, on December 16, 2015:

Image credit: Truls Tiller – Tromsø city, Norway – December 16, 2015 (via SpaceWeather)

Image credit: Truls Tiller – Tromsø city, Norway – December 16, 2015 (via SpaceWeather)

Featured image: Polar stratospheric clouds over Tromsø city, Norway on December 16, 2015. Credit: Truls Tiller (via SpaceWeather)

Share:

Commenting rules and guidelines

We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules:

  • Treat others with kindness and respect.
  • Stay on topic and contribute to the conversation in a meaningful way.
  • Do not use abusive or hateful language.
  • Do not spam or promote unrelated products or services.
  • Do not post any personal information or content that is illegal, obscene, or otherwise inappropriate.

We reserve the right to remove any comments that violate these rules. By commenting on our website, you agree to abide by these guidelines. Thank you for helping to create a positive and welcoming environment for all.

3 Comments

Leave a reply

Your email address will not be published. Required fields are marked *