The stratosphere above the Arctic Circle is getting cold … very cold.

psc_strip

That’s the only way to explain these colorful clouds that materialized over Kvaløya, Norway, on Dec. 20th.

These are polar stratospheric clouds (PSCs), and they require temperatures around -85ºC to form.

“Today, heavy rainclouds and a bitter wind greeted the people of Tromsø in northern Norway when they woke up. But all of a sudden, the clouds parted and the sky cracked open to reveal an absolutely stunning display of stratospheric clouds high above the ordinary gray rainclouds,” says photographer Fredrik Broms. “Seldom have I seen PSCs with such vivid colours as today.”

The stratosphere is extremely dry, which makes it hard for clouds of any type to form. Only when the air up there becomes extremely cold do widely-spaced water molecules coalesce to form ice crystals–the “stuff” of PSCs. High-altitude sunlight shining through these ice particles produces the clouds’ characteristic bright iridescent colors.

 

If you wish you can Leave a Reply. We will publish it after moderation. Insults and Spam are automatically deleted. Thank you for visiting my blog today.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s

%d bloggers like this: