“Daytime Auroras” … a.k.a. Polar Stratospheric Clouds

Feb. 15, 2017: On Feb. 13th, something amazing happened in the stratosphere over the Arctic Circle. Normally, the air 60,000+ feet above Earth’s surface is dry and utterly transparent.  On the eve of Valentine’s Day, however, the Arctic stratosphere filled with a gossamer haze of crystalline ice, and when sunlight hit the freezing crystals, the sky filled with clouds of intense iridescent color.

“Our guests referred to the clouds as ‘daytime auroras,’” reports Chad Blakley, who operates the Lights over Lapland tour guide service in Abisko, Sweden. One of them, Champ Cameron (@champcameron on Instagram), snapped this picture of the display:

“Champ was participating in our Sami And Reindeer Experience outside of Abisko yesterday afternoon,” explains Blakley. “The roads were very icy due to a freak rain storm and warm weather (+9 degrees C) so we nearly canceled the trip. But we heard that there were incredible clouds in the sky so we chose to brave the weather and push on.”

Good thing. They witnessed an exceptional display of polar stratospheric clouds (PSCs). PSCs are a sign of very cold temperatures in the stratosphere. For ice crystals to form in the normally arid stratosphere, temperatures must drop to around -85º C. So while it was strangely warm on the ground below, it was incredibly cold up above.

Longtime observers say PSCs are becoming more common and more intense. “I’ve been living here all my life (33 years),” says Mia Stålnacke of Kiruna, Sweden, who also photographed the colorful outbreak. “I definitely feel that these clouds are appearing more often then they used to. I remember seeing them a few times/year since I was a kid, but these last couple of years we’ve had them much more often–sometimes for almost a week straight. Others seem to feel the same way; I see local groups on Facebook flooded with photos of PSCs and comments on how often they’re appearing now.”

“Our bus driver, a longtime resident of the area, described it as the best PSC display he had ever seen,” relays Blakley. “We were overwhelmed by the natural beauty.” The clouds were so intense, they remained visible even after the sun set:

“We saw these clouds all day long, and they continued into the night,” says photographer Lars Lehnert of Abisko, Sweden. ” I’ve never seen anything quite like it.”

Once thought to be mere curiosities, some PSCs are now known to be associated with the destruction of ozone. Indeed, an ozone hole formed over the UK in Feb. 2016 following an outbreak of ozone-destroying Type 1 PSCs.

To investigate these clouds further, Spaceweather.com and the students of Earth to Sky Calculus will travel to Abisko Sweden for a week in March 2017.  We plan to launch a series of space weather balloons into the Arctic stratosphere, measuring temperature, air pressure, and ambient radiation.  If PSCs are present, our sensors will pass directly through them, and our cameras can photograph the colorful clouds at point blank range. Stay tuned!

Realtime PSC Photo Gallery