Supercooled rainbow appears over Muonio, Finland

A supercooled rainbow was observed and photographed above Muonio, Finland on December 4, 2017. Supercooled rainbows were also sighted in the Arctic last year.
"I have never seen a rainbow during the winter and I didn't even know that it is possible for them to form when the temperature is below 0 °C [32 °F]," says Valtteri Immonen who took the photograph below. "It was -6 °C [21.2 °F], no rain and no snowfall. Yet there was a huge rainbow across the sky," Immonen said.
Supercooled rainbow captured over Muonio, Finland on December 4, 2017. Credit: Valtteri Immonen (via Spaceweather.com)
"The rainbow's appearance, narrow with a supernumerary, says that it was produced with reasonable size water drops, perhaps about 0.5 mm in diameter. I surmise that the there was high-level precipitation that did not necessarily reach the ground. The drops could also have been supercooled below the normal freezing point of water," Atmospheric optics expert Les Cowley told Spaceweather.com.
Supercooled raindrops can form when droplets of liquid waterfall through layers of subfreezing air, Dr. Tony Phillips of Spaceweather.com explains. Droplets containing specks of dust or even microbes readily freeze as ice crystals form around the impurities. But when rain droplets are especially pure, they can remain in a liquid state even when the temperature drops below freezing.
"Last winter, supercooled rainbows were sighted in the Arctic as strange weather gripped the poles," Phillips said.
"Immonen's photo suggests that more of these rare rainbows may be in the offing," he concluded.
Featured image: Supercooled rainbow captured over Muonio, Finland on December 4, 2017. Credit: Valtteri Immonen (via Spaceweather.com)
If you value what we do here, create your ad-free account and support our journalism.
Your support makes a difference
Dear valued reader,
We hope that our website has been a valuable resource for you.
The reality is that it takes a lot of time, effort, and resources to maintain and grow this website. We rely on the support of readers like you to keep providing high-quality content.
If you have found our website to be helpful, please consider making a contribution to help us continue to bring you the information you need. Your support means the world to us and helps us to keep doing what we love.
Support us by choosing your support level – Silver, Gold or Platinum. Other support options include Patreon pledges and sending us a one-off payment using PayPal.
Thank you for your consideration. Your support is greatly appreciated.
Sincerely,
Teo Blašković
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:
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.