What's a sun dog? Calgary got a glimpse this week

It's been cold in Calgary. So cold that we have ice crystals floating in mid-air, and it's beautiful.

Optical phenomenon caused by refraction of sunlight through ice crystals

Sun dogs have been making a mark on Calgary's sky for the last week, thanks in part to the freezing temperatures outside.

Jesse Rogerson, who works as an educator at the Telus Spark science centre in Calgary, says sun dogs are rare.

"What's happening, it's so cold that you get these ice crystals hanging in the air, and this usually happens at a much higher altitude," he said, like up in cirrus clouds where it's really cold.

"But because Calgary's been frigid over the last little while, you get the same ice crystal happening at a much lower altitude. So very close,... basically at the surface of the earth."

(Submitted by @richcrea/Instagram)

"The reason you get these cool structures is because the water has frozen in a specific way.... They call them plates, but it's almost like a leaf, so it's flat — like a flat little chunk of water frozen in the air. And because of the way they settle, .... like a leaf falling slowly through the air, they all align horizontal parallel to the ground."

Rogerson says multiple layers of "floating leaf crystals" all stack on top of each that gives you a makeshift prism, and because of the water's chemical structure they bond in a certain way that makes them have a rainbow effect at a specific angle.

Rogerson says meteorologists call it diamond dust, but it's also referred to as parhelia or "false sun."

Solar halos are slightly different. They are a round ring around the sun where no part is brighter than other areas.

(Submitted by Theresa Malan)

Rogerson thinks they are a "cool interesting thing you get to notice in the sky" that help us connect to nature and think about how our atmosphere and sun works.

For more on the science, listen to Rogerson below:

More on the science of sun dogs


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