Dangerously cold temperatures are forecast for Sioux Falls and the surrounding area through midweek. But at least there is one bright spot in this frigid weather, and that would be the optical spectacle around the Sioux Falls sun called a "Sundog."

Many folks have been posting some great pictures on this weather phenomenon. But what causes a Sundog or Parhelion which is the scientific name for this pretty appearance in the sky. The term Parhelion is from the Greek parēlion, meaning "beside the sun." I read that at Live Science.

Sundog- Georgie Opitz-Sioux Falls

The folks at Live Science also explained what causes Sundogs: "Sundogs often appear as colored areas of light to the left or right of the sun, 22 degrees distant and at the same distance above the horizon as the sun. Sundogs are formed from hexagonal ice crystals in high and cold cirrus clouds or, during very cold weather, by ice crystals drifting in the air at low levels. These crystals act as prisms, bending the light rays passing through them. As the crystals sink through the air they become vertically aligned, refracting the sunlight horizontally so that sundogs are observed."

I've found the best way to view a sundog is by a window inside a warm room while holding a hot cup of coffee.

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