Polar Vortex Returns, Paints Sky In Prismatic Sparkles

A beautiful halo with accompanying sun dogs (bright spots left and right of the sun) and an upper tangent arc at top photographed earlier this morning Jan. 27. A second much larger and fainter halo ringed this one but doesn’t show in this picture. Credit: Bob King

Pardon my obsession with ice. It’s one of the ways I’ve come to accept this coldest of cold winters. Sparkling halos, sun dogs and ice pillars ornamenting our favorite luminaria – the sun and moon – make it hard to stay indoors.

Looking like some portal into the heavenly realms, the last week’s moon displays an oval corona and tall, wide moon pillar from light reflecting from plate-shaped hexagonal ice crystals floating horizontally in the air. Credit: Bob King

Many of these spectacular prismatic light displays have come to the U.S. and Canada by way of bitter cold polar air bundled with face-freezing winds. One word of advice. If you run out to shoot pictures, don’t do it in your slippers like I did this morning. Wear warm boots. It’s easy to shoot photos of astronomical events in daylight with any kind of camera. Just point, compose and shoot.

This is the top end of a hexagonal column-shaped ice crystal. Light refracting (bending) through billions of these crystals spreads out to form a typical solar halo. Sun dogs form when horizontal plate-shaped crystals refract sunlight.

Although we often can’t see them, the air is laced with microscopic, six-sided plate and column-shaped ice crystals that swirl about and refract the light into wonderful arcs and glows.

Light refracting through column crystals is responsible for halos; refraction through horizontally-floating plate crystals fires up those brilliant sun dogs on either side of the halo.

When not refracting light, plate-shaped crystals hovering with their flat sides parallel to the ground can also reflect the light of sun and moon to create tall columns called ice pillars.

Horizontal plate crystals reflect light to create pillars pointing up and down. On the ground and when the sun or moon is low in the sky, we see only the top pillar, but under the right conditions, when sun or moon is up high, both are visible. Credit: Keith C. Heidorn

Keep an eye out for these sights this week as we get a taste of what its like to live in the Arctic.

5 Responses

  1. George J Jelatis

    Thanks for venturing outdoors on this and other cold days to share photos like this! Can you elaborate regarding the Parry Arc? I have difficulty distinguishing between a Parry Arc and what I think is called the Upper Tangent Arc, that can appear at nearly the same place. Thank you again!

    1. astrobob

      Hi George,
      The Parry Arc is coincident with the UTA when the sun is at low altitude but separates from it as the sun rises higher and appears as a separate “smiley face” arc. Even higher, the Parry Arc gets longer and bends the other direction like a “frowny face”. At first because of altitude I thought my photo captured the Parry Arc but now I’m more inclined to think it’s the UTA.

  2. Renee Liefke

    Thank you for sharing the photos and the information, I’m so fascinated with sun dogs and sun pillars!

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