Dec
19
2005

If you live in the Twin Cities area and you were out and about this morning, you might have seen some pretty spectacular "sun dogs."

Sun dogs are formed by the refraction of sunlight through flat, six-sided ice crystals in the air. These crystals are associated with cirrus clouds and ice fogs, and only grow in temperatures between -9° and -20° C (15-25° F). Temperature inversions, though, can create sun dogs even when the ground temperature is much cooler.

As of 9:45am, it's officially 0° F in Saint Paul...

Your Comments, Thoughts, Questions, Ideas

bryan kennedy's picture

I swear I have lived here 10 years now and had never heard of these until this winter. We sure didn't get sundogs in Texas. It's a pretty amazing phenomenon. Has anyone seen these around for the last couple of years? We had some pretty warm winters lately but this year seems pretty cold.

Several friends saw a variation on sun dogs this weekend, "light pillars". The same six-sided ice crystals cause faint columns of light to extend up into the sky above street lights and other bright spots in the evening.

This also reminds me of something I saw last year. The Mutant snowflakes blog. Since snowflakes only really form with six sides this guys made a blog of advertising over the last year that featured fancy designed snowflakes that couldn't exist in the real world. It is a pretty funny satire of science in our consumer world.

posted on Mon, 12/19/2005 - 12:13pm
bryan kennedy's picture

Here are some amazingly artistic light pillar photos.

Flickr, also has a great deal of photos of both sundogs and light pillars.

Light Pillars

Light Pillars above the Twin Cities, MN
Courtesy Chuckumentary
Sundogs
A sundog or halo
Courtesy dustym


posted on Mon, 12/19/2005 - 12:50pm

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