Ultra Rare for Alabama: a 22º halo at ground level!

You don’t see this every day on Sand Mountain!  Sure, we get halos, sundogs, and arcs in the sky on a weekly basis, but we rarely see them at ground level here in Alabama.  This 22º halo from Peggy Ponds in Albertville on Tuesday, December 11th is quite a find.

Why so rare?

Halos, sundogs, and arcs form when sunlight is refracted through ice crystals.  Those crystals are hexagonal plates that look something like this:

As the sunlight bends into the spectrum upon exit from the plate, it shows off the optical phenomenon we see as a ring around the Sun or Moon.

On Tuesday, we had freezing fog that was precipitating out small ice crystals that were shaped like this.  The closest description I can find to what we observed is from the Arctic and Antarctic: diamond dust.  

We were in no wise ‘Arctic’ Tuesday morning, but conditions were just right for something like that diamond dust to develop in North Alabama.  Here’s a video I shot from Research Park in Huntsville showing the small crystals ‘snowing’ down out of a clear sky:

One thing’s for sure: the weather is never really boring. There’s always something cool to find if you’re looking in the right place!

Looking for the forecast? It’s always online at WHNT.com/Weather and in the “Daily Forecast” section on Live Alert 19!

-Jason
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