I looked out the kitchen window this afternoon to hear my kindergartener shrieking, "what is it?! Daddy! It's scary!" and to see my husband and daughters staring at the sky, eyes sheilded against the sun, mouths agape. From my vantage point, it seemed as though they were witnessing the Ascension a day early. I was nervous.
I went outside to snap the photo that appears above . . . though, if I may anthropomorphize a little, it appeared angrier in person. In the center, a dark circle around the sun. On its boundary, a brilliant rainbow (a 22 degree halo, as I've learned it's called). Intersecting this circle, a second, huge ring parallel to the horizon. This is the parhelic circle—a perfect halo around the entire valley, stretching from the sun across the sky and back again, with sun dogs on either side—two gleaming, multihued slices of sky where the halo and the giant horizontal ring intersected. With the entire valley taking on a bizarre, muted cast on an otherwise cloudless day and with my kindergartener wailing in terror, it was hard not to feel some unsettling wrongness in the weather. My husband and I both admitted to being disturbed, just slightly, by the sky, though a Google search revealed that these are common meteorological phenomenon.
The solar halo, as it turns out, is something a careful observer might see several times a year. I think I witnessed one last summer but failed to see all of its features. I remember seeing two brilliant rainbows strangely close to the sun. These would have been the sun dogs, or parhelia, bright spots which mark the intersection of the 22 degree halo and the larger parhelic circle.
In typical Marnie fashion, I've Googled this phenomenon to within an inch of its life. I am probably now qualified to teach a ninety-minute seminar on ice halos and related optical phenomena. A good summary lies here: http://www.atoptics.co.uk/halosim.htm
So, folks, next time a sinister rainbow falls over YOUR valley, tell your children to rest easy. It's only light playing on ice crystals.