Wednesday, March 10, 1999

Today's halo, with ears and hat

Did anyone else notice the bright ring around the sun today? I'm used to seeing complete rings around the moon, but this was a circular rainbow. Additionally, at (thinking of a clock face) 10:15 and 2:45, were bright Sun Dogs, extending out a good 20 degrees, like a pair of ears. With averted vision the "ears" extended even further out, with some hint of extending inward from the ring as well. Atop all this, was a horizontal Sun Dog sitting on top of the ring, like a hat. Really an amazing sight!

I did some reading last night, about lunar and solar halos, sun dogs and other atmospheric phenomena. What I (and John Hales) saw yesterday was a 22 degree halo. Most people notice this around the moon, but they are much more common around the sun. The lunar halos are just colorless, but the solar ones are usually sharply defined at the outside, where they are red, and hazy on the inside, where they are blue. In some cases, other colors are seen. I saw other colors too... this was a really outstanding halo.

The "sun dogs" that I saw are also known as "mock suns"... many of us have noticed these up a Fremont Peak as the sun is low in the west. These two sun doggies were very bright, extending away from the outer edge of the halo. They are, according to the book I read, to be found at the solar altitude, which matches perfectly with what I saw. The long extensions I noted on the dogs are "tails".... and these were very good examples ot tails on sun dogs.

I also noticed that inside the halo, the sky was darker than outside. This phenomena is also clearly described in my reading. What a sight!

Finally, the most surprising sight was the "hat" I described. It is known a cicumzenithal arc. This one was slight... as my book states that the arc can be the most beautiful of halo phenomena, being heavily color saturated. I feel lucky to have seen it... it is usually visible only a couple times a year, to those who know where to look. The view I had was subtle, appearing to be an updward bowing slight arc atop the 22 degree halo, but my wife Pat noticed it too.

Fun stuff to see.

No comments: