We were out putting up more Christmas lights this afternoon and saw what was to me a totally new and fascinating phenomenon, a circumzenithal arc. Technically not a rainbow but a halo, it comes from the sunlight being scattered by high-altitude ice crystals instead of raindrops. It stood out because of its location (directly overhead instead of on the horizon), the fact that the colors are extremely vivid, and the arc and spacing of the colors are reversed or “upside down.” Bizarre at first, but stunning.
(The “Hesperia Christmas Lights 2025 – Day Two” pictures are coming, but will have to wait.)
Given the positioning of the arc relative to the Sun and that band of ice crystals between them, I suspected the connection even if I didn’t understand or remember the math behind the optics. The article referenced above confirms that.
With a wide-angle view you can see the two sundogs on either side of the Sun, with some hints of the very faint Parry arc. One of the things that amazed me was how long the phenomenon lasted – I’m used to rainbows on the horizon only lasting maybe five to ten minutes max, often much less due to the clouds and rain moving around. With this based on high-level ice clouds that are moving much more slowly, we watched this for well over a half hour.
We Love The Stars Too Fondly 