Circumhorizontal Arc

We have had some pretty interesting atmospheric phenomenon here in Denver the past couple weeks. The jet stream has been pushing the weather patterns to the north and east of us and creating newsworthy storms on the east coast and upper mid-west, while its been relatively mild here. In addition to snowing while the sun was shining, another effect I've seen recently is a Circumhorizontal Arc, which is caused by sunlight, and sometimes moonlight, refracting off plate-shaped ice crystals suspended in the atmosphere, typically in cirrus and cirrostratus clouds. It is sometimes called a Fire Rainbow, but is actually in the ice halo family. Rainbows are refracted or reflected from water droplets in the sky. I usually see the arcs when I have polarized lens sunglasses on. The effect is harder to spot with the naked eye. This photo was taken from my study, facing west across the Highline Canal with an iPhone 7, (which you can see reflected in window at the lower right).