Three days after I had first learned about circumhorizontal arcs (from reading the Earthsky article published on June 9, 2019), I saw one! I was driving on a Forest Service road in the Elkhorn Mountains southeast of Helena, Montana, and noticed this exceptional rainbow color stripe in the early afternoon sky. Of course, I shot some photos and determined to go back and reread the article to confirm what I was seeing. The observation checked all the boxes for a circumhorizontal arc. Without the online article I would not have known what I was seeing -- thanks, Earthsky!

Camera: Olympus E-M5MarkII
Lens: Olympus M.Zuiko Digital ED 12-40mm F2.8 Pro, with polarizer
f/10 1/400 iso 200 27 mm

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