It almost looks like a Photoshop composite, but this is an uncommon but completely naturally occurring phenomenon. It’s known as a circumhorizontal arc, and this particular scene was spotted by photographer Cessna Kutz, who couldn’t help but photograph it – and who could blame her!
While technically not a rainbow, as rain has nothing to do with it, the description of “horizontal rainbow” does seem to do it justice. It’s actually light refracting through ice crystals suspended in the atmosphere. But regardless of what it’s called, it just looks beautiful.