Cirrus Spectrum

This was the first time I've seen such vivid colors in the clouds. This is known as a "circumhorizon arc." In order for this to form, the sun must be at least 58 degrees high in the sky, and the crystals in the cirrus clouds must be nearly geometrically perfect and vertically aligned. It's pretty rare to see this, though if you're observant enough, you should be able to see very faint rainbow colors like this every couple weeks or so.

Please tell me what you think!