Yesterday I saw some really colorful Iridescent Clouds. It is a fairly uncommon phenomenon. The colors are produced due to small water droplets or small ice crystals in the clouds that scatters the light. Larger ice crystals produce halos.
I've seen this phenomena a couple of times before but not this vivid. I hurried back home to grab a lens with a longer focal length to really get up close. In this photo I enhanced contrast and saturation a bit to bring to colors and structures out.