Brightly colored circumhorizon arcs (also known as circumhorizontal arcs) form when the sun is very high in the sky, higher than 58 degrees. Near to noon in mid latitudes is a good time to possibly see them. They are very large halos that are always parallel to the ground. Often only fragments are visible where there happen to be cirrus clouds. Your latitude determines how rare they are for you to see. In the USA they can be seen several times each summer by keen eyed observers, while in much of Europe they are extremely rare, and in fact impossible to see north of Copenhagen. This one was photographed in the summer in New Hampshire.