During the summer, if you’re very lucky, you may notice a cloud in the sky that looks just like a rainbow. These so-called “fire rainbows” are actually known as circumhorizontal arcs and can occur when the sun has risen higher than 58° in the sky. For those living at mid-latitudes, the best chance to see this phenomenon is in the middle of summer. The rarity of the event is highly dependent upon latitude and weather conditions. The potential for these arcs to form in Los Angeles is 5-10 times higher than in London.