A weakening storm approached the west side of the Bighorn Mountains. The sun came out and this double rainbow appeared. It was so vivid it felt like I could reach out and touch it. At first it was almost a complete circle. I rushed to capture a time lapse and had to keep wiping the raindrops off my lens. I got quite wet as a result, but it was worth it.
A double rainbow is caused by light reflecting a second time within raindrops. The secondary rainbow is located 8° apart from the primary bow, and is almost double the width. The colors are fainter, and in reverse order (VIBGYOR instead of ROYGBIV.) In between the two rainbows is a darkened part of the sky called Alexander’s Band. The sunlight is always brightest in the center of a rainbow at the anti-solar point. But since this bright light is also reflected opposite the secondary rainbow, that leaves a dark band in between.