Got drenched by fast-moving thunderstorm headed east-northeast over North Park, Colorado (near Walden, 8100 ft elevation). We stopped as the storm rose over the Medicine Bow Mountains to the east and created this amazing chromatic display at near-ground level.
Never seen anything like it before of after.
Photo Credit: Geology Jim
Click for larger image.
The chromatic display near the ground is actually the uppermost arc of a rainbow. The sun is near 40 degrees elevation behind the photographer.