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Supernumerary Rainbow

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I chased a few thunderstorms that rolled off of the mountains in the afternoon. It was good rainbow weather, but they can't form in the middle of the day. Since the radius of a rainbow is always 42° and the center is directly opposite the sun (antisolar point), the sun must be at an altitude less than 42°. Around 5PM, the sun sank to 32° and this low rainbow appeared about 10° above the horizon. I stopped at this wetland and was able to cover my camera from the rain and capture a time lapse clip that I've tried many times to get. The extra colors (green, purple, green) at the bottom of the bow are called supernumeraries. It's a rare effect that happens when the raindrops are a specific diameter and mostly uniform in size. This complex light interference can't be explained by geometric optics. In fact, supernumerary rainbows played a part in the early 1800's in confirming that light is a wave, and not just made up of particles as previously thought.

Copyright
Kevin Palmer
Image Size
5415x3615 / 12.5MB
Keywords
Contained in galleries
Recent Work, Storms, Upslope Flow, Wyoming
I chased a few thunderstorms that rolled off of the mountains in the afternoon. It was good rainbow weather, but they can't form in the middle of the day. Since the radius of a rainbow is always 42° and the center is directly opposite the sun (antisolar point), the sun must be at an altitude less than 42°. Around 5PM, the sun sank to 32° and this low rainbow appeared about 10° above the horizon. I stopped at this wetland and was able to cover my camera from the rain and capture a time lapse clip that I've tried many times to get. The extra colors (green, purple, green) at the bottom of the bow are called supernumeraries. It's a rare effect that happens when the raindrops are a specific diameter and mostly uniform in size. This complex light interference can't be explained by geometric optics. In fact, supernumerary rainbows played a part in the early 1800's in confirming that light is a wave, and not just made up of particles as previously thought.