Lawrence, you’ve caught a double red rainbow – a cousin to an ordinary multi-colored rainbow – that happens when the sun is low in the sky.
See how tall your rainbows are? The height of a rainbow corresponds (inversely) to the height of the sun in your sky. High sun, low rainbow. Low sun, high rainbow. So rainbow-watchers would know, without your having mentioned it, that the sun was low.
Now think about low suns for a moment. They typically appear reddish. That’s because – around sunset – you’re looking at the sun through a greater thickness of atmosphere than when the sun is high in the sky. At such times, the blue and green components of multi-colored sunrays are weakened by scattering during their long journey through the atmosphere to your eyes.
So red sunsets and red rainbows go hand-in-hand.
Thank you, Lawrence!
Bottom line: Photo of a red rainbow over Bellingham, Washington, on May 5, 2020.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.