photo #9384194

After a wet day in Portland, Maine, US, Bob Osborn (Member 54,749) watched the rain and wind head off as sunset brought a rare combination of rainbow and anticrepuscular rays known as a rainbow wheel. Bob had another name for the display: ‘a group of solar jellyfish working their way west’.The rays were beams of light and shadow produced by clouds obscuring the Sun on the horizon far behind Bob. Where unobstructed sunlight reached rain showers ahead, fragments of rainbow appeared. Both the rainbow and the rays were centred on the point in the sky opposite the Sun, making the rays resemble spokes within the rainbow’s rim.And there was something rarer still. Look closely at the brightest fragment, and you might notice that its bands of colour split slightly into two misaligned arcs. This was a twinned rainbow, likely formed where two populations of differently sized raindrops overlapped along Bob’s line of sight. Larger drops are more distorted by air resistance as they fall than smaller ones, their bases flattening to resemble hamburger buns. This changes the shape of the rainbow they produce, squashing the upper part of the arc downwards. Here, two differently sized populations of drops were producing slightly differently shaped bows that diverged at this point. In other words, one of Bob’s solar jellyfish had brought along a twin. Happy Cloud Appreciation Day, 2026!