MOLINE, Ill. — Atmospheric conditions came together just right on Wednesday afternoon to produce something we don't see that often here in the Quad Cities: rainbow clouds. Many of you quickly took notice, snapping pictures and sending them in via our apps. From Bettendorf to Hillsdale, these clouds were quite spectacular, especially given the dark blue background with the sky.
Why rainbow clouds form
These clouds form because of something we call cloud iridescence. Typically, this process is associated with altocumulus, cirrocumulus, ventricular and cirrus clouds. Each cloud contains millions of tiny water droplets and small ice crystals that refract and bend light. It's very similar to sun dogs, which we typically see during the colder months.
Cloud iridescence itself is quite rare. The cloud has to be thin enough and contain lots of water droplets or ice crystals. The sun's rays then encounter a small number of droplets at a time, refracting and bending that incoming light and producing the color spectrum in the sky.
These clouds are more pronounced, especially in much colder climates like the Arctic where they can appear in several day stretches.
Another interesting-looking cloud from Wednesday
In addition to the rainbow clouds, gravity waves could also be seen in our skies during the afternoon and early evening. NJMorrison captured these clouds along with a few others.
Rainbow clouds - May 8, 2024
Gravity, or wave clouds, form when stable air moves over a raised land feature, such as a hill, and is forced upward. Gravity then takes over and causes the air to sink back down, after which it begins oscillating back and forth, creating a ripple effect in the sky.
Remember, our atmosphere has similar properties and physics that are very similar to a body of water. Just like when you would drop a pebble in a lake or river, you'd see it surrounded by multiple waves shortly after. This is a very similar process.
Thanks to everyone who submitted photos!