When Anne Elle Salikala and her friends saw everyone looking up at the sky one afternoon in Pagadian City, Zamboanga del Sur, they didn’t expect that they’ll be witnessing such rare phenomenon.
As shown in the video above which was posted by Anne last April 23, 2017, there seemed to be a cloud topped with a colorful swirl of another cloud. Remember when we were taught about fairy tales and myths as kids, to mention about unicorns and that they poop rainbows? Well, scientifically, it’s not really about that. But how do these “colorful clouds” form?
This phenomenon, which rarely occurs, is called cloud iridescence or irisation, with the cloud being called as iridescent clouds. The term irisation comes from Iris, the Greek personification of the rainbow.
Often observed in altocumulus, cirrocumulus, lenticular clouds, and cirrus clouds, cloud iridescence occurs when tiny water droplets or small ice crystals are present in the air of which then individually scatter light creating rainbow-like effect in the clouds, compared to larger ice crystals which produce solar or lunar halos. Usually, the colors that can be seen with iridescent clouds are pastel just like in the video, but they can also become very vivid. And when they occur near the sun, it can be difficult for us to spot for it can get drowned in the sun’s glare.
Rare as they can be, but such iridescent clouds have already been observed in other parts of the world.