Yesterday saw a rare rainbow cloud light up the Portland city skies. This was pictured by various locals who couldn’t believe their eyes – as it’s fair to say that rainbow clouds are pretty rare. Even by Portland’s unusual weather standards, this wasn’t something that you see every day and is certainly unique. As seen below, you can see how the cloud has mixed with the rainbow colors perfectly.

Speaking on the cloud, locals said “I saw this too! Funny I was only able to see it with my shades on and thought I must’ve been seeing things!” and “Never thought I would say this, but this is a rainbow worth posting. Like a pride flag in the sky!” – You could say, this cloud brightened up the locals’ day (we’ll get our coat…)

For those wondering, this is also known as a colorful cloud or iridescent cloud, and forms as a result of a phenomenon called cloud iridescence. It occurs when the sunlight interacts with tiny water droplets or ice crystals in the cloud, causing the light to scatter and diffract.

Unsurprisingly, rainbow clouds are relatively rare and require specific conditions to occur. The cloud must have the right combination of moisture content, particle size, and sunlight angle to produce the iridescent effect. Additionally, the colors in a rainbow cloud are usually less vibrant than those in a traditional rainbow because the particles in the cloud are much smaller than raindrops.