We’ve all seen rainbows before, but have you ever heard of a phenomena called a fire rainbow? The proper term for it is circumhorizontal arc and it’s actually an optical phenomena – a ice-halo formed by plate-shaped ice crystals in high level cirrus clouds.
‘What is happening here is that on sunny afternoons, cumulus clouds boil upwards, pushing layers of moist air above them even higher where they cool and condense to form cloud caps or ‘pileus’ (Latin for cap),” explains Atmospheric Optics Expert Dr Les Cowley. “When pileus clouds form very quickly, their water droplets tend to be all the same size, the perfect condition for iridescent colors.’
deviantART photographer daslasher1 was in the perfect spot at the perfect time to capture fire rainbows high up in the sky. How often this beautiful “smeared rainbow” is seen depends both on the location and the latitude of the observer. In the United States, it is a relatively common occurrence seen several times each summer. In contrast, it is rare sight in northern Europe.