Cloud Art or Nature's Cloud Symphonies: this multi-coloured cloud phenomenon is called Sundog: rainbow cloud when ice crystals appear in clouds & refract sun's rays. Photographer Robert Arn, here in Heyworth, Illinois, US
View across the tropopause from a high flying research aircraft. Below are familiar tropospheric clouds, above are rare nacreous clouds formed at the low temperatures of the tropopause and lower stratosphere.
Nacreous Clouds Norway January 2005 ~ These clouds blazed in the sky over the Southern Norway twenty minutes after sunset January Imaged by Derick Rethans. The clouds were visible before dawn and throughout the day and evening.