Full classification: Cirrus uncinus Over Glen Coe, Highlands, Scotland.
Photographer: Geir T. Geir's Web site Summary Author: Geir T. Jim Foster This jaunty upper tangent arc (UTA) was visible in the afternoon of December from Orsta, Norway. It’s tangent to the 22 degree halo --.
Nacreous Clouds These rare clouds, sometimes called mother-of-pearl clouds, are 15 – miles) high in the stratosphere and well above tropospheric clouds.- 10 Very Rare Cloud Pictures ~ Cool Things Collection
Polar stratospheric clouds, They are also called nacreous or mother of pearl clouds, and display a wonderful spread of shifting colours as the sunlight gets diffracted by the tiny ice crystals forming the nebulosity.