The highest clouds in the sky, composed completely of ice crystals, are also the most ethereal-looking, like wisps of hair. In fact, Cirrus clouds look exactly like the Latin root of the word–curl of hair. This picture shows a variety of cirrus, including a few hooked cirrus clouds called uncinus.
The weight of the ice crystals forming the cirrus clouds cause them to fall through the troposphere in a way that makes them appear as if they were painted by angels. When they begin to thicken and turn blue this is a sign that their moisture content is building, which could eventually produce rain or snow, but that won’t come for a few days.
Due to their high moisture content, cirrus clouds also tend to produce the colorful arcs and rings called halo phenomenon.
