High-level cloud formations described as feathery, wispy or streaky are known as cirrus clouds. These clouds can be present in up to 30 percent of the Earth's atmosphere at any given moment.
Cirrus clouds typically occur at levels above 20,000 feet. They are unique among other cloud types in that they are made up of ice crystals rather than condensed liquid water. The formation of cirrus clouds is tied to the amount of metallic and mineral particles in the high troposphere, to which the ice crystals bind. These clouds can also serve as an early indicator of an incoming warm front.