Picturesque Cirrus fibratus and Cirrus uncinus

Cirrus fibratus (thin fibers in bands) and Cirrus uncinus (hooked cirrus) covered the southern sky early this afternoon. This photo is looking south from Cedar Falls, Iowa.

One explanation for the formation of Cirrus uncinus indicates that a region of rising air forms the ‘head’ of the cloud while the tail forms when ice crystals precipitation out of the head and fall into slower moving air below the head. The heads appear to be at the highest point and leading end of the cloud where the formation is dense with falling ice crystals. As the crystals fall they trail behind the head because the air below is moving slower.

The leading edge of the cirrus looked like long thin fibers.