Cirrus in all its Glory

Cirrus clouds provide some of the most artistic patterns visible in the sky. Three examples below show how winds aloft can paint a variety of patterns at the same time. These photos were taken in a few minutes of each other and include Cirrus uncinus, cirrus fibratus, and cirrus floccus with fall streaks.

These clouds are formed by changes in wind direction and speed with height. It is the differences in wind direction and speed, also known as wind shear, that create the appearance seen in these photos. Cirrus contain ice crystals which can travel longer distances than water droplets, which evaporate easily in drier air. Ice crystals do not evaporate, they sublimate, which means the ice changes from solid crystals directly to water vapor. It takes longer for sublimation to occur. The cirrus with fall streaks (virga) take their shape by precipitating ice crystals which fall through slower moving air than the top of the cloud which creates the trailing streaks of crystals.

These photos were taken from Cedar Falls, Iowa on March 27, 2023.

Cirrus uncinus (hook-shaped), cirrus fibratus (wispy fibers), and cirrus floccus (clumps of Cirrus) with fall streaks