Cirrus uncinus
From Glossary of Meteorology
cirrus uncinus
A species of cirrus without gray parts, the elements of which are often in the form of a comma, topped with either a hook or a tuft that is not rounded.
The species uncinus is unique to the genus cirrus. The hook takes the shape of a reverse question mark under positive wind shear (wind increasing with height) conditions and the shape of a question mark under negative wind shear.
