Uncinus

Definition

A species of cirrus whose filaments end in a hook or comma shape rather than a tuft. The hook points in the direction of the wind shear and marks where the ice crystals are falling most slowly.

Field note

Cirrus uncinus is nicknamed 'mare's tails' and marks the middle stage of a frontal approach: more moisture aloft than fibratus, and rain usually 12 to 24 hours away.

Related terms

• Cirrus · Cirrus
• Fibratus · fibratus
• Spissatus · spissatus