cirro-

[From CIRRUS.]

Like a lock of hair; referring to high, slender, ice-crystal clouds with a feathery appearance, sometimes pulled out into ‘mares' tails’ by strong upper-air winds. When these coalesce to form a thin layer of high cloud, they are termed cirro-stratus.

Patchy, mottled, high cirrus is cirro-cumulus, often called a mackerel sky. This forms above very active warm fronts. See also cloud.