Plain English Meaning

Thin, wispy, ice-crystal clouds high in the sky. They look feathery or streaky and often show up before a weather change moves in.

Full Definition

High-altitude clouds composed almost entirely of ice crystals, typically forming above 20,000 feet. They appear thin, wispy, or fibrous and often take the form of streaks, sheets, or feathery patches across the sky. Cirriform clouds frequently signal moisture aloft and are commonly the first visible indication of an approaching warm front.

Context Anchor

Seen in weather study and preflight weather checks when learning how clouds change as a warm front approaches.

Derivation

From the Latin 'cirrus,' meaning a curl, ringlet, or wisp of hair, plus '-form,' meaning 'in the shape of.' The name describes exactly what these clouds look like: curly, hair-like wisps stretched across the sky.