Definition
A descriptive term for clouds that are thin, wispy, and composed primarily of ice crystals, forming at high altitudes — typically above 20,000 feet. Cirriform clouds include cirrus, cirrocumulus, and cirrostratus, and are characterized by their fibrous or hair-like appearance.
Plain English
Cirriform describes the family of high, thin, icy clouds that look like wisps, streaks, or fine veils across the upper sky.
Context Anchor
Seen in weather reports, cloud descriptions, and aviation weather study when identifying high, wispy cloud types.
Derivation
From the Latin cirrus, meaning 'a curl' or 'tuft of hair,' plus the suffix -form, meaning 'shaped like.' So cirriform literally means 'shaped like a curl or wisp of hair' — which matches how these clouds look spread thinly across the upper atmosphere.
Why Pilots Care
Signals high-altitude moisture that can produce ice crystals and may indicate an approaching weather system affecting flight visibility or conditions.
Analogy
Cirriform clouds can look like thin strands of hair or brush strokes stretched across the sky.
Grounding Statement
Thin high clouds that let most sunlight through yet mark moisture far above typical cruising altitudes.
Intuition Check
Cirriform is a description of cloud appearance, not one exact cloud name. If the cloud looks thin, streaky, and hairlike, it may be described as cirriform.
Example Sentence 1
The pilot noted thin cirriform clouds streaking across the sky and suspected a warm front was moving in.
Example Sentence 2
Cirriform clouds appeared ahead of the warm front, prompting a check for possible high-level icing.