How to recognize Cirrus
Cirrus consists of ice-crystal clouds with a characteristically fibrous structure. It may appear as fine hairs, curved hooks, feather-like streaks, dense white patches with frayed edges, or long bands aligned by upper-level winds.
Typical level
High troposphere; around 5–13 km in temperate regions.
Main texture
Wispy, fibrous, hooked, or silky.
Composition
Ice crystals.
Model label
Ci · output index 4
Field clues and lookalikes
- Trace individual filaments and notice whether their ends curl or feather out.
- Contrails often begin as straighter, narrower lines linked to aircraft paths, though older trails can spread.
- Cirrostratus covers more of the sky as a veil; Cirrocumulus breaks into tiny repeated cells.
Weather context
Cirrus can occur in fair conditions, near distant weather systems, or as outflow from Cumulonimbus. Shape alone does not determine which process produced it.
Photography notes
Expose for the bright filaments and include enough surrounding sky to show their direction and spacing. Fine texture can disappear after aggressive sharpening or compression.
Classification is not forecastingCirrus may have several origins. A photograph cannot establish what weather will follow.