Cirrostratus Clouds:Pale, Veil-like Layer

Cirrostratus clouds are high, thin ice-cloud veils that cover a large part of the sky while still allowing the Sun or Moon to show through. A halo is a strong clue, and a veil that steadily thickens can precede a widespread precipitation system.

Cirrostratus fibratus undulatus (Cs fib un) with a 22° halo

How to identify cirrostratus clouds

Thin, transparent, high-altitude cloud layer capable of producing a 22° halo

Cirrostratus clouds can best be described as a cloud blanket high up in the troposphere, spread out across the sky. Found at the same altitude as their cirrus and cirrocumulus counterparts, these clouds are more widely known for being the culprit of sun and moon halos, as they’re composed of ice crystals. Like most layer clouds, cirrostratus clouds generally take on a relatively dull appearance.

Don’t take offense, but cirrostratus clouds can be a boring cloud. They have very few cloud species and varieties associated with them. One distinction that cirrostratus clouds have going for them however is that they’re one of two clouds that can be fibrous in appearance (fibratus cloud species).

They’re also one of two clouds, the other cloud being stratus, that can take on a hazy, nebulous feel (nebulosus cloud species), which is where the cloud completely lacks any kind of discernible detail. There are instances where a cirrostratus cloud might take on a wavelike appearance (undulatus cloud variety). Because cirrostratus clouds are generally very thin, the sun will always be visible, which might help you distinguish it from its close relative altostratus cloud.

Sometimes they’re so thin, they’re almost difficult to even make out.

Cirrostratus cloud examples

Cirrostratus fibratus (Cs fib) with a 22° halo

Is it cirrostratus? Check these four clues

Look for a continuous high veil and its optical effects. Thin haze, cirrus strands, and mid-level sheets can look similar at first.

Widespread veil
The cloud forms a pale, continuous sheet rather than detached heaps or rows of cloudlets.
Sun or Moon visible
The disk usually remains visible through the thin ice layer, often with only slight dimming.
Halo possible
A ring, arc, or bright spot around the Sun or Moon strongly supports an ice-crystal veil.
Little surface precipitation
Cirrostratus itself does not normally bring rain or snow to the ground.

Read how the cirrostratus veil changes

A steady increase in coverage and thickness can be more informative than the veil at one moment, especially ahead of a warm front.

Classifying cirrostratus clouds beyond the cloud type

Begin with cirrostratus as the cloud type, then add species, varieties, supplementary features, accessory clouds, or origin terms only when each detail is visible. Every illustration below links to its complete field note.

Cirrostratus cloud species

2 cloud species are associated with cirrostratus clouds. Open any field note to compare the illustration with photographs and identification guidance.

Illustration of cirrostratus fibratus clouds

Cirrostratus fibratus (Cs fib)Fiberlike, hairlikeExplore this subtype →

Illustration of cirrostratus nebulosus clouds

Cirrostratus nebulosus (Cs neb)Full of vapor, lacking detailExplore this subtype →

Cirrostratus cloud varieties

2 cloud varieties are associated with cirrostratus clouds. Open any field note to compare the illustration with photographs and identification guidance.

Illustration of cirrostratus duplicatus clouds

Cirrostratus duplicatus (Cs du)MultilayeredExplore this subtype →

Illustration of cirrostratus undulatus clouds

Cirrostratus undulatus (Cs un)Wavelike, undulatingExplore this subtype →

Cirrostratus other clouds

1 other cloud is associated with cirrostratus clouds. Open any field note to compare the illustration with photographs and identification guidance.

Illustration of cirrostratus homomutatus clouds

Cirrostratus homomutatus (Cs homut)Transformed from a human-made cloudExplore this subtype →

Compare cirrostratus with similar cloud types

Use cloud-base level, texture, structure, and sky coverage together before choosing the closest match.

Cirrostratus vs. cirrus

Cirrostratus is a continuous high veil. Cirrus is separated into recognizable fibers, hooks, or streaks with more blue sky between them.

Best clueA halo in a widespread veil favors cirrostratus; separate wispy strands favor cirrus.

Illustration of cirrostratus clouds — Cirrostratus

Cirrostratus vs. altostratus

Cirrostratus is thin, pale, and often halo-producing. Altostratus is a lower gray sheet that dims the Sun more strongly and does not normally create halos.

Best clueA sharp halo points to cirrostratus; a watery, strongly dimmed Sun points toward altostratus.

Illustration of altostratus clouds — Altostratus

Cirrostratus vs. cirrocumulus

Cirrostratus is mostly smooth and veil-like. Cirrocumulus breaks into many tiny grains, ripples, or rows.

Best clueContinuous sheet versus repeated cloudlets is the clearest distinction.

Illustration of cirrocumulus clouds — Cirrocumulus

See a cirrostratus cloud classification in action

Follow a real photograph through the visible clues that lead to a complete cloud classification.

Photograph of cirrostratus fibratus clouds

Cirrostratus fibratus (Cs fib)See how height, shape, coverage, and other clues build this full classification.Read the step-by-step lesson →

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