Cirrostratus nebulosus

Cirrostratus nebulosus is a featureless, uniform veil of high, thin cloud, composed mainly of ice crystals and often spread across much of the sky. It can produce a halo around the Sun or Moon.

Cirrostratus: A high, thin cloud genus composed mainly of ice crystals, often forming a translucent veil. Cirrostratus nebulosus is the uniform, featureless species within this cloud genus.
Halo (optical phenomenon): A ring or arc of light around the Sun or Moon, usually caused by ice crystals in the atmosphere. Cirrostratus nebulosus commonly reveals itself through a halo around the Sun or Moon.
Cirrostratus fibratus: A cirrostratus species with fibrous or hair-like structure. Its visible strands contrast with the smooth, featureless nebulosus veil.
22° halo: A luminous ring with an apparent radius of about 22 degrees around the Sun or Moon. This common halo often appears when cirrostratus ice crystals have suitable orientations.
Cloud species: A classification level describing the form and structure of clouds within a cloud genus. Nebulosus names the species-level form of this cirrostratus veil.
Refraction: The change in direction of light as it passes between materials with different optical properties. Light refracting through ice crystals produces the characteristic halo.
Cirrostratus fibratus undulatus: A cirrostratus variety whose fibrous structure shows wave-like undulations. Its rippled texture differs from nebulosus's even appearance.
Halo forecasting: The use of halos and related optical displays as clues in short-term weather observation. A halo within cirrostratus can accompany an approaching frontal cloud system.
Ice crystal: A solid particle of water with an ordered crystalline structure. Ice crystals make up the high, cold cloud and refract light into halos.
Atmospheric lifting: The upward movement of air that cools it and can lead to condensation or ice formation. Gradual ascent can spread ice crystals into a broad, uniform cloud veil.

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Cirrostratus cloudBroader topic: This species shows the smooth veil-like form commonly associated with the genus.