Definition

1. Noun:
   • A high-altitude cloud: A cirrus cloud is a type of cloud that forms at very high altitudes, typically between 4 to 8 miles (6.5 to 13 kilometers) above the Earth's surface.
   • Composition and appearance: It is composed primarily of tiny ice crystals and appears as thin, wispy, feathery, or hair-like white strands or patches in the sky.

Examples of Usage

• Noun:
  • The sky was a clear blue, streaked with delicate cirrus clouds.
  • Meteorologists noted that the approaching cirrus clouds often indicate a change in the weather.

Advanced Usage

• "Cirrus uncinus": A specific type of cirrus cloud with a characteristic hook shape.
  • The sky was filled with cirrus uncinus, their hooked ends pointing in the direction of the upper air flow.
• "Cirrus spissatus": A dense, thick patch of cirrus cloud.
  • The cirrus spissatus near the horizon made the sunset particularly dramatic.

Variants and Related Words

• Cirro- (prefix): A prefix used in cloud classification for high-altitude clouds. (e.g., cirrocumulus, cirrostratus).
• Cirriform (adj): Having the form or appearance of cirrus clouds.
  • The cirriform clouds created a beautiful, textured sky.

Synonyms

• Mare's tail: An informal term for cirrus clouds, especially when they are long and wispy.
• Feather cloud: A descriptive synonym emphasizing the cloud's delicate, feather-like appearance.

Related Phrases

• "Cirrus cloud deck": A layer of the sky covered by cirrus clouds.
  • The pilot ascended above the cirrus cloud deck into clearer air.
• "Cirrus veil": A thin, widespread layer of cirrus clouds that can obscure the sun or moon, creating a halo effect.
  • A cirrus veil covered the sun, creating a beautiful ring of light.

Related Idioms

• "A mackerel sky": While not exclusive to cirrus clouds, this idiom describes a sky with cirrocumulus clouds (a related high-altitude type) that resembles fish scales, often preceding a weather front.
  • "Mackerel sky, mackerel sky, never long wet and never long dry," is an old saying about such skies.

Noun

1. a wispy white cloud (usually of fine ice crystals) at a high altitude (4 to 8 miles)