Cirrus uncinus cloud

Cirrus uncinus
Cirrus uncinus cloud
Abbreviation	Ci unc
Genus	Cirrus ("curl")
Species	uncinus ("hook")
Altitude	above 7,000 m (23,000 ft)
Classification	Family A (High-level)
Appearance	curly, hooked
Precipitation	No, but may indicate precipitation approach.

Cirrus uncinus is a type of cirrus cloud. The name cirrus uncinus is Latin for "curly hooks". Commonly called "mare's tail", this cloud species is very thin and generally sparse in the sky.¹

The clouds occur at high altitudes, at a temperature of about −50 to −40 °C (−58 to −40 °F). They are generally seen when a warm or occluded front is approaching. They are very high in the troposphere and generally mean that precipitation, usually rain, is approaching.²

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  Cirrus uncinus clouds over Salinas Victoria, Nuevo León, Mexico
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  Cirrus uncinus clouds in the morning sky over Nandli, Himachal Pradesh, India