What does cirrocumulus mean?
Cirrocumulus is one of the ten principal cloud genera recognised by the World Meteorological Organization, denoting high, thin clouds formed entirely of ice crystals at altitudes above roughly 6,000 metres (about 20,000 feet). Unlike the wispy streaks of cirrus or the smooth veil of cirrostratus, cirrocumulus appears as delicate sheets or patches of small white ripples and granules — a pattern popularly called a 'mackerel sky' because it resembles the scaly skin of a fish. The word comes from Latin, combining cirrus ('a curl or wisp') with cumulus ('a heap or pile'). Although primarily a term of meteorology, aviation, and weather observation, it also lends itself to descriptive writing, evoking fine textures and shifting skies. Folk tradition has long regarded an extensive cirrocumulus layer as a possible harbinger of unsettled or stormy weather, since such clouds can signal an approaching frontal system. For anyone interested in reading the sky, recognising cirrocumulus is a useful step toward understanding how high-level cloud patterns relate to coming changes in the weather.
nounA type of high-altitude cloud, occurring above roughly 6,000 metres (20,000 feet), composed entirely of ice crystals and forming thin, white, patchy sheets of small ripples or granules that often create a 'mackerel sky'.
- A genus of high cloud (abbreviated Cc) consisting of thin white patches or layers of very small ripples or granules composed of ice crystals, typically found above about 6,000 m; when widespread it produces the pattern known as a mackerel sky.
"A veil of cirrocumulus rippled across the evening sky, hinting at the change in weather to come."
"By mid-morning the blue had given way to streaks of cirrocumulus, their tiny ripples catching the light like scattered fish scales."
"The forecaster noted a thickening band of cirrocumulus moving in from the west, an early sign of an approaching front."
In meteorological practice cirrocumulus is normally used as an uncountable noun referring to the cloud type generally. A Latinate plural, 'cirrocumuli', follows classical declension but is seldom encountered outside technical literature.
"Layers of cirrocumulus spread across the western horizon ahead of the cold front."
When the sky fills with tiny rippled scales like a fish's skin, sailors have long called it a 'mackerel sky' — and folk wisdom reads it as a warning that stormy weather may follow.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cirrocumulus
The word cirrocumulus was coined in the early 19th century as part of the modern cloud classification system developed by Luke Howard, who introduced his Latin nomenclature for clouds in 1803. It combines two Latin roots: cirrus, meaning 'a curl, fringe, or tuft of hair', and cumulus, meaning 'heap' or 'pile', reflecting the cloud's high, curly yet heaped appearance. Both roots remain productive in English: cirrus underlies related terms such as cirrose and cirrate, while the cumulus root connects to words like accumulation through the Latin verb cumulare, 'to pile up'.
Related word forms
How cirrocumulus is actually used
A technical meteorological term used mainly in weather forecasting, aviation, and scientific writing rather than everyday conversation. In formal classification it is one of the ten principal cloud genera defined by the World Meteorological Organization. It is almost always treated as an uncountable or mass noun in practical use; the Latinate plural 'cirrocumuli' exists but is rare outside specialist literature.
Easily confused with cirrocumulus
Cirrus consists of detached, wispy filaments or hooks, whereas cirrocumulus forms a rippled or granular sheet of small white patches.
Cirrostratus appears as a smooth, featureless whitish veil that often halos the sun or moon, while cirrocumulus shows distinct ripples or grains.
Altocumulus looks similar but sits at middle altitudes with larger, denser elements; cirrocumulus is higher, thinner, and made of ice crystals.