It is usually seen in thin cirrostratus, cirrocumulus, and altocumulus clouds.
From the ocregister.com
The other two types, cirrocumulus and cirrostratus, are also cirriform clouds.
From the en.wikipedia.org
The ice crystals in the bottoms of cirrocumulus clouds tend to be hexagonal cylinders.
From the en.wikipedia.org
The individual elements are large and darker than in cirrocumulus clouds.
From the ocregister.com
Some clouds at this level are cirrus, cirrocumulus, and cirrostratus.
From the ocregister.com
The cirrocumulus cloud then dissipates into a cirrus cloud.
From the en.wikipedia.org
In some cases, an entire genus like cirrocumulus is represented by one cloud symbol, regardless of species, varieties, or any other considerations.
From the en.wikipedia.org
High altocumulus may resemble cirrocumulus but is usually thicker and composed of water droplets so that the bases show at least some light-grey shading.
From the en.wikipedia.org
Mamma can form beneath various cloud types, including cirrus, cirrocumulus, altocumulus, altostratus and stratocumulus, where they often appear irregular in shape.
From the newscientist.com
More examples
A cloud at a high altitude consisting of a series of regularly arranged small clouds resembling ripples
Cirrocumulus clouds are high-altitude clouds that usually occur at an altitude of 5 km to 12 km. Like other cumulus clouds, cirrocumulus clouds signify convection. Unlike other cirrus clouds, cirrocumulus include a small amount of liquid water droplets, although these are in a supercooled state. ...
A principal high-level cloud type appearing as a thin, white patch of cloud without shadows, composed of very small droplets in the form of grains or ripples. ...
A cirriform cloud with vertical development, appearing as a thin sheet of small white puffs which give it a rippled effect. It often creates a "mackerel sky", since the ripples may look like fish scales. ...
Cirrus clouds with vertical development.
They are thin clouds, the individual elements which appear as small white flakes or patches of cotton, usually sowing brilliant and glittering quality suggestive of ice crystals. They form at altitudes between 16,500 to 45,000 feet above ground.
A cirriform cloud characterized by thin, white patches, each of which is composed of very small granules or ripples. These clouds are of high altitude (20,000-40,000 ft or 6000 -12,000 m).
Thin, ripply convective high clouds.
Clouds consist of patches of small, white cloud elements. They may form definite patterns at times, showing small but firm waves or ripples. They are sometimes referred to as "mackerel sky. ...