Chiefly Northeastern U.S. A sky covered with many small cirrocumulus or altocumulus clouds, resembling the markings found on a mackerel. Also referred to as regionally buttermilk sky.
a sky filled up with a normal structure of altocumulus clouds notably resembling skin of a mackerel.
a sky flecked with tiny white clouds; a cirro-cumulus. See Cloud.
A sky full of rows of cirrocumulus or small altocumulus clouds.
A sky where the clouds possess type called cirro-cumulus—that is, are damaged into fleecy masses three, four, or even more times as long as they're broad, and organized in synchronous groups. Also called mackerel-back sky.
a sky full of rows of cirrocumulus or tiny altocumulus clouds