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mackerel sky[′mak·rəl ′skī]
A sky with considerable cirrocumulus or small-element altocumulus clouds, resembling the scales on a mackerel.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
A condition in which there are rows of altocumulus or cirrocumulus clouds in the sky, which look like scales of a mackerel fish.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved