What clouds are referred to as the mackerel sky?

• A. Cirrocumulus
• B. Cumulus
• C. Stratus
• D. Altocumulus

Answer: (A)

The mackerel sky describes a sky pattern of tiny, fish-scale cloudlets arranged in tight rows. This look is produced by cirrocumulus clouds, which are high-altitude clouds made of ice crystals. They form up in the upper troposphere, roughly from 20,000 to 40,000 feet, in small patches or ripples that line up in rows, giving that delicate, scale-like appearance.

Because of their high position and fine texture, cirrocumulus create the distinctive mackerel pattern, unlike other clouds. Cumulus clouds are puffy and bottom-heavy, stratus form flat, gray cloud decks that cover the sky, and altocumulus are mid-level, larger patches or rolls rather than the fine, sparkly scales you see up high. The mackerel sky is a telltale sign of upper-level weather changes, often indicating an approaching front within hours as disturbances move through the higher atmosphere. This combination of a small-scale, high-altitude, fish-scale pattern is what set cirrocumulus apart as the clouds referred to by that nickname.