noun
cirrocumulus cloud; mackerel sky
A sky filled with small, rippled clouds resembling the scales of a mackerel. Often used in weather-related or poetic descriptions.
秋の空に鯖雲が広がっている。
Mackerel clouds are spreading across the autumn sky.
鯖雲が出ると天気が下り坂になることが多い。
When mackerel clouds appear, the weather often turns for the worse.
Compound of 鯖 (さば, mackerel) and 雲 (くも, cloud), from the resemblance of the cloud pattern to mackerel scales.