“Have you ever felt more fresh or wonderful
Than on a warm fall night
Under a Mackerel sky”
Anniversary Song by Cowboy Junkies
Mackerel sky is a popular term for a sky covered with extensive cirrocumulus or altocumulus clouds arranged in somewhat regular waves and showing blue sky in the gaps. The pattern resembles the scales on a mackerel, thus, the name. In Germany and France they are known as ‘sheep cloud’, as their pattern resembles a flock of sheep, also they are sometimes called buttermilk sky, regionally.