Altocumulus Mackerel Sky
A mackerel sky or buttermilk sky is an indicator of moisture (the cloud) and instability (the cirrus-cumulus form) at intermediate levels (2400–6100 m, 8000-20,000 ft). If the lower atmosphere is stable and no moist air moves in, the weather will most likely remain dry. However, moisture at lower levels combined with surface temperature instability can lead to rainshowers or thunderstorms should the rising moist air reach this layer. In the winter it is often said to precede snowstorms and flurries.
Mackerel skies are spoken of in the popular bywords, "Mackerel in the sky, three days dry," "Mackerel sky, mackerel sky. Never long wet and never long dry," and the nautical weather rhyme, "Mare's tails and mackerel scales / Make tall ships carry low sails." The phrase 'mackerel sky' came from the fact that it looks similar to the markings of an adult king mackerel.
Read more about Altocumulus Mackerel Sky: Gallery
Famous quotes containing the word mackerel:
“A village seems thus, where its able-bodied men are all plowing the ocean together, as a common field. In North Truro the women and girls may sit at their doors, and see where their husbands and brothers are harvesting their mackerel fifteen or twenty miles off, on the sea, with hundreds of white harvest wagons, just as in the country the farmers’ wives sometimes see their husbands working in a distant hillside field. But the sound of no dinner-horn can reach the fisher’s ear.”
—Henry David Thoreau (1817–1862)