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Mares’ tails over the Pacific Northwest

Mares' tails appear as streaks of wispy clouds in a blue sky, hook-shaped at one end, here over pointy mountains.
View at EarthSky Community Photos. | EarthSky’s own Kelly Kizer Whitt captured this photo of cirrus uncinus clouds – aka mares’ tails – at Crater Lake, Oregon, on July 19, 2021. Thank you, Kelly!

Here are two photos of beautiful, wispy cirrus uncinus clouds. The name comes from Latin and means curly hooks. But these clouds are more commonly called mares’ tails. They tend to occur high above Earth’s surface, where temperatures are very cold (~58 to ~40 degrees F or ~50 to ~40 degrees C). There’s an old weather saying:

Mares’ tails and mackerel scales make lofty ships carry low sails.

According to BBC Weather, that saying refers to the fact that, together, cirrus uncinus together with patchy altocumulus clouds often mean that rain is on its way. We also received a second mares’ tail photo from slightly north of Kelly’s location a day earlier:

Long streaks of wispy clouds, hook-shaped at one end.
View at EarthSky Community Photos. | Erik Warners in Nanaimo, B.C., Canada, caught these cirrus uncinus clouds – aka mares’ tails – on July 18, 2021. He wrote: “It resembled almost very fine woven delicate white fabric. Certainly a majestic sight. I had to be fast, as they moved quite fast.” Thank you, Erik!

Bottom line: Two photos of cirrus uncinus clouds, aka mares’ tails.

July 21, 2021

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