We had beautiful long wispy mare's tails over Central Illinois last night and I didn't have my camera with me, so just imagine Glacierman's stunning photo without the sea or the mountains . . .
Nautical lore tells us:
Mare's tails and mackerel scales
Make tall ships carry small sails
According to About.com:
mare’s tails are wispy cirrus clouds while . . . mackerel scales are small clumpy altocumulus clouds resembling fish scales in the sky. In the days of large sailing ships, this meant a storm would be approaching soon and the sails should be lowered to protect from the accompanying high winds.
We also had some mackerel scales, which looked like the ones in this photo from the University Corporation for Atmospheric Research: