A very rare sort of cloud formation. The meteorological explanation for these clouds is very hard to understand, and I don't understand it anyway, so I'll skip it. But, they look like cirrus clouds that have been whipped up into whitecaps by the wind. The top of a cirrus cloud features the classic wave shape (as seen on the label of an Ocean Spray drink) repeated, near-perfect in each iteration, over and over. Consider yourself lucky should you catch one of these.