Waves appeared to ripple out across the sky at Seawall Campground, Maine, US when Stephen Sampson (Member 58,877) took his dog Daisy out for a walk.
 
When the high, textured patches of cloud we call Cirrocumulus show undulating patterns like this, we add the term undulatus to its classification. In Stephen’s example, you can see undulations aligned at differing orientations. This criss-cross effect of overlaying waveforms are like those you sometimes see on the ocean surface. Such waves upon waves of Cirrocumulus undulatus likely echoed the surface of the Atlantic below, just a short distance from Stephen and Daisy’s walk that day.