These photos were taken from route 30 near York, PA on Dec. 2 at
about 4:25 PM. I have never seen anything like it. Can anyone
identify and explain how the "waves" form??
This is my first attempt at attaching photos to a newsgroup posting.
Hope it works well. Any suggestions for improvement are appreciated.

These photos were taken from a moving car. No place safe to stop.
By the time we did stop, about 2 min. later, the waves had all but
disappeared. I have a photo of that too if anyone is interested.
Also can change the size and resolution if that would help.