I shot with a Canon 10D and a B+W circ polarizer, facing about 160 degrees away from the sun. After I converted the image from RAW to JPG, a pattern of striating lines showed up in the sky area of the image.
I tend to think it might be caused by the polarizer, because the angle of the lines across the image seems change much like the way the polarizing effect changes relative to the sun as you rotate the filter element (ie vertical when facing away from the sun, horizontal when the sun is to the side of the frame).
