A mobile (poor quality) photo of the very beautiful undulations within the mid-level cloud layer. All clouds with `undulatus` in their name have wave-like characteristics, unda is the Latin word for a wave. They can be seen as either in the form of a continuous cloud layer with an undulating surface or as separate lines of cloud with parallel gaps in between. Their formations are shaped by the way that wind speed varies within the same cloud layer. When blowing at different speeds above and below the cloud layer, the wind is able to bunch varies cloud types into ridges, which curve, join and divide, like the lines on your finger. The weather sounding depicts lots of wind shear within the cloud layer together with a cold front at that level initiating the cloud formation. The first thumbnail depicts the same cloud photo obtained from Internet sources.