The cloud is classified as stratocumulus stratiformis opacus undulatus nimbostratogenitus becuase it was formed by the action of the wind rolling over nimbostratus clouds pretty much like how the wind acts over open water. The first thumbail shows the initial undulation formation within the previously feautureless cloud cover. As per second thumbnail showing the weather sounding, one can notice lots of wind shear hence the perfect scenario in which undulations would form within the already existing cloud cover (nimbostratus) due to difference in wind speed and direction within the same cloud cover, in this case large undulations similar to how rolling waves are seen from underwater. Light rain continued falling from the photographed cloud. The surface pressure chart on the third thumbnail shows a warm front from a low pressure system that formed due to the entrance of a cold airmass from the south over warm Libyan waters and which intensified due to a strong overhead jet stream acting pretty much like a fan extractor in an open room. The fourth and fifth thumbnails show the day’s widespread cloud cover that were actually rain clouds.