This photo depicts a thin sheet of Altocumulus clouds slowly invading the sky as typical for the species stratiformis of the variety translucidus. Long rolls of merged elements in the background become a thicker layer upwind but this may be due to perspective hence attaching the undulatus variety describing the whole cloud as altocumulus stratiformus translucidus undulatus creating a patterned ceiling in the sky. The first thumbnail is another photo of a slightly different altocumulus cloud taken earlier in the morning which may have become floccus as the merged elements seemed to decouple in the foreground along with small clear gaps in the cloud cover making it of the variety perlucidus. The second thumbnail is a cumulus congestus cloud taken just after dawn. The weather sounding on the third thumbnail depicted a rather convective atmosphere hence the formation of cumulus clouds in all the photos and also lots of speed shear at mid-levels trigerring the rolling effect on the altocumulus. The photographed clouds were observed even on the visible satellite image of the fourth thumbnail whose trigger seemed to be the very tail edge of an upper-level trough.