Formation of altocumulus due to extensive humidity in the middle levels of the atmosphere. Looks very similar to stratocumulus but classified as such after looking at the weather sounding which showed little clouds at low levels. An area of instability at 500mb was in the vicinity of Malta. The undulations in the background were formed due to wind speed shear (ie: wind speed increased at the level of the cloud). The appearance of the cloud being large may have been due to the extensive cloud coverage at the time.