The cloud formation in photo and continued in the first thumbnail was very difficult to classify given it was widespread and had a very shallow anvil. Searching the WMO cloud atlas, the photographed cloud was classified as stratocumulus cumulogenitus because of common features with the screen shot cloud in the second thumbnail and the presence of a polar maritime airmass. The cloud had a very shallow anvil that seemed to have developed, at least partially, from the spreading out of a cumuliform cloud. Only light precipitation was falling from underneath the cloud base which was not particularly thick seemingly ruling out a cumulonimbus origin with the whole cloud structure looks like it was being flattened out by strong WNW winds.
In fact, the weather sounding on the third thumbnail showed a conditionally unstable polar maritime airmass with strong winds coming from western quadrants. This polar maritime airmass which had entered the Western Mediterranean through the Rhone Valley led to the development of a cold-core 981hPa Mediterranean cyclone with the photographed cloud being part of the cloud bands witnessed in the visible satellite image and corresponding with the surface pressure of the fifth thumbnail. An upper-level trough over the Mediterranean had permitted the surface low to keep getting deeper as its centre crossed the Maltese Islands during the same night. However, its large spread meant that the storm energy was distributed over a large area.