Formation of cumulus mediocris clouds and stratocumulus above it following the passage of frontal systems during the previous night as indicated by the surface pressure chart on the third thumbnail. This was brought about by an upper-level low that brought back a cold airmass towards the Maltese Islands leading to some thermal contrasts. The first thumbnail is another photo of many cumulus clouds aligned with the westerly wind, both photos being taken in Valletta, the European Capital City of Culture 2018. The second thumbnail is the weather sounding showing instability in the first 1.5km of the atmosphere and following that level only marginal instability favouring the formation of such clouds. There was also the potential of nimbostratus clouds had the atmosphere have been moist, closer to 100% higher up.