Formation of thin stratocumulus clouds in an otherwise bright and very clear sky due to a polar continental airmass covering the Maltese Islands. Such airmass is usually very stable as cold air is heavy and the only source of instability was the much warmer sea surface as clearly shown in the weather sounding of the first thumbnail. Sea temperature was 18C whilst MAX temp did not rise above 12C on the day as a high pressure system over Central Europe directed a very cold and dry airmass towards the Maltese Islands. The third thumbnail shows the visible satellite image on the day with Sicily acting as a barrier to prevent more cloud formations.