This cloud formation might have been initiated by a warm front, though none was shown on the weather charts, because the air got noticeably warmer and wetter after the passage of these clouds. The wave-like feautures of the cloud are certainly due to wind shear which was present at mid-levels and is shown in the weather sounding. This cloud had also produced light rain. It was preceded by Cirrus spissatus as per first thumbnail which formed due to an approaching large upper trough extending from the Atlantic towards Nothern Africa which was about to bring some days of bad weather over the Central Mediterranean and Malta.