A decaying cumulus cloud at sunset because a low pressure system over Sardinia had decayed as can be seen in the second and third thumbnails showing the SLP 24 hours apart. This led to diminishing instability hence the bottom edges of the cloud could be clearly seen `tumbling` down and dissipate. The first thumbnail shows a rainbow due to remnant rain shower from decayed cumulus clouds. Diminishing surface heating from the sun could have also led to lack of buoyancy in the rising air parcel. At dawn on the same day, localized thunderstorms with heavy rain had developed over mainland Malta.