This photo shows a distant, low tube-shaped horizontal cloud which was rotating on its horizontal axis as proved by photo comparison of the same cloud several seconds earlier, refer to first thumbnail. Technically, the cloud genus is Stratocumulus. Due to its form and detachment from any clouds, the species is volutus making it a very rare cloud formation. The cloud had developed out of distant sea fog patches or stratus nebulosus which began to move inland as the wind was changing direction from NW to E as evident by the wind map on the sixth thumbnail. The change in wind direction also meant a change in the type of airmass dividing the inland hot and dry air from the cool, moist maritime layer which was advancing from the east. Given all the changes taking place in the atmosphere, this caused the sea fog to elevate and begin rotating in itself as the maritime air pushed downwards whilst the hot and dry inland airmass was being displaced upwards. Both the weather sounding and the 500mb chart on the fourth and fifth thumbnails respectively showed that all this was taking place inside an otherwise a very stable environment. As the stratus bank was lifting upon approaching land, its ascent was capped by a subsidence inversion at 758 metres above sea-level inhibiting its further growth and due to strong wind shear, the newly formed stratocumulus cloud began to roll in itself producing this amazing species. The airport reading on the eighth thumbnail proves that the cloud level was just about 550 metres and the immediate increase in humidity as the wind changed. The second thumbnail shows the previously almost invisible sea fog transforming into a roll cloud. The third thumbnail is a photo of altocumulus stratiformis perlucidus and floccus clouds harbingering the arrival of bad weather as an unseasonable trough to the north of the Balearics was heading towards Sicily. This produced a rare isolated thunderstorm on the following night.