Formation of large altocumulus undulatus clouds at Castille in Malta due to lots of wind shear as indicated by the weather sounding on the second thumbnail. Rapidly increasing wind with height at mid-levels causes the cloud to rotate in itself becoming arranged in rolls as pictured in this photo. The wind shear itself was due to strong jet stream because of the tightening of pressure at 500mb as an anomalous ridge covered Scandinavia. The 500mb chart is shown in the fourth thumbnail. The first thumbnail is a wide photo of the altocumulus cloud cover taken at the same time the photographed cloud was observed. The third thumbnail shows the mid-level clouds around the Maltese Islands that formed due to a shortwave as reported in estofex storm forecast experiment.