Cc stratiformis

Cirrostratus stratiformis clouds that formed ahead of a descending weak upper-level trough moving southeastwards towards the Maltese Islands as per fourth thumbnail and which corresponds to the satellite image of the third thumbnail taken early morning of this day. It is evident that the cloud was widespread covering most of Sicily Strait and Tunisia. Analyzing the weather sounding on the second thumbnail, it is clear that the photographed clouds formed at altitudes of between 6.4km and 11km but definitely not covering the whole altitude as the cloud was very thin being in the form of expanded horizontal fields covering the whole sky and rather grainy. Very small undulations or ripples in the cloud cover could be observed due to speed shear (wind) at altitudes between 6.7km and 7.6km from 24 knots to 34 knots remaining always from a WSW direction. The cloud is composed of very small elements with no shading differentiating it from the lower altocumulus. The first thumbnail shows another photo taken 30 minutes earlier with the cirrocumulus cloud cover having various undulations maybe indicating the lack of strong upper-level winds typical of the August jet stream. In this case, the high-level clouds were harbinger of bad weather that was yet to come as isolated thunderstorms effected parts of the Maltese Islands on the following day as described here.

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