Formation of high-level clouds with falling snowfall subliming before reaching the ground. The only difference between cirrocumulus virga and altocumulus virga is that the former do not cast distinct shadows and of course appear smaller than the latter. The photographed cloud seemed to be high-level altocumulus verging towards cirrocumulus virga as some clouds did seem to have a shadow but the weather sounding on the second thumbnail appears to confirm that these were Cc virga hence the decision to label them as such. The third thumbnail shows that the Maltese Islands were on the margins of a longwave upper-level trough which also fired lots of thunderstorms on mainland Italy on the day as per satellite image of the fourth thumbnail. Of course high clouds being so high up in the atmosphere their precipitation almost always evaporate before even getting close to the ground.