Very high and thin level clouds formed at altitudes above 7km. As per literature, these clouds cause halos as can be seen in the photo and are of course entirely composed of ice crystals which bend the sun rays to form a halo. Also, it was confirmed that bad weather was on the way for the Maltese (it did occur on Sunday) as the formed clouds were the harbinger of a polar maritime airmass that was entering the Central Mediterranean from the Rhone Valley as shown in the fourth thumbnail. The first thumbnail shows an almost clear-cut edge of these cirrostratus clouds which proofs that it was the result of approaching bad weather and which was also confirmed in the visible satellite image on the third thumbnail. The weather sounding on the second thumbnail shows almost 100% humidity at upper-level altitudes which is a must for such fragile ice crystals to form and not evaporate. Upper-level winds were light.