This cloud formation being altocumulus altostratomutatus needs to be explained along with the first thumbnail photo which was taken about 45 minutes earlier and which clearly showed altostratus translucidus clouds at a higher layer. As proved by the SLP and the Vis Sat Images on the third and fourth thumbnails respectively, the photo shows altocumulus clouds, that were still transitioning from altostratus, on the clearing edge of a frontal cloud band that was part of a mature mid-latitude cyclone that occured in the Western Mediterranean rather earlier than usual. The surface cold front had passed over our Islands earlier in the morning (before sunrise) producing only some isolated rain showers. Notice that in both photos, the cloud line was very clear cut as if a knife was used. Even the developing cumulus congestus cloud in the first thumbnail photo was inside the line of clouds before the blue sky line. That cloud was reported to have produced a small funnel. The second thumbnail shows the weather sounding just after the cold front had passed with mid-level clouds indicated at altitudes between 3.3km and 6km and cumulus starting at a base of 975 metres.