A beautiful line of altocumulus clouds at sunset with protuding cloud bubbles to the left classifying it ac castellanus. In this photo, one can notice both crepuscular rays as if there was a light source inside the cloud and on the left anti-crepuscular rays could also be noticed, these were signifying the shadows of the cloud. In this photo, other species and varieties of altocumulus could also be noticed being perlucidus and floccus in the foreground. The first thumbnail photo taken in exactly the same place but looking towards the east shows dense clouds of altocumulus castellanus which were associated with a cold front that was about to pass over the area as indicated by the third thumbnail. The second thumbnail shows weather conditions more typical of Spring with a warm-level airmass creating convective inhibition hence resulting in the photographed high-based clouds at 4.3km altitude. The fourth thumbnail shows the surface wind field at around 1600 CET corresponding with the third thumbnail pressure chart and confirming the presence of a cold front which was about to veer the wind towards the west. These clouds produced a quick thunderstorm with some blood rain.