Formation of cirrus fibratus clouds developed from the spreading out of man-made contrails hence `homomutatus`, also known as Cirrus homogenitus which could be seen in the background. Such clouds have made it a rather cloudy evening when naturally there would have been little clouds. The first thumbnail is a closer view of the same cloud. Note that due to some instability, tufts of cirrocumulus had formed within the described cloud, hence parts of it becoming cirrocumulus floccus homomutatus due to the ragged tufts. The second thumbnail is the weather sounding showing ample moisture at altitudes of between 10.5km and 13.7km but perhaps the air was too clear for high clouds to form naturally unless introducing man-made particles upon which condensation could initiate. The Maltese Islands were covered by a weak high pressure system at the time both at the surface and upper atmosphere.