Relatively dense cirrus formation originating from clouds that formed over southern Tunisia due to an upper-level trough over the area. This cloud could have been former cumulonimbus that formed at the edge of the Sahara Desert but unfortunately it is very difficult to clarify due to lack of data. The first thumbnail is cirrus vertebratus that was observed at the same time whilst the second thumbnail is the weather sounding indicating that the cloud height was the same as the jet stream level at an altitude of above 12km. Upon looking at the satellite image and the jet stream wind in the third and fourth thumbnails respectively, it was 100% ascertained that the upper-level trough over the south of Tunisia caused the cloud formation over the Maltese Islands that arrived via the wind circulation of the jet stream.