Formation of cirrus spissatus radiatus evident by the relative thickness of the high clouds and their parallelism when looking at the background. The clouds formed at altitudes of between 7km and 11km where a strong jet stream and wind shear was clearly evident in the weather sounding of the second thumbnail and the third thumbnail showing the position of the jet stream. The first thumbnail is a photo taken about an hour earlier showing that the top of the high clouds were very fibrous or striated. Such cloud structure confirms a strong overhead jet stream and normally indicates that the wind is about to get stronger at the surface which in fact it did. From the fourth and fifth thumbnails showing the surface pressure chart and the visible satellite image, it seems that the high clouds were the result of a developing cold front as an upper-level trough was about to move towards Italy.