It extends from the North Sea via The Netherlands, Belgium and central France to the Gulf of Biscay and northern Spain. This line is associated with a weak pressure discontinuity along most parts of its course. Only in the middle part, i.e. in northern France, the line is probably embedded in a stronger low pressure trough. Although this trough was not analysed in the Berliner Wetterkarte its existence is altogether adequate to the sparse observations in that area. The assumption of a pressure trough is corroborated by a marked wind shift from southwest to northwest across the respective section of Line 3.
Occasional rain is observed.
The cross section of the wind speed cuts the jet axis above the station Uccle near Paris. In the lower atmosphere the maximum potential temperatures appear between Stuttgart and Nancy, i.e. east of Line 2. Between Stuttgart and Nancy, i.e. near Line 2, the cross section shows a weak decrease of potential temperature. A rather strong drop of potential temperature is associated with Line 3 between Nancy and Uccle near Paris. This area also exhibits the highest potential instability.