These vertical cross sections are based on ECMWF data only. It could be noted that some features can be recognised even with the coarse grid of this large area model. The typical parameters are equivalent potential temperature, divergence and upward motion. Since there is no marked difference between the three different areas, only the example of the Greek convergence line is presented below. The isentropes show an unstable air mass up to 700 hPa (or even higher) characterised by decreasing values of equivalent potential temperature with height. The difference between the surface and the minimum value can exceed 10 degrees. The convective line under consideration is accompanied by the pronounced peak, located in the centre of the image at about 22,5E/37,5N. The shift between VIS and IR signals represent the core and the Cirrus shield of the cell. The unstable air mass can be observed from the surface up to 550 hPa in this region.

• There is convergence in low layers and divergence above.

The example shows pronounced convergence up to 900 hPa, above there is divergence.

• Upward motion is situated in the convergence lines on top of the convergence zone.