Vertical Motion 500 hPa Time Sequence: 27 July 2006

This chapter shows the cloud configurations in WV satellite images in relation to the vertical motion expressed as Omega in 500 hPa. Red colours indicate negative values (upward motion), blue colours mark areas of positive Omega (downward motion).

The dark stripe in WV-image from northwestern Germany to Slovenia is a very instructive example for the conceptual models "Enhancement of convection by PV" and "Convective cloud features at the leading edge of frontal cloud bands". An example for the latter can be seen over the western part of Germany (West to Southwest of the dark stripe). Here we find also upward motion. (The high value of -93 related to the Black Forest should not be considered too seriously.)

East of the dark stripe we find upward motion and convective cells, too. However, they can be explained with the conceptual model "Enhancement of convection by PV". The corresponding image in the chapter IPV 310 K shows for 12 UTC relatively high values of IPV.

During the last 3 hours the convective cells are difficult to distinguish in the WV-image. This is better possible with IR-Enhanced and RBG composites.

In the areas of convection the model reveals weak upward motion over the western parts of Germany, in accordance of the ridge axis' position. However, the model parameter "Omega 500 hPa" is only applicable for synoptical structures and not for convective cells. Mountain ranges rather often cause difficulties in interpretating structures of vertical motion.

The sequence of upward, downward and upward motion over Germany is difficult to explain. There is no hint from the surface winds where we see convergences because they cannot be put into relation to Omega in 500 hPa. Again, we see the problem to interpretate small scale convection with Omega 500 values of a numerical model.