27 July 2006: 12UTC

Divergence

This cross section shows clearly high potential instability over Germany (between 6° and 12°E). The vertical orientation of the maximum values of the equivalent potential temperature shows the position of the convergence near the surface and a divergence in middle altitudes (8 to 10°E). The satellite image shows here frontal cloud bands. From 11° to 12°E we see a divergence near the surface and a convergence in higher levels equivalent to a stabilisation tendency at this time and in this region. East of 12°E the image reveals near the surface convergence and divergence in upper levels. The convergence between 10 and 12°E corresponds well with surface measurements.

Vertical Motion

This cross section shows clearly high potential instability over Germany (between 6° and 12°E). The vertical orientation of the maximum values of the equivalent potential temperature shows the position of upward motion in lower levels (900 to 700 hPa and 8° to 10°E). The satellite image shows here frontal cloud bands. From 11° to 12°E we see an area with downward motion that is equivalent to a stabilisation tendency at this time and in this region. East of 12°E the image reveals again upward motion.

Relative Humidity

This cross section shows clearly high potential instability over Germany (between 6° and 12°E). The vertical orientation of the maximum values of the equivalent potential temperature shows the position of the convergence near the surface and a divergence in middle altitudes. Here we find higher relative humidity that fits also well with the divergence and upward motion in this area (surface to 700 hPa and 8 to 10°E). The satellite image shows here frontal cloud bands that fits also well with the corresponding relative humidity field. East of 10°E we see only low relative humidity values although the satellite image exhibits some convective cells. The reason for this might be that this numerical model is not able to simulate convective processes accurately. The humidty fields reflect probably only the synoptic scale forcings

Temperature Advection

This cross section shows clearly high potential instability over Germany (between 6° and 12°E). The vertical orientation of the maximum values of the equivalent potential temperature shows the position of the convergence near the surface and a divergence in middle altitudes (8 to 10°E).

However, the model values of temperature advection exhibit only small values in the area between 8° and 12°E.

Vorticity Advection

This cross section shows clearly high potential instability over Germany (between 6° and 12°E). The vertical orientation of the maximum values of the equivalent potential temperature shows the position of the convergence near the surface and a divergence in middle altitudes (8 to 10°E). The satellite image shows here frontal cloud bands.

Again, the model values of vorticity advection are very low in the area between 8° and 12°E.