Typical Appearance In Vertical Cross Sections

In the area of the Baroclinic Boundary an intensification of humidity in the middle and upper levels should be noticed. In the mature stage the relative humidity has high values (about 60 to 80%) in front of and above the frontal zone. Low values of about 30% can be found behind and below the crowding zone of the Cold Air Development.

The field of temperature advection is characterized by CA within the area of Cold Air Development. If there is some WA in front of the Cold Air Development it can be found at middle and high levels. Within the upper most levels of the troposphere pronounced WA can be observed, which is related to the tropopause.

The whole area of Cold Air Development is characterized by PVA. As usual the values of the PVA generally are increasing with height (see Front Intensification By Jet Crossing and Comma ).

The fields of divergence and omega do not show any specific features: there is upward motion in connection with the cloud configuration mostly caused by increase of PVA with height. Circulation cells of divergence and omega, which are distinct features of fronts, cannot be found in the Cold Air Development.

The pixels of the IR, WV and VIS images show high values. In the cross section line across the Baroclinic Boundary they are somewhat lower in the initial stage and characterized by a lot of local peaks indicating the cellular structure of the cloud spiral (see Cloud structure in satellite image and Meteorological physical background ).

06 March 2009/00.00 UTC - Meteosat 9 Airmass RGB image; position of vertical cross section indicated
06 March 2009/00.00 UTC - Vertical cross section; black: isentropes (ThetaE)
06 March 2009/12.00 UTC - Meteosat 9 HiResVis image; position of vertical cross section indicated
06 March 2009/12.00 UTC - Vertical cross section; black: isentropes (ThetaE)
06 March 2009/12.00 UTC - Vertical cross section; black: isentropes (ThetaE), red thick: WA, red thin: CA
06 March 2009/12.00 UTC - Vertical cross section; black: isentropes (ThetaE), green thick: PVA, green thin: NVA