Typical Appearance In Vertical Cross Sections
- Isentropes:
Often there is a conditionally unstable stratification in the lower and middle troposphere, with isentropic values decreasing with height. Otherwise isentropes show a shape of a ridge with the isolines far from each other in the area of the Upper Level Low. - Relative Vorticity:
Due to the cyclonic circulation within the Upper Level Low there is a maximum of relative vorticity. - Temperature Advection:
The air within an Upper Level Low is colder than in the surroundings. Therefore, there is distinct cold advection ahead of the Upper Level Low, and warm advection behind it. - Potential Vorticity:
There is a maximum of potential vorticity above the centre of the Upper Level Low.
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15 September 2005/12.00 UTC - Meteosat 8 IR 10.8 image; position of vertical cross section indicated
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Relative vorticity
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15 September 2005/12.00 UTC - Vertical cross section; black: isentropes (Thetae), blue: relative vorticity
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Temperature advection
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15 September 2005/12.00 UTC - Vertical cross section; black: isentropes (Thetae), red thin: temperature advection - CA, red thick:
temperature advection - WA
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Potential vorticity
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15 September 2005/12.00 UTC - Vertical cross section; black: isentropes (Thetae), dark green: potential vorticity
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