Absolute Vorticity
As discussed in the previous section, the localised spin of an air mass is described by a quantity termed "Relative Vorticity". However, as the earth rotates, it is also having an impact on the motion of air masses.
First Thoughts
Relative vorticity at 250 hPa from the ECMWF forecasting system for 6 December 2021 at 12.00 UTC over southern Africa.