Potential Vorticity
For adiabatic motion ( i.e., is
a constant) the density is
= P(Cv/Cp). For motions
between layers of constant
![zeta](https://pds-atmospheres.nmsu.edu/images/zeta2.gif)
![partial](https://pds-atmospheres.nmsu.edu/images/partial.gif)
![Theta](https://pds-atmospheres.nmsu.edu/images/Theta.gif)
![partial](https://pds-atmospheres.nmsu.edu/images/partial.gif)
In the Shallow Water Model, where is a constant
( i.e., incompressible),
the conserved quantity is usually written as:
![ident](https://pds-atmospheres.nmsu.edu/images/ident.gif)
![zeta](https://pds-atmospheres.nmsu.edu/images/zeta2.gif)
example : flow over a mountain
<u> is eastward (westerly) then flow turns towards equator as it passes mountain, then oscillates around original latitude.
<u> is westward (easterly) then flow turns equatorward (note flow turning poleward `bucks' the flow causing it to turn equatorward. System is returned to original latitude after it passes mountain. No oscillations.