Potential vorticity (PV) is a quantity which is proportional to the product of vorticity and stratification that, following an air parcel, can only be changed by adiabatic or frictional processes. It plays an important role in the generation of vorticity in cyclogenesis (the birth and development of a cyclone), especially along the polar front.

It is also useful in tracing intrusions of stratospheric air deep into the troposphere in the vicinity of jet streaks, a concentrated region within a jet stream where the wind speeds are the strongest.

Baroclinic instability requires the presence of a potential vorticity gradient along which waves amplify during cyclogenesis.