Potential vorticity (PV) is a measure that combines spin (vorticity) and atmospheric stability into a single quantity.

Meteorologists often refer to ‘energy’ moving through the atmosphere, which typically means a pocket of high potential vorticity (PV) associated with an upper-level disturbance. This signals a dynamically active disturbance capable of enhancing lift and causing clouds and/or precipitation

It is commonly expressed in PV Units (PVU), where 1 PVU = 10⁻⁶ K·m²/(kg·s). PV is conserved in adiabatic flow, making it a powerful diagnostic tool. In operational forecasting, values around 1.5–2.0 PVU often mark the dynamic tropopause, helping identify stratospheric intrusions and upper-level disturbances. Strong PV anomalies aloft can enhance lift and are frequently associated with developing storms and areas of active weather. Most interestingly, the PVU units often correspond to the dark areas in water vapor images (Channel 9).