Determination of Potential Instability
In the ear1y 1930's, Rossby introduced a criterion for the instability or stability of a layer resulting when it is lifted as a whole, as at a front or mountain. This criterion came to be known as "potential instability," also known as "convective instability." To determine potential instability, one compares the lapse rate of the wet-bulb temperature to the moist adiabatic lapse rate: