Determining Stability » Stability Types Stability Types, Lapse Rates, and Virtual Temperature (Tv)
The skew-T, as with other thermodynamic diagrams, provides a useful tool to apply the parcel method and assess atmospheric stability. With it, you can compare the lapse rate of the virtual temperature (Tv) curve for a given layer with the lapse rate of the corresponding dry adiabat (in the unsaturated parcel case) or saturation adiabat (in the saturated case).
The skew-T, as with other thermodynamic diagrams, provides a useful tool to apply the parcel method and assess atmospheric stability. With it, you can compare the lapse rate of the virtual temperature (Tv) curve for a given layer with the lapse rate of the corresponding dry adiabat (in the unsaturated parcel case) or saturation adiabat (in the saturated case).
In present forecasting practice, the ambient temperature (T) curve is used for these comparisons instead of the more exact Tv curve to allow faster evaluation of stability or instability. It should be noted, however, in very warm, moist environments the substitution of T for Tv can be a source of significant error in evaluating stability.