Enthalpy

Enthalpy is the thermodynamic state function H = U + pV, internal energy plus the pressure-volume product, so that at constant pressure a change in enthalpy equals the heat added. In seawater thermodynamics under TEOS-10 specific enthalpy is derived from the Gibbs function and underpins heat-content and air-sea heat-flux calculations. Potential enthalpy, the enthalpy a parcel would have if moved adiabatically to the surface, is the conservative heat variable, and Conservative Temperature is defined as potential enthalpy divided by the fixed heat capacity 3991.867 J per kg per K. This makes Conservative Temperature, not potential temperature, the property that conserves heat in mixing.