A simple method to estimate entropy of atmospheric gases from their action

A convenient model for estimating the total entropy ({\Sigma}Si) of atmospheric gases based on physical action is proposed. This realistic approach is fully consistent with statistical mechanics, but uses the properties of translational, rotational and vibrational action to partition the entropy. When all sources of action are computed as appropriate non-linear functions, the total input of thermal energy ({\Sigma}SiT) required to sustain a chemical system at specific temperatures (T) and pressures (p) can be estimated, yielding results in close agreement with published experimental third law values. Thermodynamic properties of gases including enthalpy, Gibbs energy and Helmholtz energy can be easily calculated from simple molecular and physical properties. We propose that these values for entropy are employed both chemically for reactions and physically for computing atmospheric profiles, the latter based on steady state heat flow equilibrating thermodynamics with gravity. We also predict that this application of action thermodynamics may soon provide superior understanding of reaction rate theory, morphogenesis and emergent or self-organising properties of many natural or evolving systems.