Temperature lapse rates at restricted thermodynamic equilibrium in the Earth system
2015 (English)In: Dynamics of atmospheres and oceans (Print), ISSN 0377-0265, Vol. 69, 26-36 p.Article in journal (Refereed) Published
Equilibrium temperature profiles obtained by maximizing the entropy of a column of fluid with a given height and-volume under the influence of gravity are discussed by using numerical experiments. Calculations are made both for the case of an ideal gas and for a liquid with constant isobaric heat capacity, constant compressibility and constant thermal expansion coefficient representing idealized conditions corresponding to atmosphere and ocean. Calculations confirm the classical equilibrium condition by Gibbs that an isothermal temperature profile gives a maximum in entropy constrained by a constant mass and a constant sum of internal and potential energy. However, it was also found that an isentropic profile gives a maximum in entropy constrained by a constant mass and a constant internal energy of the fluid column. On the basis of this result a hypothesis is suggested that the adiabatic lapse rate represents a restricted or transitory and metastable equilibrium state, which has a maximum in entropy with lower value than the maximum in the state with an isothermal lapse rate. This transitory equilibrium state is maintained by passive forces, preventing or slowing down the transition of the system to the final or ultimate equilibrium state.
Place, publisher, year, edition, pages
2015. Vol. 69, 26-36 p.
Adiabatic processes, Temperature gradients, Thermodynamic equilibrium, Energy, Entropy
IdentifiersURN: urn:nbn:se:kth:diva-166344DOI: 10.1016/j.dynatmoce.2014.10.001ISI: 000353009100003ScopusID: 2-s2.0-84913534812OAI: oai:DiVA.org:kth-166344DiVA: diva2:810667
QC 201505082015-05-082015-05-072015-05-08Bibliographically approved