Suchergebnisse

I. Review of Basic Concepts and Systems of Units -- 1.1. Systems -- 1.2. Properties -- 1.3. Composition and State of a System -- 1.4. Equilibrium -- 1.5. Temperature. Temperature Scales -- 1.6. Systems of Units -- 1.7. Work of Expansion -- 1.8. Modifications and Processes. Reversibility -- 1.9. State Variables and State Functions. Equation of State -- 1.10. Equation of State for Gases -- 1.11. Mixture of Ideal Gases -- 1.12. Atmospheric Air Composition -- Problems -- II. The First Principle of Thermodynamics -- 2.1. Internal Energy -- 2.2. Heat -- 2.3. The First Principle. Enthalpy -- 2.4. Expressions of Q. Heat Capacities -- 2.5. Calculation of Internal Energy and Enthalpy -- 2.6. Latent Heats of Pure Substances. Kirchhoff's Equation -- 2.7. Adiabatic Processes in Ideal Gases. Potential Temperature -- 2.8. Polytropic Processes -- Problems -- III. The Second Principle of Thermodynamics -- 3.1. The Entropy -- 3.2. Thermodynamic Scale of Absolute Temperature -- 3.3. Formulations of the Second Principle -- 3.4. Lord Kelvin's and Clausius' Statements of the Second Principle -- 3.5. Joint Mathematical Expressions of the First and Second Principles. Thermodynamic Potentials -- 3.6. Equilibrium Conditions and the Sense of Natural Processes -- 3.7. Calculation of Entropy -- 3.8. Thermodynamic Equations of State. Calculation of Internal Energy and Enthalpy -- 3.9. Thermodynamic Functions of Ideal Gases -- 3.10. Entropy of Mixing for Ideal Gases -- 3.11. Difference Between Heat Capacities at Constant Pressure and at Constant Volume -- Problems -- IV. Water-Air Systems -- 4.1. Heterogeneous Systems -- 4.2. Fundamental Equations for Open Systems -- 4.3. Equations for the Heterogeneous System. Internal Equilibrium -- 4.4. Summary of Basic Formulas for Heterogeneous Systems -- 4.5. Number of Independent Variables -- 4.6. Phase-Transition Equilibria for Water -- 4.7. Thermodynamic Surface for Water Substance -- 4.8. Clausius-Clapeyron Equation -- 4.9. Water Vapor and Moist Air -- 4.10. Humidity Variables -- 4.11. Heat Capacities of Moist Air -- 4.12. Moist Air Adiabats -- 4.13. Enthalpy, Internal Energy and Entropy of Moist Air and of a Cloud -- Problems -- V. Aerological Diagrams -- 5.1. Purpose of Aerological Diagrams and Selection of Coordinates -- 5.2. Clapeyron Diagram -- 5.3. Tephigram -- 5.4. Curves for Saturated Adiabatic Expansion. Relative Orientation of Fundamental Lines -- 5.5. Emagram or Neuhoff Diagram -- 5.6. Refsdal Diagram -- 5.7. Pseudoadiabatic or Stüve Diagram -- 5.8. Area Equivalence -- 5.9. Summary of Diagrams -- 5.10. Determination of Mixing Ratio from the Relative Humidity -- 5.11. Area Computation and Energy Integrals -- Problems -- VI. Thermodynamic Processes in the Atmosphere -- 6.1. Isobaric Cooling. Dew and Frost Points -- 6.2. Condensation in the Atmosphere by Isobaric Cooling -- 6.3. Adiabatic Isobaric (Isenthalpic) Processes. Equivalent and Wet-Bulb Temperatures -- 6.4. Adiabatic Isobaric Mixing (Horizontal Mixing) Without Condensation -- 6.5. Adiabatic Isobaric Mixing with Condensation -- 6.6. Adiabatic Expansion in the Atmosphere -- 6.7. Saturation of Air by Adiabatic Ascent -- 6.8. Reversible Saturated Adiabatic Process -- 6.9. Pseudoadiabatic Process -- 6.10. Effect of Freezing in a Cloud -- 6.11. Vertical Mixing -- 6.12. Pseudo- or Adiabatic Equivalent and Wet-Bulb Temperatures -- 6.13. Summary of Temperature and Humidity Parameters. Conservative Properties -- Problems -- VII. Atmospheric Statics -- 7.1. The Geopotential Field -- 7.2. The Hydrostatic Equation -- 7.3. Equipotential and Isobaric Surfaces. Dynamic and Geopotential Height -- 7.4. Thermal Gradients -- 7.5. Constant-Lapse-Rate Atmospheres -- 7.6. Atmosphere of Homogeneous Density -- 7.7. Dry-Adiabatic Atmosphere -- 7.8. Isothermal Atmosphere -- 7.9. Standard Atmosphere -- 7.10. Altimeter -- 7.11. Integration of the Hydrostatic Equation -- Problems -- VIII. Vertical Stability -- 8.1. The Parcel Method -- 8.2. Stability Criteria -- 8.3. Lapse Rates for Dry, Moist and Saturated Adiabatic Ascents -- 8.4. The Lapse Rates of the Parcel and of the Environment -- 8.5. Stability Criteria for Adiabatic Processes -- 8.6. Conditional Instability -- 8.7. Oscillations in a Stable Layer -- 8.8. The Layer Method for Analyzing Stability -- 8.9. Entrainment -- 8.10. Potential or Convective Instability -- 8.11. Processes Producing Stability Changes for Dry Air -- 8.12. Stability Parameters of Saturated and Unsaturated Air, and Their Time Changes -- 8.13. Radiative Processes and Their Thermodynamic Consequences -- 8.14. Maximum Rate of Precipitation -- 8.15. Internal and Potential Energy of the Atmosphere -- 8.16. Internal and Potential Energy of a Layer with Constant Lapse Rate -- 8.17. Margules' Calculations on Overturning Air Masses -- 8.18. Transformations of a Layer with Constant Lapse Rate -- 8.19. The Available Potential Energy -- Problems -- Appendix I -- Answers to Problems.

AbstractFoundations of thermodynamics are reviewed in terms of the elementary processes driving spontaneous evolution in physical systems. These processes lead to ergodic and mixing behavior as well as to conservation of macroscopic quantities such as total energy; finally a tendency towards order through instabilities results when the environment is cold enough. Instabilities are in turn considered as processes driving a spontaneous evolution in complex systems in their natural environment; again ergodic and mixing behavior is exhibited as well as new conserved quantities. As a result, a second thermodynamics is built which relates complexity to the corpuscular nature of matter. Thus, general properties of complex systems are pointed out, such as spontaneous and irreversible tendency towards complexity, development by stages and information flow between systems of different complexity.

How to predict the evolution of ecosystems is one of the numerous questions asked of ecologists by managers and politicians. To answer this we will need to give a scientific definition to concepts like sustainability, integrity, resilience and ecosystem health. This is not an easy task, as modern ecosystem theory exemplifies. Ecosystems show a high degree of complexity, based upon a high number of compartments, interactions and regulations. The last two decades have offered proposals for interpretation of ecosystems within a framework of thermodynamics. The entrance point of such an understanding of ecosystems was delivered more than 50 years ago through Schrodinger's and Prigogine's interpretations of living systems as "negentropy feeders" and "dissipative structures", respectively. Combining these views from the far from equilibrium thermodynamics to traditional classical thermodynamics, and ecology is obviously not going to happen without problems. There seems little reason to doubt that far from equilibrium systems, such as organisms or ecosystems, also have to obey fundamental physical principles such as mass conservation, first and second law of thermodynamics. Both have been applied in ecology since the 1950s and lately the concepts of exergy and entropy have been introduced. Exergy has recently been proposed, from several directions, as a useful indicator of the state, structure and function of the ecosystem. The proposals take two main directions, one concerned with the exergy stored in the ecosystem, the other with the exergy degraded and entropy formation. The implementation of exergy in ecology has often been explained as a translation of the Darwinian principle of "survival of the fittest" into thermodynamics. The fittest ecosystem, being the one able to use and store fluxes of energy and materials in the most efficient manner. The major problem in the transfer to ecology is that thermodynamic properties can only be calculated and not measured. Most of the supportive evidence comes from aquatic ecosystems. Results show that natural and culturally induced changes in the ecosystems, are accompanied by a variations in exergy. In brief, ecological succession is followed by an increase of exergy. This paper aims to describe the state-of-the-art in implementation of thermodynamics into ecology. This includes a brief outline of the history and the derivation of the thermodynamic functions used today. Examples of applications and results achieved up to now are given, and the importance to management laid out. Some suggestions for essential future research agendas of issues that needs resolution are given.

How to predict the evolution of ecosystems is one of the numerous questions asked of ecologists by managers and politicians. To answer this we will need to give a scientific definition to concepts like sustainability, integrity, resilience and ecosystem health. This is not an easy task, as modern ecosystem theory exemplifies. Ecosystems show a high degree of complexity, based upon a high number of compartments, interactions and regulations. The last two decades have offered proposals for interpretation of ecosystems within a framework of thermodynamics. The entrance point of such an understanding of ecosystems was delivered more than 50 years ago through Schrödinger's and Prigogine's interpretations of living systems as "negentropy feeders" and "dissipative structures", respectively. Combining these views from the far from equilibrium thermodynamics to traditional classical thermodynamics, and ecology is obviously not going to happen without problems. There seems little reason to doubt that far from equilibrium systems, such as organisms or ecosystems, also have to obey fundamental physical principles such as mass conservation, first and second law of thermodynamics. Both have been applied in ecology since the 1950s and lately the concepts of exergy and entropy have been introduced. Exergy has recently been proposed, from several directions, as a useful indicator of the state, structure and function of the ecosystem. The proposals take two main directions, one concerned with the exergy stored in the ecosystem, the other with the exergy degraded and entropy formation. The implementation of exergy in ecology has often been explained as a translation of the Darwinian principle of "survival of the fittest" into thermodynamics. The fittest ecosystem, being the one able to use and store fluxes of energy and materials in the most efficient manner. The major problem in the transfer to ecology is that thermodynamic properties can only be calculated and not measured. Most of the supportive evidence comes from aquatic ...