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Mikielewicz, Dariusz, Jan Wajs, and Elżbieta Żmuda. "Organic Rankine Cycle as Bottoming Cycle to a Combined Brayton and Clausius - Rankine Cycle." Key Engineering Materials 597 (December 2013): 87–98. http://dx.doi.org/10.4028/www.scientific.net/kem.597.87.
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A preliminary evaluation has been made of a possibility of bottoming of a conventional Brayton cycle cooperating with the CHP power plant with the organic Rankine cycle installation. Such solution contributes to the possibility of annual operation of that power plant, except of operation only in periods when there is a demand for the heat. Additional benefit would be the fact that an optimized backpressure steam cycle has the advantage of a smaller pressure ratio and therefore a less complex turbine design with smaller final diameter. In addition, a lower superheating temperature is required compared to a condensing steam cycle with the same evaporation pressure. Bottoming ORCs have previously been considered by Chacartegui et al. for combined cycle power plants [ Their main conclusion was that challenges are for the development of this technology in medium and large scale power generation are the development of reliable axial vapour turbines for organic fluids. Another study was made by Angelino et al. to improve the performance of steam power stations [. This paper presents an enhanced approach, as it will be considered here that the ORC installation could be extra-heated with the bleed steam, a concept presented by the authors in [. In such way the efficiency of the bottoming cycle can be increased and an amount of electricity generated increases. A thermodynamic analysis and a comparative study of the cycle efficiency for a simplified steam cycle cooperating with ORC cycle will be presented. The most commonly used organic fluids will be considered, namely R245fa, R134a, toluene, and 2 silicone oils (MM and MDM). Working fluid selection and its application area is being discussed based on fluid properties. The thermal efficiency is mainly determined by the temperature level of the heat source and the condenser conditions. The influence of several process parameters such as turbine inlet and condenser temperature, turbine isentropic efficiency, vapour quality and pressure, use of a regenerator (ORC) will be presented. Finally, some general and economic considerations related to the choice between a steam cycle and ORC are discussed.
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Sands, David. "The Carnot Cycle, Reversibility and Entropy." Entropy 23, no. 7 (June 25, 2021): 810. http://dx.doi.org/10.3390/e23070810.
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The Carnot cycle and the attendant notions of reversibility and entropy are examined. It is shown how the modern view of these concepts still corresponds to the ideas Clausius laid down in the nineteenth century. As such, they reflect the outmoded idea, current at the time, that heat is motion. It is shown how this view of heat led Clausius to develop the entropy of a body based on the work that could be performed in a reversible process rather than the work that is actually performed in an irreversible process. In consequence, Clausius built into entropy a conflict with energy conservation, which is concerned with actual changes in energy. In this paper, reversibility and irreversibility are investigated by means of a macroscopic formulation of internal mechanisms of damping based on rate equations for the distribution of energy within a gas. It is shown that work processes involving a step change in external pressure, however small, are intrinsically irreversible. However, under idealised conditions of zero damping the gas inside a piston expands and traces out a trajectory through the space of equilibrium states. Therefore, the entropy change due to heat flow from the reservoir matches the entropy change of the equilibrium states. This trajectory can be traced out in reverse as the piston reverses direction, but if the external conditions are adjusted appropriately, the gas can be made to trace out a Carnot cycle in P-V space. The cycle is dynamic as opposed to quasi-static as the piston has kinetic energy equal in difference to the work performed internally and externally.
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Wiśniewski, Sławomir, and Aleksandra Borsukiewicz-Gozdur. "The influence of vapor superheating on the level of heat regeneration in a subcritical ORC coupled with gas power plant." Archives of Thermodynamics 31, no. 3 (September 1, 2010): 185–99. http://dx.doi.org/10.2478/v10173-010-0022-9.
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The influence of vapor superheating on the level of heat regeneration in a subcritical ORC coupled with gas power plantThe authors presented problems related to utilization of exhaust gases of the gas turbine unit for production of electricity in an Organic Rankine Cycle (ORC) power plant. The study shows that the thermal coupling of ORC cycle with a gas turbine unit improves the efficiency of the system. The undertaken analysis concerned four the so called "dry" organic fluids: benzene, cyclohexane, decane and toluene. The paper also presents the way how to improve thermal efficiency of Clausius-Rankine cycle in ORC power plant. This method depends on applying heat regeneration in ORC cycle, which involves pre-heating the organic fluid via vapour leaving the ORC turbine. As calculations showed this solution allows to considerably raise the thermal efficiency of Clausius-Rankine cycle.
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Saslow, Wayne M. "A History of Thermodynamics: The Missing Manual." Entropy 22, no. 1 (January 7, 2020): 77. http://dx.doi.org/10.3390/e22010077.
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We present a history of thermodynamics. Part 1 discusses definitions, a pre-history of heat and temperature, and steam engine efficiency, which motivated thermodynamics. Part 2 considers in detail three heat conservation-based foundational papers by Carnot, Clapeyron, and Thomson. For a reversible Carnot cycle operating between thermal reservoirs with Celsius temperatures t and t + d t , heat Q from the hot reservoir, and net work W, Clapeyron derived W / Q = d t / C ( t ) , with C ( t ) material-independent. Thomson used μ = 1 / C ( t ) to define an absolute temperature but, unaware that an additional criterion was needed, he first proposed a logarithmic function of the ideal gas temperature T g . Part 3, following a discussion of conservation of energy, considers in detail a number of energy conservation-based papers by Clausius and Thomson. As noted by Gibbs, in 1850, Clausius established the first modern form of thermodynamics, followed by Thomson’s 1851 rephrasing of what he called the Second Law. In 1854, Clausius theoretically established for a simple Carnot cycle the condition Q 1 / T 1 + Q 2 / T 2 = 0 . He generalized it to ∑ i Q i / T g , i = 0 , and then ∮ d Q / T g = 0 . This both implied a new thermodynamic state function and, with appropriate integration factor 1 / T , the thermodynamic temperature. In 1865, Clausius named this new state function the entropy S.
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Nowak, W., A. Borsukiewicz-Gozdur, and A. A. Stachel. "Using the low-temperature Clausius–Rankine cycle to cool technical equipment." Applied Energy 85, no. 7 (July 2008): 582–88. http://dx.doi.org/10.1016/j.apenergy.2007.09.001.
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Stachel, Aleksander A., and Sławomir Wiśniewski. "Influence of the type of working fluid in the lower cycle and superheated steam parameters in the upper cycle on effectiveness of operation of binary power plant." Archives of Thermodynamics 36, no. 1 (March 1, 2015): 111–23. http://dx.doi.org/10.1515/aoter-2015-0008.
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Abstract In the paper presented have been the results of the analysis of effectiveness of operation of binary power plant consisting of combined two Clausius-Rankine cycles, namely the binary cycle with water as a working fluid in the upper cycle and organic substance as a working fluid in the lower cycle, as well as a single fluid component power plant operating also in line with the C-R cycle for superheated steam, with water as a working fluid. The influence of the parameters of superheated steam in the upper cycle has been assessed as well as the type of working fluid in the lower cycle. The results of calculations have been referred to the single-cycle classical steam power plant operating at the same parameters of superheated steam and the same mass flow rate of water circulating in both cycles. On the basis of accomplished analysis it has been shown that the binary power plant shows a greater power with respect to the reference power plant.
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Chmielniak, Tadeusz, and Henryk Łukowicz. "Condensing power plant cycle — assessing possibilities of improving its efficiency." Archives of Thermodynamics 31, no. 3 (September 1, 2010): 105–13. http://dx.doi.org/10.2478/v10173-010-0017-6.
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Condensing power plant cycle — assessing possibilities of improving its efficiency This paper presents a method for assessing the degree of approaching the paper output of the Clausius-Rankine cycle to the Carnot cycle. The computations to illustrate its use were performed for parameters characteristic of the current state of development of condensing power plants as well as in accordance with predicted trends for their further enhancing. Moreover there are presented computations of energy dissipation in the machines and devices working in such a cycle.
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Smith, Samuel, Paul W. Staten, and Jian Lu. "How Moist and Dry Intrusions Control the Local Hydrologic Cycle in Present and Future Climates." Journal of Climate 34, no. 11 (June 2021): 4343–59. http://dx.doi.org/10.1175/jcli-d-20-0780.1.
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AbstractModels disagree on how much the hydrologic cycle could intensify under climate change. These changes are expected to scale with the Clausius–Clapeyron relation but may locally diverge due in part to the uncertain response of the general circulation, causing the hydrologic cycle to inherit this uncertainty. To identify how the circulation contributes, we link circulation changes to changes in the higher moments of the hydrologic cycle using the novel dynamical framework of the local hydrologic cycle, the portion of the hydrologic cycle driven by moist or dry intrusions. We expand this dynamical framework, developing a closed budget that diagnoses thermodynamic, advective, and overturning contributions to future hydrologic cycle changes. In analyzing these changes for the Community Earth System Model Large Ensemble, we show that overturning is the main dynamic contributor to the tropical and subtropical annual response, consistent with a weakening of this circulation. In the extratropics, we show that advective contributions, likely from storm track changes, dominate the response. We achieve a cleaner separation between dynamic and thermodynamic contributions through a semiempirical scaling, which reveals the robustness of the Clausius–Clapeyron scaling for the local hydrologic cycle. This scaling also demonstrates the slowing of the local hydrologic cycle and how changing subtropical dynamics asymmetrically impact wave breaking and suppress meridional moisture transport. We conclude that dynamic changes in the subtropics are predominantly responsible for the annual, dynamic response in the extratropics and thus a significant contributor to uncertainty in future projections.
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Martinelli, Mario. "Entropy, Carnot Cycle, and Information Theory." Entropy 21, no. 1 (December 20, 2018): 3. http://dx.doi.org/10.3390/e21010003.
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The fundamental intuition that Carnot had in analyzing the operation of steam machines is that something remains constant during the reversible thermodynamic cycle. This invariant quantity was later named “entropy” by Clausius. Jaynes proposed a unitary view of thermodynamics and information theory based on statistical thermodynamics. The unitary vision allows us to analyze the Carnot cycle and to study what happens when the entropy between the beginning and end of the isothermal expansion of the cycle is considered. It is shown that, in connection with a non-zero Kullback–Leibler distance, minor free-energy is available from the cycle. Moreover, the analysis of the adiabatic part of the cycle shows that the internal conversion between energy and work is perturbed by the cost introduced by the code conversion. In summary, the information theoretical tools could help to better understand some details of the cycle and the origin of possible asymmetries.
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Boos, William R. "Thermodynamic Scaling of the Hydrological Cycle of the Last Glacial Maximum." Journal of Climate 25, no. 3 (February 1, 2012): 992–1006. http://dx.doi.org/10.1175/jcli-d-11-00010.1.
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Abstract In climate models subject to greenhouse gas–induced warming, vertically integrated water vapor increases at nearly the same rate as its saturation value. Previous studies showed that this increase dominates circulation changes in climate models, so that precipitation minus evaporation (P − E) decreases in the subtropics and increases in the tropics and high latitudes at a rate consistent with a Clausius–Clapeyron scaling. This study examines whether the same thermodynamic scaling describes differences in the hydrological cycle between modern times and the last glacial maximum (LGM), as simulated by a suite of coupled ocean–atmosphere models. In these models, changes in water vapor between modern and LGM climates do scale with temperature according to Clausius–Clapeyron, but this thermodynamic scaling provides a poorer description of the changes in P − E. While the scaling is qualitatively consistent with simulations in the zonal mean, predicting higher P − E in the subtropics and lower P − E in the tropics and high latitudes, it fails to account for high-amplitude zonal asymmetries. Large horizontal gradients of temperature change, which are often neglected when applying the scaling to next-century warming, are shown to be important in large parts of the extratropics. However, even with this correction the thermodynamic scaling provides a poor quantitative fit to the simulations. This suggests that circulation changes play a dominant role in regional hydrological change between modern and LGM climates. Changes in transient eddy moisture transports are shown to be particularly important, even in the deep tropics. Implications for the selection and interpretation of climate proxies are discussed.
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Martinkova, Marta, and Jan Kysely. "Overview of Observed Clausius-Clapeyron Scaling of Extreme Precipitation in Midlatitudes." Atmosphere 11, no. 8 (July 25, 2020): 786. http://dx.doi.org/10.3390/atmos11080786.
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This paper presents an overview of recent observational studies on the Clausius-Clapeyron precipitation-temperature (P-T) scaling in midlatitudes. As the capacity of air to hold moisture increases in connection with increasing temperature, extreme precipitation events may become more abundant and intense. The capacity of air to hold moisture is governed by the Clausius-Clapeyron (CC) relation, approximately 7% per °C. Departures from this, so called super-CC scaling and sub-CC scaling, are consequences of different factors (moisture availability, type of precipitation, annual cycle, the percentile of precipitation intensity and regional weather patterns). Since the moisture availability and enhanced convection were considered as the most important drivers governing the P-T scaling, dew point temperature as a scaling variable is discussed in detail and methods of disaggregation of precipitation events into convective and non-convective are also reviewed.
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BORSUKIEWICZGOZDUR, A., and W. NOWAK. "Comparative analysis of natural and synthetic refrigerants in application to low temperature Clausius–Rankine cycle." Energy 32, no. 4 (April 2007): 344–52. http://dx.doi.org/10.1016/j.energy.2006.07.012.
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Drożyński, Zbigniew. "Entropy increase as a measure of energy degradation in heat transfer." Archives of Thermodynamics 34, no. 3 (September 1, 2013): 147–60. http://dx.doi.org/10.2478/aoter-2013-0021.
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Abstract Heat transfer is an irreversible process. This article defines the entropy increment as a measure of energy degradation in heat transfer realized in typical surface heat exchangers. As an example of the proposed entropy increase method, presented below are the calculations for heat exchangers working in a typical Clausius-Rankine cycle. The entropy increase in such exchangers inevitably leads to increased fuel consumption and, as a further consequence, to increased carbon dioxide emission.
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Nowak, Wladyslaw, Aleksander A. Stachel, and Aleksandra Borsukiewicz-Gozdur. "Possibilities of implementation of absorption heat pump in realization of the Clausius–Rankine cycle in geothermal power station." Applied Thermal Engineering 28, no. 4 (March 2008): 335–40. http://dx.doi.org/10.1016/j.applthermaleng.2006.02.031.
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Lorenz, David J., and Eric T. DeWeaver. "The Response of the Extratropical Hydrological Cycle to Global Warming." Journal of Climate 20, no. 14 (July 15, 2007): 3470–84. http://dx.doi.org/10.1175/jcli4192.1.
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Abstract The change in the hydrological cycle in the extratropics under global warming is studied using the climate models participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. The changes in hydrological quantities are analyzed with respect to the increases expected from the Clausius–Clapeyron (C–C) equation, which describes the rate of increase of a hydrological quantity per temperature increase. The column-integrated water vapor increases at a rate close to the C–C rate, which is expected if relative humidity remains nearly constant. The poleward moisture transport and the precipitation increase with temperature at a rate less than the C–C rate, with the precipitation increasing the least. In addition, the intermodel variance of poleward moisture transport and precipitation is explained significantly better when the zonal-mean zonal wind change as well as the temperature change is taken into account. The percent increase in precipitation per temperature increase is smallest during the warm season when energy constraints on the hydrological cycle are more important. In contrast to other hydrological quantities, the changes in evaporation in the extratropics are not explained well by the temperature or zonal wind change. Instead, a significant portion of the intermodel spread of evaporation change is linked to the spread in the poleward ocean heat transport change.
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Brönnimann, Stefan, Jan Rajczak, Erich M. Fischer, Christoph C. Raible, Marco Rohrer, and Christoph Schär. "Changing seasonality of moderate and extreme precipitation events in the Alps." Natural Hazards and Earth System Sciences 18, no. 7 (July 27, 2018): 2047–56. http://dx.doi.org/10.5194/nhess-18-2047-2018.
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Abstract. The intensity of precipitation events is expected to increase in the future. The rate of increase depends on the strength or rarity of the events; very strong and rare events tend to follow the Clausius–Clapeyron relation, whereas weaker events or precipitation averages increase at a smaller rate than expected from the Clausius–Clapeyron relation. An often overlooked aspect is seasonal occurrence of such events, which might change in the future. To address the impact of seasonality, we use a large ensemble of regional and global climate model simulations, comprising tens of thousands of model years of daily temperature and precipitation for the past, present, and future. In order to make the data comparable, they are quantile mapped to observation-based time series representative of the Aare catchment in Switzerland. Model simulations show no increase in annual maximum 1-day precipitation events (Rx1day) over the last 400 years and an increase of 10 %–20 % until the end of the century for a strong (RCP8.5) forcing scenario. This fits with a Clausius–Clapeyron scaling of temperature at the event day, which increases less than annual mean temperature. An important reason for this is a shift in seasonality. Rx1day events become less frequent in late summer and more frequent in early summer and early autumn, when it is cooler. The seasonality shift is shown to be related to summer drying. Models with decreasing annual mean or summer mean precipitation show this behaviour more strongly. The highest Rx1day per decade, in contrast, shows no change in seasonality in the future. This discrepancy implies that decadal-scale extremes are thermodynamically limited; conditions conducive to strong events still occur during the hottest time of the year on a decadal scale. In contrast, Rx1day events are also limited by other factors. Conducive conditions are not reached every summer in the present, and even less so in the future. Results suggest that changes in the seasonal cycle need to be accounted for when preparing for moderately extreme precipitation events and assessing their socio-economic impacts.
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Kjellsson, Joakim, Kristofer Döös, Frédéric B. Laliberté, and Jan D. Zika. "The Atmospheric General Circulation in Thermodynamical Coordinates." Journal of the Atmospheric Sciences 71, no. 3 (February 27, 2014): 916–28. http://dx.doi.org/10.1175/jas-d-13-0173.1.
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Abstract The zonal and meridional components of the atmospheric general circulation are used to define a global thermodynamic streamfunction in dry static energy versus latent heat coordinates. Diabatic motions in the tropical circulations and fluxes driven by midlatitude eddies are found to form a single, global thermodynamic cycle. Calculations based on the Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) dataset indicate that the cycle has a peak transport of 428 Sv (Sv ≡ 109 kg s−1). The thermodynamic cycle encapsulates a globally interconnected heat and water cycle comprising ascent of moist air where latent heat is converted into dry static energy, radiative cooling where dry air loses dry static energy, and a moistening branch where air is warmed and moistened. It approximately follows a tropical moist adiabat and is bounded by the Clausius–Clapeyron relationship for near-surface air. The variability of the atmospheric general circulation is related to ENSO events using reanalysis data from recent years (1979–2009) and historical simulations from the EC-Earth Consortium (EC-Earth) coupled climate model (1850–2005). The thermodynamic cycle in both EC-Earth and ERA-Interim widens and weakens with positive ENSO phases and narrows and strengthens during negative ENSO phases with a high correlation coefficient. Weakening in amplitude suggests a weakening of the large-scale circulation, while widening suggests an increase in mean tropical near-surface moist static energy.
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Grzesiak, Szymon, and Andrzej Adamkiewicz. "Application of Steam Jet Injector for Latent Heat Recovery of Marine Steam Turbine Propulsion Plant." New Trends in Production Engineering 1, no. 1 (October 1, 2018): 235–44. http://dx.doi.org/10.2478/ntpe-2018-0030.
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Abstract This paper presents the results of previously carried out analyses regarding efficiency and criteria evaluation of various propulsion plants of modern LNG (Liquid Natural Gas) carriers. The results of previous identification and quality assessment of waste heat energy sources of a CST (Conventional Steam Turbine) plant are presente. In this paper the possibility of use a steam jet injector in order to recover the latent heat is analysed. Calculations were carried out for an injector equipped with a de Laval nozzle, determining the thermodynamic state parameters of the mixture of drive steam and sucked in steam as well as the steam on the outlet of the injector for the various ejection ratios. On the basis of the results of the injector calculation, the heat balance of a simple regenerative Clausius – Rankine steam cycle (with one regenerative heater – deaerator) was carried out. The degree of regeneration (increase of the thermal efficiency) for cycle using the regenerative injector was determined. Based on results the further research directions for complex plants using a steam jets are indicated.
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Iñiguez, José. "A Revision of Clausius Work on the Second Law. 3. On the Non-Zero Net Value of Carnots Reversible Cycle." Entropy 1, no. 4 (October 30, 1999): 126–37. http://dx.doi.org/10.3390/e1040126.
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Lu, Jian, Koichi Sakaguchi, Qing Yang, L. Ruby Leung, Gang Chen, Chun Zhao, Erik Swenson, and Zhangshuan J. Hou. "Examining the Hydrological Variations in an Aquaplanet World Using Wave Activity Transformation." Journal of Climate 30, no. 7 (April 2017): 2559–76. http://dx.doi.org/10.1175/jcli-d-16-0561.1.
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Building on the recent advent of the concept of finite-amplitude wave activity, a contour-following diagnostics for column water vapor (CWV) is developed and applied to a pair of aquaplanet model simulations to understand and quantify the higher moments in the global hydrological cycle. The Lagrangian nature of the diagnostics leads to a more tractable formalism for the transient, zonally asymmetric component of the hydrological cycle, with a strong linear relation emerging between the wave activity and the wave component of precipitation minus evaporation ([Formula: see text]). The dry-versus-wet disparity in the transient hydrological cycle is measured by [Formula: see text], and it is found to increase at a super-Clausius–Clapeyron rate at the poleward side of the mean storm track in response to a uniform sea surface temperature (SST) warming and the meridional structure of the increase can be largely attributed to the change of the meridional stirring scale of the midlatitude Rossby waves. Further scaling for [Formula: see text] indicates that the rate of the wavy hydrological cycle, measured by the ratio of [Formula: see text] to the CWV wave activity, is subdued almost everywhere in the extratropics, implying an overall weakening of the transient circulation. Extending the CWV wave activity analysis to the transient moist regions helps reveal some unique characteristics of atmospheric rivers in terms of transport function, minimum precipitation efficiency, and maximum hydrological cycle rate, as well as an overall weakening of the hydrological cycle rate in the atmospheric river regions under SST warming.
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Back, Larissa, Karen Russ, Zhengyu Liu, Kuniaki Inoue, Jiaxu Zhang, and Bette Otto-Bliesner. "Global Hydrological Cycle Response to Rapid and Slow Global Warming." Journal of Climate 26, no. 22 (October 29, 2013): 8781–86. http://dx.doi.org/10.1175/jcli-d-13-00118.1.
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Abstract This study analyzes the response of global water vapor to global warming in a series of fully coupled climate model simulations. The authors find that a roughly 7% K−1 rate of increase of water vapor with global surface temperature is robust only for rapid anthropogenic-like climate change. For slower warming that occurred naturally in the past, the Southern Ocean has time to equilibrate, producing a different pattern of surface warming, so that water vapor increases at only 4.2% K−1. This lower rate of increase of water vapor with warming is not due to relative humidity changes or differences in mean lower-tropospheric temperature. A temperature of over 80°C would be required in the Clausius–Clapeyron relationship to match the 4.2% K−1 rate of increase. Instead, the low rate of increase is due to spatially heterogeneous warming. During slower global warming, there is enhanced warming at southern high latitudes, and hence less warming in the tropics per kelvin of global surface temperature increase. This leads to a smaller global water vapor increase, because most of the atmospheric water vapor is in the tropics. A formula is proposed that applies to general warming scenarios. This study also examines the response of global-mean precipitation and the meridional profile of precipitation minus evaporation and compares the latter to thermodynamic scalings. It is found that global-mean precipitation changes are remarkably robust between rapid and slow warming. Thermodynamic scalings for the rapid- and slow-warming zonal-mean precipitation are similar, but the precipitation changes are significantly different, suggesting that circulation changes are important in driving these differences.
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Lu, Jianhua, and Ming Cai. "Stabilization of the Atmospheric Boundary Layer and the Muted Global Hydrological Cycle Response to Global Warming." Journal of Hydrometeorology 10, no. 1 (February 1, 2009): 347–52. http://dx.doi.org/10.1175/2008jhm1058.1.
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Abstract Both the global precipitation and evaporation in global warming simulations increase at 1%–3% K−1, much smaller than the rate suggested from the Clausius–Clapeyron (C–C) relation (6%–6.5% K−1). However, the reduction of surface sensible heat flux over the global ocean (5.2% K−1) matches the difference between the fractional increase of evaporation and the C–C relation, implying that the fractional decrease of the Bowen ratio over the global ocean follows the C–C relation closely. The analysis suggests that the stabilization of the atmospheric boundary layer (ABL) in response to global warming is the main factor responsible for the simultaneous reduction of the surface sensible flux and the muted increase in the surface latent heat. Because the stabilization of the ABL causes the same amount of fractional change in both the sensible and latent heat fluxes, the fractional decrease of the Bowen ratio closely follows the C–C relation. The ABL stabilization mechanism for the muted increase in the global hydrological cycle in response to global warming is physically consistent with two other proposed mechanisms, namely, the atmospheric energy constraint and the reduction of convective mass flux.
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Smyth, Jane E., Rick D. Russotto, and Trude Storelvmo. "Thermodynamic and dynamic responses of the hydrological cycle to solar dimming." Atmospheric Chemistry and Physics 17, no. 10 (May 30, 2017): 6439–53. http://dx.doi.org/10.5194/acp-17-6439-2017.
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Abstract. The fundamental role of the hydrological cycle in the global climate system motivates a thorough evaluation of its responses to climate change and mitigation. The Geoengineering Model Intercomparison Project (GeoMIP) is a coordinated international effort to assess the climate impacts of solar geoengineering, a proposal to counteract global warming with a reduction in incoming solar radiation. We assess the mechanisms underlying the rainfall response to a simplified simulation of such solar dimming (G1) in the suite of GeoMIP models and identify robust features. While solar geoengineering nearly restores preindustrial temperatures, the global hydrology is altered. Tropical precipitation changes dominate the response across the model suite, and these are driven primarily by shifts of the Hadley circulation cells. We report a damping of the seasonal migration of the Intertropical Convergence Zone (ITCZ) in G1, associated with preferential cooling of the summer hemisphere, and annual mean ITCZ shifts in some models that are correlated with the warming of one hemisphere relative to the other. Dynamical changes better explain the varying tropical rainfall anomalies between models than changes in relative humidity or the Clausius–Clapeyron scaling of precipitation minus evaporation (P − E), given that the relative humidity and temperature responses are robust across the suite. Strong reductions in relative humidity over vegetated land regions are likely related to the CO2 physiological response in plants. The uncertainty in the spatial distribution of tropical P − E changes highlights the need for cautious consideration and continued study before any implementation of solar geoengineering.
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Kiselev, V. G. "On the ambiguity of an ideal gas entropy concept." Power engineering: research, equipment, technology 22, no. 4 (November 15, 2020): 32–42. http://dx.doi.org/10.30724/1998-9903-2020-22-4-32-42.
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Based on a critical analysis of the existing characteristics of an ideal gas and the theory of thermodynamic potentials, the article considers its new model, which includes the presence of an ideal gas in addition to kinetic energy of potential (chemical) energy, in the framework of which the isothermal and adiabatic processes in it are studied both reversible and irreversible, in terms of changes in the entropy of the system in question, observed in case. In addition, a critical analysis was made of the process of introducing the concept of entropy by R. Clausius, as a result of which the main requirements for entropy were established, the changes of which are observed in isothermal and adiabatic quasistatic processes, in particular, it was revealed that if in isothermal processes involving one in a perfect gas, the entropy ST is uniquely characterized by the value , regardless of whether the process is reversible or not, then when the adiabatic processes occur, the only requirement made of them is the condition of mutual destruction adiabats in this Carnot cycle. As a result of this circumstance, in fact, in thermodynamics various “adiabatic” entropies are used, namely; const SA = const R ln V и C V ln T , and in addition, as established in this paper, CV, which leads, despite the mathematically perfect introduction of the concept of entropy for the Carnot cycle, to the impossibility of its unambiguous interpretation and, therefore, the determination of its physicochemical meaning even for perfect gas. A new concept is introduced in the work: “total” entropy of an ideal gas SS = R ln V + C V , satisfying the criteria of R. Clausius, on the basis of which it was established that this type of entropy multiplied by the absolute temperature characterizes a certain level of potential energy of the system, which can besuccessively converted to work in an isothermal reversible process, with the supply of an appropriate amount of heat, and in the adiabatic reversible process under consideration.
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Allan, Richard P. "Examination of Relationships between Clear-Sky Longwave Radiation and Aspects of the Atmospheric Hydrological Cycle in Climate Models, Reanalyses, and Observations." Journal of Climate 22, no. 11 (June 1, 2009): 3127–45. http://dx.doi.org/10.1175/2008jcli2616.1.
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Abstract Relationships between clear-sky longwave radiation and aspects of the atmospheric hydrological cycle are quantified in models, reanalyses, and observations over the period 1980–2000. The robust sensitivity of clear-sky surface net longwave radiation (SNLc) to column-integrated water vapor (CWV) of 1–1.5 W m−2 mm−1 combined with the positive relationship between CWV and surface temperature (Ts) explains substantial increases in clear-sky longwave radiative cooling of the atmosphere (QLWc) to the surface over the period. Clear-sky outgoing longwave radiation (OLRc) is highly sensitive to changes in aerosol and greenhouse gas concentrations in addition to temperature and humidity. Over tropical ocean regions of mean descent, QLWc increases with Ts at ∼3.5–5.5 W m−2 K−1 for reanalyses, estimates derived from satellite data, and models without volcanic forcing included. Increased QLWc with warming across the tropical oceans helps to explain model ensemble mean increases in precipitation of 0.1–0.15 mm day−1 K−1, which are primarily determined by ascent regions where precipitation increases at the rate expected from the Clausius–Clapeyron equation. The implications for future projections in the atmospheric hydrological cycle are discussed.
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Merlis, Timothy M., Tapio Schneider, Simona Bordoni, and Ian Eisenman. "The Tropical Precipitation Response to Orbital Precession." Journal of Climate 26, no. 6 (March 15, 2013): 2010–21. http://dx.doi.org/10.1175/jcli-d-12-00186.1.
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Abstract Orbital precession changes the seasonal distribution of insolation at a given latitude but not the annual mean. Hence, the correlation of paleoclimate proxies of annual-mean precipitation with orbital precession implies a nonlinear rectification in the precipitation response to seasonal solar forcing. It has previously been suggested that the relevant nonlinearity is that of the Clausius–Clapeyron relationship. Here it is argued that a different nonlinearity related to moisture advection by the atmospheric circulation is more important. When perihelion changes from one hemisphere’s summer solstice to the other’s in an idealized aquaplanet atmospheric general circulation model, annual-mean precipitation increases in the hemisphere with the brighter, warmer summer and decreases in the other hemisphere, in qualitative agreement with paleoclimate proxies that indicate such hemispherically antisymmetric climate variations. The rectification mechanism that gives rise to the precipitation changes is identified by decomposing the perturbation water vapor budget into “thermodynamic” and “dynamic” components. Thermodynamic changes (caused by changes in humidity with unchanged winds) dominate the hemispherically antisymmetric annual-mean precipitation response to precession in the absence of land–sea contrasts. The nonlinearity that enables the thermodynamic changes to affect annual-mean precipitation is a nonlinearity of moisture advection that arises because precession-induced seasonal humidity changes correlate with the seasonal cycle in low-level convergence. This interpretation is confirmed using simulations in which the Clausius–Clapeyron relationship is explicitly linearized. The thermodynamic mechanism also operates in simulations with an idealized representation of land, although in these simulations the dynamic component of the precipitation changes is also important, adding to the thermodynamic precipitation changes in some latitudes and offsetting it in others.
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Dong, Lu, L. Ruby Leung, Jian Lu, and Fengfei Song. "Mechanisms for an Amplified Precipitation Seasonal Cycle in the U.S. West Coast under Global Warming." Journal of Climate 32, no. 15 (July 3, 2019): 4681–98. http://dx.doi.org/10.1175/jcli-d-19-0093.1.
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Abstract The mean precipitation along the U.S. West Coast exhibits a pronounced seasonality change under warming. Here we explore the characteristics of the seasonality change and investigate the underlying mechanisms, with a focus on quantifying the roles of moisture (thermodynamic) versus circulation (dynamic). The multimodel simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) show a simple “wet-get-wetter” response over Washington and Oregon but a sharpened seasonal cycle marked by a stronger and narrower wet season over California. Moisture budget analysis shows that changes in both regions are predominantly caused by changes in the mean moisture convergence. The thermodynamic effect due to the mass convergence of increased moisture dominates the wet-get-wetter response over Washington and Oregon. In contrast, mean zonal moisture advection due to seasonally dependent changes in land–sea moisture contrast originating from the nonlinear Clausius–Clapeyron relation dominates the sharpened wet season over California. More specifically, the stronger climatological land–sea thermal contrast in winter with warmer ocean than land results in more moisture increase over ocean than land under warming and hence wet advection to California. However, in fall and spring, the future change of land–sea thermal contrast with larger warming over land than ocean induces an opposite moisture gradient and hence dry advection to California. These results have important implications for projecting changes in the hydrological cycle of the U.S. West Coast.
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Kennedy, Ivan R., and Migdat Hodzic. "Action and Entropy in Heat Engines: An Action Revision of the Carnot Cycle." Entropy 23, no. 7 (July 5, 2021): 860. http://dx.doi.org/10.3390/e23070860.
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Despite the remarkable success of Carnot’s heat engine cycle in founding the discipline of thermodynamics two centuries ago, false viewpoints of his use of the caloric theory in the cycle linger, limiting his legacy. An action revision of the Carnot cycle can correct this, showing that the heat flow powering external mechanical work is compensated internally with configurational changes in the thermodynamic or Gibbs potential of the working fluid, differing in each stage of the cycle quantified by Carnot as caloric. Action (@) is a property of state having the same physical dimensions as angular momentum (mrv = mr2ω). However, this property is scalar rather than vectorial, including a dimensionless phase angle (@ = mr2ωδφ). We have recently confirmed with atmospheric gases that their entropy is a logarithmic function of the relative vibrational, rotational, and translational action ratios with Planck’s quantum of action ħ. The Carnot principle shows that the maximum rate of work (puissance motrice) possible from the reversible cycle is controlled by the difference in temperature of the hot source and the cold sink: the colder the better. This temperature difference between the source and the sink also controls the isothermal variations of the Gibbs potential of the working fluid, which Carnot identified as reversible temperature-dependent but unequal caloric exchanges. Importantly, the engine’s inertia ensures that heat from work performed adiabatically in the expansion phase is all restored to the working fluid during the adiabatic recompression, less the net work performed. This allows both the energy and the thermodynamic potential to return to the same values at the beginning of each cycle, which is a point strongly emphasized by Carnot. Our action revision equates Carnot’s calorique, or the non-sensible heat later described by Clausius as ‘work-heat’, exclusively to negative Gibbs energy (−G) or quantum field energy. This action field complements the sensible energy or vis-viva heat as molecular kinetic motion, and its recognition should have significance for designing more efficient heat engines or better understanding of the heat engine powering the Earth’s climates.
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Takahashi, Ken. "Radiative Constraints on the Hydrological Cycle in an Idealized Radiative–Convective Equilibrium Model." Journal of the Atmospheric Sciences 66, no. 1 (January 1, 2009): 77–91. http://dx.doi.org/10.1175/2008jas2797.1.
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Abstract The radiative constraints on the partitioning of the surface energy budget and, hence, on the strength of the hydrological cycle are analyzed in an idealized one-dimensional radiative–convective equilibrium model formulated in terms of the energy budgets at the top of the atmosphere, the subcloud layer, and the free atmosphere, which enables it to predict both surface relative humidity and the air–sea temperature difference. Using semigray radiative transfer, a semianalytical solution was obtained that explicitly shows how the surface latent heat flux (LHF) is related to the radiative properties of the atmosphere. This solution was also used in conjunction with a full radiative transfer code and was found to provide reasonably realistic quantitative estimates. In the model the LHF is fundamentally constrained by the net longwave flux divergence above the level of condensation by lifting (LCL) and by the atmospheric absorption of shortwave radiation, with only a weak indirect control by near-surface moisture. The latter implies that the Clausius–Clapeyron relation does not directly constrain the strength of the hydrological cycle. Under radiative perturbations, the changes in LHF are determined by the changes in the net longwave fluxes at the LCL, associated mainly with the changes in the longwave transmissivity, and by the changes in shortwave absorption by the atmosphere (e.g., by increased water vapor). Using a full radiative transfer model with interactive water vapor feedback with the semianalytical solution indicates a rate of change in LHF with greenhouse forcing of around 2 W m−2 K−1 of surface warming, which corresponds to the Planck feedback (∼3.2 W m−2 K−1) multiplied by a coefficient of order one that, to first approximation, depends only on the relative magnitudes of the net longwave radiation fluxes at the LCL and the top of the atmosphere (i.e., on the shape of the vertical profile of the net longwave flux).
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Lintner, B. R., P. Gentine, K. L. Findell, and G. D. Salvucci. "The Budyko and complementary relationships in an idealized model of large-scale land–atmosphere coupling." Hydrology and Earth System Sciences 19, no. 5 (May 4, 2015): 2119–31. http://dx.doi.org/10.5194/hess-19-2119-2015.
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Abstract. Two well-known relationships in hydrology and hydrometeorology, the Budyko and complementary relationships, are examined within an idealized prototype representing the physics of large-scale land–atmosphere coupling developed in prior work. These relationships are shown to hold on long (climatologic) timescales because of the tight coupling that exists between precipitation, atmospheric radiation, moisture convergence and advection. The slope of the CR is shown to be dependent on the Clausius–Clapeyron relationship between saturation-specific humidity and temperature, with important implications for the continental hydrologic cycle in a warming climate; e.g., one consequence of this dependence is that the CR may be expected to become more asymmetric with warming, as higher values of the slope imply a larger change in potential evaporation for a given change in evapotranspiration. In addition, the transparent physics of the prototype permits diagnosis of the sensitivity of the Budyko and complementary relationships to various atmospheric and land surface processes. Here, the impacts of anthropogenic influences, including large-scale irrigation and global warming, are assessed.
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Lintner, B. R., P. Gentine, K. L. Findell, and G. D. Salvucci. "The Budyko and complementary relationships in an idealized model of large-scale land–atmosphere coupling." Hydrology and Earth System Sciences Discussions 11, no. 8 (August 7, 2014): 9435–73. http://dx.doi.org/10.5194/hessd-11-9435-2014.
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Abstract. Expressions corresponding to two well-known relationships in hydrology and hydrometeorology, the Budyko and complementary relationships, are derived within an idealized prototype representing the physics of large-scale land–atmosphere coupling. These relationships are shown to hold on long (climatologic) time scales because of the tight coupling that exists between precipitation, atmospheric radiation, moisture convergence and advection. The slope of the complementary relationship is shown to be dependent the Clausius–Clapeyron relationship between saturation specific humidity and temperature, with important implications for the continental hydrologic cycle in a warming climate, e.g., one consequence of this dependence is that the complementary relationship may be expected to become more asymmetric with warming, as higher values of the slope imply a larger change in potential evaporation for a given change in evapotranspiration. In addition, the transparent physics of the prototype permits diagnosis of the sensitivity of the Budyko and complementary relationships to various atmospheric and land surface processes. Here, the impacts of anthropogenic influences, including large-scale irrigation and global warming, are assessed.
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Dufour, Ambroise, Olga Zolina, and Sergey K. Gulev. "Atmospheric Moisture Transport to the Arctic: Assessment of Reanalyses and Analysis of Transport Components." Journal of Climate 29, no. 14 (June 28, 2016): 5061–81. http://dx.doi.org/10.1175/jcli-d-15-0559.1.
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Abstract The atmospheric water cycle of the Arctic is evaluated via seven global reanalyses and in radiosonde observations covering the 1979–2013 period. In the regional moisture budget, evaporation and precipitation are the least consistent terms among different datasets. Despite the assimilation of radiosoundings, the reanalyses present a tendency to overestimate the moisture transport. Aside from this overestimation, the reanalyses exhibit a remarkable agreement with the radiosondes in terms of spatial and temporal patterns. The northern North Atlantic, subpolar North Pacific, and Labrador Sea stand out as the main gateways for moisture to the Arctic in all reanalyses. Because these regions correspond to the end of the storm tracks, the link between moisture transports and extratropical cyclones is further investigated by decomposing the moisture fluxes in the mean flow and transient eddy parts. In all reanalyses, the former term tends to cancel out when averaged over a latitude circle, leaving the latter to provide the bulk of the midlatitude moisture imports (89%–94% at 70°N). Although the Arctic warms faster than the rest of the world, the impact of these changes on its water cycle remains ambiguous. In most datasets, evaporation, precipitation, and precipitable water increase in line with what is expected from a warming signal. At the same time, the moisture transports have decreased in all the reanalyses but not in the radiosonde observations, though none of these trends is statistically significant. The fluxes do not scale with the Clausius–Clapeyron relation because the increasing humidity is not correlated with the meridional wind, particularly near the surface.
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Holmberg, Henrik, and Pekka Ahtila. "The thermal analysis of a combined heat and power plant undergoing Clausius–Rankine cycle based on the theory of effective heat-absorbing and heat-emitting temperatures." Applied Thermal Engineering 70, no. 1 (September 2014): 977–87. http://dx.doi.org/10.1016/j.applthermaleng.2014.05.100.
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Trenberth, Kevin E., Aiguo Dai, Roy M. Rasmussen, and David B. Parsons. "The Changing Character of Precipitation." Bulletin of the American Meteorological Society 84, no. 9 (September 1, 2003): 1205–18. http://dx.doi.org/10.1175/bams-84-9-1205.
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From a societal, weather, and climate perspective, precipitation intensity, duration, frequency, and phase are as much of concern as total amounts, as these factors determine the disposition of precipitation once it hits the ground and how much runs off. At the extremes of precipitation incidence are the events that give rise to floods and droughts, whose changes in occurrence and severity have an enormous impact on the environment and society. Hence, advancing understanding and the ability to model and predict the character of precipitation is vital but requires new approaches to examining data and models. Various mechanisms, storms and so forth, exist to bring about precipitation. Because the rate of precipitation, conditional on when it falls, greatly exceeds the rate of replenishment of moisture by surface evaporation, most precipitation comes from moisture already in the atmosphere at the time the storm begins, and transport of moisture by the storm-scale circulation into the storm is vital. Hence, the intensity of precipitation depends on available moisture, especially for heavy events. As climate warms, the amount of moisture in the atmosphere, which is governed by the Clausius–Clapeyron equation, is expected to rise much faster than the total precipitation amount, which is governed by the surface heat budget through evaporation. This implies that the main changes to be experienced are in the character of precipitation: increases in intensity must be offset by decreases in duration or frequency of events. The timing, duration, and intensity of precipitation can be systematically explored via the diurnal cycle, whose correct simulation in models remains an unsolved challenge of vital importance in global climate change. Typical problems include the premature initiation of convection, and precipitation events that are too light and too frequent. These challenges in observations, modeling, and understanding precipitation changes are being taken up in the NCAR “Water Cycle Across Scales” initiative, which will exploit the diurnal cycle as a test bed for a hierarchy of models to promote improvements in models.
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Roderick, M. L., F. Sun, W. H. Lim, and G. D. Farquhar. "A general framework for understanding the response of the water cycle to global warming over land and ocean." Hydrology and Earth System Sciences Discussions 10, no. 12 (December 13, 2013): 15263–94. http://dx.doi.org/10.5194/hessd-10-15263-2013.
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Abstract. Climate models project increases in globally averaged atmospheric specific humidity at the Clausius–Clapeyron (CC) value of around 7% K−1 whilst projections for precipitation (P) and evaporation (E) are somewhat muted at around 2% K−1. Such global projections are useful summaries but do not provide guidance at local (grid box) scales where impacts occur. To bridge that gap in spatial scale, previous research has shown that the following relation, Δ(P − E) ∝ P − E, holds for zonal averages in climate model projections. In this paper we first test whether that relation holds at grid box scales over ocean and over land. We find that the zonally averaged relation does not hold at grid box scales. We further find that the zonally averaged relation does not hold over land – it is specific to zonal averages over the ocean. As an alternative we tested whether the long-standing Budyko framework of catchment hydrology could be used to synthesise climate model projections over land. We find that climate model projections of Δ(P − E) out to the year 2100 conform closely to the Budyko framework. The analysis also revealed that climate models project little change in the net irradiance at the surface. To understand that result we examined projections of the key surface energy balance terms. In terms of global averages, we find the climate model projections are dominated by changes in only three terms of the surface energy balance; an increase in the incoming longwave irradiance while the responses are (mostly) restricted to the outgoing longwave irradiance with a small change in the evaporative flux. Because the change in outgoing longwave irradiance is a function of the change in surface temperature, we show that the precipitation sensitivity (i.e. 2% K−1) is an accurate summary of the partitioning of the greenhouse-induced surface forcing. With that we demonstrate that the precipitation sensitivity (2% K−1) is less than the CC value (7% K−1) because most of the greenhouse-induced surface forcing is partitioned into outgoing longwave irradiance (instead of evaporation). In essence, the models respond to elevated [CO2] by an increase in atmospheric water vapour content that increases the incoming long-wave irradiance at the surface. The surface response is dominated by a near equal increase in outgoing long-wave irradiance with only minor changes in other terms of the surface energy balance.
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Norris, Jesse, Gang Chen, and J. David Neelin. "Thermodynamic versus Dynamic Controls on Extreme Precipitation in a Warming Climate from the Community Earth System Model Large Ensemble." Journal of Climate 32, no. 4 (February 2019): 1025–45. http://dx.doi.org/10.1175/jcli-d-18-0302.1.
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The moisture budget is evaluated as a function of the probability distribution of precipitation for the end of the twentieth century and projected end of the twenty-first century in the Community Earth System Model Large Ensemble. For a given precipitation percentile, a conditional moisture budget equation relates precipitation minus evaporation ( P − E) to vertical moisture transport, horizontal moisture advection, and moisture storage. At high percentiles, moisture advection and moisture storage cancel and evaporation is negligible, so that precipitation is approximately equal to vertical moisture transport, and likewise for projected changes. Therefore, projected changes to extreme precipitation are approximately equal to the sum of thermodynamic and dynamic tendencies, representing changes to the vertical profiles of moisture content and mass convergence, respectively. The thermodynamic tendency is uniform across percentiles and regions as an intensification of the hydrological cycle, but the dynamic tendency is more complex. For extreme events, per degree of warming, in the mid-to-high latitudes the dynamic tendency is small, so that precipitation approximately scales by the Clausius–Clapeyron 7% K−1 increase. In the subtropics, a drying tendency originating from dynamics offsets the thermodynamic wetting tendency, with the net effect on precipitation varying among regions. The effect of this dynamic drying decreases with increasing percentile. In the deep tropics, a positive dynamic tendency occurs with magnitude similar to or greater than the positive thermodynamic tendency, resulting in generally a 10%–15% K−1 precipitation increase, and with a >25% K−1 increase over the tropical east Pacific. This reinforcing dynamical tendency increases rapidly for high percentiles.
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Gimsa, Jan. "Active, Reactive, and Apparent Power in Dielectrophoresis: Force Corrections from the Capacitive Charging Work on Suspensions Described by Maxwell-Wagner’s Mixing Equation." Micromachines 12, no. 7 (June 23, 2021): 738. http://dx.doi.org/10.3390/mi12070738.
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A new expression for the dielectrophoresis (DEP) force is derived from the electrical work in a charge-cycle model that allows the field-free transition of a single object between the centers of two adjacent cubic volumes in an inhomogeneous field. The charging work for the capacities of the volumes is calculated in the absence and in the presence of the object using the external permittivity and Maxwell-Wagner’s mixing equation, respectively. The model provides additional terms for the Clausius-Mossotti factor, which vanish for the mathematical boundary transition toward zero volume fraction, but which can be interesting for narrow microfluidic systems. The comparison with the classical solution provides a new perspective on the notorious problem of electrostatic modeling of AC electrokinetic effects in lossy media and gives insight into the relationships between active, reactive, and apparent power in DEP force generation. DEP moves more highly polarizable media to locations with a higher field, making a DEP-related increase in the overall polarizability of suspensions intuitive. Calculations of the passage of single objects through a chain of cubic volumes show increased overall effective polarizability in the system for both positive and negative DEP. Therefore, it is proposed that DEP be considered a conditioned polarization mechanism, even if it is slow with respect to the field oscillation. The DEP-induced changes in permittivity and conductivity describe the increase in the overall energy dissipation in the DEP systems consistent with the law of maximum entropy production. Thermodynamics can help explain DEP accumulation of small objects below the limits of Brownian motion.
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Roderick, M. L., F. Sun, W. H. Lim, and G. D. Farquhar. "A general framework for understanding the response of the water cycle to global warming over land and ocean." Hydrology and Earth System Sciences 18, no. 5 (May 6, 2014): 1575–89. http://dx.doi.org/10.5194/hess-18-1575-2014.
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Abstract. Climate models project increases in globally averaged atmospheric specific humidity that are close to the Clausius–Clapeyron (CC) value of around 7% K−1 whilst projections for mean annual global precipitation (P) and evaporation (E) are somewhat muted at around 2% K−1. Such global projections are useful summaries but do not provide guidance at local (grid box) scales where impacts occur. To bridge that gap in spatial scale, previous research has shown that the "wet get wetter and dry get drier" relation, Δ(P − E) ∝ P − E, follows CC scaling when the projected changes are averaged over latitudinal zones. Much of the research on projected climate impacts has been based on an implicit assumption that this CC relation also holds at local (grid box) scales but this has not previously been examined. In this paper we find that the simple latitudinal average CC scaling relation does not hold at local (grid box) scales over either ocean or land. This means that in terms of P − E, the climate models do not project that the "wet get wetter and dry get drier" at the local scales that are relevant for agricultural, ecological and hydrologic impacts. In an attempt to develop a simple framework for local-scale analysis we found that the climate model output shows a remarkably close relation to the long-standing Budyko framework of catchment hydrology. We subsequently use the Budyko curve and find that the local-scale changes in P − E projected by climate models are dominated by changes in P while the changes in net irradiance at the surface due to greenhouse forcing are small and only play a minor role in changing the mean annual P − E in the climate model projections. To further understand the apparently small changes in net irradiance we also examine projections of key surface energy balance terms. In terms of global averages, we find that the climate model projections are dominated by changes in only three terms of the surface energy balance: (1) an increase in the incoming long-wave irradiance, and the respective responses (2) in outgoing long-wave irradiance and (3) in the evaporative flux, with the latter change being much smaller than the former two terms and mostly restricted to the oceans. The small fraction of the realised surface forcing that is partitioned into E explains why the hydrologic sensitivity (2% K−1) is so much smaller than CC scaling (7% K−1). Much public and scientific perception about changes in the water cycle has been based on the notion that temperature enhances E. That notion is partly true but has proved an unfortunate starting point because it has led to misleading conclusions about the impacts of climate change on the water cycle. A better general understanding of the potential impacts of climate change on water availability that are projected by climate models will surely be gained by starting with the notion that the greater the enhancement of E, the less the surface temperature increase (and vice versa). That latter notion is based on the conservation of energy and is an underlying basis of climate model projections.
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Nogueira, Miguel. "The multi-scale structure of atmospheric energetic constraints on globally averaged precipitation." Earth System Dynamics 10, no. 2 (April 15, 2019): 219–32. http://dx.doi.org/10.5194/esd-10-219-2019.
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Abstract. This study presents a multi-scale analysis of cross-correlations based on Haar fluctuations of globally averaged anomalies of precipitation (P), precipitable water vapor (PWV), surface temperature (T), and atmospheric radiative fluxes. The results revealed an emergent transition between weak correlations at sub-yearly timescales (down to ∼5 days) to strong correlations at timescales larger than about ∼1–2 years (up to ∼1 decade). At multiyear timescales, (i) Clausius–Clapeyron becomes the dominant control of PWV (ρPWV,T≈0.9), (ii) surface temperature averaged over global land and over global ocean (sea surface temperature, SST) become strongly correlated (ρTland,SST∼0.6); (iii) globally averaged precipitation variability is dominated by energetic constraints, specifically the surface downwelling longwave radiative flux (DLR) (ρP,DLR≈-0.8) displayed stronger correlations than the direct response to T fluctuations, and (iv) cloud effects are negligible for the energetic constraints in (iii), which are dominated by clear-sky DLR. At sub-yearly timescales, all correlations underlying these four results decrease abruptly towards negligible values. Such a transition has important implications for understanding and quantifying the climate sensitivity of the global hydrological cycle. The validity of the derived correlation structure is demonstrated by reconstructing global precipitation time series at 2-year resolution, relying on the emergent strong correlations (P vs. clear-sky DLR). Such a simple linear sensitivity model was able to reproduce observed P anomaly time series with similar accuracy to an (uncoupled) atmospheric model (ERA-20CM) and two climate reanalysis (ERA-20C and 20CR). The linear sensitivity breaks down at sub-yearly timescales, whereby the underlying correlations become negligible. Finally, the relevance of the multi-scale framework and its potential for stochastic downscaling applications are demonstrated by deriving accurate monthly P probability density functions (PDFs) from the reconstructed 2-year P time series based on scale-invariant arguments alone. The derived monthly PDFs outperform the statistics simulated by ERA-20C, 20CR, and ERA-20CM in reproducing observations.
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Matthews, Dr J. Brian. "Isle of Man, Galapagos and sunspot data show net cooling hid double exponential ocean warming danger: +3°C in 2014, +4°C likely by 2016." JOURNAL OF ADVANCES IN PHYSICS 9, no. 2 (July 4, 2015): 2355–71. http://dx.doi.org/10.24297/jap.v9i2.1436.
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Anthropogenic global warming (AGW) heat is trapped by the greenhouse gas (GHG) blanket, and the ocean surface layer. It is 93% in the ocean and drives atmospheric warming. The 111-year mean daily surface temperatures are 10.5±0.5°C at Port Erin (PE) Isle of Man compared with 9.6±4.8°C in Central England (CET) air. The Port Erin 5½-year max-min heat cycle synchronizes to the 11-year solar heat pump sunspot cycle. Tropical heat arrives 2 years after a solar maximum on wind-driven currents in the stratified sea surface. Runoff from bottom-up melted Arctic icesheets arrives 3½ year later at solar minimum. These warm and cold waters are the biodiversity source. PE is unique with seasonal meltwaters of Pacific and Atlantic origin. The North Pacific warms twice as fast as other oceans. All ocean near-surface gyre currents harmonize with sunspot cycles. Net cooling by polar icemelt masks catastrophic exponential ocean warming and icemelt. Eleven counter-rotating surface gyres carry heat and nutrients globally in verified ocean surface circulation system.Exponential growth is unsustainable in a finite system. It trends to infinity. Double-exponential gets there twice as quickly. The GHG blanket, grown double-exponentially for 250 years, is now in control. Ocean heat absorption takes 150-250 years. Arctic icemelt increases double-exponentially. The Arctic long-term annual freeze-melt volume cycle is 16.8±1.3 thousand cubic km per year. Polar land icemelt adds ~500 km3 per year. Freeze-brine of salinity >40‰ and temperature –1°C, sinks to the bottom. Equatorial evaporative-brine of salinity >36.4‰ and >28°C floats subsurface under fresh warm layers thickening westwards in tropical meridional cells to ~75m depth. This is consistent with observed extreme weather.Heat imbalance forced Pacific Ocean temperatures above proposed limits of +2°C in 1993, to +3°C in 2014, and is on track for +4°C for 2016. Century-long daily records confirm processes ongoing for 300 years. Coast locations are where impacts are felt and real-time data collected. Corporate governance degraded physics teaching in only 60 years. Individual discovery and data collection was lost. Big science is unnecessary. Satellites cannot do plankton tows. Computer models are governed by the rule of ‘garbage-in garbage-out’. They must be verified by in situ data that cannot be collected retrospectively. Continuous timeseries surface profile data from fixed ocean station locations on a global variable-boundary network are essential. Scientists, if well-trained in ocean experimental physics, can do the hard work.Time-poor scientists, stripped of their intellectual property rights, under rewarded, poorly educated, and ruthlessly exploited by growth-obsessed commercial interests, missed catastrophic global warming and multiple extreme consequences. Climate scientists abandoned classical physics and Newton-Hooke field verification in favor of unverified beliefs, models, and apps. Climate studies confuse heat with temperature, do not include basal icemelt, density temperature-salinity function, Clausius-Clapeyron evaporation exponential skin temperature function, asymmetric brine-heat sequestration, solar and tidal pumping, infra-red GHG heat trap, vertical tropical cells, freshwater warm pools; or wind-driven surface currents at 3 percent of windspeed. Climate model mistaken assumptions lead to the absurd conclusion that evaporation in the Labrador Sea at midnight in midwinter is greater than at the midday Equator.The Isle of Man provides an ideal location for continued monitoring and mitigation research, teaching and public service in a dedicated non-commercial independent multidisciplinary university-type setting. Quality teaching is the major priority. Commercial monopoly rights need replacement with free, fully open discussions and publications. Quality not quantity should be paramount. Internationally competitive academics should control subservient lower paid support staff.Every day without ocean surface data means vital scientific truth lost of interest and concern to all populations. Predictions are groundless without accurate continuous ocean surface data. Skeptics, politicians, statisticians, those with stakes in the status quo, and established research censors obstructing scientific progress squabble in ignorance while the globe burns.
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Larch, Mario, and Wolfgang Lechthaler. "BUY NATIONAL AND THE BUSINESS CYCLE." Macroeconomic Dynamics 20, no. 5 (June 29, 2015): 1196–218. http://dx.doi.org/10.1017/s1365100514000790.
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By concentrating a stimulus on the domestic economy, Buy National clauses are argued to lead to higher fiscal multipliers. We show that this argument falls short. Although it is true that domestic demand for domestic goods is increased, at the same time foreign demand for domestic goods is reduced by adverse changes in the real exchange rate. The two effects are of similar magnitude, so that Buy National clauses do not lead to a stronger stimulus to GDP. Apart from that, restricting the stimulus to domestic products makes the stimulus more expensive, because cheap foreign products are ignored. Consequently, real public consumption is lowered by Buy National clauses.
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Mendes Rodrigues, Mariana Carla, Guilherme Corrêa Soares, Vicente Tadeu Lopes Buono, and Leandro de Arruda Santos. "Effects of Pseudoelastic Cycling under Different Temperatures on Physical and Mechanical Properties of a NiTi Alloy." Advances in Science and Technology 97 (October 2016): 134–40. http://dx.doi.org/10.4028/www.scientific.net/ast.97.134.
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The effects of pseudoelastic cycling under different temperatures on physical and mechanical properties of a NiTi superelastic wire were investigated by uniaxial tensile testing. The samples were cyclically deformed up to 6% strain under several test temperatures above the austenite finish temperature (Af). In order to approach a cyclic saturation level, number of cycles was established as 20. The temperature at which mechanical cycling was performed played a strong role on residual strain, dissipated energy and also on the critical stress to induce martensite, being consistent with the Clausius-Clapeyron relationship. It was found that an increase in test temperature resulted in more significant changes in the alloy’s functional behavior, but cyclic stability tended to be reached within fewer cycles. X-ray diffraction results showed that no martensite was stabilized at any condition and that austenite diffraction peaks intensities increased with test temperature, which was attributed to stress relaxation. Tensile tests until rupture and three point bending tests revealed that the mechanical response of the specimens cycled at higher temperatures and as received were fairly similar, and that specimens cycled at lower temperatures exhibited a slightly higher flexibility.
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McCoy, Daniel T., Paul R. Field, Gregory S. Elsaesser, Alejandro Bodas-Salcedo, Brian H. Kahn, Mark D. Zelinka, Chihiro Kodama, et al. "Cloud feedbacks in extratropical cyclones: insight from long-term satellite data and high-resolution global simulations." Atmospheric Chemistry and Physics 19, no. 2 (January 30, 2019): 1147–72. http://dx.doi.org/10.5194/acp-19-1147-2019.
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Abstract. A negative extratropical shortwave cloud feedback driven by changes in cloud optical depth is a feature of global climate models (GCMs). A robust positive trend in observed liquid water path (LWP) over the last two decades across the warming Southern Ocean supports the negative shortwave cloud feedback predicted by GCMs. This feature has been proposed to be due to transitions from ice to liquid with warming. To gain insight into the shortwave cloud feedback we examine extratropical cyclone variability and the response of extratropical cyclones to transient warming in GCM simulations. Multi-Sensor Advanced Climatology Liquid Water Path (MAC-LWP) microwave observations of cyclone properties from the period 1992–2015 are contrasted with GCM simulations, with horizontal resolutions ranging from 7 km to hundreds of kilometers. We find that inter-cyclone variability in LWP in both observations and models is strongly driven by the moisture flux along the cyclone's warm conveyor belt (WCB). Stronger WCB moisture flux enhances the LWP within cyclones. This relationship is replicated in GCMs, although its strength varies substantially across models. It is found that more than 80 % of the enhancement in Southern Hemisphere (SH) extratropical cyclone LWP in GCMs in response to a transient 4 K warming can be predicted based on the relationship between the WCB moisture flux and cyclone LWP in the historical climate and their change in moisture flux between the historical and warmed climates. Further, it is found that that the robust trend in cyclone LWP over the Southern Ocean in observations and GCMs is consistent with changes in the moisture flux. We propose two cloud feedbacks acting within extratropical cyclones: a negative feedback driven by Clausius–Clapeyron increasing water vapor path (WVP), which enhances the amount of water vapor available to be fluxed into the cyclone, and a feedback moderated by changes in the life cycle and vorticity of cyclones under warming, which changes the rate at which existing moisture is imported into the cyclone. Both terms contribute to increasing LWP within the cyclone. While changes in moisture flux predict cyclone LWP trends in the current climate and the majority of changes in LWP in transient warming simulations, a portion of the LWP increase in response to climate change that is unexplained by increasing moisture fluxes may be due to phase transitions. The variability in LWP within cyclone composites is examined to understand what cyclonic regimes the mixed-phase cloud feedback is relevant to. At a fixed WCB moisture flux cyclone LWP increases with increasing sea surface temperature (SST) in the half of the composite poleward of the low and decreases in the half equatorward of the low in both GCMs and observations. Cloud-top phase partitioning observed by the Atmospheric Infrared Sounder (AIRS) indicates that phase transitions may be driving increases in LWP in the poleward half of cyclones.
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Liepert, Beate G., and Michael Previdi. "Do Models and Observations Disagree on the Rainfall Response to Global Warming?" Journal of Climate 22, no. 11 (June 1, 2009): 3156–66. http://dx.doi.org/10.1175/2008jcli2472.1.
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Abstract Recently analyzed satellite-derived global precipitation datasets from 1987 to 2006 indicate an increase in global-mean precipitation of 1.1%–1.4% decade−1. This trend corresponds to a hydrological sensitivity (HS) of 7% K−1 of global warming, which is close to the Clausius–Clapeyron (CC) rate expected from the increase in saturation water vapor pressure with temperature. Analysis of two available global ocean evaporation datasets confirms this observed intensification of the atmospheric water cycle. The observed hydrological sensitivity over the past 20-yr period is higher by a factor of 5 than the average HS of 1.4% K−1 simulated in state-of-the-art coupled atmosphere–ocean climate models for the twentieth and twenty-first centuries. However, the analysis shows that the interdecadal variability in HS in the models is high—in particular in the twentieth-century runs, which are forced by both increasing greenhouse gas (GHG) and tropospheric aerosol concentrations. About 12% of the 20-yr time intervals of eight twentieth-century climate simulations from the third phase of the Coupled Model Intercomparison Project (CMIP3) have an HS magnitude greater than the CC rate of 6.5% K−1. The analysis further indicates different HS characteristics for GHG and tropospheric aerosol forcing agents. Aerosol-forced HS is a factor of 2 greater, on average, and the interdecadal variability is significantly larger, with about 23% of the 20-yr sensitivities being above the CC rate. By thermodynamically constraining global precipitation changes, it is shown that such changes are linearly related to the difference in the radiative imbalance at the top of the atmosphere (TOA) and the surface (i.e., the atmospheric radiative energy imbalance). The strength of this relationship is controlled by the modified Bowen ratio (here, global sensible heat flux change divided by latent heat flux change). Hydrological sensitivity to aerosols is greater than the sensitivity to GHG because the former have a stronger effect on the shortwave transmissivity of the atmosphere, and thus produce a larger change in the atmospheric radiative energy imbalance. It is found that the observed global precipitation increase of 13 mm yr−1 decade−1 from 1987 to 2006 would require a trend of the atmospheric radiative imbalance (difference between the TOA and the surface) of 0.7 W m−2 decade−1. The recovery from the El Chichón and Mount Pinatubo volcanic aerosol injections in 1982 and 1991, the satellite-observed reductions in cloudiness during the phase of increasing ENSO events in the 1990s, and presumably the observed reduction of anthropogenic aerosol concentrations could have caused such a radiative imbalance trend over the past 20 years. Observational evidence, however, is currently inconclusive, and it will require more detailed investigations and longer satellite time series to answer this question.
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Xue, Ti-Wei, and Zeng-Yuan Guo. "What Is the Real Clausius Statement of the Second Law of Thermodynamics?" Entropy 21, no. 10 (September 24, 2019): 926. http://dx.doi.org/10.3390/e21100926.
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In this paper, we first analyze the difference between the second law of thermodynamics and the laws in other disciplines. There are some phenomena in other disciplines similar to the Clausius Statement of the second law, but none of them has been accepted as the statement of a certain law. Clausius’ mechanical theory of heat, published in the nineteenth century, is then introduced and discussed in detail, from which it is found that Clausius himself regarded “Theorem of the equivalence of the transformation of heat to work, and the transformation of heat at a higher temperature to a lower temperature”, rather than “Heat can never pass from a colder to a warmer body without some other change”, as the statement of the second law of thermodynamics. The latter is only laid down as the fundamental principle for deriving the theorem of the equivalence of transformations. Finally, based on the theorem of the equivalence of transformations and the average temperature method, a general quantitative relation among the heat, the work, and the temperatures is obtained for arbitrary cycles, which is thus recommended as an alternative mathematic expression of the second law. Hence, the theorem of the equivalence of transformations is the real Clausius Statement of the second law of thermodynamics.
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Ilc, Gašper. "Jespersen's cycle in Slovenian." Linguistica 51, no. 1 (December 31, 2011): 349–63. http://dx.doi.org/10.4312/linguistica.51.1.349-363.
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The paper examines the syntactic status of the negative marker in standard Slovenian and its Pannonian dialects in terms of the grammaticalisation process known as Jespersen's cycle. Assuming that Jespersen's Cycle can be observed synchronically, the paper focusses on the correlation between the morpho-phonological strength of the negative marker and the syntactic derivation of negative clauses. The data analysis identifies at least three different stages of Jespersen's cycle in modern Slovenian: (i) the clitic-likenegation, (ii) the bipartite negation, and (iii) the adverb-like negation, the first occurring in standard Slovenian and the latter two in the Pannonian dialect group. In terms of the generative syntactic derivation, the analysis proposes that the negative marker occupies three different structural positions: (i) the head of the Negation phrase (clitic-like negation), (ii) the specifier of the Negation phrase (adverb-like negation) or (iii) both syntactic positions (bipartite negation). In addition, the paper explores the question whether the syntactic position of the negative marker determines the semantic interpretation of multiple occurrences of negative elements, in particular, the negative concord and the double negation interpretation. The analysis shows that in Slovenian the morpho-phonological properties of the negative marker and its structural position bear no consequences for the semantic interpretation of multiple occurrences of negative elements.
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Pak, Marjorie. "Clause-final negation and the Jespersen cycle in Logoori." Proceedings of the Linguistic Society of America 5, no. 1 (March 23, 2020): 187. http://dx.doi.org/10.3765/plsa.v5i1.4700.
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This paper looks at Jespersen-cycle effects in Logoori (Bantu, western Kenya), where a clause-final adverb daave (neg2) reinforces or replaces the older negative prefixes si- and ta- (neg1). In main-clause indicatives, neg1 is nearly obsolete ((?si)-a-sooma daave ‘s/he’s not reading’), while in subjunctives neg1 remains obligatory (u-*(ta)-sooma daave ‘don’t read’). Recognizing that this pattern cannot be fully attributed to the phonological weakness of neg1 (cf. Jespersen 1917:4ff), I provide a supplementary grammar-competition analysis, in which the availability of a high-attaching, semantically negative daave in main clauses leads to the rapid erosion of neg1 si-.
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Witzenhausen, Elisabeth. "Von Negation zu Domänensubtraktion." Beiträge zur Geschichte der deutschen Sprache und Literatur 141, no. 1 (February 22, 2019): 1–30. http://dx.doi.org/10.1515/bgsl-2019-0001.
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Abstract Middle Low German (MLG) underwent Jespersen’s Cycle, a change in the expression of sentential negation, whereby a preverbal marker ni (stage I) was adjoined by an adverbial niht (stage II) in the transition towards MLG, and was eventually replaced by it (stage III). In this article, I argue that the single preverbal particle ne/en in MLG became a marker of negation which is located syntactically higher, i. e. above the clause boundary, than the clause in which ne/en appears. This analysis is based on a corpus study investigating MLG exceptive clauses (English unless-clauses). Both on semantic and syntactic grounds, it is shown that these clauses can be explained as being complements of an operator that subtracts the proposition in the exceptive clause from the modal domain of a universal quantifier.
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Eisfeld, Sonja M., and Barbara Niehoff. "Gonad morphology, oocyte development and spawning cycle of the calanoid copepod Acartia clausi." Helgoland Marine Research 61, no. 3 (March 16, 2007): 193–201. http://dx.doi.org/10.1007/s10152-007-0066-7.
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Van Den Einde, David. "A xenon power cycle and the second law of thermodynamics." Physics Essays 32, no. 3 (September 18, 2019): 394–98. http://dx.doi.org/10.4006/0836-1398-32.3.394.
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Xenon plus a molecular solid solute that yields a positive excess enthalpy of solution reaction form the working fluid for a transcritical power cycle. Xenon exhibits large changes in induced polarities with the change in density in the temperature and pressure range of the cycle described. A difference in excess enthalpy of solution between the reaction in xenon’s dense liquid state and expanded supercritical fluid state affects the cycle’s efficiency by internally elevating the temperature of heat input from near the cycle’s T2 to near its T1 before that energy affects gas expansion. This positive excess enthalpy differential establishes conditions in the cycle that allows for complete exhaust heat regeneration. The energy transfer invalidates Carnot’s and Clausius’s original assumption that the rate an ideal gas can convert heat energy to work by its expansion and contraction establishes heat as the lowest form of energy to which all other forms degrade.