Climate change is an important societal issue. Large effort in society is spent on addressing it. For adequate measures, it is important that the phenomenon of climate change is well understood, especially the effect ...Climate change is an important societal issue. Large effort in society is spent on addressing it. For adequate measures, it is important that the phenomenon of climate change is well understood, especially the effect of adding carbon dioxide to the atmosphere. In this work, a theoretical fully analytical study is presented of the so-called greenhouse effect of carbon dioxide. The effect of this gas in the atmosphere itself was already determined as being of little importance based on empirical analysis. In the current work, the effect is studied both phenomenologically and analytically. In a first attempt of energy transfer by radiation only, it is solved by ideal-gas-law equations and the atmosphere is divided into an infinite number of layers each absorbing and reemitting infrared radiation (surpassing the classical Beer-Lambert analysis of absorption). The result is that the exact structure of the atmosphere is irrelevant for the analysis;we might as well keep the two-box model for any analytical approach. However, the results are unsatisfactory in that they cannot explain the profile of the atmosphere. In a new approach, the atmosphere is solved by taking both radiative as well as thermodynamic processes into account. The model fully fits the empirical data and an analytical equation is given for the atmospheric behavior. Upper limits are found for the greenhouse effect ranging from zero to a couple of mK per ppm CO2. It is shown that it cannot explain the observed correlation of carbon dioxide and surface temperature. This correlation, however, is readily explained by Henry’s Law (outgassing of oceans), with other phenomena insignificant. Finally, while the greenhouse effect can thus, in a rudimentary way, explain the behavior of the atmosphere of Earth, it fails describing other atmospheres such as that of Mars. Moreover, looking at three cities in Spain, it is found that radiation balances only cannot explain the temperature of these cities. Finally, three data sets with different time scales (60 years, 600 thousand years, and 650 million years) show markedly different behavior, something that is inexplicable in the framework of the greenhouse theory.展开更多
One of the ingredients of the anthropogenic global warming hypothesis is the existence of large positive feedback in the climate system. An example is polar ice that, once melted, turns into blacker water that will in...One of the ingredients of the anthropogenic global warming hypothesis is the existence of large positive feedback in the climate system. An example is polar ice that, once melted, turns into blacker water that will increase radiation absorption and this rein-forces the melting. This causes a run-away scenario with a point of no return. Here it is shown that the polar ice can also have negative feedback aspects, where a melting of polar ice will cause it to reappear.展开更多
One of the issues of Thermodynamics is the question of what exactly thermo-dynamic equilibrium means.It is often interpreted as thermalequilibrium.The question is if this is correct.This is especially relevant for the...One of the issues of Thermodynamics is the question of what exactly thermo-dynamic equilibrium means.It is often interpreted as thermalequilibrium.The question is if this is correct.This is especially relevant for the case of the atmosphere,where gravitational energy also plays a role,which might allow for temperature gradients in equilibrium.In order to answer this question,this work goes back to Boltzmann’s original ideas.As will be shown here,thermo-dynamic equilibrium also means thermal equilibrium in this case.Moreover,it will also be shown why a lapse rate(a linear drop of temperature with alti-tude)is observed in a mechanically stable atmosphere.The implications for climate research are discussed.展开更多
The feedback between carbon dioxide,CO_(2),and the temperature of the atmos-phere is analyzed.Starting with the assumption that the average temperature is a function of the carbon-dioxide concentration in the atmosphe...The feedback between carbon dioxide,CO_(2),and the temperature of the atmos-phere is analyzed.Starting with the assumption that the average temperature is a function of the carbon-dioxide concentration in the atmosphere,[CO_(2)],the so-called greenhouse effect,feedback is introduced into the system:in-creased temperature can further increase the CO_(2) concentration that causes the temperature rise in so-called positive feedback.On the basis of the availa-ble data,it is argued that this cannot be the case;the feedback must be negative at the moment.Moreover,the observed correlation between[CO_(2)]and tem-perature varies across different time scales,suggesting different processes are at work.It is not possible to explain all the data with a single phenomenon like the greenhouse effect,even when feedback is included.展开更多
Carrier multiplication is demonstrated in a solid-state dispersion of germanium nanocrystals in a silicon–dioxide matrix.This is performed by comparing ultrafast photo-induced absorption transients at different pump ...Carrier multiplication is demonstrated in a solid-state dispersion of germanium nanocrystals in a silicon–dioxide matrix.This is performed by comparing ultrafast photo-induced absorption transients at different pump photon energies below and above the threshold energy for this process.The average germanium nanocrystal size is approximately 5–6 nm,as inferred from photoluminescence and Raman spectra.A carrier multiplication efficiency of approximately 190%is measured for photo-excitation at 2.8 times the optical bandgap of germanium nanocrystals,deduced from their photoluminescence spectra.展开更多
文摘Climate change is an important societal issue. Large effort in society is spent on addressing it. For adequate measures, it is important that the phenomenon of climate change is well understood, especially the effect of adding carbon dioxide to the atmosphere. In this work, a theoretical fully analytical study is presented of the so-called greenhouse effect of carbon dioxide. The effect of this gas in the atmosphere itself was already determined as being of little importance based on empirical analysis. In the current work, the effect is studied both phenomenologically and analytically. In a first attempt of energy transfer by radiation only, it is solved by ideal-gas-law equations and the atmosphere is divided into an infinite number of layers each absorbing and reemitting infrared radiation (surpassing the classical Beer-Lambert analysis of absorption). The result is that the exact structure of the atmosphere is irrelevant for the analysis;we might as well keep the two-box model for any analytical approach. However, the results are unsatisfactory in that they cannot explain the profile of the atmosphere. In a new approach, the atmosphere is solved by taking both radiative as well as thermodynamic processes into account. The model fully fits the empirical data and an analytical equation is given for the atmospheric behavior. Upper limits are found for the greenhouse effect ranging from zero to a couple of mK per ppm CO2. It is shown that it cannot explain the observed correlation of carbon dioxide and surface temperature. This correlation, however, is readily explained by Henry’s Law (outgassing of oceans), with other phenomena insignificant. Finally, while the greenhouse effect can thus, in a rudimentary way, explain the behavior of the atmosphere of Earth, it fails describing other atmospheres such as that of Mars. Moreover, looking at three cities in Spain, it is found that radiation balances only cannot explain the temperature of these cities. Finally, three data sets with different time scales (60 years, 600 thousand years, and 650 million years) show markedly different behavior, something that is inexplicable in the framework of the greenhouse theory.
文摘One of the ingredients of the anthropogenic global warming hypothesis is the existence of large positive feedback in the climate system. An example is polar ice that, once melted, turns into blacker water that will increase radiation absorption and this rein-forces the melting. This causes a run-away scenario with a point of no return. Here it is shown that the polar ice can also have negative feedback aspects, where a melting of polar ice will cause it to reappear.
文摘One of the issues of Thermodynamics is the question of what exactly thermo-dynamic equilibrium means.It is often interpreted as thermalequilibrium.The question is if this is correct.This is especially relevant for the case of the atmosphere,where gravitational energy also plays a role,which might allow for temperature gradients in equilibrium.In order to answer this question,this work goes back to Boltzmann’s original ideas.As will be shown here,thermo-dynamic equilibrium also means thermal equilibrium in this case.Moreover,it will also be shown why a lapse rate(a linear drop of temperature with alti-tude)is observed in a mechanically stable atmosphere.The implications for climate research are discussed.
文摘The feedback between carbon dioxide,CO_(2),and the temperature of the atmos-phere is analyzed.Starting with the assumption that the average temperature is a function of the carbon-dioxide concentration in the atmosphere,[CO_(2)],the so-called greenhouse effect,feedback is introduced into the system:in-creased temperature can further increase the CO_(2) concentration that causes the temperature rise in so-called positive feedback.On the basis of the availa-ble data,it is argued that this cannot be the case;the feedback must be negative at the moment.Moreover,the observed correlation between[CO_(2)]and tem-perature varies across different time scales,suggesting different processes are at work.It is not possible to explain all the data with a single phenomenon like the greenhouse effect,even when feedback is included.
基金This work was financially supported by the Foundation for Fundamental Research on Matter(FOM).
文摘Carrier multiplication is demonstrated in a solid-state dispersion of germanium nanocrystals in a silicon–dioxide matrix.This is performed by comparing ultrafast photo-induced absorption transients at different pump photon energies below and above the threshold energy for this process.The average germanium nanocrystal size is approximately 5–6 nm,as inferred from photoluminescence and Raman spectra.A carrier multiplication efficiency of approximately 190%is measured for photo-excitation at 2.8 times the optical bandgap of germanium nanocrystals,deduced from their photoluminescence spectra.
