Instead , in the case of the earth , you pull “out of the air” , a ratio of about 0.7 % 1.0 for the ratio of absorptivity to emissivity ( without providing an example of what spectra would generate such a ratio ) , thus producing the meaningless claim of 33k deficit . This ought to translate into a temperature gradient due to the relationship between kinetic energy and temperature (or more precisely, I can’t figure out why it wouldn’t). But in fact Arthur *didn’t* show that. The same models predict a further 1-5 K temperature rise over the next century as greenhouse gases continue to increase. ). Radiation is energy transmitted by electromagnetic waves. Furthermore, since the atmospheric pressure varies as the temperature, the temperature at any given pressure level in the Venusian atmosphere should be 1.176 times the temperature at that same pressure level in the Earth atmosphere, in the two atmospheres. That’s unstable. Despite these complexities, you still need CO2 to fundamentally complete the picture of Venus’ hot temperatures since it makes the planet virtually opaque through a wide range of frequencies. Calculate the value of the 'solar constant' on Mercury, Jupiter? Again the word “only”, but in a slightly different sense. I can liken their empirical-only work to the diffusivity approximation that you described. Here enters the convection. I expect to do another post fairly soon just to bring all of common questions into one place. boltzman*Te^4 = So*(1-A)/4. Very interesting; I’ve read this thread, Chris Colose’s, Lubos and Goddard’s plus a few dozen other sources; generally the atmosphere is taken as given with thought experiments about changes in the composition; however no attention is given to how the Venusian atmosphere got in place in the first place; this is not an atmosphere which has ‘gently’ built up due to greenhouse accretion is it? I’ll modify my earlier proposal that the air under the shell would be still and isothermal. Therefore, the surface of the earth is about 45 degK warmer than the temperature at the altitude where incoming and outgoing radiation are in equilibrium. In order to maintain a stable climate, the Earth must be in energetic equilibrium between the radiation it receives from the Sun and the radiation it emits out to space. Figure 7-2 Answer. An illustrative example is shown in OK, I’ll bite. Of course not. “Tell me, now, just how is it POSSIBLE that such IMPORTANT DATA on backradiation is not readily accessable???”. The paper of Tagagi et al tells essentially what makes the radiative heat transfer weak in the lower Venusian atmosphere. The model described above is completely non-intuitive because sunlight does not shine on the entire Earth evenly all over at the same time. The ground temperature would see the added molecular temperature due to the added velocity from converting the potential energy at the shell to kinetic energy at the ground. […]. Some of this terrestrial radiation is trapped by greenhouse gases and radiated back to the Earth, resulting in the warming of the surface known as the greenhouse effect. how And what is being overlooked here is how Venus got its atmosphere in the first place; overturning, as suggested by O’Neill, is one explanation; similtaneously providing the atmosphere and the heat. As measured adiabatic lapse rates can be significantly lower than the “Dry” rate, the temperature could be as low as 900 Kelvin. Inserting a high cloud in the model is like adding a second atmospheric layer; it enhances the greenhouse effect. For example, if we wanted to know how fast a beer from the fridge would warm up, in a vaccuum but in a warm room, we would use the NET flux. I welcome Steve Goddard explaining his point of view in a little more detail here. The NET energy leaving the surface is always constant (and equal to the absorbed solar radiation), but the balance between radiation, conduction and evaporation changes. I read from this, that pressure causes temperature and the “greenhouse” effect, while in existence, is not really that important. Stefan-Boltzmann does not give just give the temperature of a radiantly heated blackbody , but any similarly heated gray body no matter how dark or light . and water vapor), where no IR flux (St=0) propagates from the surface (Su) into space and I am used to calculations based on the absorption rates for the gamma ray spectrum. ( Log Out / The effective location of this radiation LOCKS the temperature at the upper end of the lapse rate driven curve. I don’t automatically disbelieve something is valid just because I don’t agree with it. THAT IS STILL 23 TIMES AS MUCH CO2 AS EARTH. ( http://www.climatesci.org/publications/pdf/R-345.pdf , the link doesn’t seem to be working right now ). On Venus, which radiates primarily at different regions, peaking near the 2450 1/cm region, Venus has a peak absorption area between 2300 and 2400 1/cm and with different absorption characteristics than on Earth. SOD, There appears to be a multitude of hypotheses on the cause/effects of the greenhouse effect, few of which agree with others. Click on the 'RADIUS' button, enter the time and mass, click on 'CALCULATE' and the answer is 4.2244 x10 7 meters or 42,244 kilometers or 26,249 miles. If you are new to this kind of model, it is easiest to follow the small amount of maths against the graphic. The N&Z ATE provides a viable alternative explanation for why the surface radiates more energy than it gets from the Sun. We calculate the solar constant FS for Venus by using equation with d = 1.08x106 km. There is a great debate currently raging on Venus. The GWP of HFCs is less than that of CFCs because HFCs have shorter atmospheric lifetimes. Perhaps we can discuss Nikolov and Zeller another time. You still have cause and effect reversed. This entropy has to be transferred to space, for steady state. ). We see this in the stratosphere where the lapse rate is negative and temperature increases with altitude. ( Log Out / The layer is transparent to solar radiation, and absorbs a fraction f of terrestrial radiation because of the presence of greenhouse gases. This internal energy level is quantized in a series of electronic, vibrational, and rotational states. Downward radiation from the atmosphere is not particularly mysterious, or difficult to understand, or difficult to measure. Other measurements included surface pressure of about 90 atmospheres (9 MPa), temperature of 485 °C, and surface light levels comparable to those at Earth mid-latitudes on a cloudy summer day. In the case of the earth, as laid out in the CO2 series, the reason the surface of the earth is so much warmer than predicted from simple energy balance is because various trace gases, including water vapor and CO2, absorb the upward radiation from the earth’s surface and reradiate it in all directions. Despite these problems, all GCMs tend to show a linear relationship between the initial radiative forcing and the ultimate perturbation to the surface temperature, the difference between models lying in the slope of that relationship. Earth, but with a tiny 100% greenhouse gas atmosphere)? ). I’m still highly skeptical to say the least that any structure can make heat stay up hill other than the small amount calculated for the gravity well . If indeed CO2/ghgs did cause the PETM, and CO2 by itself did not because it did not rise before, then the PETM seems to suggest when CO2 does peak temp becomes independent of it [assuming any dependence] and the climate sensitivity must be less than IPCC assumptions. If have a model of the Venusian atmosphere and initialize it as isothermal at the surface temperature of 730 K, what happens? V is a dependent variable and is determined by P and T. I must disagree. Emission spectrum of an object. greenhouse gases and other atmospheric variables Calculate the value of the 'solar constant' on Mercury, Jupiter? Consider Venus with it’s existing atmosphere, and put a totally opaque enclosure (to incoming Solar radiation) around the entire planet at the average location of present outgoing long wave radiation. I think that should be “when the lapse rate exceeds the adiabatic lapse rate”. Do you think this is right? This is not right as then it could be greater than one for a very thick atmosphere. Again, we have to measure the temperature of All the IR radiation from the surface gets absorbed at very low altitude and then transferred further by the conduction-like radiative process and convection. It is the net surface radiation that you need. These create the atmospheric motions that, through the adiabatic mechanism, maintain the lapse rate. Because of the quantized nature of radiation, an object can emit radiation at a certain wavelength only if it absorbs radiation at that same wavelength. The solar year of Venus should be shorter than the solar year of Mars because Venus is closer to the sun, so its rotation around the sun should take less time than a full rotation of the Sun for Mars. SOD, Yes, that is precisely what I wanted you to see, and understand. In the "symmetric stretch" mode the CO2 molecule has no dipole moment, since the distribution of charges is perfectly symmetric; transition to a higher energy level of that mode does not change the dipole moment of the molecule and is therefore forbidden. In the case of Venus, it’s a long way down. I learned about this reference after writing my above comment. First of all, you forget to mention that on top of Venus’ atmosphere temperatures are very low, about – 33° C, while on the middle of the atmosphere temperatures are about + 20°C, and so it is impossibile that on Venus there could be a “backradiation” from atmospheric colder gases and CO2 which could “heat” the surface up to 464° C, It is correct – as Steven Goddard said – to consider the very high pressure at the surface, i.e 92 bars compared with only 1 bar on Earth surface as the main factor that can explain the huge temperature. The explanatory reason for this is that as the “surface” temperature increases, the thermal spectrum moves to shorter and shorter wavelengths. (As Motl points out, Goddard’s analysis (as usual) isn’t properly grounded in fundamental physics, so the question really comes down to SOD vs. Direct human perturbation to water vapor (as from combustion or agriculture) is negligibly small compared to the large natural source of water vapor from the oceans. I haven’t read your other replies and I doubt that I will. For the actual case of Venus, the different Solar angles at different latitudes cause Hadley cell circulation and the planet rotation (and thus temporal variation of Solar insolation) causes more circulation. Formula To calculate the solar constant, it is enough to divide the energy flow that the Sun emits by the ratio of areas between the surface of the Sun (the solar radio) and that of … paper on trend exaggeration for 2 m mounted thermometers. N&Z’s theory is the complete opposite of strongly predictive. Many people have written about the evolution of the Venutian atmosphere… Just use google scholar. If you know the temperature profile and the concentrations of various gases (primarily water vapor, as it varies the most) then you can calculate accurate values of atmospheric radiation. As a result it radiates almost the same energy as the surface did before the cloud formed, and there is little greenhouse warming . Another important point from the above discussion is that all greenhouse gases are not equally efficient at trapping terrestrial radiation. So my argument that heat transfer by conduction is higher at the surface of Venus than the Earth is wrong. See my http://CoSy.com for the quantitative implementation of these relationships for gray spheres , and the offer of a cash prize to any student extending them to full spectra . The lapse rate must be locally at least the adiabatic lapse rate that applies to the composition of atmosphere at that point. represents something desperately needed to help elevate the level of debate between the public and climate scientists. Total flux or what? There is presently much interest in developing an international environmental policy aimed at greenhouse gas emissions. Yet another definition of the flux distribution function is relative to the wavenumber n = 1/l = n/c. The temperature profile varies with altitude and time exactly as expected for diffusive heat transfer from warm air to a cold surface. 2. More generally, molecules that can acquire a charge asymmetry by stretching or flexing (CO2, H2O, If the increase in greenhouse gases moved the height of the radiation going to space, this would change the surface temperature, but in the case of Venus, the change would be relatively small for a huge change in greenhouse gases. 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