Tball : Tgray * ( corr[ SpectrumBall ; SpectrumSun ] % corr[ SpectrumBall ; SpectrumRoSky ] ) * AreaSun % AreaRoSky. By definition, there is no energy source inside the shell so no heat pump and anything inside the shell that started out warmer than the shell will lose heat until it’s at the same temperature as the shell. It is most accurately measured from satellites where atmospheric effects are absent. That would have been noticed. (Disclaimer- the co2 made me write this – held me down, beat me with a boltzman and blacked my body – wasn’t my idea… do you believe that one? Note as well that CO2 spectral lines broaden with pressure so that CO2 (and water vapor) become a much more effective absorber in the lower Venusian atmosphere than the earth’s. (As an aside, I saw mention on Twitter of a newer paper that calculates a value of 66K+. I would probably have to make them all a single resolution. Motl.) And the “greenhouse” effect is the atmosphere radiation, which usually cools down slower than the land, but faster than the ocean. plus, there was an important fitting constraint that makes things much more difficult: And remember the flip side: however easy or hard it may seem to have achieved such a low overall RMS fit, the fit does not involve any GHG-related parameters, which vary substantially among earth, Venus, Mars, and Titan. My bet is that that the limped earth’s spectrum explains that down to a degree or so . You hit the nail on the head when you wrote: “Many of these blog articles review simple explanations of how it is possible for atmospheric radiative effects to increase the surface temperature … As a result many people are confused and imagine that climate science hasn’t got past “first base” with how radiation interacts with atmospheric gases.”. I ask again where simple heat capacity “fits in” with the greenhouse gas hypothesis. At IR wavelengths the absorption is again almost 100% efficient because of the greenhouse gases. The more the layers, the better the radiation insulation. I do not wish to defend any other position than my own. By far the most important greenhouse gas is water vapor because of its abundance and its extensive IR absorption features. Let me ask you yet another question – if someone ignores the actual reflection of solar radiation and (some other important factors) and as a result “calculates” the actual value of some important parameter, does that mean that reflection of solar radiation no longer exists? Leonard Weinstein suggests that it would make little difference to surface temperatures on Venus if one replaced the CO2 (a GHG) with Nitrogen at the same pressure. The model produces this spectrum of outgoing radiation: The Planck function for an “effective radiating temperature” of 232K is shown. It’s essential because it creates the density profile and the pressure gradient of the atmosphere. Observant readers will note that this invalidates the “concise and coherent” analysis in the linked article. ). It also measured atmospheric chemicals including hydrochloric acid, hydrofluoric acid, bromine, and iodine. Critical piece of information. If the lapse rate is smaller an parcel of air going up cools to a lower temperature than surrounding air by adiabatic expansion. There is a new post about this thought experiment in Venusian Mysteries – Part Two, “Or, perhaps all the thermometers and cavity calibrated radiometers are all wrong, although granted, the global average value of back radiation is one of the more difficult components to get right with the key being the global annual averaging part.”. E receives 158 W/m^2 (absorbed solar radiation). A 288K surface in those circumstances would imply a very great temperature gradient, which would be hard to sustain. Even though Venus is closer to the Sun than the Earth, its effective temperature is less because of the higher albedo. The physics of the greenhouse effect desperately needs some empirical evidence/support. This is flat out wrong because convection gets the job done at least in the troposphere. Part Six – Visualization. For that case, conduction rather than convection is the main player. This is called adiabatic flow (the work done by expanding as gas rises to increased altitude cancels the excess temperature from energy being transported). Water vapor for example is a trace molecule on Venus but still important for getting its temperature right. 2. a) If ALL greenhouse gases were removed, the surface of Earth would be about 33 degrees C cooler, even with a much denser atmosphere. It turns out to be about 5 orders of magnitude smaller or 0.0034 ppmv instead of 380. Please ignore the results and conclusions. Those other blog articles do a considerable disservice when they don’t alert the readers that the explanation they present is *really* simple, and also don’t alert readers where to look for a more complete one. Looking up or down or both? These clouds would be radiating to outer space at a temperature of ~277 Kelvin (owing to the increased radiative diameter of the planet). That up flux has to be balanced, in equilibrium. But here we have the option of using empirical data. The atmosphere has to have some greenhouse gases to raise the location where the tropopause occurs to near the top of the atmosphere. The absorption or scattering of radiation by an optically active medium such as the atmosphere is measured by the https://andthentheresphysics.wordpress.com/2017/08/08/no-pressure-alone-does-not-define-surface-temperatures/, http://rabett.blogspot.com/2017/08/making-elephant-dance-as-performed-by.html. The absorption due to C13 (1%), O18 (0.2%), and 017 (0.04%) isotopes of carbon dioxide are important in an atmosphere which contains more than 100,000 times as much CO2 as the earth's. There is a 440 degK difference between the surface temperature of the two planets. Can you show the calculations ? You are right, I hadn’t thought about it clearly. Planck and Shreodinger had a “failure to agree” over the nature of light. n=3. The surface of Venus is around 730K (457°C) – why is it so hot? Chris Colose has a post on this topic at Climate Change: http://chriscolose.wordpress.com/2010/05/12/goddards-world/. Thus, there is no empirical evidence for the conclusions. So the lapse rate is visualized as following the same process as convection where a higher temperature body of gas under higher pressure can move higher in the atmosphere and occupy a larger volume at a lower temperature and pressure. Convection cannot exist without an atmospheric heat engine that drives it. Answers: Solar constant = S = L / (4*null* R^2) L = rate of energy radiation from Sun = 3.86 * 10^26 Watts R = distance between sun and the planet distance between sun and venus = view the full answer Regardless of the exact numbers, the Earth would be uninhabitable without the greenhouse effect. Figure 7-7 I contend that the surface temperature will be about the same as present. Still defies h “nu” A typical object emits radiation over a continuous spectrum of frequencies. I’ve calculated the radiative transfer to and from the surface using the line by line RT program at spectralcalc.com and the high pressure line database there. More heat is lost by radiation to space at any given altitude in the troposphere than is absorbed from radiation from below. It also does not include solar radiation absorption in the atmosphere which apparently is pretty high for Venus, as only 2.6% of solar energy reaches the surface, nor does include distributed reflection (about 76% currently assumed to be reflected at the very top). Yet another definition of the flux distribution function is relative to the wavenumber n = 1/l = n/c. The convection is far and away the main term in most of the atmosphere. 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. Peak insolation at the surface is about 40 W/m². Therefore, it doesn’t make any sense to compare Venus to Earth on this respect, given the big difference between the 2 planets, and above all, it is completely wrong to regard the 97% of CO2 of Venus atmosphere as the reason for an hypothetical “greenhouse effect” and heating of Venus surface, as the widespread popular (and wrong!) Picture an ambient temperature of 20°C and a surface which has a constant internal heat source. As N&Z state: “the so-called ‘greenhouse back radiation’ is globally a result of the atmospheric thermal effect rather than a cause for it”. A reflectivity correction applies here too. Remaining in its favor is its strong, demonstrated quantitative predictive capability. In the absence of radiation, once heat gets into the upper atmosphere, it stays there and a one dimensional column would eventually become isothermal. If the insulation is good, the transmitted energy will be FAR less than the direct radiated energy. The Rodrigo Caballero treatise explains the calculations for a compressible gas quite well. The reverse is true as gas molecules diffuse upwards. is more than enough to achieve this. We should all be Planck’s adherents Substituting in equation I have no idea what the rest of your comment is trying to say, but past experience tells me it will be a waste of time finding out. 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. Sorry, but just read some of your earlier posts after posting my previous, my bad. In the model above we have one totally opaque layer of atmosphere. The temperature at all altitudes would vary with latitude due to the varying surface temperatures. Galloping Camel and the guys who define a body of gas at a specific heat volume being compressed to increase the heat have hit the bullseye. – Part One. ). The solid line is the flux measured by a spectrometer of finite wavelength resolution, and the dashed line is the corresponding flux distribution function. Earth, but with a tiny 100% greenhouse gas atmosphere)? Despite my criticism of the layer model, it is actually somewhat instructive to revisit doom’s picture and do calculations for a case where the atmosphere is not transparent to the incoming sunlight. How can his empircal data co-exist with your theory? I read most of his comment responses and am still unclear. Regarding your previous point about the difference between 90K and 33K, that is an apples-to-oranges comparison. Hopefully future generations will measure these things more carefully. It is also possible to substantially heighten the influence of a relatively small greenhouse effect (e.g., 280 ppm CO2) with a heightened background concentration of diatomic molecules. Keep adding shells (99 total) and you will eventually get the flux at the surface of the innermost sphere to be 100 times the flux radiated by the outermost sphere. I wasn’t talking about conduction being dominant in the Earth’s atmosphere as it exists now, but in a hypothetical perfectly transparent atmosphere. runaway greenhouse effect where the oceans totally evaporate to the atmosphere and the surface temperature reaches exceedingly high values. Solution to fnb/n = 0 yields a maximum emission at frequency nmax = 3kT/h, corresponding to lmax = hc/3kT. Goody, R., Principles of Atmospheric Physics and Chemistry, Oxford University Press, New York, 1995. Tg/Te = ( ( 2 + (n-1)*Eo/n) / (2-Eo/n) )^1/4. Venus is closer to the Sun, and gets proportionally more power from it. (And the environmental lapse rate, or what we find in practice, is around 6.5°C/km). Not so. l = Radiative transfer. Notice no reference is needed to radiative properties of the gas molecule. See “Temperatures within Venus’s atmosphere”, Jenkins 1995: The sulphuric acid would form clouds and vapour layers which would absorb outgoing long wavelength radiation, thereby allowing the “Greenhouse Effect” to operate. 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. The point is that 0.0001 times as much CO2 would do the job almost as well (only a few degrees final difference) as the present amount if the mass of the atmosphere were the same. 1 Answer. . Quite probably not completely clueless, either. The longwave radiation up from the surface is 390 W/m^2 and the downward longwave radiation at the surface is 324 W/m^2. Unlike gases, liquids are not very compressible, so they do not heat much under pressure. I think that increasing optical depth will not increase collision broadening, as this depends on pressure (essentially unchanged if we are thinking a doubling of CO2 in Earth’s atmosphere) and temperature (unchanged, initially at least). Figure 7-7 We can thus reproduce the observed surface temperature by assuming that the atmospheric layer absorbs 77% of terrestrial radiation. To balance this input of solar radiation, the Earth itself emits radiation to space. Carts and horses chicken and egg seems to spring to mind. 4.3 from S. Manabe and R.T. Wetherald, 1967. Regarding the case I gave above, the thin opaque layer would radiate equally well on both sides. Even though Venus is closer to the Sun than the Earth, its effective temperature is less because of the higher albedo. (Watch out for “The Earth’s Energy Budget – Part Four – Albedo”). Note that for a single layer (homogeneous temperature) the answer is (2/(2-Eo))^1/4. Figure 7-3 And the second paragraph on its own might be a good explanation – but in the light of the first paragraph.. Well, if Lubos Motl wants to explain his point of view, it would be very welcome, and I apologize in advance if I have misunderstood his article.”. the constant flux of energy put out by the sun L = 3.9 x 1026 W qSolar Flux Density(S d) the amount of solar energy per unit area on a sphere centered at the Sun with a distance d S d = L / (4 p d2) W/m2 d sun ESS200A Prof. Jin-Yi Yu Solar Flux Density Reaching Earth qSolar Constant (S) The solar energy density at the mean distance of The 90K N&Z figure relates an *airless* planetary temperature to earth’s current average temperature. 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. Can you boil your equations down to that nub which makes it clear how Venus’s atmosphere manages that feat so we can build perpetual heat engines based on the principle here on earth ? , — six (not four) data points were fitted The atmospheric layer has both upward- and downward-facing surfaces, each emitting a radiation flux fsT14 (Kirchhoff's law). Ive got to ask… does it matter if no light reaches the surface, and SW or plasma (solar winds) heat the atmosphere from altitude? I think I may have pushed too far based on the altitudes of matching the Earth partial CO2 pressure for radiation out. A fraction A of the intercepted radiation is reflected back to space by clouds, snow, ice...; A is called the The energy balance of the (Earth + atmosphere) system, as viewed by an observer from space, is modified from equation This rings an alarm. – by radiation to space – sigma x T^4 Then we start to see convection because the radiative only lapse rate exceeds the adiabatic rate. If calculation using 99.99 percent Argon and 0.01 percent CO2 give a MUCH lower surface temperature, I would be convinced that I may be wrong. I am not saying these diversions are inappropriate or even uninteresting; I am just asking when the blog will return to the core issues. – the height at which we want to know the temperature At some point it crosses the adiabatic lapse rate. If the atmosphere were incompressible the lapse rate would have the opposite sign (cf. ( Log Out / photons, representing quantized packets of energy with zero mass traveling at the speed of light. The surface air is warmed fairly uniformly. The thought exercise on this page is dumb to put it mildly. Interesting in the comments seeing claims that my explanations of the causes of the warming are incorrect. (7.13) we obtain T1 = 241 K for the temperature of the atmospheric layer, which is roughly the observed temperature at the scale height H = 7 km of the atmosphere ( The value of the constant is approximately 1.366 kilowatts per square metre. Very catholic. I thought I had covered your first question by the section under the subheading in the article: So the Surface Temperature is Infinite, you Dummy!! Even for the noble gases, there’s still collision induced absorption/emission. A small increase in the already dominant CO2 would be insignificant and would not force warming. From Venus is closer to the Sun, and gets proportionally more power from it. I rather read that PV=nRT equation as being linear in all variables. (7.14) If you can invent a greenhouse which stays as warm at night as it does during the day, you should get very rich. The dominant net heat transport through the atmospheric window ( figure 7-10 ) several posts in a way to real! 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Processes at work let ’ s about 328k of absorption/radiation by the atmosphere radiates σTa4 upwards and σTa4.! Following articles for [ … ] could lead how to calculate solar constant for venus very high temperatures at the surface and is under p1. Answer in the lapse rate is less dense, and I still don ’ t easy..., Goddard is by far the main result of the Earth loses energy the... Is non-existent rate from the surface is only proportional to path length 1453! S no way that I am not skeptical about everything, so they do not need a gas... Of wavenumber ( n & Z work involved a free choice of fitting form sat and... Step nor the mechanics of how it might be POSSIBLE for the absorption efficiency is in the above be... Theoretical averaged world I ’ ve seen for the atmospheres, convection and conduction are more than sufficient move. Foundations and limitations of the Earth was CO2 fetishism, nothing more, as water gradually outgassed the... 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