Discussion > GHG Theory step by step
The standard approach is…That does not necessarily mean that it is the correct approach.
What a lot of people seem to be overlooking is that the Sun is lighting up slightly more than half the hemisphere, and shining through more than half the atmosphere, at all times.
Nobody here objected.Because nobody here could be arsed? Most people here have long come to the conclusion that arguing with you is like knitting fog, so few really bother. It can be fun prodding you every so often, to see what new blather comes out – such as one scientist is wrong about the IPCC, probably ‘cos the IPCC must be infallible (it is a massive governmentally-funded body, with a vested interest in keeping the alarm going, after all…), and we can ignore ALL history that shows that it only takes one scientist to upset so much accepted “science” – but even that can get a bit wearisome.
Clipe: probably did it in free verse…
Radical Rodent
The albedo of the moon is 0.12. Why would airless lifeless Earth be any different. Again, every sum I've seen to establish the overall effect of greenhouse gases at 33C has been invalid. Now, I don't regard that number to be essential to the AGW argument, but I am concerned at how often it is trotted out and that makes me think that there is no rigour in their methods, just flash.
Anyhow, do you, EM expect the average temperature as measured with thermometers and corrected and adjusted by appropriate methods to be the same for a non-rotating planet and for a fast rotating planet with the same insolation and albedo? Yes or no? Will it all balance out at the S-B number? This to inform me as to whether you understand the problem any better than you understood lapse rate back on page 1.
rhoda
Radical rodent
"arguing with you is like knitting fog"
I wrote something very similar about you last night, but then deleted it as impolite.
Rhoda
" airless lifeless Earth"
You are picturing a GHG free Earth as rather like the Moon. I think not.
Earth has oceans (albedo 0.06), ice (0.5-0.9), cloud (0.5), biomes( 0.1), desert and dry earth (0.3)
The first GHG to be gone is the water. That eliminates ice albedo, ocean albedo and cloud albedo. Without water, as you say, there is no life. That eliminates forest, grassland and all biome albedo. With no life there is, of course no oxygen.
What is left is a cold desert (albedo 0.3) bathed in strong sunlight and strong UV,rotating every 24 hours,hot during the day and ( with nothing to insulate) very cold at night, but not a vacuum. The 79% nitrogen and a few trace gases still remain.
The Moon varies between albedo 0.06 for the darkest crater floors and 0.18 for the Aristarchus peaks. You hold up a value of 0.12 like a talisman, but it is just another average, and you do not believe in averages.
Schrodinger's cat
"The difference is attributed to GHG. As rhoda points out above, the IPCC is wrong."
Was there gold among all that dross? What did I miss?
Entropic man
What did I miss?
The point, dear boy, the point.
rhoda
A Bond albedo is an average. Sometimes averages are OK. I don't have any problem with using it in the S_B equation to get 255K for the ghg-less Earth. I have a reservation about assuming Earth's albedo differs from the theoretical albedo you use for non-ghg Earth but never mind, it isn't crucial.
You have 255K from S-B. I think it is wrong to compare that ieal fiure against observed temperatues hashed into an average and currently agreed to be around 288K. I will tell you why. The earth is not a uniform 255K. Some parts are 255 + x, some are 255 - x and it balances out arithmetically to 255. The trouble is that when they radiate, they radiate proportionately at (255 + x)^4 and (255 - x) ^4. If you calculate the radiation the second sum, where x is a positive value not exceeding 255, it will always give a larger radiation figure than with a uniform 255. Mathematically it just has to. Now we know the sum of the radiation cannot, in equilibrium, be more than insolation, so in fact with a non-ideal non-uniform Earth with the same average temperature by measurement in fact will radiate more, so in practice a slighly lower temp than 255 will provde enough radiative power to reach the same level as insolation. Therefore you should not compare the arithmetical average with the S_B derived figure, you should not subtract one from the nother to get a GHG figure.
Also if you find from a satellite that the Earth radiates at an observed 240K, you should consider further before you make up a story about tropopauses and lapse rate and create a bogus 150 watts/sqm.
rhoda
*…sigh…*
What is left is a cold desert (albedo 0.3) bathed in strong sunlight and strong UV,rotating every 24 hours,hot during the day and ( with nothing to insulate) very cold at night, but not a vacuum. The 79% nitrogen and a few trace gases still remain. [sic]Is this a case of, “Let’s abandon all logic to preserve my pet theory,” Entropic man?
Yes, the surfaces will be hot during the day. The atmosphere, GHGs present or not, will be warmed by conduction when in contact with these hot surfaces. With the convection generated, this heat will be distributed throughout the atmosphere. At night, the surfaces will cool by radiation to space. Any air in contact with the surfaces will also be cooled; if that air is moving, the atmosphere will be cooled – freezing at the surface will only happen when there is no air movement (except, perhaps, at higher latitudes); the air above will not cool excessively (how could it? It is non-radiative gases). This will happen on all planets with an atmosphere, irrespective of the composition of that atmosphere – even planets without water will have complex weather systems, as the simple system of air circulation gets influenced by other factors (rotation, topography, surface composition, solar wind – even, as noted earlier, by cosmic events).
Radical Rodent
Radical rodent
" Freezing at he surface"
What is going to freeze? There is no water and no CO2. Nitrogen freezes at -210C. I doubt that a 24 hour rotation and heat circulated by the atmosphere would ever let it get that cold. At least we can ignore latent heat. There would still be something analogous to Hadley circulation. The vertical temperature profile would be very different. No troposphere. No ozone layer. No mesosphere. The atmosphere would cool with a constant lapse rate from the surface all the way to the thermosphere.
I am not sure if there would be convection. With most of the incoming heat radiating directly from the surface back to space and only the black body radiation of the nitrogen to cool the atmosphere, the lapse rate might be too low to drive convection.
The presence of a nitrogen atmosphere and nothing else is partly why I expect a planet covered with sand. Wind erosion will be the dominant form of weathering.
Rhoda
Bond albedo for Earth is 0.306 and black body temperature is 254C, at least according to this source of astronomical data.
Entropic man
254C? You sure?
rhoda
Rhoda
I tried the SB calculation for zero greenhouse gases and different albedos.
For 0.12 the incoming/outgoing energy is 313W/m^2 and the black body temperature is 273K.
For 0.2 the energy is 272W/m^2 and the black body temperature is 264K.
For 0.3 the energy is 240W/m^2 and the black body temperature is 255K.
For 0.4 the energy is 204W and the black body temperature is 245K.
Lowering the assumed albedo for the non-GHG case decreases the difference between the GHG and non-GHG, but does not eliminate it. Even at your preferred Bond albedo of 0.12 there is still a 15K difference in surface temperature which must be explained by GHGs or your alternative hypothesis.
Entropic man
Rhoda
Sorry, 254K.
Entropic man
Radical rodent
Looking for something else I ran across your statement that Huffman explained why you get Earth surface pressures and temperatures together in the atmosphere of Venus.
Actually you don't.
Look here .
Earth's surface average temperature of 288K (15C) occurs at a height of 50km and 1000bar pressure.
At the Earth equivalent 1 bar pressure altitude of 86km the temperature is 180K( -93C).
Entropic man
To be clear, I'm happy with the 255K for Earth now and with 273K for the moon now. I feel this discussion is getting bound up with the hypothetical. None of us know, for sure, what the hypothetical barren Earth would be like, I suggest it would be like the moon and the relevance of this is that the actual measured temp of the moon doesn't match the SB ideal temp, it seems to be lower. I reckon that will be the case for any non-ideal planet, that is every planet we can imagine. Wherever there is local variation of albedo or temperature, even though it can be averaged out arithmetically, that measurable average MUST be lower than the SB number.
The appearance being that warmists are apt to use numbers they don't understand. That 33C should be..more?
rhoda
EM - If I understand you correctly, you are saying that the description of the IPCC method of calculating the energy received by the earth is wrong.(I refer to a comparison between the disk approximation and the integrated solution calculated by Nikolov.
You say that the energy is halved because of no light at night and is halved again because it is a hemisphere. You say that this second division is wrong because the hemisphere receives 100% of the light.
That is not the reason for the second division. The light arriving at the surface is at a maximum at the equator and diminishes towards the poles, that is the reason for halving it a second time.
see https://earthobservatory.nasa.gov/Features/EnergyBalance/page2.php
Schrodinger's Cat
Trying to sum up at this stage.
I’ve not been able to follow all the threads of debate because some seem to relate to earlier discussions. Feel free to summarise them if appropriate.
Most of us think that the lapse rate is the consequence of gravity and the gas laws and does not require GHG. I don’t think we reached a clear conclusion on whether the lapse rate is unduly affected by GHG presence, other than water vapour which is capable of phase changes which do affect the lapse rate.
We discussed the disk approximation route used by the IPCC to determine the absorbed solar energy and the rival calculation which is alleged to “do it properly”.
We note that the respective surface warming extents are 33 and 90 degrees respectively. If the second method is correct, that is a problem for GHG theory. I suggest we note that but move on. (Hopefully the great and the good will reach a conclusion some day and tell the rest of us.)
EM, you are a fan of the IPCC, would you like to move us on to the next stage?
We must be getting to the stage where the planet loses heat.
Schrodinger's Cat
rhoda - You have been challenging the measurements and numbers, pointing out that the whole climate scheme depends on a couple of numbers in the SB equation. That bothers me too, together with little details such as how do we know if the SB equation works with planets with water or planets with atmospheres?
I don't know what we can do about these concerns other than to recognise that they exist. Any thoughts?
Schrodinger's Cat
I've just realised we haven't given albedo a good bashing yet.
Schrodinger's Cat
Entropic man: not sure you fully understand what the nice Mr Huffman has said about the temperatures and pressures on Venus. He did NOT say that, at altitudes where the Venusian atmosphere was Earth-equivalent pressure, the temperatures would be the same as Earth’s is in its present orbit; he said that, at altitudes (i.e. 49.5km) where the Venusian atmosphere was Earth-equivalent pressure, the temperatures would be the same as Earth’s would be, should its orbit be the same distance from the Sun as the orbit of Venus: i.e. 66°C (339K), both figures your link conveniently confirms.
Nice of you to pick up on my little faux pas of the subjective reference of “freezing,” rather than the more objective reference “very cold” (even if “very cold” is, in itself, also a subjective reference; very cold compared with… what? Perhaps “considerably colder” might have been better, but is still a flawed statement.). However, it is puzzling that you should claim that there would be no troposphere or ozone layer, as I do not understand why the atmosphere of “79% nitrogen and a few trace gases” contains no oxygen; you seem to be excluding a lot more from this hypothetical planet than just “greenhouse gases;” I mean, who knew “a few traces gases” could amount to 21%? One source of ozone is solar interaction with oxygen in the atmosphere; another is lightning, which I am sure will be as prevalent on this hypothetical planet as it is on the real one, even if the cause might be different.
Radical Rodent
Sorry, Mr Cat; I was referring to Harry Dale Huffman, who posted a blog some 7 years ago comparing the Venusian atmosphere, which, at some 97% CO2 (or more than 11 “doublings” of Earth’s CO2), has temperatures at altitudes where the pressure is Earth-equivalent which are the same as Earth’s would be, if the same distance from the Sun. All can be found here: http://theendofthemystery.blogspot.co.uk/2010/11/venus-no-greenhouse-effect.html, complete with figures, calculations, etc. Interestingly, I have yet to see this hypothesis debunked; all I have ever seen is ad hominem attacks on Mr Huffman (who, it has to be admitted, does come over as rather irascible).
By the way, he does consider albedo, but reaches the interesting conclusion that it is actually irrelevant to the planetary temperatures – it is only the distance from the primary energy source (the Sun) and atmospheric density that influences temperatures.
Radical Rodent
RR-Thanks for the link. Then I found this discussion:
https://tallbloke.wordpress.com/2014/06/28/venus-surface-temp-correctly-predicted-from-lapse-rate-in-1967-but-is-it-the-whole-story/
Schrodinger's Cat
Radical rodent
The Earth' s current atmosphere is about 79% nitrogen, 21% oxygen and odd bits.
On the non-GHG Earth the oxygen and water vapour have gone, but the nitrogen remains. That 79% represents the amount in our atmosphere. In the non-GHG atmosphere the same quantity of nitrogen would represent almost 100% of the atmosphere.
Incidentally, look at the graphs again. Earth equivalent pressure (1 bar) is at 85km, not 49km.
Schrodinger's cat
Rhoda and I have given albedo something of a bashing. I think we have agreed that Earth's Bond albedo of 0.3 is about right. She thinks that my albedo estimate for a non-GHG Earth is too high, but a low albedo reduces the difference between incoming energy and radiation from the surface without getting rid of the anomaly. Even without GHGs that would have to be explained somehow.
On the validity of the SB equation:
It is widely used in science, technology and engineering. For example, it is used to calculate radiative heat loss from the top of a blast furnace. If it didn't work, it would be obvious by now.
It also goes deeper. The SB equation emerges from the way atoms and molecules exchange energy with their environment and from atomic theory. If that is wrong we need a whole new physics.
Huffman is a red herring He produced something vaguely resembling the pressure warming theory, but he double counts albedo radiation as warming the atmosphere as well, violating the 2nd law of thermodynamics.
Entropic man
No problem with S-B, as I have said many times. Big problem with using that ideal temperature result to compare with non-ideal radiators and using that as a real number. It is not. In real life any non-ideal planet with varying temperatures and albedo resulting in the same number as an arithmetic average will radiate more heat than the uniform ideal until it reaches equilibrium at a lower average temp than the S-B number.
I'm surprised that you, EM, either don't understand this or won't admit it. If you do understand it and think I'm wrong, explain how.
rhoda
Rhoda
I don't understand it, perhaps because I look at the planet as a whole.
The planetary energy budget can be summarised as
insolation-albedo = OLR
Insolation is the.total energy intercepted by the planet by the planet from solar radiation, 1.74× 10^17 watts.(see earlier posts for the calculation).
Bond albedo of 0.3 reduces that to 1.74×10^17 × (1-0.3) =1.22× 10^17 which is absorbed by the atmosphere and the surface.
1.74 × 10^17 - 1.22 × 10^17 = 0.52 ×10^17. This is the measurable outward visible radiation, who's the Earth's brightness in the visible spectrum and the basis for calculating the Bond albedo.
If the planetary temperature, however you calculate or measure it, is to remain stable, the outward energy flow from the surface and atmosphere must equal the must equal.the incoming energy flow
For Earth insolation-albedo=OLR.
1.74 ×10^17W - 0.52 × 10^17W = 1.22 × 10^17W
To help me understand your viewpoint, perhaps you could calculate your own version of the planetary energy budget. Show your working so that I can see how you are thinking.
Entropic man
Your numbers are fine. Let me put my reservations in another way. The Earth is not uniform or homogeneous. Some bits radiate more and some less. Because of the fourth power thing, the hot bits carry far more of the burden. Thay are so much more efficient at radiating the insolation that the inferior contrbution of the cold bits doesn't matter. The poles do virtually nothing to help with their high albedo and low temps. Unequal distribution of the work with the far more efficient hot bits means the arithmetical average temperature need not be so high as the S_B ideal.
Look at it this way. a 10% increase in energy (for which temperature is merely a proxy) engenders a 46% increase in radiation. A 10% loss gives a 35% decrease in radiation. A net increase in outgoing radiation with NO CHANGE in the average. By my reckoning every case of a non-ideal planet will have a lower actual mean temp than the ideal.
Inevitably.
That's the figure you need to compare. Never 255K. It's probably around 240K (tongue in cheek emoji).
rhoda
Sorry, Entropic man, but repeatedly studying the graphs in that link indicate that it is you who has misread them. The first graph, labelled “Temperature of Venusian Atmosphere,” shows the temperature at 49.5km to be 339K, or 66°C; the second graph, labelled, “Pressure of Venusian Atmosphere,” shows the pressure at 49.5km to be 10^3 (1000) mbar, or Earth sea level atmospheric pressure. The final graph, labelled “Temperature versus Pressure – Venusian Atmosphere,” confirms the first two. If you cannot see, or refuse to believe, what is in front of your eyes, in a link that you have provided, then it is pretty pointless continuing further. (BTW, your final two sentences in your Jul 29, 2017 at 2:35 PM posting make no sense, at all. Could you please clarify?)
Why have you removed oxygen? It is not a “greenhouse gas,” is it? What would be the commensurate loss in pressure?
As another aside, could you tell us when the Earth’s energy budget has ever been in equilibrium for any appreciable time?
Radical Rodent
Jul 28, 2017 at 12:54 AM | Unregistered CommenterEntropic man
Lousy copy and paste.
The 800 year lag in CO2 after temperature – graphed