Guest Post by Willis Eschenbach
Once again, the crazy idea that downwelling longwave radiation (DLR, also called infra-red or IR, or “greenhouse radiation”) can’t heat the ocean has raised its ugly head on one of my threads.
Figure 1. The question in question.
There are lots of good arguments against the AGW consensus, but this one is just silly. Here are four entirely separate and distinct lines of reasoning showing that DLR does in fact heat the oceans.
Argument 1. People claim that because the DLR is absorbed in the first mm of water, it can’t heat the mass of the ocean. But the same is true of the land. DLR is absorbed in the first mm of rock or soil. Yet the same people who claim that DLR can’t heat the ocean (because it’s absorbed in the first mm) still believe that DLR can heat the land (despite the fact that it’s absorbed in the first mm).
And this is in spite of the fact that the ocean can circulate the heat downwards through turbulence, while there is no such circulation in the land … but still people claim the ocean can’t heat from DLR but the land can. Logical contradiction, no cookies.
Argument 2. If the DLR isn’t heating the water, where is it going? It can’t be heating the air, because the atmosphere has far too little thermal mass. If DLR were heating the air we’d all be on fire.
Nor can it be going to evaporation as many claim, because the numbers are way too large. Evaporation is known to be on the order of 70 w/m2, while average downwelling longwave radiation is more than four times that amount … and some of the evaporation is surely coming from the heating from the visible light.
So if the DLR is not heating the ocean, and we know that a maximum of less than a quarter of the energy of the DLR might be going into evaporation, and the DLR is not heating the air … then where is it going?
Rumor has it that energy can’t be created or destroyed, so where is the energy from the DLR going after it is absorbed by the ocean, and what is it heating?
Argument 3. The claim is often made that warming the top millimetre can’t affect the heat of the bulk ocean. But in addition to the wind-driven turbulence of the topmost layer mixing the DLR energy downwards into lower layers, heating the surface affects the entire upper bulk temperature of the ocean every night when the ocean is overturning. At night the top layer of the ocean naturally overturns, driven by the temperature differences between surface and deeper waters (see the diagrams here). DLR heating of the top mm of the ocean reduces those differences and thus delays the onset of that oceanic overturning by slowing the night-time cooling of the topmost layer, and it also slows the speed of the overturning once it is established. This reduces the heat flow from the body of the upper ocean, and leaves the entire mass warmer than it would have been had the DLR not slowed the overturning.
Argument 4. Without the heating from the DLR, there’s not enough heating to explain the current liquid state of the ocean. The DLR is about two-thirds of the total downwelling radiation (solar plus DLR). Given the known heat losses of the ocean, it would be an ice-cube if it weren’t being warmed by the DLR. We know the radiative losses of the ocean, which depend only on its temperature, and are about 390 w/m2. In addition there are losses of sensible heat (~ 30 w/m2) and evaporative losses (~ 70 w/m2). That’s a total loss of 390 + 30 + 70 = 490 w/m2.
But the average solar input to the surface is only about 170 watts/square metre.
So if the DLR isn’t heating the ocean, with heat gains of only the solar 170 w/m2 and losses of 390 w/m2 … then why isn’t the ocean an ice-cube?
Note that each of these arguments against the idea that DLR can’t warm the ocean stands on its own. None of them depends on any of the others to be valid. So if you still think DLR can’t warm the ocean, you have to refute not one, but all four of those arguments.
Look, folks, there’s lot’s of good, valid scientific objections against the AGW claims, but the idea that DLR can’t heat the ocean is nonsense. Go buy an infrared lamp, put it over a pan of water, and see what happens. It only hurts the general skeptical arguments when people believe and espouse impossible things …
w.
Tim Folkerts says:
August 21, 2011 at 5:53 am
“The one key detail you left out of your analogy is the sun!”
no I have not. where does the initial energy or heat come from
The sun and only the sun warms the planet. Back radiation does not. This GHG backradiation theory is just illogical nonsense.
My analogy is valid. At best LWR very slightly slows the cooling rate by a small fraction. But as radiation travel at the speed of light the reduced cooling is very small. Energy leaves the surface in part (but what %?) as radiation (at the speed of light) and a small fraction of this energy (4% at most) might return due to CO2. But with less heating impact than when it left the surface.
And as cool can not warm hotter etc. The GHG backradiation theory should be kicked into touch. Let warmists / alarmists hold onto it. But sceptics should no longer believe in this theory.
tallbloke says:
August 21, 2011 at 8:29 am
“Then something less than half of it gets bounced back down again”
Much less than half due to CO2. Around 92% of radiation leaving the surface just passes straight through CO2
So in fact less than half of 8%. (and this is only of the small percentage that does actually leave as radiation).
@Hockey schtick at August 21, 2011 at 9:11 am
////////////////////////////////////////////////////////////////////////////////////////////
Unfortunately, your response is typical of the confusion propagated in the AGW debate.
Solar cookers can concentrate ‘hot’ solar 5800K radiation to heat something/to cook. Solar cookers can concentrate ‘cold’ 250K and below DLR radiation to cool something/freeze something.
What solar cookers can not do is concentrate ‘cold’ DLR to in some way raise something above ambient temperature.
Contrast solar energy which we can use to produce electricity which can then be used to heat (your kettle) or cool something (your fridge), or we can use solar energy to run a turbine thence to create electricity etc. DLR cannot be used in this way.
@Hockey schtick
I fired off my last response without fully/properly reading your comment. Sorry for that.
I think that we are both agreed, that ‘solar cookers’ can when using DLR only cool, not heat. They do not demonstrate that DLR is somehow warming the ground or even slowing the rate of cooling.
OK. Tim, Willis, and all others who wish to contribute:
Please try use those (average, whole earth) values and equations to address this specific question at this specific location:
Two 1 square meter areas in the Arctic at latitude 85 are hit by energy. The first is smooth but ice-covered, the second is calm water, open ocean.
Each is hit by 50 watts/meter ambient rays from directly above, and by 100 Watts/meter^2 direct rays at 85 degrees incidence angle.
Emissivity of open water = .98; emissivity of ice = .99
Albedo of open water = 0.07; albedo of ice = 0.80
At 85 degrees zenith angle, 60% of received energy is reflected from a smooth surface.
Temperature of open water = 276K,
temperature top of ice = temp air = 274 K,
temp of space = 3K
What are the net radiation fluxes into (and out of) the two meter squares.
Why-o-why are you going on about why? Nowhere in my comment did I use that word.
Obviously, you have never hunted rabbit or any other game for that matter. Rabbits are not rubber toy balls thrown for your dog to intercept. They have little rabbit brains and big rabbit eyes which see a dog on a intercept vector, and change course frequently. A successful hunt of any game depends on knowledge of the game and his habits and habitats. Knowing why a (ie) rabbit behaves like a rabbit is essential to predicting where he will be. However I cannot see what any of this has to do with photon annihilation. GK
Ian W says:
August 15, 2011 at 2:54 pm
If the light is at any angle less than about 40 degrees then most of the light reflects from the surface (see Willis’ last post). This reflection of sunlight at low angles of insolation is another reason that the sunlight on the oceans near the poles does not warm the water much (as you pointed out).
This is incorrect, 50% reflectivity occurs at angles of less than 10º to the horizontal, the Brewster angle for water is ~53º.
Tim Folkerts,
“Of course, this is a gross over-simplification.”
Yes it is. You left out the major player, convection, that GHG’s encourage, that takes all that extra heat the GHG’s transfer to their local parcel to the upper trop where it is radiated away.
Tallbloke,
“Where does ‘back radiation come from? Well, it was first emitted by the ocean, thereby cooling it. Then something less than half of it gets bounced back down again, along with ‘new’ longwave derived from the absorption of solar shortwave in the atmosphere.”
I would suggest that it may be much worse. That is, in the lower trop, GHG’s collide with other particles more often then emitting spontaneously. This would mean a lot of that energy would be used in warming the local parcel and driving convection instead of being radiated up and down. I would love to see some paper on what the breakdown actually is!! Apparently this holds at least until we get to the strat where the pressure is much less.
RACookPE1978 says: August 21, 2011 at 1:50 pm
>Please try use those (average, whole earth) values and equations to address
>this specific question at this specific location:
I’m not sure what your point will be, but I’m game. I will use your numbers, which seem to be in the right ballpark, but which I have not verified independently.
>Each is hit by 50 watts/meter ambient rays from directly above,
I am assuming these are the “DLR” (thermal IR) from the atmosphere.
>Emissivity of open water = .98; emissivity of ice = .99
Well, this allows us to figure out how much IR is absorbed
WATER: 50 W/m^2 * 0.98 = 49 W/m^2
ICE: 50 W/m^2 * 0.99 = 49.5 W/m^2
>and by 100 Watts/meter^2 direct rays at 85 degrees incidence angle.
OK. I take this to mean the solar radiation.
>Albedo of open water = 0.07; albedo of ice = 0.80
>At 85 degrees zenith angle, 60% of received energy is
>reflected from a smooth surface.
Now we can get the incoming solar energy
WATER: 100 W/m^2 * (1-0.07) * (1-.60) = 37.2 W/m^2
ICE: 100 W/m^2 * (1-0.8) = 18.6 W/m^2
[I am assuming that the albedo of the ice is angle-independent, since the ice tends to have a rough surface, not a smooth reflecting surface. If this is not the assumption you were making, then you will need to specify the conditions and/or give the refelction from this particualr patch of ice at 85 degree angle]
>Temperature of open water = 276K,
>temperature top of ice = temp air = 274 K,
>temp of space = 3K
This allows us to get outflowing IR energy
ICE: 0.0000000567*(274^4)*(0.99) = 316 W/m^2
WATER: =0.0000000567*(276^4)*0.99 = 326 W/m^2
[The temperature of space is not directly relevant for two reasons. 1: the number would be so small that it would be negligible 2: You already specified the total incoming flux as 50 W/m^2, which would include radiation from both the atmosphere and from space.]
Both scenarios have a net outflow of energy of about 250 W/m^2. Both the ice and the water would be cooling in these circumstances.
So now that I have done this, what was your point???
Myrrh says:
August 17, 2011 at 3:05 pm
Visible light and and the two shortwave energies either side of UV and Nr Infrared are not thermal energies,
That means they do not heat things.
You are not scientists if you ignore this challenge.
As you have been told many times before you are totally wrong with this assertion.
As proof when I focus my frequency-doubled Nd:YAG laser (532nm, green) on a cloud of soot the soot particles sublime (T ~4500K), they have been heated by the green light. The same experiment can be done using the undoubled light (1064 nm, IR).
Tim Folkerts says: August 21, 2011 at 11:55 am
Your own “proper equations” show that GHGs & clouds reduce energy loss by ~ 320 W/m^2 from the surface.
Wrong, Earth emits to space the exact same amount of energy it receives, as the satellite observations show. The surface is hotter with an atmosphere than without due to pressure – i.e. the adiabatic lapse rate -no GHE necessary. Using the adiabatic lapse rate alone without any GHE fully explains the temperature profiles of Venus, Earth, and Mars. Trying to explain the same with a GHE leads to an underestimate of Venus temp by 419C, and overestimate of Earth by 23C and Mars by 19C. Radiative transfer CANNOT be considered in isolation without the rest of thermodynamics, and pyregometers CANNOT be used to determine HEAT FLOW.
Tim Folkerts @ur momisugly August 21, 2011 at 12:36 pm
Tim, I think something is missing, for instance dew usually forms on still nights, so your carport would mostly not be well ventilated. Also, my car, right now in the open, has dew on its vertical windows, so how do they emit and absorb “ULR” and “DLR“?
Radiation from a surface is not just up, but in all directions equally and hemispherically. Radiation from the air is in all directions equally and spherically. Lateral radiation is much greater than up and down.
Phil. @ur momisugly August 21, 2011 at 3:24 pm
You are wasting your time with Myrrh
For instance, when I pointed him to the following in Wikipedia, he retaliated with: an incandescent bulb emits 95% IR which is thermal, and how they use water cooled bulbs to maximise plant growth. (paraphrasing)
Bob_FJ says: “Tim, I think something is missing, for instance dew usually forms on still nights, so your carport would mostly not be well ventilated. Also, my car, right now in the open, has dew on its vertical windows, so how do they emit and absorb “ULR” and “DLR“?”
I was trying to make the preemptive point that difference was NOT because the air was warmer under the carport, which would ALSO prevent dew. The difference is the “DLR” from the roof of the carport. Since the car-port is warmer than the air higher up, it can “slow the cooling” overnight so that the dew does not form there.
You can also see this when dew forms on the windshield, but not on the side windows. The side windows “see” quite a bit of energy from the ground’s IR to keep warm, while the windshield “sees” mostly the colder sky.
“Radiation from a surface is not just up, but in all directions equally “
Yep — I agree completely.
Some further notes to the experiment I described earlier.
I have repeated the experiment using smaller water containers and I would highly recommend this approach to others wanting to check the results. I used two small 200ml plastic Tupperware style tubs, insulated on the sides and base with foam and foil. A hole (force fit) was drilled for the thermometer probe in the side of each container. The lids were cut out in the centre leaving only the clip on rim. This allows the cling wrap to be easily positioned on the water surface and prevents loss of the top layer of water through capillary action.
The use of smaller containers means the results are observable in as little as 15 min. Typical results in a room around 20C were –
For 40C water free to evaporatively cool, both containers cooled 4.5 degrees in 15 min. Both samples continue to cool in sync to room temperature.
For 40C water cooling only through radiation and conduction the containers both cool slower than the evaporatively cooled samples. The container under the foil “Sky” cooled 2.5C in 15 min. The container under the clear “Sky” cooled faster at 2.8C in 15 min. The two samples continue to diverge in temperature as much as 1.2C in the first 45 min. After several hours the samples converge to room temperature.
I believe the results I am getting are consistent and repeatable and possibly even “robust” ;). It should be noted that although my clear “Sky” was actually a ceiling around 20C, the foil “Sky” was reflecting most of the IR emitted by the warm water, not just under 50% of the 10 to 20 micron frequency. Also I have not yet repeated the small scale test with the artificial wind from computer fans. I urge others to repeat this style of experiment to confirm the result.
My conclusion is that backscattered LWIR cannot slow the cooling rate of Earth’s oceans to any measurable degree. Given that the oceans cover 71% of the planets surface, estimates for climate sensitivity should probably be reduced from 1C to per CO2 doubling to 0.29C. This figure is likely to be smaller again, as plants that cool through transpiration may need to be subtracted from equations. I would further speculate that anthropogenic emissions of CO2 cannot cause dangerous, catastrophic or even measurable global warming even if we burnt all known and projected fossil fuel reserves.
kuhnkat says:
August 20, 2011 at 5:42 pm
Myrrh,
As I and at least two others have pointed out, whether PURE water is TOTALLY transparent to Visible wavelengths or not, the oceans of THIS world Earth contain a rather large amount of organic and inorganic matter that is NOT TRANSPARENT to Visible wavelengths. Our oceans could not provide fish, seaweed, salt, minerals, phytoplankton, mammals, crustaceans and numerous other interesting and tasty things to us if they were pure water. The Arctic and Antarctic would have MUCH more sea ice due to freezing more easily and not absorbing as much energy if they were totally transparent. Sometimes a physical truth is overidden by the messy facts of what we actually are dealing with.
The messy fact I’m dealing with is that the claim is that Visible light converts WATER to heat.
That Visible is the main HEATING MECHANISM of the Earth’s surface BECAUSE Thermal Infrared DOESN’T GET HERE. B.S. to such strawish distractions.. ‘That Blue visible travels further into the oceans and therfeore is absorbed creating heat deep in the oceans’ is the claim. Deal with the fact that this claim as it stands is B.S. Which is what I am addressing.
AGWScience Fiction Inc. has REVERSED the properties of Visible and Thermal Infrared, a.k.a. in TRADITIONAL PHYSICS, LIGHT and HEAT, and, it makes various statements to ‘back’ its fiction, including saying that Heat, i.e. long wave thermal infrared, doesn’t even get to the surface! Totally stupid. Heat, thermal infrared is what you feel direct from the Sun. If you can’t feel it, you’re on Earth.
To which, I have given more than sufficient information to show how ludicrous all that AGWSFiction is. I have also shown that it is a deliberate campaign of disinformation. To dumb down the population..
As an article I linked to above shows, there is even a rather busy biozone in the very region under discussion here. Please actually consider this possibility. Denying reality is a lonely job.
What’s lonely here, is defending reality against cr*p science fiction.
Good science fiction is at least internally coherent – in AGWScience fiction we have Blue visible ‘transparent’ in the atmosphere and yet heating the oceans, nothing about it therefore heating the water in the atmosphere..
That’s besides the all the other nonsense such as the atmosphere being transparent to Visible, when reflection/scattering is because of absorption at electron scale, as I’ve already gone through.
So try not to get too distracted, stick with the main claim which is the reversal of properties between Heat and Light. If you understand what AGWScience has done here you’ll realise just how insidiously it has permeated itself into the education system, and so into the ‘general physics knowledge’ of the world. Which will leave the world ignorant again if it isn’t stopped. Or rather, leave the oiks ignorant.
I could give you a page with reference statements about this ‘greenhouse effect’ from various ‘accepted’ sources to show how much they’ve succeeded, but you, now, would just read it and think it was actually real science. I’m asking you to examine these claims, in the very basics.
kuhnkat says:
August 20, 2011 at 9:45 pm
Myrrh,
“You are postulating that light created by the Sun is eternal.”
You do realize that most Cosmology and Physics do come close to that?? Remember the Microwave Background Radiation?? It has alledgedly been literally flying around the universe since the BB!!! That would be about 14 billion years the last I checked. If you disagree with BB, I can understand that. If you think electromagnetic radiation attenuates because it uses up its initial energy just propagating in less than one light year, I think we have a problem. If you think the oceans are so pure that visible light doesn’t get absorbed or reflected by something, you have a serious reality issue.
As I’ve said, stick with what I’m arguing against. You may have noticed that I have given some information on other ways visible energy is actually used in the oceans..
Hockey Schtick says: August 21, 2011 at 4:08 pm
Wrong
Damned if it do; damned if I don’t. YOU were championing the ideas that “that is why the physics literature expresses heat transfer on the potential difference (Ta^4 – Te^4)”
and
“The whole DLR heating red herring is based on this false assumption of 2 way heat transfer. Doing the calculations this way leads to false answers because it does not consider the fact that if a cold body could heat a warm body, the warm body would simply emit more heat to compensate. Doing the calculation properly using only the potential difference eliminates this error.”
YOUR one-way heat transfer equation shows that without GHG & clouds, the net IR transfer away from the surface would be about – 390 W/m^2, while with GHG’s and clouds, it is about -50 W/m^2. This means the surface is not losing ~ about 340 W/m^2 less than it would if there was not the atmosphere to “buffer” the loss. The cooling from current conditions would be dramatic if the atmosphere were not cutting the loss from the surface from -390 to only -40!
“Earth emits to space the exact same amount of energy it receives, as the satellite observations show. “
This much I can agree with. It radiates that much because the solution to YOUR equation suggests and average temperature of ~ 255 K for the earth as seen from outer space. Since the surface is indeed much warmer than 255 K, the atmosphere must blocking some of that surface radiation and re-radiating from a cooler higher altitude (which is, in fact, the greenhouse effect).
“Using the adiabatic lapse rate alone without any GHE fully explains the temperature profiles of Venus, Earth, and Mars. “
True enough. The adiabatic lapse rate is an important idea. Once you know the temperature at the “Top of the atmosphere”, you can use that to predict the surface temperature.
But now, explain to me — without the greenhouse effect or radiation balance from gases in the atmosphere — what sets the top-of-atmosphere temperatures of those planets. Without knowing the starting point, you can’t extrapolate down to the surface, so you need a first-principles estimate of the TOA temperature.
Konrad,
I have enjoyed reading your experiments. It is great to see some actual data.
One thing confuses me — perhaps you can clarify.
No Myrrh,
several times you have claimed that the ocean is transparent to VISIBLE light. Make up your mind what you are arguing. You have NOT made it clear other than a garbled message that somehow VISIBLE light carries no energy that can be thermalized.
Phil. says:
August 21, 2011 at 3:24 pm
Myrrh says:
August 17, 2011 at 3:05 pm
Visible light and and the two shortwave energies either side of UV and Nr Infrared are not thermal energies,
That means they do not heat things.
You are not scientists if you ignore this challenge.
As you have been told many times before you are totally wrong with this assertion.
? 🙂 Who are you? Show me the science. And as I’ve said each time also, prove I’m wrong.
Show me how Visible Blue light from the Sun is able to heat the water of the oceans when water is a transparent medium for visible light, that means, it passes through it without being absorbed. It needs to be absorbed to even have a chance of creating heat.
And, the corollary to this, show why the claim that the atmosphere is transparent to visible light is not b.s. because, reflection/scattering is a result of visible light being absorbed by the electrons of the nitrogen and oxygen molecules which comprise practically 100% of our atmosphere. Visible light therefore should be heating up the sky since, the claim is that the oceans absorb it and so get heated..
As proof when I focus my frequency-doubled Nd:YAG laser (532nm, green) on a cloud of soot the soot particles sublime (T ~4500K), they have been heated by the green light. The same experiment can be done using the undoubled light (1064 nm, IR).
What’s a laser? Or is this another one of your ‘instruments I have used’ which further questioning shows you know zilch about? Which page did you get that detail from? How is your green laser different from the green light of the Sun which reaches the surface of Earth? How many such lasers from the Sun would it take to convert land and oceans to heat for them to radiate out the amount of thermal infrared claimed in the KT97? Would there be anything left??
Myrrh says:
August 21, 2011 at 6:34 pm
Show me how Visible Blue light from the Sun is able to heat the water of the oceans when water is a transparent medium for visible light, that means, it passes through it without being absorbed. It needs to be absorbed to even have a chance of creating heat.
=========================================
Myrrh, a quick tap on the shoulder – visible light doesn’t make it all the way to the bottom (except on SpongeBob SquarePants).
Myrrh,
“Show me how Visible Blue light from the Sun is able to heat the water of the oceans when water is a transparent medium for visible light, that means, it passes through it without being absorbed. It needs to be absorbed to even have a chance of creating heat. ”
You have apparently changed your claim. You now have narrowed it down to BLUE light. Is this your final claim or are you going to change it again?? It is not easy to respond to changing claims. Blue is only one area of the spectrum. Maybe you can tell us what wavelengths or frequencies you are actually referring to??
Myrrh, you are very confused about the Greenhouse effect. I don’t necessarily agree with all of it, but, it does NOT claim that atmospheric water vapor converts VISIBLE Light to heat!! It converts your lovely THERMAL RADIATION to rotational energy and more THERMAL RADIATION. These excited water molecules bumping into non-GHG’s then transfer some of the absorbed energy.
If you are disagreeing with the idea that visible energy heats the ocean it would be good to help us understand what does. What actually warms the ocean if not the visible??
Please show your work again. I seem to have skipped over where you showed this.
Tim Folkerts,
Sorry, just like Willis you ARE double counting. The 324w/m2 down comes from the 390w/m2 up which came from… The SB computation would actually give an ~66w/m2 UP ONLY!!!! This is still only a very rough approximation as SB is only confirmed between objects where we know their temperature and emissivity.
Consider, the equation requires the temperature, or average temperature of the emitting surface. You yourself point out that the surface the ground is emitting against ranges from the 3K space to the 290k or whatever next to the ground. How do we get the average temperature when we do not know it??
When we MEASURE 390 up or 324 down the instrument already has the assumptions of SB built into the circuitry and tells us what we ASSUME!! That is, what is the actual emissivity of the volume the ground is emitting against?? The more expensive instruments are adjustable so we can get more accurate readings, but, how do we determine how it should be set? The cheap ones are set to about .8-.9 I think. How can we get a reliable number when we cannot provide a correct emissivity for the computation??? I believe CO2 is about .2 in the atmosphere and Water vapor may be close to .9. So, what is the emissivity for the whole atmosphere?
http://www.xylenepower.com/Emissivity.htm
uses spectra from the Mars Global Surveyor to provide emissivity of the earth = .7566
Here is a nice link going over the development, implementation and use of pyrometers, pyrgeometers, IR thermocouples, and IR thermometers. Maybe someone can correct me if I’ve garbled the info?
http://www.omega.com/literature/transactions/volume1/thermometers1.html
I am of the opinion that Stefan-Boltzman gives a poor result computing emission between the surface and the atmosphere. Here is another of the arguments:
http://en.wikipedia.org/wiki/Stefan-Boltzmann_law
“Finally, this proof started out only considering a small flat surface. However, any differentiable surface can be approximated by a bunch of small flat surfaces. So long as the geometry of the surface does not cause the blackbody to reabsorb its own radiation, the total energy radiated is just the sum of the energies radiated by each surface; and the total surface area is just the sum of the areas of each surface—so this law holds for all convex blackbodies, too, so long as the surface has the same temperature throughout.”
Notice that it is stated that the geometry cannot allow the black, or grey, body to absorb its own radiation. It also states the temperature should be the same among the pieces. Our atmosphere DOES absorb some of its own radiation and the temperature of the radiating volume varies quite a bit!!! The author also makes a common error. He computes the earth’s temperature using straight SB and says the SURFACE would be 6c ignoring the atmosphere is part of the composite surface that actually is radiatively interacting with the emissions of the sun.
Basically the models and more advanced work may handle these issues, but, these back of the envelope computations using an emissivity of 1 are simply wrong.