Guest Post by Wim Röst
Abstract
It is said that the Earth’s surface temperature variations are controlled by [human-induced] greenhouse gases1. This is not the case. When cooling systems dominate, surface temperatures are set by the cooling system and not by the system that is warming the surface. On Earth the surface cooling system dominates; temperatures are set by the natural cooling system. The strength of natural surface cooling is set by temperature. Adding greenhouse gases to the atmosphere does not make any difference for surface temperatures. Their initial warming effect is neutralized by extra surface cooling and by a diminished uptake of solar energy. The cooling system dominates.
Introduction
The Earth was assembled from ‘space debris’ orbiting the Sun. Gravity made objects like ‘space rocks’ and ice comets coalesce. When accretion took place, gravity melted all assembled objects and a big ‘snooker ball’ of molten material was built. The proto-Earth was also warmed by the Sun, but eventually it cooled down until ‘energy in’ equaled ‘energy out.’ Currently, the surface of the Earth is at balance at around 15 degrees Celsius. A similar planet, with no oceans or atmosphere would have stopped cooling at around 5.3 degrees Celsius, if it reflected no sunlight. Why did the surface of the Earth stop cooling at 15 degrees? And why didn’t the Earth’s surface stop cooling at, for example, 50 degrees Celsius?
Answering those questions reveals that it is not greenhouse warming that sets the level of the Earth’s surface temperatures but the mechanisms cooling the surface. The Earth’s additional cooling systems determine surface temperatures: evaporation, convection, and cloud cooling. All are H2O related.
And the main reason the Earth stayed about ten degrees warmer than its 5.3°C ‘rock temperature? ‘ As will be argued, it is the existence of large oceans in combination with their self-produced water vapor greenhouse effect.
5.3°C
The temperature an Earth-like object in space would have if the planet did not have an atmosphere while receiving the same amount of solar radiation as the Earth is 5.3°C. Only radiation would warm and cool the object. This Stefan-Boltzmann calculator shows that such a planet would have a surface temperature of 5.3 degrees Celsius or 278.5K. But our Earth has a higher global surface temperature, 15 degrees Celsius. The atmospheric greenhouse effect partly accounts for this.
Greenhouse effects
On Earth greenhouse effects are huge, but that does not mean they are decisive in setting the final temperature of the surface of the Earth. There is not just one greenhouse effect, there are two, and each have their own surface warming effect. The first greenhouse effect is back radiation. After surface radiation is absorbed by greenhouse gases the atmosphere is warmed. A warmer atmosphere radiates more energy back to the surface: back radiation. Back radiation adds 333 W/m2 to the 161 W/m2 of surface absorbed solar energy. Back radiation is a strong surface warming force.
The second greenhouse effect warms Earth because of the diminished efficiency of radiative surface cooling. When effective cooling is diminished, more energy remains at/near the surface and both the surface and Earth warm. On Earth only about 40 W/m2 out of 396 W/m2 surface radiation directly reaches space: an efficiency of about 10% or a direct emissivity of only 0.1.
Both greenhouse effects each have their own surface warming effect. For each greenhouse effect its consequence for surface temperatures can be calculated. Separately and together the two greenhouse effects result in huge initial surface warming effects.
Without additional cooling: 270.1°C
Figure 1 shows the surface temperature of an Earth-equivalent ‘rock planet’ with greenhouse effects added, but only warmed and cooled by radiation. Our real Earth has additional systems cooling the surface: cooling by evaporation, convection, and clouds. These additional surface cooling systems cool the surface much further than ‘by radiative cooling only.’ From the initial greenhouse temperature of 270.1°C to the actual surface temperature of 15°C. The additional cooling sets the final surface temperatures. Of decisive importance: the strength of Earth’s additional cooling depends upon water and temperature.
Temperature dependency of additional cooling
The Earth’s additional cooling is predominantly H2O related. Surface temperatures determine the quantity of water vapor in the air. And the quantity of atmospheric water vapor determines the total cooling effect. In this way, surface temperatures determine the strength and the dynamics of H2O related cooling.
Figure 2 shows the equilibrium vapor pressure and temperature according to the Clausius-Clapeyron relation. As shown in the graphic a rise in temperature from zero to 30 degrees Celsius multiplies the equilibrium vapor pressure of water vapor by six times.
When surface temperatures go down by one degree Celsius/K, the quantity of water vapor goes down by about 7% and by consequence all water vapor related cooling processes diminish in strength. At a certain temperature level, ‘energy in’ will equal ‘energy out’. When surface temperatures don’t change, H2O related surface cooling will remain constant. But the small rise in temperature by only one degree Celsius (or one K, a 0.3% rise in temperature) will result in about 7% more water vapor. That huge rise in water vapor content empowers all H2O related cooling processes, often with a more than a proportional cooling result (tropical convection, tropical clouds). As shown by figure 2, H2O related cooling is very dynamic, especially in the higher temperature range. Dynamic additional cooling even limits the temperature of open oceans.
Limitation
Open tropical oceans have a maximum average yearly temperature of 30°C to 32°C. Richard Willoughby reports that less than one percent of the ocean surface exceeds 32 °C for more than a few days at a time. Additional cooling factors limit ocean temperatures to this temperature level. Oceans comprise 71% of the Earth’s surface.
Redistribution of tropical energy
Tropical oceans distribute warm water to the poles in quantities varying over time. The higher the inflow of warm tropical water at higher latitudes, the higher the local quantity of atmospheric water vapor, the main greenhouse gas. Rising water vapor over high latitudes results in a diminished efficiency of local surface radiation in reaching space. Less radiative cooling means that these high latitudes will warm and also that the Earth as a whole will warm. Over time, countervailing processes at the surface (adapting oceans and weather systems) will restore the previous equilibrium temperature (if all other things, like the Milankovitch orbital parameters remain the same). The time frame involved is decades and/or centuries.
Why not 50°C?
Why didn’t the surface of the Earth stop cooling at a temperature level of 50°C? At a surface temperature of 50°C, upward convection of surface energy is huge. High convection will be present over large surface areas. At 50 degrees Celsius oceans will actively be cooled day and night and during the day clouds will reflect most of incident sunlight back to space before it can warm the oceans. Under these circumstances, oceans cool quickly. At the current global temperature of 15°C cooling by evaporation and associated cooling processes diminish enough to balance ‘surface energy in’ and ‘surface energy out’.
Why 15°C?
Why are oceans at a global temperature of 15°C evaporating exactly the quantity of water vapor needed to equal ‘surface energy in’ and ‘surface energy out’? This temperature level is determined by the intrinsic properties of the H2O molecule. The H2O molecule is very hygroscopic; there is a strong bond between molecules, and it is not easy for an individual molecule to escape from the water surface to the atmosphere. To escape a molecule needs to have a very high kinetic energy. To have enough energy, the surface temperatures has to be high enough and at a global average surface temperature of 15°C enough water vapor molecules can escape to achieve thermal equilibrium.
Intrinsic properties of the H2O molecule set the general global level for surface temperatures. Is there still some role left for greenhouse gases? Well, there is.
Oceans create their own greenhouse
Water vapor is the main greenhouse gas, responsible for about half of the greenhouse effect while clouds (also H2O) count for another 25%. Are oceans able to create a greenhouse effect strong enough to raise their own temperatures? Sure, they are.
At the equator insolation is intense and no ice is possible over the oceans: solar uptake of energy is large and when oceans are still at low temperatures, effective radiative and evaporative surface heat loss is low. Therefore, tropical oceans have to heat up. The small quantity of water vapor released at temperatures just above zero Celsius is high enough to get a strong greenhouse warming effect: the first water vapor molecules are most effective in absorbing spaceward surface radiation. When oceans cannot lose 100% of the solar energy absorbed, they will warm. By the evaporation of water vapor, oceans create their own greenhouse effect: not all surface radiated energy disappears to space and oceans need an additional way to lose their accumulated solar energy. Oceans must warm to the point that rising evaporation and enhanced tropical clouds fully compensate for the strongly diminished efficiency of ocean surface emission. If started at low temperatures, oceans will warm till the Earth has an average surface temperature (for present orbital and continental configuration) of 15 degrees Celsius and ‘energy in’ equals ‘energy out’.
Why surface temperatures are not sensitive to greenhouse gases, except for water vapor
Adding an extra 3.7 W/m2 (for a doubling of CO2) to the calculator only increases the initial surface temperature one degree Celsius/K, from 270.1°C to 271.1°C. Additional cooling then must rise by 1/270.1 or 0.37% to compensate for the extra warming force. What would happen with surface cooling when surface temperatures rise by that one degree Celsius?
- Evaporative cooling (responsible for 78 W/m2 of surface cooling) would speed up by some 7% (Clausius-Clapeyron)
- Convection would speed up to a large degree because of both the higher surface temperature and the higher content of water vapor (+7%) in the warmest and most humid air columns
- As result of higher convection, more tropical clouds will form over larger surface areas and earlier in the day and more sunlight will be reflected to space before it can reach and warm the surface, thus solar absorption diminishes.
Because all surface cooling occurs in concert, the slight 0.37% initial warming following CO2 doubling is potentially more than compensated by the huge cooling resulting from the H2O-related processes. Additional surface cooling easily compensates for any greenhouse warming caused by ‘CO2 doubling’. Whatever the level of greenhouse warming, additional cooling dominates surface temperatures and surface temperatures regulate additional H2O based surface cooling in order to have surface temperatures remaining at the level prescribed by the intrinsic properties of the H2O molecule.
Only a change in orbital and/or continental configuration will change the general temperature level upward or downward. Under unchanged circumstances surface temperatures have a very strong tendency to remain at the same general level because of ‘built-in’ physical properties of H2O molecules involved in additional cooling.
Reserve capacity
At current temperatures, Earth’s H2O related cooling processes operate at a low level. Strong convective updraft of surface energy is visible above 25°C. Thus, at the surface of the Earth a large capacity to cool is currently dormant. A slight rise in temperature is sufficient to activate multiple powerful cooling systems in a very dynamic way. Most of the time (nights, mornings) and over most locations (all locations below 25°C) H2O related surface cooling is dormant but easy to activate. Any rise in temperatures activates many forms of surface cooling, while at diminishing temperatures H2O surface cooling activities diminish accordingly. The system seems to be made to keep surface temperatures at about the same level.
How to understand present warming?
A change in the distribution of tropical ocean absorbed energy to the North Pacific (El Niño effect) and/or to the Arctic (by warm subsurface inflows into the Arctic Ocean that cause ice melt) enhances atmospheric water vapor over large surface areas at higher latitudes. As argued before, a warming of higher latitudes results in a diminished radiative cooling of the Earth and so in warming. But, on the Earth’s time scale those (and other) changes are only temporary: they can last decades, a century or a bit more. Although not always easy to recognize, warming and cooling periods alternate in cyclic patterns. Those cyclic patterns are irregular by the ever-changing chaotic interactions of the many components of the ocean/atmosphere temperature system. Cooling always follows warming, like the night always follows the day. Sometimes we need more patience to discover how nature regulates and stabilizes surface temperatures – as it has always done.
Conclusions
The Earth cooled from a hot molten mass just after its formation to the present Earth with its solid crust and its lower surface temperatures. Two greenhouse effects (back radiation and blocking surface radiation) were not able to maintain the surface temperature at 270 degrees Celsius. This is the temperature Earth would have if it were only cooled by surface-emitted radiation. Earth’s additional surface cooling systems, all dominated by the various phases of water, kicked in to cool the surface to its average 15 degrees Celsius.
The additional surface cooling systems of the Earth depend on the H2O molecule. H2O related cooling processes are progressively temperature dependent: the warmer the surface, the stronger the cooling. Temperature itself regulates and limits surface temperatures. For a given configuration the level of surface temperatures is set by the intrinsic properties of the H2O molecule and not by the strength of greenhouse warming; additional H2O based surface cooling compensates for any radiative warming. Cooling is dominant. The immediately available H2O related surface cooling is huge, and its reserve capacity is as endless as the oceans.
Decadal and centennial temperature variations around the current global average of 15°C result from a changed distribution of tropical ocean absorbed energy over the latitudes. Natural warming events are temporary, because over time enhanced surface cooling cancels extra surface warming. Cooling always follows warming, but cooling the Earth takes time, often more time than warming. We need to think in timescales of the Earth to see the changes in surface temperatures in the right way. Earth’s warming and cooling periods happen over decades, centuries and sometimes over millennia.
With regards to commenting, please adhere to the rules known for this site: quote and react, not personal. And when commenting, please don’t use abbreviations but words.
About the author: Wim Röst studied human geography in Utrecht, the Netherlands. The above is his personal view. He is not connected to firms or NGOs or funded by government(s).
Andy May was so kind to correct and improve the English text where necessary or helpful. Thanks!
Footnote
1Lacis, A., Schmidt, G., Rind, D., & Ruedy, R. (2010, October 15). Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature. Science, 356-359. Retrieved from https://science.sciencemag.org/content/330/6002/356.abstract
Interestingly, this, on the surface is similar to the comments that @willis eschenbach periodically makes about natural cooling due to the water cycle in the tropics. Willis will probably correct me about that, but I like this analysis (and the contributions made by Willis)
Alex Cruickshank: “Interestingly, this, on the surface is similar to the comments that @willis eschenbach periodically makes about natural cooling due to the water cycle in the tropics”.
WR: I learned a lot from Willis’ research and observations. He is right in his Thermostat Hypothesis and and about the big role of the oceans. I myself am interested in the physical mechanisms that play a role in the dynamics of the system and I try to unravel them by posing the main questions for a geographer: what happens, where, and why there?
Wim,
your hypothesis does indeed contradict and is not coherent with Milanchovitch cycles theory of climate.
Are you taking the position that your hypothesis is superior to it.
M. cycles theory of climate is a superb, beautiful and a brilliant theory.
And not falsified yet.
It is not construed by the means of loosely assumptions.
The earth’s surface temps seasonally vary very considerably… due to earth’s seasonal dimming…
as per the seasonal total sunshine variation.
This is a fact.
Even in the case of M.cycles theory of climate being false, still the base of it, global dimming part, has merit in considerarion of impacting the global cooling in long term climate.
Wim you can’t have both.
Either M. cycles or your hypothesis.
And you bound to take a clear declared position in this one.
cheers
Whiten: “Wim, your hypothesis does indeed contradict and is not coherent with Milanchovitch cycles theory of climate.”
WR: Whiten, first what I wrote in the post above was:
“Over time, countervailing processes at the surface (adapting oceans and weather systems) will restore the previous equilibrium temperature (if all other things, like the Milankovitch orbital parameters remain the same).”
“If all other things like Milankovitch orbital parameters remain the same”. I think this is clear enough.
For a given orbital constellation a certain ‘standard surface temperature’ results. But when orbit changes, the behavior of the oceans must change. Some latitudes get less Sun energy and other latitudes more. Some parts of the oceans are becoming more saline, others less. Ocean behavior and so weather patterns must change and so the level of surface temperatures. So I fully agree with the influence of Milankovitch’s cycles but to avoid confusing discussions the post was written for a fixed orbital situation.
Still,
regardless of you understanding it or not;
You hypothesis still firmly contradicts the M. cycles theory of climate.
Denying this, firmly diminishes the hypothetical value of your claim… either it being in the promise of anthropogenic or natural angle.
Sorry but it is what it is.
Your hypothesis, competes within the radiative climate theorizing class.
Against the M. cycles radiative theory of climate… simple as that.
cheers
Whiten: “You hypothesis still firmly contradicts the M. cycles theory of climate.”
WR: You don’t explain why you think the post would contradict the Milankovitch theory.
Climatically, according to M. cycles radiative theory of climate;
Global cooling is a result caused by global dimming… as per total global sunshine reduction…. triggered by a runaway albedo effect due to max seasonal dimming-cooling and further increased by the further global cooling which further increases global dimming.
The main base mechanism of total variation of seasonal dimming over time, happens to be considered the Milanchovitch cycles.
It is dimming that causes cooling… global dimming that cause global cooling, in proportion of total sunshine variability versus earth’s surface, either hard or atmospheric surface.
Let me repeat it again;
the most significant temp variation of surface is observed within the seasonal total sunshine varition,
between dimming season versus bright season…. aka winter season versus summer season.
Your hypothesis competes against M. cycles in the proposition of radiative climate cooling.
It is not good for the value of a given hypothesis…
actually even it will consist as with a significant diminishing value if it denies a clear and real condition of contradiction.
cheers
Whiten: “The main base mechanism of total variation of seasonal dimming over time, happens to be considered the Milanchovitch cycles.”
WR: May I suggest you to study the theory of Milankovitch cycles first? I am not interested in continuing this discussion.
Wim, let me ask you a question.
How difficult you think it will be for the AGW CC to be transformed to a runaway anthropogenic catastrophic global cooling?
Let me tell you, it can happen over night.
It simply requires that a considerable global dimming and cryosphere cooling observed, and also a correction of global warming and tropicat warming, aka a tropical hotspot considered, in consideration of oceans and not atmosphere.
I guess you not able or capable of understanding this, as you know not the M. cycles radiative theory of climate.
So you deny that the main direct impact of M. cycles is to the seasonal dimming.
Amazing.
Ok your choice.
cheers
“quote and react, not personal”
Wim.
With all due respect, this is not personal.
At least, not from my perspective.
It is how it is.
Please think it carefully.
The main point in my last reply to you.
cheers
I would call that “personal.” If you don’t see that it is, then it explains your behavior. However, I suggest that you assess your ‘perspective.’
Truth is truth Clyde.
Wim does not know anything about M. cycles climate theory.
Simple as that.
And still Wim finds himself as an authority of advising about climate science.
Killarious, would you not say!
Clidy boy!!!
You somehow claiming that I would have taken a different approach and a different stand, if some one else was the author of this particular post!
Is that it!
cheers
“With all due respect”
You are not showing any respect. You should.
And from my point of view, I have to consider, forced to consider, that you have no comprehension of the respect, or its meaning.
respect is earned, not given or taken
cheers
Quote!!??
Do I have to quote now the very comment of yours I replied to?
Whiten you sound a lot like Griff. Are you another paid Chinese troll?
I’m always troubled by such dogmatic claims, particularly when there is so little support offered for the opinion.
oh, well… that will be your problem, to solve if you can.
Not me problemo, your problemo, body!
cheers
Please go away.
All bluster and bluff imbedded with insults.
The whole point is to distract from the article, not discuss it.
Not worth wasting time reading many repetitious without information red herring posts whose sole purpose is to thread bomb.
Whiten, M-cycles dominate in the long term, but they are very slow. In the meantime, the ebb and flow of global temperature is explained by the processes so eloquently described here. The CO2-is-everyting crowd ignore natural variation because, they claim, it can only have a small effect on multi-decadal trends. But this work shows that the modern warming could be all or mostly due to natural variations in a complex system. Other recent work supports this view, such as the 2021 paper which shows that about 70% of the warming of the past 20 years was due to less cloud, not to an enhanced greenhouse effect. https://wattsupwiththat.com/2021/10/10/radiative-energy-flux-variations-from-2000-2020/
Yes.
Long term consideration… overall.
But still firmly based in the strong significance observation of the short term, seasonal dimming-cooling.
The very initial condition of M. cycles mechanism.
cheers
You seem to be having a problem with the concept of “assuming all other parameters are held constant,” the core of the experimental process with multiple variables. Wim made it very clear that his analysis was for the current situation, acknowledging that the Milankovitch Cycles change very slowly, with the implication that things will be different in the future, and equilibriums will be different. You seem to be reaching for something to invalidate Wim’s analysis. I think that you have failed.
Definitely failed.
Oh yes, like climate is constant till it is CC (anthropogenic, man made).
Well!
No I think you have missed something. This post talks about influences on global surface/atmospheric temperatures over time scales relevant to the current global warming discussion – decades to centuries. Milankovitch cycles are talking about the longer term effect (thousands to millions of years of the orbital relationship of earth to sun and the affect of those changes on total insulation. These are two completely different factors and time scales. As the author states his explanation is relevant to periods of time too short to detect the Milankovitch influences. The latter likely determine stage of Earths climate such as ice age/hot house earth and the variation in timing of seasonality. These are not contradictory, they are complimentary influences.
Well said Andy.
Let me say this.
LIA does not contradict the M. Cycles theory,
because no clause of dimming there causing cooling there… as far as observations considered… or otherwise.
Still LIA a very strong climatic event.
Cooling event, global but with no global dimming to consider.
Well, that is how and why the M. cycles radiative theory of climate is so brilliant and beautiful.
cheers
Thanks for putting things in the proper perspective, Andy.
whitten be like:
” Why worry about a freak wave?
” The tide is going -Out-!…..”
😉
Please, forgive me!
Since our planet’s surface first cooled enough to form a crust, average global temperature has ranged from about -50 degrees C during Snowball Earth episodes to nearly 30 C, as during the end Permian mass extinction event.
Milankovitch cycles are important, but not the whole story in climate change.
Why has Earth apparently warmed from ~14 degrees C a century ago to ~15 C now? IMO the effect of a fourth molecule of plant food in 10,000 dry air molecules, from whatever sources, is negligible. Most of this beneficial warming stems from the same causes as more powerful past warming cycles in the Holocene and prior interglacials of the past 2.58 million years. It’s mostly natural, not man-made.
From the first rule of thumb;
The M. Cycles theory is the story mate, the main story of radiative theory of climate.
Stop denying it…the very merit of it.
Please.
cheers
Besides John,
I like to think and consider, that we, us, go well back there, mate.
😶
cheers
The Milankovitch Cycles are an exogenous forcing on a system that attempts to equilibrate all the parameters affecting climate. I think that it is YOU who does not understand the “M. Cycles theory.”
Man, that is an idiotic insult to Milanchovitch… silly body.
Oh well you are fully entitled to your idiotic silliness… for what ever reason or motivation.
cheers
John.
Your comment reply to me is not coherent with Wim’s hypothetical position in his post, I think.
Please understand,
specifically, climate change means anthropogenic man made climate.
My engagement with Wim it is mainly at the best possible specific, and non colloquial.
cheers
“Please understand,
specifically, climate change means anthropogenic man made climate” ???
Ummm……..NO ! The climate has been changing for over 4 billion years.
Excellent essay which clarifies a lot of things to me. The Earth has a very fast and efectivecooling mechanism that counteracts warming. Moreover it has a lot of reserve. Wilis Eschenbach ‘s observations in the tropics stroke me and now this idea of warming and cooling is clarified for the Earth as a whole.
This is the first essay that elaborates on the crucial role of oceans that Henk Tennekes pleaded for in his essays on climate models. http://scienceandpublicpolicy.org/commentaries-essays/commentaries/tennekes-climate-models
Thanks a lot Wim!
Thank you, Noud. It is good to point at Henk Tennekes and at his early insights. For people who don’t know his name, from the given link a short biography:
Short Biography:
Hendrik Tennekes, retired Director of Research, Royal Netherlands Meteorological Institute; Atmospheric scientist; a scientific pioneer in the development of numerical weather prediction and former director of research at The Netherlands’ Royal National Meteorological Institute; and an internationally recognized expert in atmospheric boundary layer processes.
Wim has done an excellent job of explaining in plain English, essay style, the outgoing heat increase that occurs due to convection, reflection from clouds, and radiation from a warmer surface that controls the planet’s average temperature. I particularly liked the “Why not 50 C” section. Good job, Wim Röst….and worthy of being taught in high school classrooms.
Thanks!
This Text also reminds me of Willis Eschenbach’s idea of a “built-in earth-thermostat” due to tropic evaporation and cloud formation.
WR: all kudos for Willis Eschenbach. I referred earlier to him: “He is right in his Thermostat Hypothesis and about the big role of the oceans.”
Already in 2009 Willis launched his Thermostat Hypothesis: http://wattsupwiththat.com/2009/06/14/the-thermostat-hypothesis/
In his words: “Abstract: The Thermostat Hypothesis is that tropical clouds and thunderstorms actively regulate the temperature of the earth. This keeps the earth at a equilibrium temperature.”
And Muller’s work where he claims a two percent increase in clouds would offset all human-derived CO2 warming.
It appears to me that Willis and Wim are describing the mechanism for how this works worldwide.
CO2 is not the control knob of the Earth’s temperatures.
Water vapor is the control knob. It all makes sense.
Tom Abbott: “And Muller’s work where he claims a two percent increase in clouds would offset all human-derived CO2 warming.”
WR: Considering that there are many cooling mechanisms at work in concert, only a part of that two percent needs to be realized to get the total cooling needed to neutralize.
I’m Ok until this … “Back radiation is a strong surface warming force.” A cooler object (the atmosphere) can not heat a warmer object (the earth). Greenhouse gases only slow surface cooling.
I’m with you there.
John Shewchuk: “A cooler object (the atmosphere) can not heat a warmer object (the earth).”
WR: This already has been discussed many times. It is not the subject of this thread. But interesting is, that when you put both effects individually in the calculator, the diminished efficiency of radiative surface cooling is by far the larger one.
If it’s not the subject, then why did you state … ““Back radiation is a strong surface warming force.”? If a warmer object actually absorbed heat from cooler objects — the only event which can stop that process from continuing is spontaneous combustion of that object.
John Shewchuk: Why did you state … ““Back radiation is a strong surface warming force.”?
WR: All radiation warms, feel the Sun heated wall from half a meter when the Sun already went down. The confusion arises by [not] identifying the object. The Earth as a whole does not warm by back radiation, but the surface of the Earth does [also] warm by the energy it receives from the lowest atmosphere. The surface and surface temperatures are what I am talking about.
Tim Gorman: “Your statement seems to imply that heat from “back radiation” is retained by the surface.”
WR: My main point is that heat does not get lost to space because it becomes absorbed and by consequence does not leave. Absorbed energy is transmitted to N2 and O2 molecules in the atmosphere. The warmer the atmosphere, the more emission takes place: a higher temperature simply results in more radiation. Put a higher temperature in the calculator and a higher emission will appear:
https://www.omnicalculator.com/physics/stefan-boltzmann-law
Where does the back radiation come from if the energy is all absorbed and transmitted to other molecules in the atmosphere?
A good question for Kiehl-Trenberth 2009 where the number for back radiation comes from: https://journals.ametsoc.org/view/journals/bams/90/3/2008bams2634_1.xml?tab_body=pdf
It does! What we are dealing with is an infinite series of reflections and re-radiation going on continually at the speed of light. Yes, dampening takes place, but apparently it takes longer than 24 hours to reduce the temperature to the background temperature of space, so at the next sunrise the surface starts being heated again.
Yes, the atmosphere does not “provide any permanent surface warming.” The net effect is to slow down the cooling until the next sunrise.
Actually, at night when the sun isn’t shining, the surface of the Earth would only see the extreme cold of deep space were it not for the slight but measurable back radiation of the atmosphere. Heat will not conduct from cold object to a warmer one, but photons radiate from all objects above absolute zero. The long-wavelength (cool) photons will be absorbed unless the object has 100% reflectivity at the wavelength of the photons. Thus, a cooler object CAN contribute to the radiative warming of a hotter object.
You might think you can heat up a hotter object than you. Put a thermometer in a hot cup of coffee, stand next to it, and see if you can make the coffee temperture rise.
Oh dear. The earth will be cooler but so will the atmosphere.
Photons do not radiate from all objects above absolute zero. Where is your evidence?
Hottel showed in 1954 that, below a partial pressure of 0.006096 atm-m and a temperature of 33 °C, the total emissivity of the carbon dioxide was not quantifiable because it was almost zero.
Pure pish by you!
Clyde says:”…photons radiate from all objects above absolute zero.”
So can you apportion out how much the N2 and the O2 radiate of the back radiation he talks about?
How exactly do they slow surface cooling? Be specific. You have an object which is radiating heat and which is at a certain temperature. Above it is another object which is cooler and which absorbs the radiated heat.
Why does this have any effect on the temperature of the first object? There must be some mechanism. You say its not back radiation, that doesn’t happen. OK, what is it?
Michel, see my comment above: “WR: This already has been discussed many times. It is not the subject of this thread.”
As long as the object hasn’t a temp of 0k, it radiates too.
You talk about objects radiating and by doing so don’t immediately change their temperature. And their numbers are huge. Until they catch another photon from below or above or by conduction from below they are cooler than their neighbors for a certain time.
Warmer objects radiate more and/or faster than cooler ones. So on average the whole lot is cooling.
Yes, michel, a body radiates at its temperature. Only sentient bodies are aware of other bodies in the vicinity.
And as usual no evidence is offered.
Evidence … you can not get warm by walking into a walk-in freezer. That cooler freezer will not warm you up. That cooler object can not warm you up. Also, the cooler atmosphere will not warm up the earth.
But if you walk into Freezer B that isn’t as cold as Freezer A, you will be warmer given your fixed metabolic rate, which is analagous to a fixed solar constant for the planet….
And if you put on a coat that you found in the freezer your core body temperature will increase even though the coat was cooler than your body. That cooler body (coat) was the cause of the warmer body (you) getting even warmer. The coat didn’t “heat” your body in the sense that it was the source of heat. But it did decrease Eout thus augmenting the metabolic Ein to increase your temperature.
I have never seen a CO2 molecule with a coat.
CO2 molecules wear hoodies, John. Try and keep up. 🙂
I haven’t either. But I have seen a planet with a GHG layer.
CO2 is magic….no benefits to life on earth but cataclysmic to humans 🤓
Okay, let’s be more technically accurate, instead of involving confusing insulating coats, body metabolism, SB equations and the like. If you put an object, say a bag of sand, that has an internal heat source, say a 100 watt electric heater inside, into cold Freezer A, and next day into less cold Freezer B….Then in which freezer do you think the surface temperature of the object will be higher ? Obviously neither freezer is “heating” the object. The object is being heated by the 100 watt energy source… As does the Sun heat the Earth…It just can’t be explained more simply than this….
It’s not as simple as you might think. Without knowing all the particulars you simply don’t know what will happen. Will both freezers *freeze* the bag of sand? If so, what will the temp of the bag of sand be? What is the temperature of frozen ice in the freezer? Is the bag of sand resting on frozen meat or is it directly on a metal shelf?
Think about it.
Tim, I can calculate all those things, at least approximately, as a result of years doing heat transfer calcs, but I’m trying to keep it simple and descriptively correct here. Bag of sand on frozen meat ? You aren’t helping…..
The entire point is that it is *not* a simple thing. Your proposal is not descriptively correct. The answer to your proposal is: no way to tell.
Yep. And since everyone universally accepts that the definition of “warmed” means ΔT > 0 then the act of moving the bag of sand from freezer A to freezer B caused it to warm. But it was the 100 W internal energy source that “heated” it.
Sorry John, I was agreeing with you and Phillip Bratby not criticising you. I was pointing out that the advocates of back radiation like Willis and his ilk do not have any experimental evidence to back up their claims.
Lukewarmists are just warmists who haven’t yet come out of the closet.
No problem. Things do get intense here sometimes. It’s funny yet sad to see those believe in a myth — which if true — would cause everyone to spontaneously combust.
Not so sure about “Greenhouse gases only slow surface cooling.” though”, John, but get your point.
Another claim that needs evidence to support it.
Keep the good fight, John.
H2O and clouds are the major player and CO2 the minor player. Plus we are in a CO2 famine and need more to make our earth healthier. CO2 is a miracle molecule.
John and Michel,
Consider this from Roy Spencer:
“(Technical diversion: This is where the Sky Dragon Slayers get tripped up. They claim the colder atmosphere cannot emit IR downward toward a warmer surface below, when in fact all the 2nd Law of Thermodynamics would require is that the NET flow of energy in all forms be from higher temperature to lower temperature. This is still true in my discussion.)”
Energy balance controls the surface temperature. A more complete explanation of how the GHGs (greenhouse gases) make the surface warmer than it would be in their absence can be seen here:
What Causes the Greenhouse Effect? « Roy Spencer, PhD (drroyspencer.com)
Also, remember Wim’s key point. If there were no water, but the other GHGs remained, and the surface cooled itself via radiation only (no convection), like Venus, the surface would be much, much hotter. Water’s main contribution is to cool the surface from a very high temperature. These energy fluxes are always relative, that is Roy’s point. No one really understands Thermodynamics, it’s too freaking complicated.
The IR emitted by the Earth *cools* it. Thus the atmosphere can only partially re-heat the Earth. Once the Earth is reheated, it will re-radiate that “reheat” back toward space where part will escape to space so the atmosphere will only be able to send back even less “back heat” the second time around – a damped function over time.
Or are you and Spencer suggesting that the “back radiation heat” is permanently retained by the Earth? If so, why does it retain some heat and not other heat?
All three of the energy transports (conduction, convection, radiation) need to be understood as time functions and analyzed as a holistic whole in order to understand what is happening over time.
Tim Gorman: “The IR emitted by the Earth *cools* it.”
WR: What is meant by ‘the Earth’? The surface of the Earth with its badly cooling surface-emission or the upper atmosphere from where effective emission to space takes place? Confusing. A strict distinction between the two is necessary.
Earth as in surface. The surface of the earth doesn’t “retain” heat as long as space is cooler than the surface of the earth.
Yes, but the RATE of loss is controlled by specific heat and thermal conductivity, and the temperature of the radiating bodies determines the wavelength of the emitted photons. Thus, the cooler the atmosphere, the less energy each photon carries. This is part of your “damped function.”
Tim,
Neither of us is claiming any of the back radiation is permanently retained, all of it eventually makes its way to space.
True.
This is a very complicated subject and this is probably not the post to get deeply into it. The following post, in the link below, and the paper it is based upon might be a good place to start:
The Greenhouse Effect, A Summary of Wijngaarden and Happer | Andy May Petrophysicist
Got it. I’ll look at the link when I get a chance. Thanks.
Hi Andy
From Erl Happ in the comment from your link at your site.
“It should not be in doubt that cloud cools. Global cloud cover peaks in December when heating of the atmosphere by the landmasses is least. Cloud cover is least in July- August. That’s when solar irradiance is 6.7% weaker due to orbital distance. And yet, the Earth is warmest in July-August when heating of the atmosphere by the vast landmasses of the northern hemisphere is at its peak.”
Erl’s observations are correct, but attribution purely to the vast land masses is open to discussion.
From May transport of heat pole-ward is restricted, and Mid July restriction to pole-ward transport tightens further. That is, it takes more physical energy to get it there, not heat energy to do with the EPTG, just sheer grunt to get it there. That is why the Cyclone season kicks in. Cyclones primarily occur due to the restrictive transport of equatorial heat pole-ward. If convection volume is high early in the season (May) that creates the cyclone start date.
My conclusions are that Earths ocean cooling systems are not as net efficient as contemplated. Evidence of this are the very high seasonal humidity levels at equatorial latitudes, and the variation in annual ACE values. High humidity would not occur if the transport system was 100% efficient. Look at the humidity curve for the southern states and Erl’s comment.
We have no accurate measure of the volume (depth, surface area and overchurn rate) of heat presented at the surface of the oceans, and what portion of that volume is convected and what volume remains.
Earth’s long term (about 60 years) slight rise and fall in surface temperature identifies the heat accumulation and removal efficiency cycle at this time and place in the M Cycle, and other variables such El Nino / La Nina.
An aside, but relavent..
Look what is happening above Antarctica during this La Nina 2020 and 2021. New records, its nothing to do with chemistry just atmospheric transport.
https://ozonewatch.gsfc.nasa.gov/meteorology/figures/merra2/wind/u60s_100_2021_merra2.pdf
https://ozonewatch.gsfc.nasa.gov/meteorology/figures/ozone/to3mins_2021_toms+omi+omps.pdf
Kind Regards
Martin
Did you forget about the glowing orb in the daytime sky?
The energy isn’t retained, it is replenished daily.
This semantic obsession is tiresome. The back-radiation partially negates the upwelling radiation. It slows the cooling. The net flow of heat is always from the warmer surface to the colder atmosphere and subsequently from the relatively warmer atmosphere to the very cold outer space.
The atmosphere as an insulator can only affect the minimum temp, not the maximum temp. The maximum temp is set by the glowing orb in the sky.
Tim, the key to the question is what is the limit of the damped function, and for a finite world, how long will it take to achieve the limit? It doesn’t happen instantaneously. It is limited by the speed of light and the distance between the surface of the Earth and the H20/CO2 absorbing layer(s). It is evident that as soon as the sun sets it starts to cool. The rate of cooling is a function the amount of water vapor primarily, and secondarily the amount of the minor greenhouse gases. Clearly, the radiative cooling takes long enough that the process is re-set the next morning.
Radiative effects happen pretty quickly, the speed of light is pretty fast.
I agree that the radiative cooling is a time function and it *should* be handled that way. As far as water vapor is concerned, there isn’t a lot of water vapor over deserts yet deserts cool off very fast with a large delta change. Which is what I think you are getting at. Yet if CO2 is very well mixed over the globe then there should be an impact that can be measured over deserts at night. If CO2 is not well mixed around the globe then it’s impact can’t be considered to be ubiquitous as the climate models assume.
As Andy points out (and I agree) the subject is very complicated – and the models simply don’t do it justice. Too many assumptions and tuning parameters.
Deserts cool quickly at night BECAUSE their is no water vapor (thus, no clouds) to stop the heat escaping to space, proving that CO2 has little affect on temp..
From a thermodynamic standpoint, the atmosphere simply can not “heat” the surface. This is where it becomes important to define very accurately what is being discussed. The surface is the land, rocks, sand, and ocean, eg., the “solid” part of the earth. The atmosphere is the phenomena commonly referred to as air.
These form two separate bodies. The “surface” is warmed by the sun and radiates to the second body the “atmosphere”. The atmosphere can not cause the surface to be warmer than the sun, the original source of energy. However, as an insulator with a heat conductance, as radiation is absorbed from the surface, the atmosphere will heat. At the boundary the atmosphere can even approach the temperature of the surface and because of the low conductance cause cooling of the surface to be very slow. Please note, nowhere does the surface cooling gradient reverse, that just isn’t possible. At best, the surface and atmosphere could reach thermal equilibrium, i.e. equal temperatures at the boundary.
The part that is never discussed is how much of the sun’s near IR is absorbed by H2O that is in the atmosphere. Even water vapor can absorb this and for sure precipitated vapor, i.e., clouds can also absorb this near IR raising the effective temperature of the atmosphere.
Back radiation simply can not raise the temperature of the surface as I have defined it. The atmosphere warms as any insulator would from radiation (and convection/conduction) from the surface. The surface cooling is slowed by the insulator. This is the main reason that Tmin’s have been rising, the insulator’s conductance has been reduced.
Each photon results in energy being input.
If the atmosphere warms, it emits more photons. Resulting in more photons striking the solid/liquid earth. More photons means more energy is being input, which means the surface gets warmer.
Sorry but no. It means the surface cools at a slower rate. As long as the surface is the hotter object it will cool. Warming is relative. The correct description is important when dealing with warmists. Slower cooling results in higher Tmin temps and all the great things that come from it.
Making the earth hotter is what drives hysteria about BURNING UP.
Don’t get me wrong as I’m the first to say that the “climate crisis” is a scam.
It’s the energy balance that matters as the Earth total system (surface, bulk below the surface, and atmosphere) can only cool by radiating the energy received from the sun and the energy created by radioactive decay inside the Earth to space. If you introduce GHG’s in the atmosphere that can absorb the long wavelengths emitted from the surface and reradiate a portion of that radiation back to the surface, the surface will receive more energy than without the “back radiation”. It will cool less rapidly and thus stay warmer. An object that cools slower will be warmer than an object that cools faster.
To achieve a balance, the surface will get warmer until the radiation emitted from the surface matches the heat received from the sun. I taught thermo at a major university for years – this has been known for well over a century and forms the basis for how we design many things that actually work.
This raises MINIMUM temp by limiting the amount of cooling at night. That’s far from turning the earth into a burning cinder. In fact, it is a positive, not a negative. Record harvests over the past 20 years, 14% increased greening of the earth, lower number of cold deaths, etc.
meab, Well said, I wish I could have taken your course!
You would have passed, Andy.
And you would be wrong.
The surface will warm from the sun, yes. That is new energy and will raise the temp of the earth’s surface to a temp higher than the atmosphere. Unless the atmosphere gets warmer than the surface, the atmosphere can not raise the temperature of the surface of the globe. It can only reduce the cooling gradient, it can not force the gradient to reverse. The earth will continue to cool, just at a slower rate. If you taught thermo you should know this.
One must be cautious about describing the system. The surface is the land and oceans. The atmosphere is is a separate object with a separate temperature gradient, an insulator if you will, complicated for sure, but still an insulator.
The fly in the ointment is the near infrared from the sun that adds heat to the atmosphere via water in the atmosphere. It is what “burns” off fog and re-evaporates precipitated water, e.g., clouds. I suspect this is really where “back radiation” comes from. It also can add to the radiation leaving the earth.
Is this an opinion, meab?
Warmer is not the same as warming. Cooling slower is not warming, as in temperature rising. The energy re radiated back to the warmer Earth from the cooler atmosphere cannot raise the temperature of the Earth. This is where the Global warming hypothesis collapses.
If the Earth radiates x photons then x-space = b will remain for the atmosphere to back radiate. when those “b” photons warm the earth then it will turn around and radiate those “b” photons back toward the atmosphere. Some will go to space leaving b – s = c for the atmosphere to back radiate. The earth will than re-radiate “c” photons toward the atmosphere and some will escape to space. The atmosphere will then back radiate c – s = d …. on and on.
x > b > c > d > …… = 0
The earth doesn’t retain the back radiated heat. That would be required in order for the back radiation to warm the earth.
A small point: They are not the same photons. Some of the secondary ‘b’ photons will be reflected instead of being absorbed; they do not contribute to an increase in temperature.
Those that are absorbed at the surface will infinitesimally increase the temperature so that the next radiated photon will have a shorter wavelength than what might have been emitted had it not absorbed the photon, because the emission of the photons results in cooling. However, it will have a longer wavelength than the first emission. Basically, in the infinite-series of absorptions and emissions, each successive emission will be a photon with a longer wavelength and lower energy content than earlier emissions because cooling dominates over warming from back radiation. It is further complicated because water will increase temperature less with the absorption of a back-radiated photon than rocks or sand. So, to model the whole process one has to know the surface covering and the initial temperature at sunset. Not a simple problem!
“Those that are absorbed at the surface will infinitesimally increase the temperature”
Do you actually believe that, Clyde Spencer?
Or do you know it?
The photons striking the surface add energy and viewed at that atomic scale, you can I suppose talk about warming. But at the macro scale, there are more photons carrying energy away from the surface (cooling) than are striking the surface. So the net effect at the macro scale is to cool the surface but not as rapidly as would be the case in the absence of back-radiation from the atmosphere.
The temperature primarily determines the wavelength of the emitted photons, and the wavelength increases as the temperature decreases. The number of photons is determined by the number of emitting molecules, that is, the density of the atmosphere.
Clyde I mostly agree with you but earlier you said everything above absolute zero radiates so the number of radiating molecules should 100%.
Actually this happens in Antarctica, where the enhanced greenhouse effect reverses and additional CO2 causes the surface to cool. Wind can bring in air that is warmer than the surface, this happens many places in the local winter, but all the time in Antarctica. For more details see here:
The Greenhouse Effect, A Summary of Wijngaarden and Happer | Andy May Petrophysicist
As I’ve said, this is an incredibly complicated subject, and this isn’t the right post to get into it.
If what you say is true, Andy, then what Jim Gorman says in general must also be true. Hot heats cool not the other way round.
But the ‘consensus‘ greenhouse gas model projects most warming: in polar regions, at night, and during winter. Did you just say that the ‘consensus‘ model of the greenhouse gas effect is wrong?
If so, what empirical validation and falsification tests do you propose for a replacement to the Manabe/Hansen model?
Don’t tell this this isn’t the time nor place. It’s your place and editors here effectively banned robust criticisms of this ‘consensus‘ model.
Andy, I’ve got to think a bit on this one. My gut tells me the surface would cool quickest while emitting straight to space. How would CO2 enhance cooling? The surface is at a given temperature and emitting at that temperature. I don’t see how CO2 could make it emit faster. Atmospheric CO2 is an insulator. It can’t suck heat out of the surface it can only slow the gradient of heat going to space by intercepting it.
In Antarctica the lapse rate often reverses such that the upper atmosphere is warmer than the surface. Since CO2 impedes the transmission of IR radiation it will block more DWIR energy than UWIR energy. The surface energy budget in this configuration has Eout > Ein so the surface cools.
Perfectly explained, Jim Gorman.
But not for lukewarmists, of course. 🙂
Oh speak of the devil, here comes MarkW. :DDD
Venus’s surface temperatures can only be explained by the Atmospheric Thermal Effect; not by a Greenhouse gas effect.
Venus’s bond albedo is over twice earth’s (Bond Albedo: Venus = 0.77, Earth = 0.31). So most incoming solar radiation is reflected away from Venus by it’s atmosphere. Venus gets less sun than earth. Of 23% of initial radiation absorbed by Venus the vast majority of it is absorbed by its clouds and atmosphere, with only a tiny amount reaching its surface. Venus’s daytime surface gets about 12% the amount of sunlight of earth. During Venus’ long night the temperature drop is only 5C (Venus surface temperature. Day = 737K, Night = 732K).
Venus loses about 160W/M² to space. It obviously must be losing about this at night too. Multiply this by the length of a Venusian night, = 1401 hours, to get the energy lost per square metre (1 Watt = 1 Joule/second). Over night each square metre of Venus loses 160 × 1401 × 60 × 60 = 806,976,000 Joules. No way does back-radiation keep Venus’s surface hot at night.
NASA Venus factsheet
Correction. In “Venus’s daytime surface gets about 12% the amount of sunlight of earth“, I meant absorbs not “gets”.
So Andy how do you increase the temperature of a body?
I have this equation:
dU=Q + W= mCpdT
What do you have?
Andy has E=hf….the energy of photons, to increase the temperature of a body by the same mCpdT. The guys who came up with the dQ+dW stuff didn’t even know about photons, a tribute to their brilliance for divining an answer before really knowing what “heat” was.
I think that you don’t appreciate the niceties of radiation.
Thermodynamics which you seem to be quoting ‘Cant pass heat from a cooler to a hotter’ is only true of net transfers.
But transfer from a hotter to a colder decreases as the colder gets hotter, the amount by which it decreases can be expressed as a reverse flow of back radiation.
Mutatis mutandis, whether you interpret this as subtracting a reverse radiation flow or reducing a forward radiation flow is in essence mere semantics.
It’s not worth getting involved in these arguments – as with ‘do wings create lift because of Bernoulli (pressure differentials) or Newton (momentum change of air molecules)’ merely reveals a lack of understanding that these are in fact the same thing. Just as we can argue all day about wavelength and frequency, in terms of fixed velocity waves. In the end they too are also the same thing, expressed different ways.
I appreciate the laws of thermodynamics. A cooler object can not warm a warmer (or of equal) temperature object. It can however, slow the warmer object’s cooling trend as it is warmed by the warmer (earth) object.
I think you just agreed with Wim …
😉
Yes, most if not all of the participants in this recurring argument are like the blind men inspecting the same elephant.
Oh dear, another lukewarmist who wants to marry Greta.
What’s the temperature of an individual CO2 molecule that emits this energy? It must be “warmer” than a CO2 molecule that ahs already emitted the energy? How does the temperature of the emitting molecule compare to surface temperature?
son of mulder, The temperature of the molecule determines the energy it emits and the frequency. Excess energy is lost in collisions with neighboring gas molecules. The number of collisions determines the temperature of the gas.
Greenhouse gases also block the more abundant incoming infrared than the lesser outgoing infrared. Insulation helps in both keeping a house cool in summer and warm in winter.
I’m wondering if there be a misunderstanding of the 2LOT here. The 2LOT says that within an isolated system heat moves from warm to cool. Note that isolated means the system is evolving by its own means (no passage of mass or energy across the system boundaries). The 2LOT does not say that cool bodies cannot be a factor in warm bodies getting warmer. Nor does it say that warm bodies cannot get warmer and cool bodies cannot get cooler. It only says that heat flows from warm bodies to cool bodies when those bodies are evolving by their own means.
Pay attention to the flow of heat in the Sun, Earth, and Space system which is mostly isolated.
Sun (5780 K) ==> Earth (288 K) ==> Space (3 K)
The existence of GHGs between the Earth and Space does not substantially change the flow of heat. It is still consistent with the 2LOT because heat is still flowing from warm to cool. The only thing that is different is that there is another body between Earth and Space that the heat must flow through. GHGs do not cause heat to flow backwards. It is still flowing in the same direction.
Hot (Sun) ==> Warm (Earth) ==> Cool (GHGs) ==> Cold (Space)
Here is an experiment I want you to try. Open your oven door, turn it on high, and wait for the temperature inside to achieve a steady-state and record the value. Now close the oven door. The oven door will be cooler than than the inside yet it will still impede the transmission of heat to the outside causing the inside to get warmer. This is a scenario where positioning a cool body (door) caused a warm body (inside) to get warmer. Don’t hear what I didn’t say. I didn’t say heat flowed from the cool body (door) to the warm body (inside). The heat is still flowing from hot (burner) to cold (outside). The only thing we did was put a thermal barrier (door) between the inside and outside. This thermal barrier does not cause heat to flow backwards. It is still flowing in the same direction.
Burner => Inside => Door => Outside
It is also a good time to remind you of the energy and temperature relationship.
ΔT = ΔE/(mc)
T is temperature, E is energy, m is mass, and c is the specific heat capacity of the mass. And per the 1LOT we know that
ΔE = Ein – Eout
This means we can rewrite the temperature and energy equation as follows.
ΔT = (Ein – Eout)/(mc)
Now it is easy to see what happens when you perturb Eout and leave Ein unchanged. When ΔEout > 0 then T decreases and when ΔEout < 0 then T increases.
A cooler body can not heat a warmer body. Every time I sit next to a hot cup of coffee — which is hotter me — the coffee cools.
What happens if you toss a blanket at room temperature over your shoulders?
Good try. I heat up because my metabolism is generating heat – and the blanket reduces cooling by convection — like the glass ceiling in a greenhouse. If you put a blanket over a dead object (like the earth) the object cools more slowly. Back-radiation to a hotter object is a myth.
JS: “Back-radiation to a hotter object is a myth.”
It is very real. I just pointed my IR thermometer up towards the cooler sky and the thermopile recorded DWIR and provided a temperature reading based on it. ESRL has a few radiometers in which they all also confirm that DWIR from a cooler sky makes it to the warmer surface. And, of course, most numerical weather prediction models including the GFS, ECMWF, RAP, HRRR etc. use radiative transfer models like the RRTMG that compute the back-radiation from the cooler sky to the warmer surface. If they didn’t their forecast skill would be considerably lower perhaps even to the point of pulling even 24 hour ACC scores below 0.6.
But did the sky make your coffee warmer (in the shade of course)?
Where is your evidence that back radiation raises the surface temperature?
There is none so why do you push this junk science?
If the earth heats from back radiation exactly what does it cause earth to do? Does it retain the heat or radiate it away?
Remember, the 2LOT speaks to *net* transfer of heat.
The surface has an energy budget. On average the surface has a budget of Ein = 8e24 joules and Eout = 8e24 joules each year. It is typically easier to express these in terms of average fluxes Fin = 502 W/m2 and Fout = 502 W/m2. Fout = Fsensible + Flatent + Fuwir and Fin = Fsolar + Fdwir. The “back radiation” is Fdwir and is on average about 342 W/m2. Fuwir is the radiant emission and is on average about 397 W/m2. Because the 397 W/m2 is only an average it cannot be technically used in the SB law at least not without considering what Trenberth calls the rectification effect. Fortunately the rectification effect of Earth is only about 6 W/m2 so the error when plugging 397 W/m2 into the SB law is only on the order of 1 C. Note that SBlaw(397 W/m2) = 289 K.
TG: “If the earth heats from back radiation exactly what does it cause earth to do?”
If an increase in back radiation occurs (ΔFdwir > 0) and all other things remain equal then Fin > Fout and the surface begins accumulating energy and the temperature will increase per ΔT = ΔE/mc.
TG: “Does it retain the heat or radiate it away?”
Be careful with the term “heat”. Remember, in thermodynamics “heat” is the net transfer of energy between bodies at different temperatures. If ΔE > 0 then the surface is being heated by something else. If ΔE < 0 then surface is doing the heating of something else. In other words, it cannot retain heat and radiate it away at the same time. It’s either one or the other. What it can do is both send and receive energy at the same time. If Fin > Fout then the surface is being heated or you might say retaining heat. If Fout > Fin then the surface is doing the heating. You might say it is losing heat. Note that when it loses heat it can do so via conduction, convection, or radiation. So it doesn’t have to necessarily radiate it away.
Again…heat is the net transfer of energy. If Ein = Eout then ΔE = 0 and there is no heating going on either way. But there are still energy in and out flows happening. There’s just not a net flow and thus no change in T.
“The surface has an energy budget.
The surface has an energy budget that is TIME DEPENDENT. You simply can’t take a “global average” and use it for anything.
“the surface begins accumulating energy”
How does it accumulate energy without increasing its radiation (base on the 4th power of the temperature)? Remember “watts” is a measure of energy flow, not of energy itself. watt-hour is a measure of energy. Multiplying watts/m^2 by m^2 gives you the rate of energy flow in watts. You have to multiply that by time in order to determine energy flow.
And you *still* haven’t explained how the earth can “retain” heat!
Put that cup of coffee on a hot plate so that Ein > 0, allow it to achieve a steady-state, and record the temperature. Now put insulation around the cup that is cooler than the coffee such that ΔEout < 0 and wait for the new steady-state. What happens to the temperature of the coffee?
Stand next to that coffee and see if you can make it hotter. I keep failing.
What happens to the temperature when you place a thermal barrier between the coffee and the ambient environment though?
I’ve never seen an ambient environment.
I’ll have to ask my thermos flask.
The temp sure doesn’t go UP!
How do you get ΔEout < 0? That’s the same as having Ein!
An insulator that is *cooler* than the coffee simply can’t warm the coffee. ΔEout < 0 simply can’t happen.
ΔEout < 0 is the mathematical language equivalent of saying the energy exiting the boundaries of the system decreased. For example, if the upwelling radiation at TOA of Earth decreased by 1% then ΔEout = -39e21 joules after 1 year. That does not mean Ein = 3.9e24 joules over the same period has changed in any way. Eout can and does change independently of Ein. It’s the same for a cup of coffee on a 50 W hot plate. Insulating the cup and reducing Eout does not change Ein = 50 W * t.
BTW…there is analog for mass that is more intuitive. If you have a tub with 1000 kg of water with an inlet and outlet then you can model the change in mass within the tub as ΔM = Min – Mout. If the tub has Min = 100 kg and Mout = 100 kg each hour then ΔM = 0 kg. But if you close the outlet valve slowing the flow down by 10% then ΔMout = -10 kg over the next hour and then ΔM = 100 kg – (100 kg – 10 kg) = +10 kg. M is now M = M + ΔM = 1010 kg. This is none other than a formulation of the law of conservation of mass!
Heat *loss* doesn’t warm the hotter object. You keep trying to say that an insulator can warm an object. It can’t. Net heat flow from the system can’t be from the colder object to the warmer object. Otherwise you can have a refrigerator that requires no work to be done to cool things. It’s why refrigerators *require* a compressor motor that contributes the work required.
Less heat loss does *not* warm the hotter object.
TG said: “Heat *loss* doesn’t warm the hotter object.”
I didn’t say heat loss warms the hotter object. What I said was that lowering Eout causes the hotter object to get even warmer.
TG said: “You keep trying to say that an insulator can warm an object. It can’t.”
Yes it can. Do the experiment. Turn your oven on high with the door open and wait for the temperature inside to reach steady-state. Now insulate the inside of the oven more by closing the door. The temperature will increase inline with expectations from the 1LOT.
TG said: “Otherwise you can have a refrigerator that requires no work to be done to cool things.”
Nope. The 2LOT does not invalidate the 1LOT. They are both essential and fundamental laws of physical reality. The refrigerator requires work to be done to move heat from cool to warm just like the oven requires an input of heat to warm further in the presence of more insulation.
TG said: “Less heat loss does *not* warm the hotter object.”
Yes it does. Well, technically it is more appropriate to say less energy loss can cause a hotter object to warm when the object is also has input of energy. Remember the energy and temperature equation.
ΔE = (Ein – Eout)/mc
Ein is the energy crossing the system boundary going in, Eout is the energy crossing the system boundary going out, m is the mass and c is the specific capacity of the mass. For an 8 oz cup of coffee mc = 227 g * 4 j/g.C = 908 j/C. If there is a 50 W input then there must be a 50 W output for the temperature of the coffee to be in a steady-state (ΔT = 0). If you then insulate the coffee more and reduce the power output so that it is now 45 W then after 10 minutes Ein = 50 W * 600 s =30000 j and Eout =45 W * 600 s = 27000 j. Then ΔT = (30000 – 27000) / 908 j/C = +3.3 C. Understand that ΔT > 0 causes dEout/dt > 0 so after a certain amount of increase in the temperature Eout will increase and balance Ein again and a new steady-state will be achieved so T cannot increase indefinitely. It only increases in proportion to the amount of energy accumulated.
Duh, even with the door closed, there is still heat loss from the oven into the kitchen. Closing the door means the thermostat that regulates the heating element doesn’t have to apply as much power to reach the setpoint temperature.
All insulation does is delay the cooling by increasing thermal resistance. That’s it.
CM said: “All insulation does is delay the cooling by increasing thermal resistance.”
You need to be careful with terminology here. “cooled” is defined as ΔT < 0 and “cooling” is defined as dT/dt < 0. Adding insulation does not cause ΔT < 0 nor dT/dt < 0. What it is does is impede the transmission of outwardly directed energy. It cause ΔEout < 0.
Note that the oven experiment is intended to be done on the high setting to prevent the thermostat from cutting off Ein when the door is open. In other words, the setpoint is high enough that the steady-state temperature with the door open is not achievable that way you get to observe the temperature rise immediately when the door is closed and before the thermostat cuts Ein to zero. There are other ways to demonstrate this experimentally but I’ve found the oven experiment to be one of the easiest and tends have large ΔT that illustrates the point decisively.
No, what it does is slow heat transfer across a temperature gradient.
In the oven, the gradient is:
Heating element>
Oven air>
Oven insulation>
Room air
with a second path if the door is open:
Heating element>
Oven air>
Room air
This is the heat flow.
Exactly! Insulation provides no energy by itself. The only energy it can have is what it absorbs. It will always be at a temperature less than or equal to the source. That means it can not “heat” the source, only slow its cooling.
Obviously bwx has never had to design a heat sink for a power semiconductor or he would know this.
I agree. He’s never had the pleasure of checking a heat sink by touching it to see if it’s cool enough – and finding a blister!
Lowering Eout can *NOT* cause an object to get warmer. That’s a violation of the 2nd law of thermodynamics. Entropy increases.
Until you get that into your head there is absolutely no reasoning with you.
You are arguing that blue is green. You’ve cherry picked something out of a book somewhere without understanding the context or studying the whole subject. You are prone to doing this. Stop it.
So, the hot plate (higher temp.) is causing the temp. of the coffee to rise. The insulation is slowing down the loss of heat (cooling). The temp of the coffee will still rise without the insulator.
Remove the hot plate, the temp. of the coffee will cool even with the insulator. At no point, is the insulator causing the temp. to rise. Warmer is not the same as warming.
Somehow folks don’t or can’t understand that thermal equilibrium is reached between the heat source and the absorber. An insulator can not affect that thermal equilibrium. It is the insulator that absorbs heat from the hot body and has its temperature increase. The conductivity of the insulator will determine that temperature.
If the conductivity is 0, the insulator will reach the temperature of the hot body, i.e., thermal equilibrium. If the conductivity is 1, the insulator will pass that heat immediately to the next body, just like the insulator wasn’t there!
In no case, even when the conductivity is 0, will the insulator cause the hot body to exceed the thermal equilibrium established with the source. Too many folks somehow think “back radiation” is ADDED to the heat from a source so that the final temperature can be higher than what the source can support. There just is no way.
Two red hot identical spheres of iron are suspended near each other in a vacuum box….according to thermodynamics, the 2 hemispheres facing each other will cool more slowly than the 2 hemispheres facing away. The 2 surfaces closest to each other will maintain the highest temp as the 2 spheres cool.Over time, the 2 spheres will attain the same temp. There is no increase in temp of the surface of either sphere, but there is uneven mirror image cooling of each sphere. Everyone agree with this?
I’m not sure what your point here is. Nor am I sure where you are getting your information from. The 2LOT is basically “entropy increases”. That’s it in a nutshell.
If a cooler object were to warm a hotter object it would result in a *decrease* of entropy, not an increase. It may be possible according to the math but it never happens in nature. If it could we could have perpetual motion machines.
Read the following carefully:
Clausius’s Statement
TG said: “I’m not sure what your point here is.”
My point is that the 2LOT does not say that cool bodies cannot get cooler, warm bodies cannot get warmer, or that the presence of a cool body cannot cause a warm body to get warmer.
TG said: “Nor am I sure where you are getting your information from.”
From texts on thermodynamics.
TG said: “If a cooler object were to warm a hotter object it would result in a *decrease* of entropy, not an increase.
That’s right.
TG said: “It may be possible according to the math but it never happens in nature.”
It happens in your own home with your refrigerator and your air conditioner. Without the cooler evaporator coils the warmer condenser coils could not get warmer. In this case heat is flowing from cool to warm. In Clausius’s own words why does this not violate the 2LOT?
TG said: “If it could we could have perpetual motion machines.”
Nope. Don’t forget about the 1LOT.
Short answer — work is done in refrigerators and air conditioners.
Jim is correct.
Work is done. ΔU = Q + W
Go reread your textbooks. You obviously missed a bunch! As usual, you are cherry-picking from books without a full understanding of the subject.
You totally missed the expansion valve in the refrigerator and the PV = nRT that describes that part of the cycle. And you missed the compressor that is a required part of the cycle as well.
Jim is correct about work being done on the system. That makes him incorrect about “It may be possible according to the math but it never happens in nature.” because entropy decreases all of the time. The refrigerator and air conditioner are familiar examples of this. He’s also incorrect when he implied that if the lowering of entropy were possible (it is) then that means that that perpetual motion machines are possible as well.
Sorry, he’s correct.
Lord Kelvin: ‘t is impossible for a self-acting machine, unaided by any external agency, to convey heat from one body to another at a higher temperature.”
This is why perpetual motion machines are not possible.
The 2LOT is really about entropy and that’s not a 2 way thing.
Well your dT = dE/(mc) is nice but the m and c (Cp) of the atmosphere has changed as we have in essence swapped O2 for CO2 molecules. CO2 has more mass. O2 has a Cp of around .91 and CO2 is around .84 depending on temperature.
So even if dE went up it is possible (mc) went up and there is no increase in T.
Besides CO2 isn’t effected by IR in causing warming or else there would be another column in specific heat tables showing 2 values one with and one without.
“The existence of GHGs between the Earth and Space does not substantially change the flow of heat. It is still consistent with the 2LOT because heat is still flowing from warm to cool. ”
Everything in the air does substantially change the flow of heat through an insulator thereby changing the temperature of the insulator. Various gradients and interactions have an effect. You can’t just do a simplistic analysis as you have shown and get an answer as to what temps will do. They are time dependent gradients with varying inputs and outputs.
The air does not make heat flow backwards Space ==> Earth ==> Sun.
I think that this is an issue of semantics, criticizing something said by someone for whom English is a second language. I understand that “Greenhouse gases only slow surface cooling.”, but accept that “Back radiation is a strong surface warming force.” is essentially correct in terms of the net effect.
No matter how close I get to a cup of hot coffee, regardless of how much colder I am, I am not able to increase the heat of that hot coffee. I keep trying though.
Put the cup on a hot plate, allow it to achieve a steady-state, and record the temperature. Now get close enough that the entire palm of your hand forms a good seal around the opening such that you reduce Eout and observe that the temperature will increase. Obviously wear heat resistant gloves so that you don’t burn yourself.
Your hand simply can’t warm the coffee. It can lower the heat loss but heat loss will most assuredly still occur.
You continue to confuse lowering Eout with raising temperature. It doesn’t. It can’t.
Where do you think the amount of energy represented by Eout without hand and Eout with hand goes if not into raising the temperature of the liquid?
2nd law. A cooler object can’t warm a hotter object. Entropy increases.
“Back radiation is a strong surface warming force.”
Yet you do not offer any empirical evidence, Clyde.
You are a lukewarmist, Clyde. A friend of Greta?
Think of it this way, although an oversimplification: Insolation is absorbed at the surface heating it. Heat is radiated up through the atmosphere. Some goes directly into space. All is reradiated randomly, meaning about half goes upward and half downward. Photons are not effected by Pauli exclusion nor electrical or magnetic repulsion from one another. This means nothing prevents them from traveling downward toward a radiating surface, nor upward directly into the sun. Roughly half get back to the surface warming it and raising the temperature. The additional temperature is radiated upward going through the same process, so half is again received at the surface. This is half of half. This repeats at the speed of light until stability is reached at some somewhat warmer surface temperature and atmospheric temperature. At those temperatures the entire original insolation has been radiated into space.
Obviously this ignores all sorts of things, but does give some idea of why “greenhouse” (I hate that term) gasses can warm the surface by delaying reradiation into space.
Oops! “All” should be “All remaining”
“Roughly half get back to the surface warming it…” is a myth. A cooler object does not heat a warmer object. You can believe it — but you can not feel it — or measure it. The belief in a cooler object heating a warmer object leads to spontaneous combustion.
Any object above absolute zero radiates energy. Any object receiving that radiation REGARDLESS OF ITS TEMPERATURE will absorb some of that photonic energy resulting in a temperature increase.
Simpler statement: any object that absorbs a photon increases its energy level. It doesn’t matter where or from how far away that photon originated.
Just because a cooler object radiates does not mean a hotter object becomes hotter. To believe this leads to the concept of spontaneous combustion. That’s why the 2nd Law of Thermodynamics is a law.
A hotter may absorb a photon, some argue about that. But, if the hot object is radiating say 10 photons/time and absorbs 1 additional it will then radiate 11, thereby cooing still. This is a rough example. The point is that the hot object CONTINUES to radiate at a hot temperature. As it continues to cool and cold object continues to warm, both the warming and cooling rates will slow until equilibrium is reached.
This essay appears to be nonsense. Over the last 100 million years the earth has been significantly warmer than at present, take the Paleocene-Eocene Thermal Maximum for
example. How was that possible if greenhouse cooling limited the temperature to 15 degrees?
Ditto. While those green gases slow cooling, thermal convection is the primary cooling agent — which those energy balance graphics rarely show.
John Shewchuk: “thermal convection is the primary cooling agent”
WR: Agree. Energy budget figures all give the (first) impression that radiation is the primary factor. But evaporation and convection are of decisive importance for surface temperatures. Both are regulated by surface temperature itself.
The lapse rate which is due to expansion that determines atmospheric temperatures. The lapse on earth is reduced by the evaporation and condensation of in clouds. This lapse is averaged at 6C per km of height. The S-B equation applies to surfaces. Gas do not have a surface but water drops and ice particles in clouds do have a surface. Liquid water has an emissivity of around 0.97 while ice has an emissivity only around 0.5. Radiation from the surface can melt ice particle which takes in heat. However, due to the higher emissivity more heat is lost to space so ice is formed at the top of clouds. The clouds slow down the loss of heat from the surface. There is no back radiation from the the second law of thermodynamics. The idea of net radiation is unphysical as described by Prof Claes Johnson (https://claesjohnson.blogspot.com/(https://claesjohnson.blogspot.com/) Net implies there are two separate streams of radiation one going from hot Earth surface to cold space which is correct and one going the opposite which is false. When radiating to the bottom of clouds the temperature of the receiver is less than space so less heat flows from the surface than with a clear sky. Most farmers will have experience frost on plants when the sky is clear when when the air temperature has not dropped below freezing.
Here’s a simple experiment, which I have never tried. Put a small mirror in a freezer and let it get as cool as possible. After some time, measure its temperature. It should be well below freezing. Next get a cardboard tube, put an infrared lamp in one end of it, and point the other end at the cold mirror at, say, a 45 degree angle. Now hold your hand in the reflected infrared light. Does it feel warm? I think it will. So the cold object (the mirror) heated a warmer object (your hand), thus apparently counteracting the 2nd law.
It didn’t absorb and emit, it merely reflected incoming radiation.
Either way, a photon is returned to the surface. If a photon strikes the surface, does it not cause some small quantum of warming? That is was emitted by a “cold” CO2 atom doesn’t seem to matter. It’s still a photon.
Lots of things to consider in your statement, not the least is that a photon isn’t just a photon. What is emitted is actually an EM wave (electromagnetic wave) at a given frequency and power. The frequency and power determine what the wavelength of photons are and the power determines how many photons are carried by the wave. This is related back to the temperature of the object.
Here is a question for you. Can a block of gold at 300K heat a space filled with CO2 at 100K when they are separated to prevent convection/conduction and there is radiation only.
I see no one gave you an answer. It would appear that the block of gold is radiating at a wavelength the CO2 can’t intercept. The EM wave just passes the CO2 by. The block of gold would, however, cool.
What absorbs that photon? What substance in the dirt, plants, or whatever absorbs photons with the wavelength of CO2?
It has to be a front-surface mirror, not conventional aluminum-on glass. The glass absorbs IR beyond 2-3 um.
Carlo. Good point. So make it a polished sheet of Aluminum, which reflects 95% of IR.
No. Your hand is still being warmed by the higher temp. of the lamp, not the cooler mirror. If you were reflecting to a surface with a higher temp. than the lamp, it would not raise the temp. of the surface.
One day in the future Claes will be shown to be correct.
But climate change lukewarmists on this website and others will make sure it happens later than sooner.
Izaak Walton: “Over the last 100 million years the earth has been significantly warmer than at present, take the Paleocene-Eocene Thermal Maximum for
example. How was that possible if greenhouse cooling limited the temperature to 15 degrees?”
WR: This has been treated in an earlier post. The proposed (reversed) circulation of the oceans and water vapor play the main role. The mechanism is described here: https://wattsupwiththat.com/2018/06/15/how-the-earth-became-a-hothouse-by-h2o/
P.S. Better not give an opinion before the question is posed and a possible answer has been given. Facts and reasoning are interesting, simple opinions are not.
And there is the fact that this would appear to be the only article claiming that climate scientists have dramatically underestimated the strength of the greenhouse effect. Claiming that the greenhouse effect would warm the earth from 5C to 270C seems excessive. Nowhere else would you find any such claim about the strength of the greenhouse effect.
Izaak Walton: “Claiming that the greenhouse effect would warm the earth from 5C to 270C seems excessive. Nowhere else would you find any such claim about the strength of the greenhouse effect.”
WR: Well observed. But the calculator tells. More precisely, 270˚C is the temperature the surface of an object in space without oceans and without an atmosphere would get by adding the Earth’s greenhouse effects to the calculator that calculates temperatures for objects only cooled and warmed by radiation.
That 270.1˚C reveals that greenhouse warming effects for the surface initially are huge. This implies that forces cooling the surface must be very high as well and must be very effective also. And given the stability of the Earth’s surface temperatures, the surface’s cooling system must regulate temperatures very well, so there must be a mechanism behind it.
I don’t follow this, Wim:
“More precisely, 270˚C is the temperature the surface of an object in space without oceans and without an atmosphere would get by adding the Earth’s greenhouse effects to the calculator that calculates temperatures for objects only cooled and warmed by radiation.”
Surely, no greenhouse effects are possible if there is no atmosphere to cause them.
John Power: “Surely, no greenhouse effects are possible if there is no atmosphere to cause them.”
WR: Correct John, it is a calculation for a theoretical situation. You don’t need greenhouse molecules to simulate their temperature effect on surface temperatures.
Thanks, Wim. I think I understand what you meant now.
But now I have a problem with the calculation itself. In your calculation, you have given your hypothetical dry, rocky, atmosphere-less planet an emissivity of 0.1, which appears unrealistically low to me. Why did you not set it much closer to the black body emissivity of 1.0? You appear to have treated the planet as a black body when you calculated its surface temperature to be 5.3⁰C. Why are you not treating it similarly in this case?
Setting the emissivity to 1 and keeping the ‘Radiated power’ at 494 W/m2 in the Stefan-Boltzmann Law Calculator to which you gave the link returns a surface temperature of 32.36⁰C, which looks a lot cooler to me than the 270.14⁰C which you obtained.
John Power: “an emissivity of 0.1, which appears unrealistically low to me”
WR: The 0.1 was explained here in the post: “On Earth only about 40 W/m2 out of 396 W/m2 surface radiation directly reaches space: an efficiency of about 10% or a direct emissivity of only 0.1.”
The numbers are from the Kiehl-Trenberth Earth’s Energy Budget 2009. As you can see only 40 W/m2 out of 396 W/m2 emitted by the surface is able to reach space directly through the so-called ‘atmospheric window’. The rest of surface radation is absorbed.
WR: The 0.1 was explained here in the post: “On Earth only about 40 W/m2 out of 396 W/m2 surface radiation directly reaches space: an efficiency of about 10% or a direct emissivity of only 0.1
JP: That explains what you did, Wim, but it does not explain why you did it. To the best of my knowledge, the Earth’s surface emissivity has nothing to do with the fraction of the surface radiation that is emitted directly to space. Instead, it is defined as the ratio of the amount of radiation emitted to the amount that would be emitted by an ideal black body at the same temperature and wavelength. Therefore, I think your estimate of 0.1 is not valid, regardless of whatever the (unverified) values for the various power-fluxes presented in the Kiel-Trenberth Earth Energy Budget 2009 might be.
I also still think the figure of 0.1 is unrealistically low in any case, for two reasons which are:
1: The overwhelming majority of the individual areas which make up the global surface have emissivities that exceed 0.8 in the Infra-Red waveband in which the surface is generally radiating, so it seems highly unlikely to me that the global mean surface emissivity could be less than 0.7;
2: If the Earth had no oceans and no atmosphere as you hypothesise, its surface emissivity would be practically the same as that of the Moon, which NASA’s Moon Fact Sheet indicates is 0.89 (i.e. 1 – Moon’s Bond albedo 0.11).
John Power: “I also still think the figure of 0.1 is unrealistically low in any case”
WR: The number is derived from the data in the figure. Only 40 W/m2 directly reaches space, 356 W/m2 out of 396 W/m2 radiated by the surface is absorbed by the atmosphere (by greenhouse gases and clouds). Effective surface-emission: 0.1
You have already put that argument, Wim, and I have already replied to it, addressing your points carefully. You, however, are not addressing mine – at all. I do not have time to waste just talking to myself, so I shall bid you goodbye.
You must have seen that the calculation is a calculation for a theoretical situation. We could add a lot of things but that would complicate a lot.
Izaak, I might add to what Wim said that we have a perfect example in our own solar system. Venus has no oceans and no water and its surface temperature is 464 degrees.
Not quite a perfect example. Higher pressure causes higher temperature. Venus’ atmosphere has a surface pressure nearly 100 times higher than on earth.
John Shewchuck: “Higher pressure causes higher temperature.”
WR: ..causes a higher initial temperature. After that, on Earth, the higher surface temperature would activate the Earth’s H2O surface cooling system. The Earth’s H2O surface cooling reacts on any warming impulse, restoring surface temperatures.
Just like CO2, H2O slows earth’s cooling. The sun does all the heating. Nothing is restored as the sun constantly heats the earth and cooling (convection and radiation) continually sheds excess heat — whether slower or faster depending on many interactive factors.
John, the only way the earth-atmosphere system can cool is by radiation to space. All the heat “lost” from rising air (adiabatic expansion cooling), is returned when the air falls back to the surface (adiabatic compression warming), unless some of the heat is radiated to space.
I understand and thanks for elaboration. I was just talking immediate “surface” cooling by convection — which I agree some later radiates to space. And yes — all earth cooling is finally done via radiation.
Yet there is water vapor involved in convection. As it cools it precipitates giving up latent heat thereby cooling further. That is a net loss.
Jim, I think you meant to say, “as it cools it condenses.” But there is no “loss of heat” when water vapor condenses. What was latent heat becomes sensible heat, which can become latent heat again if/when water evaporates. Total heat, called enthalpy, is unchanged.
John Shewchuk, The higher pressure (that is gravity) controls the density of the CO2 in Venus’ atmosphere, it is actually supercritical at the surface and Venus is covered in a supercritical ocean of CO2. But, Venus is near equilibrium and the surface pressure isn’t changing much. The high temperature simply reflects the extraordinarily long time it takes thermal energy to escape and the low heat capacity of the atmosphere.
If Venus had oceans, evaporating water vapor would carry away the excess thermal energy and help store it at a lower temperature. Remember, water vapor is less dense than CO2, it rises.
The total heat content of Earth (due to the oceans mainly) is over four times the heat content in Venus’s atmosphere and supercritical CO2 ocean. See the post below (Table 1) for more details and a spreadsheet of Earth vs. Venus:
Can Earth be compared to Venus? | Andy May Petrophysicist
I guess we could blame increasing earth temperatures from increasing CO2 pressure — which then could make the atmosphere hotter than earth — which can then heat the earth’s crust. I wonder if the climate models use that as a parameterization input.
Andy, there is no such thing as heat content. You are mistakenly confusing heat content with heat capacity. Heat capacity is related to the specific heat of sea water in this case.
Heat is the defined as the internal energy transferred from a hotter object to a cooler object.
Heat is not a stored commodity.
Do your homework instead coming on here with a calculated degree of ignorance.
Leave the hyperbole to Greta.
Venus’ surface is hot despite receiving less sunlight than Earth’s because it rotates so slowly, and its dense air and high winds keep its dark side toasty during its long night. Some heat might also travel from the lit side through the crust.
Mercury, by contrast, cools off at night, depite high daytime temperature, slow rotation (while faster than Venus’) and receiving more sunlight.
That Venus’ atmosphere is mostly CO2 is a less important factor.
Agree — and a cooler object can not heat a warmer object.
The finer points of thermodynamics are above my physics education level, so I accept Dr. Spencer’s explanation:
http://www.drroyspencer.com/2010/07/yes-virginia-cooler-objects-can-make-warmer-objects-even-warmer-still/
And I accept my own experiments. No matter how close or how long I stand next to a cup of coffee hotter than me — I am not able to increase its temperature. Each of my experiments confirms the Second Law of Thermodynamics … but I keep experimenting anyway. Even my cat tries to make the hot coffee hotter … but still no luck.
In that case, the small effect is not measurable, and overridden by the coffee cup’s transfer of heat to the surrounding air and table. Net flow is from hotter to cooler, but the photons you radiate do warm the hot surface, however slightly.
“But the photons you radiate do warm the hot surface, however slightly” … only works if the radiation comes from a hotter object. So, I guess in the cold winter time, when I’m outside naked, I will heat up the earth slightly. I tried that and the neighbors complained. So the earth remained cold that night.
You’ve not tried it with all breeds of cats, John.
Tish, Tish!
Unless your name is Willis, John.
Then it can heat our world by back radiation.
Amazing what a degree in Psychology can achieve.
Earth surface temperature is temperature of entire ocean. The entire ocean average is about 3.5 C. And atmosphere temperature is insignificant as compared to heat content of ocean.
So ocean and atmosphere average is still around 3.5 C,
What about the Paleocene-Eocene Thermal Maximum?
The ocean was much warmer.
If ocean was 10 C rather than 3.5 C it has huge effect upon global averaged surface air temperature. An ocean of “only” 5 C has huge effect upon global averaged surface air temperature. One can’t have ocean of 5 C and have any arctic sea ice- even in a cold winter there can’t be much.
The average global air of 15 C, doesn’t tell you much about Earth surface temperature- other than 15 C is a cold temperature. One has to be in an Ice Age to have this global average surface air temperature. And we are in 34 million year old Ice Age- we already know this.
And within the 34 million year the most recent 2 million year has been the coldest- and ocean has not been 5 C within the last 2 million years. Most of the other 32 million years has had periods when ocean was 5 C or warmer. And lot of time of Earth history, the ocean has more than 10 C. Not sure if Paleocene-Eocene Thermal Maximum had ocean of 10 C or more, but it had huge amount ocean volcanic activity. Why it so much volcanic activity, I don’t know.
They say more then 80% of all volcanic activity of Earth surface occurs in the Ocean.
And entire ocean bottom is a young surface, something like 200 million year old- most it much younger. And at moment, it appears there not so much global volcanic activity as there has been, and one could say in terms volcanic activity the Paleocene-Eocene Thermal Maximum was very active time period- both on land and mostly in the ocean.
gbaikie: “Earth surface temperature is temperature of entire ocean.”
WR: No. The Earth’s surface temperature is the temperature of the Earth’s surface and the average temperature of the whole ocean is the average temperature of the whole ocean.
More precisely, the average temperature of the surface of the oceans is 18˚C. Because Land on average is much colder, the average surface temperature of the Earth is only 15˚C. The average temperature of all ocean water is estimated at 3.9˚C (or from your source 3.5˚C).
Izaak, Wim’s essay is about how did we get to 15 degrees today. This is not a paleoclimatology essay. He’s trying to get to a description of how water controls our current temperature. Bringing in the whole Phanerozoic temperature record would burden the essay with a lot of stuff that is irrelevant to today’s temperature.
Water has always controlled earth’s temperature. Water’s surface temperature gives the Earth it’s surface temperature of 15 C. It’s 15 C average because the tropical ocean average temperature is about 26 C. And tropical ocean surface has always been about 25 C. The global ocean surface averages about 17 {or 18 C}- because of 40% of it {the tropical ocean surface] is so warm, and always warm, or remaining 60% ocean surface is fairly cool {but even this cooler surface ocean is causing higher global air temperature as compared to what the land area in the 60% of the rest of world would cause- or tropical ocean is Earth’s heat engine but warmer water outside the tropics is causing the global average temperature of 15 C}
Or liquid water surface water in arctic has large warming effect. And thick polar sea ice, does not this warming effect upon land areas. The heat loss needed to make make polar sea ice is also a warming effect. The main warming effect of liquid water in arctic is the surface water cools and falls, and replaced warmer water, which cools and falls. But this regional warming effect, is globally a cooling effect- or why we are in an Ice Age- the entire ocean is cold. But the cold ocean of about 3.5 C is still causing world to be warmer as compared to colder ocean.
But ocean is 3 C or cooler, one get more polar ice, which prevents ocean water to regionally warm, but also stops, the generation of cold water falling and global cooling {ocean the getting colder}.
gbaikie: “And tropical ocean surface has always been about 25 C.”
WR: Very important is the quantity of clouds we find at different ocean temperatures. The least cloud coverage enables the most solar uptake. The next figure by Willis Eschenbach shows that the H2O system enables most solar to enter the oceans around 25 degrees.
From: https://wattsupwiththat.com/2018/02/12/glimpsed-through-the-clouds/
Above 25 degrees clouds form that shade the surface: they stop the ocean warming. At low temperatures, low and well covering clouds prevent radiative surface heat loss. The whole cloud system seems to enable maximum heat uptake at 25 degrees.
As an aside: I think this is why there has never been a real Snowball Earth: the high solar uptake (by intense tropical insolation) around 25 degrees of ocean temperatures prevents the cooling of tropical oceans. I cannot imagine how tropical oceans ever could have cooled below temperatures in the mid-twenties.
Especially not, when there were still places where considerable quantities of deep warm ocean water were produced.
But—hard to believe I’m supporting a comment by Izaak!—the question is still of interest. The argument has to withstand scrutiny of how it can be said to be consistent with paleoclimates.
Perhaps worthy of a separate discussion. Surely the physics didn’t change over the billions of years. If the argument is valid, it must be possible to show that it was also the case during the PETM, just that other factors determined the average temperature while the same mechanism maintained the homeostasis around the setpoint that was determined by different conditions.
To you it is “nonsense” because you don’t read very carefully or just don’t understand the written word. The 15 C is derived based on Earth’s current orbital dynamics and continental configuration. Reread the article, then try to comment intelligently.
Interesting paper and I respect the thought that has gone into it. As a non-scientist though I do have a query. The author says that the average temperature of the earth is 15ºC. I thought that figure was for the current ‘Icehouse Earth’ period and that the overall average temperature was 19ºC. Don’t shoot me, I’m only the piano player…
John V. Wright: WR: “Interesting paper”
WR: Thanks!
John V. Wright: The author says that the average temperature of the earth is 15ºC. I thought that figure was for the current ‘Icehouse Earth’ period and that the overall average temperature was 19ºC.
WR: 15˚C indeed is the actual average temperature. The overall average temperature over periods you mention (19˚C) is an estimation but an interesting number. When ‘snooker ball Earth’ the very first moments became covered by oceans, there hardly was any Land if only. All surface temperatures were set by the behavior of oceans and the weather above, and redistribution of tropical energy took place unrestricted by continents. It would be interesting to know the surface temperature that would result for that “All Ocean World”. How exactly would the weather pattern be in that situation, how would the system of horizontal and vertical movements in the oceans perform? And with what for surface temperatures as result? An intriguing question.
“The H2O molecule is very hygroscopic”
My apologies, but this terminology is nonsense.
Water cannot be hygroscopic by definition. Water = H2O is the subject of a hygroscopic substance and not a hygroscopic substance itself.
Next you’ll be claiming that the dehydrated water I’m selling is fake. It works perfectly well, just add water, et voilà!
Ron: “Water cannot be hygroscopic by definition. Water = H2O is the subject of a hygroscopic substance and not a hygroscopic substance itself.”
WR: Wikipedia: “Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment.”
Ron: “Water cannot be hygroscopic by definition. Water = H2O is the subject of a hygroscopic substance and not a hygroscopic substance itself.”
WR: Wikipedia: “Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment,(…)”
Both absorption and adsorption are not describing a process with the same molecule on both ends.
It is just not the appropriate term even if one can conclude what the intention is.
Wim,
If H2O was not ‘hygroscopic’, it would have a boiling point of about -200 degrees C, this value is the average of Ne and CH4. But it’s actual boiling point suggests that ~6 molecules are continually bound together. Water behaves as a material with molecular weight of 100, about 6 times its actual molecular weight of 18 (n-heptane, m.w. 100, boils at 98 degrees C).
Thank you, interesting. Looking for some more info about molecular weight and boiling point I found the following:
“Now compare the boiling point of water. This is certainly a low molecular mass compound; 18.0 [formula]. and yet water has high melting and boiling points. Here, of course, the potent intermolecular force of hydrogen bonding operates, which was certainly not the case for the alkane series.”
https://socratic.org/questions/how-does-molecular-weight-affect-boiling-point