Guest post by Ira Glickstein
A real greenhouse has windows. So does the Atmospheric “greenhouse effect”. They are similar in that they allow Sunlight in and restrict the outward flow of thermal energy. However, they differ in the mechanism. A real greenhouse primarily restricts heat escape by preventing convection while the “greenhouse effect” heats the Earth because “greenhouse gases” (GHG) absorb outgoing radiative energy and re-emit some of it back towards Earth.
The base graphic is from Wikipedia, with my annotations. There are two main “windows” in the Atmospheric “greenhouse effect”. The first, the Visible Light Window, on the left side of the graphic, allows visible and near-visible light from the Sun to pass through with small losses, and the second, the Longwave Window, on the right, allows the central portion of the longwave radiation band from the Earth to pass through with small losses, while absorbing and re-emitting the left and right portions.
The Visible Light Window
To understand how these Atmospheric windows work, we need to review some basics of so-called “blackbody” radiation. As indicated by the red curve in the graphic, the surface of the Sun is, in effect, at a temperature of 5525ºK (about 9500ºF), and therefore emits radiation with a wavelenth centered around 1/2μ (half a micron which is half a millionth of a meter). Solar light ranges from about 0.1μ to 3μ, covering the ultraviolet (UV), the visible, and the near-infrared (near-IR) bands. Most Sunlight is in the visible band from 0.38μ (which we see as violet) to 0.76μ (which we see as red), which is why our eyes evolved to be sensitive in that range. Sunlight is called “shortwave” radiation because it ranges from fractional microns to a few microns.
As the graphic indicates with the solid red area, about 70 to 75% of the downgoing Solar radiation gets through the Atmosphere, because much of the UV, and some of the visible and near-IR are blocked. (The graphic does not account for the portion of Sunlight that gets through the Atmosphere, and is then reflected back to Space by clouds and other high-albedo surfaces such as ice and white roofs. I will discuss and account for that later in this posting.)
My annotations represent the light that passes through the Visible Light Window as an orange ball with the designation 1/2μ, but please interpret that to include all the visible and near-visible light in the shortwave band.
The Longwave Window
As indicated by the pink, blue, and black curves in the graphic, the Earth is, in effect, at a temperature that ranges between a high of about 310ºK (about 98ºF) and a low of about 210ºK (about -82ºF). The reason for the range is that the temperature varies by season, by day or night, and by latitude. The portion of the Earth at about 310ºK radiates energy towards the Atmosphere at slightly shorter wavelengths than that at about 210ºK, but nearly all Earth-emitted radiation is between 5μ to 30μ, and is centered at about 10μ.
As the graphic indicates with the solid blue area, only 15% to 30% of the upgoing thermal radiation is transmitted through the Atmosphere, because nearly all the radiation in the left portion of the longwave band (from about 5μ to 8μ) and the right portion (from about 13μ to 30μ) is totally absorbed and scattered by GHG, primarily H2O (water vapor) and CO2 (carbon dioxide). Only the radiation near the center (from about 8μ to 13μ) gets a nearly free pass through the Atmosphere.
My annotations represent the thermal radiation from the Earth as a pink pentagon with the designation 7μ for the left-hand portion, a blue diamond 10μ for the center portion, and a dark blue hexagon 15μ for the right-hand portion, but please interpret these symbols to include all the radiation in their respective portions of the longwave band.
Sunlight Energy In = Thermal Energy Out
The graphic is an animated depiction of the Atmospheric “greenhouse effect” process.
On the left side:
(1) Sunlight streams through the Atmosphere towards the surface of the Earth.
(2) A portion of the Sunlight is reflected by clouds and other high-albedo surfaces and heads back through the Atmosphere towards Space. The remainder is absorbed by the Surface of the Earth, warming it.
(3) The reflected portion is lost to Space.
On the right side:
(1) The warmed Earth emits longwave radiation towards the Atmosphere. According to the first graphic, above, this consists of thermal energy in all bands ~7μ, ~10μ, and ~15μ.
(2) The ~10μ portion passes through the Atmosphere with litttle loss. The ~7μ portion gets absorbed, primarily by H2O, and the 15μ portion gets absorbed, primarily by CO2 and H2O. The absorbed radiation heats the H2O and CO2 molecules and, at their higher energy states, they collide with the other molecules that make up the air, mostly nitrogen (N2), oxygen (O2), ozone (O3), and argon (A) and heat them by something like conduction. The molecules in the heated air emit radiation in random directions at all bands (~7μ, ~10μ, and ~15μ). The ~10μ photons pass, nearly unimpeded, in whatever direction they happen to be emitted, some going towards Space and some towards Earth. The ~7μ and ~15μ photons go off in all directions until they run into an H2O or CO2 molecule, and repeat the absorption and re-emittance process, or until they emerge from the Atmosphere or hit the surface of the Earth.
(3) The ~10μ photons that got a free-pass from the Earth through the Atmosphere emerge and their energy is lost to Space. The ~10μ photons generated by the heating of the air emerge from the top of the Atmosphere and their energy is lost to Space, or they impact the surface of the Earth and are re-absorbed. The ~7μ and ~15μ generated by the heating of the air also emerge from the top or bottom of the Atmosphere, but there are fewer of them because they keep getting absorbed and re-emitted, each time with some transfered to the central ~10μ portion of the longwave band.
The symbols 1/2μ, 7μ, 10μ, and 15μ represent quanties of photon energy, averaged over the day and night and the seasons. Of course, Sunlight is available for only half the day and less of it falls on each square meter of surface near the poles than near the equator. Thermal radiation emitted by the Earth also varies by day and night, season, local cloud cover that blocks Sunlight, local albedo, and other factors. The graphic is designed to provide some insight into the Atmospheric “greenhouse effect”.
Conclusions
Even though estimates of climate sensitivity to doubling of CO2 are most likely way over-estimated by the official climate Team, it is a scientific truth that GHGs, mainly H2O but also CO2 and others, play an important role in warming the Earth via the Atmospheric “greenhouse effect”.
This and my previous posting in this series address ONLY the radiative exchange of energy. Other aspects that control the temperature range at the surface of the Earth are at least as important and they include convection (winds, storms, etc.) and precipitation that transfer a great deal of energy from the surface to the higher levels of the Atmosphere.
I plan to do a subsequent posting that looks into the violet and blue boxes in the above graphic and provides insight into the process the photons and molecules go through.
I am sure WUWT readers will find issues with my Atmospheric Windows description and graphics. I encourage each of you to make comments, all of which I will read, and some to which I will respond, most likely learning a great deal from you in the process. However, please consider that the main point of this posting, like the previous one in this series, is to give insight to those WUWT readers, who, like Einstein (and me :^) need a graphic visual before they understand and really accept any mathematical abstraction.
Well, I think the odds are getting better by the day/week/month that the mini-fusion project at LPPhysics.com will succeed. If it does, energy at 1/20 best current costs will soon (5 yrs. fwd) be plentiful (on-planet fuel is adequate for 10X current electric demand till about the Red Giant Sun stage). Space travel will become inexpensive and easy.
Take it from there.
Thanks for the responses to my query re the Igloo above. And to all the other contributors.
To be honest I have a huge problem with ice warming me up by returning my body heat back to me.
It just does not seem correct. I can see that the air would warm up. So it will reduce my rate of cooling. But actually warm me up. This seems like fiction.
I will keep an open mind on this though. But in the sky dragon book the statement in ch 15 ‘that a blanket can at best maintain your body temperature it can not give you a fever’ This makes sense. I can not see how there is any way to ever increase an objects temperature by reflecting back heat from that object. A small heat source in a perfect reflecting container will not and can not eventually produce a huge heat by reflecting the heat back.
I guess my question is is this statement correct or not. Chapter 15 Hans Schreuder again (I am not looking for an answer and do not expect this to be resolved quickly)
“The world has all too easily accepted greenhouse effect explanations that confuse the familiar reduction of CONVECTION heat loss with the production of radiative heat GAIN”.
I will continue following discussions on this issue with interest.
Ira Glickstein and davidmhoffer will need to revise their basic thermodynamics.
Get hold of a physics textbook work through the section on the Carnot Cycle.
They will find that there is no net heat only heat.
It always moves from a higher temperature object to a lower temperature object never the reverse.(Clausius).
Thermodynamic HEAT is unfortunately often confused with the vernacular meaning of heat.
The idea of heat coming back from the colder object is almost always used with radiant transfer as backradiation.
Coupled with this is the notion of “well if the colder object wasn’t there” and the thing being there instead is absolute zero (-273K).
Well the same line of reasoning would give you “back conduction” and “back convection” .
Object is at 350K, object B is at 270K and object C is at -273K.
Arrange and substitute these objects with suitable steps to allow conduction and convection.
This will give you “back conduction” and “back convection” .
Oliver Ramsay says:
March 2, 2011 at 10:07 pm
The other neat thing about igloos is that you can plop a chunk of seal-meat down in the middle of it, then go out hunt a polar bear. When you come back the meat is cooked to perfection. The radiation from the meat has been converted to heat and redirected at the said meat, thereby heating the dinner.
So, the meat being dead meat is radiating energy which is bouncing back from the inside walls of the igloo and cooking it? Gosh, how long then does it take to cook a live child which davidmhoffer leaves lying around in igloos, who are generating even more heat than the chunk of dead seal-meat?
Why then do Eskimos/Innuit build small fires in igloos to cook their food? Sometimes leaving meat to freeze and eating it raw?
http://people.howstuffworks.com/igloo.htm/printable
http://www.ehow.com/about_6513672_life-igloo.html
Urban myth from ignorance of life in the snowy wastes or deliberate misinformation from AGW to promote the idea that back-radiation from a cold object can heat a warmer object? I’d go for the second. Or, third option perhaps, someone’s sark remark to an AGW pushing backradiation heat flow from colder to hotter object.., and being taken as entirely plausible by AGW crowd.
Ira Glickstein, PhD says:
March 2, 2011 at 7:58 pm
Please NOTE Myrrh (GRRRH!) that the quote you got is about CONDUCTION, not RADIATION. That is why it says “..if a high temperature object is placed in contact with one of lower temperature,..” If the object are NOT in contact with each other (i.e., not connected by a good conductor, but RADIATING at each other with vacuum or air or some good insulator between) the hot to cold rule does not apply except to the NET transfer of energy. Got it?
Yes, yes, Ira, I’ve got it, but that was just an example. I’m trying to explore how this concept as you give it came into existence because it’s not anything to do with these laws as I can understand them, and more importantly, I’ve read countless times from people involved in heat transfer in the applied sciences who say the idea as you present it violates these laws. You can’t both be right. Shouting at me doesn’t make you right, but I’ll give it a go for emphasis too..
It violates the 2nd Law of Thermodynamics which says that HEAT FLOW IS ALWAYS FROM HOTTER TO COLDER.
THIS APPLIES TO ALL RADIATION STATES ACCORDING TO THE 2ND LAW.
“THE SECOND LAW STATES THAT SPONTANEOUS NATURAL PROCESSES … THAT HEAT CAN SPONTANEOUSLY FLOW ONLY FROM A HIGHER-TEMPERATURE REGION TO A LOWER-TEMPERATURE REGION, BUT NOT THE OTHER WAY AROUND.”
“The second law of thermodynamics may be summarized as follows:
“When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself, but not in equilibrium with each other at first, are at some time allowed to interact, breaking the isolation that separates the two systems, and they exchange matter or energy, they will eventually reach a mutual thermodynamic equilibrium.”
Radiation then, is such an exchange of energy. The 2nd law thus applies equally to radiation as it does to conduction.
Spontaneously in nature. That means, that no extra work is being done to alter it. Otherwise, you end up with the ludicrous notion as described in the Trenberth graphic that back-radiation keeps bouncing between the ‘greenhouse gas’ and Earth, raising the global temperature of Earth. Or the igloo that cooks a chunk of raw meat.
In the 1st Law – “This is a statement of conservation of energy. The net change in internal energy is the energy that flows in as heat minus the energy that flows out as the work that system performs on its environment.”
This is the only mention of “net”, of net change, I don’t understand how that can apply to “net as transfer of radiation” outside of it relating to the flow of heat energy as above and by breaking the 2nd Law of heat flowing always from hot to cold and never the other way around, naturally spontaneous, that is, without work being done to change it.
[I don’t know how I’m doing here in the eyes of those arguing against AGW here by saying AGW violates these laws. I’m still working my way through it, do feel free to correct me but keep the explanations simple..]
Ira says re the drop of ink in glass of water stirred – The above is certainly true, but only for statistical reasons. If the inky water is continually stirred, the molecules of ink will assume different positions with respect to the molecules of water. If, to take a very simply example, there were two molecules of ink and 14 molecules of water…
This was given as an example of processes that are one way as heat transfer is one way. As the example of the perfume wafting into a room from a bottle it won’t spontaneously waft its way back into the bottle, or from the extreme therefore of the whole lot evaporating. Sure, given infinite time it’s possible.., or work can be done to separate out the smell from the room together with all the molecules of alcohol and water that made up the perfume and get it back into the bottle, but that would take an awful lot of work, of energy expended to achieve such a thing, same in re-constituting the ink in solution back into its original constituent parts, but, given that statistically that ain’t going to happen for all the spilt ink and evaporated perfume in the world unless you wan’t to wait for an infinitely long time for it to happen and then maybe it never will, (you are assuming it is bound to happen but it’s ‘statistically as likely not to happen as to happen’ has to be included, so there’s no “bound to” about it), or are willing to expend energy to do this for all the examples past present and future, then, for all practical natural processes purposes, the ink stays mixed and the perfume evaporated. One way process.
So, radiation is included, not just conduction, which means that it is impossible for a cooler molecule to transfer heat to a hotter one because that would violate the 2nd Law.
The explanations I give above in quotes come from wiki’s Laws of thermodynamics.
As with the NASA page I showed you, you are contradicted here re radiation not constrained by these Laws as you are re claiming that it’s shortwave solar heating the Earth and not as normal Science has always stated, that it’s the Thermal energy we feel from the Sun and which heats the Earth.
I have now worked out to my own satisfaction that Real Science is that it’s Thermal energy heating the Earth and not short wave Solar, by looking a the different aspects involved and understanding more about them.
Prove that it’s short wave “Solar”heating the Earth which you claim in your diagrams above and is that we feel as warmth as you have continued to expand on the description to me, or have the courtesy to say you are wrong.
To prove you are right you MUST contradict all the information given on the NASA page I posted.
You’re not just arguing with me or my understanding. I am agreeing with what is written on that NASA page.
Should I put that in CAPS, to get your attention? Unless you can prove NASA wrong, your energy premise is wrong and what follows from that premise will be out of context of the Real World energy balance which is by Thermal radiation from the Sun, these Thermal energies which are the Heat energies which are long wave IR.
Here it is again:
http://science.hq.nasa.gov/kid/imagers/ems/infrared.html
Phil. says
March 2, 2011 at 7:32 pm
Re: Myrrh says (March 2, 6:42 pm): “So, if as Ira says “the filament of the incandescent light bulb is heated to temperatures similar to the Sun’s surface”, and we know such a lightbulb gives most of its energy in Heat and not Light, in Thermal IR, 95%, and only a small amount in Visible, only 5%, then what is really “the most” energy given off by the Sun?”
Nonsense which rambles on confusing the english meaning of ‘heat’ and ‘light’
deleted.
? A lightbulb gives out 95% of its energy in Heat and only 5% of its energy in Visible Light. Heat is Thermal IR.
It’s been confused by AGW.
It may well “peak” in the Visible by energy states, but the Visible as % of the total energy emitted is relatively tiny compared with the total amount of energy emitted.
The amount, therefore the real “most”, of the energy emitted from the lightbulb is Thermal IR.
The Sun thus, if similar as Ira has it, should also be emitting the same kind of ratio of Visible to Thermal. [Assuming that the real difference between thermal and visible energies are understood, not as Ira has it that Solar is the Heat energy we feel from the Sun]. I have seen this figure put at 80% in Thermal for the Sun.
How, your info on light bulbs and sun temps, the light bulb compares with the sun re what Ira said, I think, I could be wrong, he meant that the heat it takes to produce white visible light from the sun is the same as that it takes to produce visible light from the lightbulb. The sun even hotter will produce shorter wavelengths also.
mkelly says:
March 2, 2011 at 11:42 am
Phil. says:
March 2, 2011 at 9:19 am
Phil, the -18 C comes from the standard model of radiated heat transfer given approx 240 w/m2 at surface. Thus having GHG’s take us up 33 degrees to 15 C.
Correct.
Without any GHG no H2o, CO2 etc the sun would essentially have free rein with no absorbtion, so surface would get 340 w/m2 thus raising up to 278 K or 5 C to start. I think the 340 number used is to low.
Well you have forgotten to consider reflection (i.e. albedo)
It can easly be show via a pan of water and a thermometer that large protion of the surface get 700-1000 w/m2. Heck SOD has a graph on his web site showing the radiance of the sun on a plot of ground in Canada where measured solar radiation is about 700 w/m2.
The 340 value is an average so of course there are places and times where it is exceeded.
em>I think that ignoring the (PV=nRT) pressure of the atmosphere is a mistake. STP is 0 C. So not a bizarre statement. You are free to agree or disagree as you wish.
Thank you for your permission to disagree with junk science! STP is an arbitrary reference point and has no significance at all. All that PV=nRT tells us is that at the surface atmospheric density is a function of Temperature, n/V=P/RT where P is ~constant.
Also, would N2 or O2 cool if they went up. If they cannot radiate just going up will do little. Granted some work will be done so energy will be lost but how much?
Yes due to adiabatic expansion, just like the N2 atmosphere on Triton does.
As 99% of atmosphere is N2 and O2 we need to look at them. I am trying to find out. I have an idea they do radiate just like any matter at a temperature but I have not seen a temperature graph for each showing their respective pattens or amounts. If they do not I will change my idea.
You have been shown data here which shows exactly how weakly N2 and O2 interact with IR, but it doesn’t agree with you preconceived belief so you ignore it. Your ‘idea’ contradicts a century of science on the structure of molecules and their interaction with radiation as well as the experimental basis for it.
to Al Tekhasski
To me the dolts are heavily weighted towards the pro-AGW crowd.
pro-AGW vs. anti-AGW is not a good way to put it. That seems to be a way that a pro-AGW person would look at it.
I never consider someone who is trying to learn more about the science, its methods, and ramifications, to be a dolt. Most of the people here, by far, are in that category.
For those still confused about how O2 and N2 can absorb/emit energy, yet accomplish this with absorbing/emitting in the thermal IR spectrum, this article just up might help…
http://wattsupwiththat.com/2011/03/03/feb-uah-global-temperature-anomaly-goes-slightly-negative/
Note that the article specifies that the satellites detect the temperature of O2 by taking readings in the microwave spectrum. Thus, O2 absorbs/emits in the microwave spectrum (which is directly adjacent to the thermal IR spectrum).
The physical chemists are right. A black body is an imaginary, ideal surface that can absorb/emit any wavelength. Individual atoms can only absorb/emit in specific quanta. The larger the variety of atoms in your object, the more it will approximate a black body. The more your object is composed of a single element, the less it will approximate a black body.
Whether or not it is explicitly stated, “HEAT” ALWAYS MEANS “NET HEAT” = “NET TRANSFER OF ENERGY”.
Look at the Maxwell-Boltzmann distribution, for example here: http://bouman.chem.georgetown.edu/S02/lect4/image8.gif. In any object at any temperature, there will be some fast moving, high energy atoms and some slow moving, low energy atoms.
If you put a block of 100C metal into a cup of 0C water, we all agree there will be “heat” from the surface of the metal to the water. Now look microscopically at the individual atoms and individual collisions — some metal atoms will have lower energy
than some water atoms. When a high energy water molecule collides with a low energy metal atom, the metal atom will gain energy. Let me repeat — THE WARM METAL GAINED SOME ENERGY FROM THE COOLER WATER.
This is not a violation of the 2nd law, because there is, on average, a NET transfer of energy from the warm metal to the cooler water. Every second there are billions of instances where energy was transferred from the cooler water to the warmer metal; there are simply MORE transfers the other way! The same applies to transfer by radiation. There are many photons transferring energy from the cold object to the warm object; there are simply MORE photons transferring energy from the warm object to the cold object!
Tim Folkerts
Whether or not it is explicitly stated, “HEAT” ALWAYS MEANS “NET HEAT” = “NET TRANSFER OF ENERGY”.
Tim what is your definition of Heat?
Clausius was well aware of radiation when he postulated his famous Second Law.
He was writing about the Macro World rather than the Micro World.
The transfer of heat in the Macro World always moves spontaneously from the higher temperature object to the lower temperature object never the reverse.
The thermodynamic meaning of heat implies the ability to do work in the given situation.
This applies to the radiation moving from the hotter surface to the colder surface.
It does not apply to the radiation moving from the colder surface to the warmer surface.
So there is no dual heat transfer only heat transfer from higher to lower temperature objects
to Phil
You should learn to read more carefully.
http://www.its.bldrdoc.gov/pub/journal_articles/liebe_journ_quant_spectrosc_radiat_trans_vol48-1992/liebe_journ_quant_spectrosc_radiat_trans_vol48-1992.pdf
“Abstract-Over 5000 absolute absorption values for pressure-broadened O2 lines in dry air were measured at frequencies from 49 to 67 GHz in O.l-GHz-increments. The controlled laboratory studies were carried out at three temperatures (6, 30, and 54°C) for 11 pressure values ranging between 1.3 and 101 kPa.”
1. They measured only in the 49 to 67 Ghz band. That is a very, very tiny fraction of the entire long wavelength band (10 microns and above, to meters of wavelength) of interest for radiational heat transfer in the atmosphere to outer space.
2. They tested O2 only at 6, 30, and 54°C. That is not representative of O2 in the upper troposphere and stratosphere.
One very little understood property of matter (atoms, molecules, etc) is that their real life emittance (thus absorption) changes as a function of their internal temperature and outside temperature (thermal radiation field). Emittance, thus absorption, changes as a function of its environment.
The emittance and absorption found in a laboratory are only valid for THOSE SPECIFIC CONDITIONS. That is your mistake. You think the laboratory is the real world. It is not.
The heat or energy balance at equilibrium should result in a sustainable biosphere, too cold and we all freeze to death to hot and we all boil to death. It has to be just right a ‘goldilocks scenario’ in fact. In the discussions of global warming a heat input to the equation which is rarely seen or mentioned is nuclear fission in rocks. I do recall some time ago, from a scientific paper, that nuclear fission was a very important heat contributor to the biosphere and that it contributed 50% of the heat necessary to sustain life. Without it would we be locked into a long ice age?
Domenic and Al Tekhasski: I agree with the highlighted statement above.
IMHO, those in the climate science debate may be roughly grouped into:
(1) Alarmists: Like “Chicken Little” who cried “the sky is falling” when he was hit by an acorn falling off a tree, the Alarmists think they are warning and saving the world from a “tipping point” that will cause “runaway warming” within a decade or so because of the coincidence of a warming trend and CO2 rise over the past century. This group uses non-scientific arguments (“coal trains are death trains”) and knowlingly bends data to the breaking point or stays silent while non-scientists like former VP Al Gore spout nonsense. IMHO, their belief system is more like a religious mission than true science. They may also harbor conspiratorial views of corporations, globalization, etc., yet, confoundingly, they trust the government, including nacent world government, to fix the problem.
(2) Warmists: These are valid scientists who interpret the data in the most precautionary way possible, slanting it (but generally not breaking it) to emphasize what may happen due to human activities that are unprecedented in the history of the Earth. They generally favor action to curtail the human activities they see as dangerous.
(3) Lukewarmers: These are valid scientists who interpret the data midway between Warmists and Skeptics. They favor moderate action to curtail some aspects of human activities, and tecnological adaptation to deal with whatever climate change may occur.
(4) Skeptics: These are valid scientists who interpret the data in the most optimistic way possible, slanting it (but generally not breaking it) to emphasize the uncertainty about how much human activities may affect climate change and to point out the misinterpretation and misrepresentation of the data by the Warmists and Alarmists. They generally favor little or no action to curtail human activities others see as dangerous, believing (corrrectly IMHO) that increased CO2 is inevitable and that the supposed solutions would wreck world economies and, in the end, do little to curb warming, which is mostly due to natural cycles and processes that may well bring us cooling in coming decades. Besides, a moderate rise in CO2 and temperatures will be beneficial to much or most of the world population. Whatever happens, civilization will adapt. Skeptics usually distrust the ability of government, particularly nascent world government, to get much of anything right. (If the government was in charge of the Sahara Desert, within six months, there would be a shortage of sand :^)
(5) Deniers: Mirror image of the Alarmists, they are like the ostrich who sticks his head in the sand to shut out the real events in the world. Deniers are sometimes motivated by religious faith that God will not allow humans to destroy ourselves, that humans are not capable of changing God’s plan, etc. This group uses non-scientific arguments (“the atmospheric ‘greenhouse effect’ in a scam) and ignorantly bends data to the breaking point or cheers while non-scientists like certain elected officials spout nonsense. IMHO, their belief system is more like a religious mission than true science. They may also harbor conspiratorial views of environmental groups and the government.
So, where does AGW come in? Well, from my point of view (as a Lukewarmer-Skeptic) it is absolutely true, in a scientific sense, that human activities over the past century have changed climate to some extent, probably minor compared to natural cycles and processes. Thus, IMHO, the central three belief systems, from Warmist to Skeptic, all accept AGW as scientific fact. The main differences are “how much?” and “what should we do about it?” That is the basis for robust discusion.
The outlier groups, Alarmists and Deniers, are non-scientific and should be ignored because they are not qualified for rational discussion.
Forgot to tick the comments box.
Bryan;
The thermodynamic meaning of heat implies the ability to do work in the given situation.
This applies to the radiation moving from the hotter surface to the colder surface.
It does not apply to the radiation moving from the colder surface to the warmer surface.>>>
I’m very interested in how this works Bryan. How is it that radiation going in one direction is able to do work, but radiation going in the other direction is unable to do work? Do the photons carry with them documentation regarding their temperature of origin to determine if they have a work permit or not? Do they compare permits to other photons going the other way? Seems to me this would be required as the photon not knowing the temperature of the destination would need to periodicaly check the state of the union (these sound like unionized photons to me, but that is only an assumption on my part) to determine if they are permted to do work along the way. Or do the photons upon arrival, determine the temperature at destination, compare to documentation of temperature of origin, and only then make a determination if they are allowed to do work or not?
This is very intriguing Bryan. Exciting. Who knew that a photon travelling at the speed of light, carrying a tiny bit of energy with it, and having charactersitics identical to other photons save for direction, would know if that packet of energy is allowed to do work or not? Does this not imply some sort of system capable of exchanging information between photons? Are the photons then indpendant decision makers arriving at their own conclusions, or do they await instructions to be communicated to them by a higher authority? Is this perhaps the very communication system that would confirm the existance of Gaia taking a firm hand in control of the universe?
Phil. says:
March 3, 2011 at 6:48
“You have been shown data here which shows exactly how weakly N2 and O2 interact with IR, but it doesn’t agree with you preconceived belief so you ignore it. Your ‘idea’ contradicts a century of science on the structure of molecules and their interaction with radiation as well as the experimental basis for it.”
I must have missed that. The graph I saw never said anything about temperature. That is my specific question. If it was intended to say that those areas are the only frequency they emit/aborb under all temperatures I misunderstood the graph.
You seem so angry. I was not granting you permission to do anything I was trying to be polite/civil. If you chooe otherwise please let me know.
Adiabatic lapse rate accepts the fact that pressure causes heat. Less pressure less heat. So PV=nRT is valid. I know very little of Triton.
My heat transfer book shows insolation varys between 1063 w/m^2 at 90 deg to sun down to 41 w/m^2 at 5 deg. So if we are going to average then 55o w/m^2 should closer to what the surface receives. See what George said above.
I did not forget reflection or albedo I just forgot to type in “etc.” after absorption. When at work hurrying to type something out it is possible to misspell or forget a word.
I have very little preconcieved ideas about N2 and O2 radiation since I have seen little written about it and have found little. If they cannot as I said I can accept that.
But as you have read here there are varied opinions of this.
Ira
Have you read Slaying the Climate Dragon. Or followed the debate on this book
http://judithcurry.com/2011/01/31/slaying-a-greenhouse-dragon/
Referring to comment 5. No one said the greenhouse effect is a scam (CAGW is another matter). But science moves on. The greenhouse theory seems suspect as has been shown above. Name calling (deniers etc) will not change that.
And a few extra parts of CO2 will not destroy the planet. Whether humans can (I doubt it though) is not relevant to this AGW debate.
Myrrh says:
March 3, 2011 at 6:32 am
? A lightbulb gives out 95% of its energy in Heat and only 5% of its energy in Visible Light. Heat is Thermal IR.
It’s been confused by AGW.
It hasn’t been confused at all except for those like you who don’t understand what they’re talking about. The light distribution emitted by and incandescent body is well described by the Stefan-Boltzmann law, visible light ranges from ~400nm to about ~770nm (some use slightly different limits).
It may well “peak” in the Visible by energy states, but the Visible as % of the total energy emitted is relatively tiny compared with the total amount of energy emitted.
The amount, therefore the real “most”, of the energy emitted from the lightbulb is Thermal IR.
Not by any reasonable definition of ‘Thermal IR’, usually 3-15 microns (an application driven nomenclature associated with imaging, not any fundamental distinction). Most is probably in the NIR.
The Sun thus, if similar as Ira has it, should also be emitting the same kind of ratio of Visible to Thermal.
No because similar is in this case a factor of two as I showed above, particularly for a ‘cool’, longer life lamp. I’ve told you what the ratio is above, can’t you read?
[Assuming that the real difference between thermal and visible energies are understood, not as Ira has it that Solar is the Heat energy we feel from the Sun]. I have seen this figure put at 80% in Thermal for the Sun.
I’m sure you have, doesn’t make it right though, by the above definition ‘thermal IR’ from the sun is extremely low. All absorbed light from the sun, no matter what wavelength will heat up the earth, 1 W/m^2 absorbed will heat up an object equally, your fantasy notwithstanding.
Test
My previous post has not appeared
[Reply: That’s because there were a lot of posts in the spam folder. Yours was one of them. Posted now. ~dbs, mod.]
Bryan says:
March 3, 2011 at 8:14 am
The transfer of heat in the Macro World always moves spontaneously from the higher temperature object to the lower temperature object never the reverse.
The thermodynamic meaning of heat implies the ability to do work in the given situation.
This applies to the radiation moving from the hotter surface to the colder surface.
It does not apply to the radiation moving from the colder surface to the warmer surface.
So there is no dual heat transfer only heat transfer from higher to lower temperature objects
There is energy transfer in both directions resulting in a net transfer of heat from the hotter to the cooler
Ira
Have you read Slaying the Climate Dragon. Or followed the debate on this book. At judith Curry’s website for example
Referring to comment 5. No one said the greenhouse effect is a scam (CAGW is another matter). But science moves on. The greenhouse theory seems suspect as has been shown above. Name calling (deniers etc) will not change that.
And a few extra parts of CO2 will not destroy the planet. Whether humans can (I doubt it though) is not relevant to this AGW debate.
izen says:
March 3, 2011 at 12:08 am
Reed Coray says:
March 2, 2011 at 9:40 pm
“….I also believe that if you allow conduction of energy between objects, depending on the rate of energy transfer via conduction, the temperature of the original object will be lower than the original object temperature in the absence of the second object. Note that the presence of conduction does not eliminate backradiation–it will still be present. If true, we have reached a state where (a) backradiation exists and (b) the temperature of the original object is lowered….”
No point in putting on a coat in cold weather then…
Izen, is it correct to infer that for a fixed internal energy source, you believe that the steady-state temperature of an object is always increased in the resence of backradiation?
The key phrase in my statement was “depending on the amount of conduction”. Most coats are made of material that minimizes conduction. The simplist example I can think of to demonstrate that backradiation can simultaneously exist with lower temperatures is to consider a blackbody sphere with a fixed internal thermal energy source. To achieve steady state, the surface of the sphere must radiate energy away from the sphere at a rate equal to the internal energy source. The rate of energy radiated away from a blackbody sphere is proportional to the square of the sphere radius. Thus, for a fixed rate of internal energy generation, as the radius of the sphere increases the “steady-state” temperature of its surface decreases. Fix that radius at a finite value and determine the steady-state surface temperature. Now place a larger radius spherical shell around and centered on the sphere. Assume that the thermal conduction properties of this shell are such that its temperature is everywhere the same. Call this shell a “coat”. In the absence of conduction and convection, the presence of the shell (coat) will result in an increase in the sphere surface temperature. In the terminology of many, the increae in temperature is the result of backradiation from the surface of the shell. However, if thermally conducting rods are inserted that join the sphere and the shell such that the sphere surface and the shell surface can be brought to the same or very nearly the same temperature, then because the shell’s surface is larger than the sphere’s surface and thus can radiate the energy from the fixed internal energy source to space at a lower temperature, that temperature (both the shell and the sphere) will be lower than in the absence of the shell–notwithstanding backradiation from the shell’s inner surface to the sphere’s surface.
On another topic. Several commentors have noted that for a situation where radiation is the only form of energy transfer, “heat” and “net” radiative energy transfer are the same thing. I agree. When discussing thermal energy transfer between objects by conduction, people seldom, if ever, discuss “backbumping”. For example, one model of conduction energy transfer between two objects made of the same material is that the “aggregate” speed of the random motion of the molecules of the object at the higher temperature is greater than the “aggregate” speed of the random motion of the molecules of the object at the lower temperature. When the two objects are brought into contact, some of the motion of the faster moving molecules of the higher temperature object is transfered to the motion of the slower moving molecules of the lower temoperature object; thereby increasing the “aggregate” speed of the colder object’s molecules and decreasing the “aggregate” speed of the warmer object’s molecules. However, since molecular speed is a distribution, not a single value, some of the molecules of the colder object will be moving faster than some of the molecules of the warmer object. When two such molecules collide, energy may be transfered from the colder object to the warmer object. Call this cold-to-warm object energy transfer “backbumping”. Most discussions of thermal energy transfer via conduction, don’t separately analyze “forwardbumping” and “backbumping”, they just discuss net energy transfer–i.e., heat.
davidmhoffer says:
March 3, 2011 at 1:13 am
“C’mon Oliver. S’plain it. I’ll ridicule…. I mean read it in the morning.”
—————————
I don’t doubt that you’ll ridicule…. nor that you’ll sort of read it. But understand it?
Recall the sage counsel of your grandmother; she knew the score.
Before sending you out to play in the snow, she gave you a big pair of woolen socks and said “Here, these will keep you warm!”
You came in later and she handed you a steaming mug of cocoa, saying “This will warm you up”.
She never got them reversed. How did you?
Perhaps it’s this notion that if there’s any aperture in the dwelling, all the heated air will rush out and be replaced by frigid outside air in the blink of an eye. With a more nuanced approach you can size and locate your ventilation openings to compromise between convected heat loss and asphyxiation. If you get it wrong, the igloo walls will not save you with their back radiation. As an aside, most of the inhaled O2 of a breath is simply exhaled without finding its way into the bloodstream.
It’s very bizarre to me that an igloo can heat a heat source but it can’t heat a non-heat source. Anything that is hotter than an adjacent thing is a potential heat source. However, the cooler thing is not a heat source to the hotter thing. Yes, they radiate back and forth, but they don’t radiate heat. Heating occurs when the average kinetic energy of the molecules in the thing rises. If it goes down, we say that it has lost heat, if it stays the same, we say it has stayed the same. In spite of all the to-ing and fro-ing of packets of energy.
The vibrational excitement that an absorbed photon causes within a molecule does not necessarily get turned into translational motion of that molecule, which would be termed heating IF there were enough similar occurrences to elevate the AVERAGE kinetic energy of a whole bunch of molecules. Heat is not a property of individual particles.
Photosynthesis is not a heat process.
On the other hand….. If we built the igloos in the shape of a pyramid, we’d really be onto something.
A few general comments and then I may slink back to the rest of life for a while …
* Whatever Clausius or Carnot may have said 150 years ago, that is not the final word. Science moves forward. If you want to understand heat and entropy and the 2nd law at a fundamental level, you really should look at the more modern approach of Statistical Mechanics. (For example, a quick look at the online physics courses listed at MIT shows “Statistical Physics I & II”, and “Statistical Mechanics I &II”, but no “Thermodynamics” class!)
* “Heat” is a very abused word – used to mean different things by different people in different settings.
-> In thermodynamics, heat is akin to work — it is a process that transfers energy. You can be working on an object (applying force*distance), but you don’t “have work”. Similarly, you can be heating an object (perhaps holding a cold object in your hands) , but you don’t “have heat”. Delta(E) = δQ – δW where δQ is the heat that was applied TO the system, and δW is the work that was applied to the system.
–> In other circumstance, people (including scientists and engineers) use “heat” to mean “thermal energy” or “internal energy”. In this meaning an object can “have heat”. This is, however, at odds with the formal thermodynamics meaning.
–> Colloquially heat can mean “temperature” but this is never used in science as far as I know.
* Thermodynamics deals with averages and net values (summations) (hence the term “Statistical Mechanics”. Pressure in a gas is the net force provide by trillions of collisions of individual molecules divided by the area where they hit. Heat is the net transfer of energy during trillions of interactions (photons, phonons, collisions, …).
So energy does indeed flow from hot objects to cold object AND from cold objects to warm objects (via those photons, phonons, collisions …). It is only the NET flow (ie “heat”) will always be from hot to cold (for sufficiently large systems averaged over sufficiently large times).
Specifically, energy does flow from the cooler atmosphere to the warmer surface via photons. But more energy flows the other way, so “heat” is doing what it is supposed to do. That flow of energy via photons from the atmosphere by itself can never raise the surface temperature above the temperature of the atmosphere (becasue more energy is going the other way). But that flow energy combined with the flow of energy from the sun can make the surface warmer than it would have been with no energy from the atmosphere.
That’s the physics. You may go back to arguing the semantics of whether the atmosphere is “warming the ground” or simply “slowing the cooling” if you like.