Guest Post by Ira Glickstein
This series began with a mechanical analogy for the Atmospheric “Greenhouse Effect” and progressed a bit more deeply into Atmospheric Windows and Emission Spectra. In this posting, we consider the interaction between air molecules, including Nitrogen (N2), Oxygen (O2), Water Vapor (H2O) and Carbon Dioxide (CO2), with Photons of various wavelengths. This may help us visualize how energy, in the form of Photons radiated by the Sun and the Surface of the Earth, is absorbed and re-emited by Atmospheric molecules. 
DESCRIPTION OF THE GRAPHIC
The animated graphic has eight frames, as indicated by the counter in the lower right corner. Molecules are symbolized by letter pairs or triplets and Photons by ovals and arrows. The view is of a small portion of the cloud-free Atmosphere. (Thanks to WUWT commenter davidmhoffer for some of the ideas incorporated in this graphic.)
- During the daytime, Solar energy enters the Atmosphere in the form of Photons at wavelengths from about 0.1μ (micron – millionth of a meter) to 4μ, which is called “shortwave” radiation and is represented as ~1/2μ and symbolized as orange ovals. Most of this energy gets a free pass through the cloud-free Atmosphere. It continues down to the Surface of the Earth where some is reflected back by light areas (not shown in the animation) and where most is absorbed and warms the Surface.
- Since Earth’s temperature is well above absolute zero, both day and night, the Surface radiates Photons in all directions with the energy distributed approximately according to a “blackbody” at a given temperature. This energy is in the form of Photons at wavelengths from about 4μ to 50μ, which is called “longwave” radiation and is represented as ~7μ, ~10μ, and ~15μ and symbolized as violet, light blue, and purple ovals, respectively. The primary “greenhouse” gases (GHG) are Water Vapor (H2O) and Carbon Dioxide (CO2). The ~7μ Photon is absorbed by an H2O molecule because Water Vapor has an absorption peak in that region, the ~10μ Photon gets a free pass because neither H2O nor CO2 absorb strongly in that region, and one of the 15μ Photons gets absorbed by an H2O molecule while the other gets absorbed by a CO2 molecule because these gases have absorption peaks in that region.
- The absorbed Photons raise the energy level of their respective molecules (symbolized by red outlines).
- The energized molecules re-emit the Photons in random directions, some upwards, some downwards, and some sideways. Some of the re-emitted Photons make their way out to Space and their energy is lost there, others back down to the Surface where their energy is absorbed, further heating the Earth, and others travel through the Atmosphere for a random distance until they encounter another GHG molecule.
- This frame and the next two illustrate another way Photons are emitted, namely due to collisions between energized GHG molecules and other air molecules. As in frame (2) the Surface radiates Photons in all directions and various wavelengths.
- The Photons cause the GHG molecules to become energized and they speed up and collide with other gas molecules, energizing them. NOTE: In a gas, the molecules are in constant motion, moving in random directions at different speeds, colliding and bouncing off one another, etc. Indeed the “temperature” of a gas is something like the average speed of the molecules. In this animation, the gas molecules are fixed in position because it would be too confusing if they were all shown moving and because the speed of the Photons is so much greater than the speed of the molecules that they hardly move in the time indicated.
- The energized air molecules emit radiation at various wavelengths and in random directions, some upwards, some downwards, and some sideways. Some of the re-emitted Photons make their way out to Space and their energy is lost there, others back down to the Surface where their energy is absorbed, further heating the Earth, and others travel through the Atmosphere for a random distance until they encounter another GHG molecule.
- Having emitted the energy, the molecules cool down.
DISCUSSION
As in the other postings in this series, only radiation effects are considered because they are the key to understanding the Atmospheric “Greenhouse Effect”. I recognize that other effects are as important, and perhaps more so, in the overall heat balance of the Earth. These include clouds which reflect much of the Sun’s radiation back out to Space, and which, due to negative feedback, counteract Global Warming. Other effects include convection (wind, thunderstorms, …), precipitation (rain, snow) and conduction that are responsible for transferring energy from the Surface to the Atmosphere. It is also important to note that the Atmospheric “Greenhouse Effect” and a physical greenhouse are similar in that they both limit the rate of thermal energy flowing out of the system, but the mechanisms by which heat is retained are different. A greenhouse works primarily by preventing absorbed heat from leaving the structure through convection, i.e. sensible heat transport. The greenhouse effect heats the earth because greenhouse gases absorb outgoing radiative energy and re-emit some of it back towards earth.
That said, how does this visualization help us understand the issue of “CO2 sensitivity” which is the additional warming of the Earth Surface due to an increase in atmospheric CO2? Well, given a greater density of CO2 (and H2O) molecules in the air, there is a greater chance that a given photon will get absorbed. Stated differently, a given photon will travel a shorter distance, on average, before being absorbed by a GHG molecule and be re-emitted in a random direction, including downwards towards the Surface. That will result in more energy being recycled back to the Surface, increasing average temperatures a bit.
By the way, although I (and, as I see now, David) have pointed out that CO2 absorbs and emits rather than reflects, it is perhaps worth considering what would happen if we surrounded a blackbody chicken with a perfect reflector.
Case 1 – A chicken not being heated by any energy source: In this case, all the radiation emitted by the chicken would be reflected by the perfect reflector and end up being absorbed again by the chicken. So, if the chicken was at a temperature such that it emitted 500 W, it would also absorb 500 W. Since the power in and out are equal, the chicken is in radiative equilibrium and its temperature would not change. Of course, there is no such thing as a perfect reflector and to the extent that the reflector is imperfect (and assuming our chicken was initially at a higher temperature than the surroundings), there would be some escape of energy and the chicken would slowly cool off over time.
Case 2 – A chicken being heated by an internal energy source (say, a radioactive chicken) at a constant power of, say, 100 W. In this case, all the radiation emitted by the chicken would be reflected by the perfect reflector and end up being absorbed by the chicken. The chicken would indeed get hotter and hotter indefinitely. However, in the real world, there are no perfect reflectors; rather, the reflector would either transmit or absorb some small fraction of the radiation. If it transmits, then eventually the chicken will reach a temperature such that the amount of radiation it is emitting is so large that the amount of this emission that is being transmitted through the reflector is 100 W. If the reflector absorbs, then by, Kirchkhoff’s Law (which is a requirement of the 2nd Law), it also emits and so the chicken and reflector will heat up until the reflector reaches a temperature such that the net amount it is emitting out into the surroundings (i.e., the amount it is emitting to the surroundings minus that it is absorbing from the surroundings) is 100 W.
So, nothing is particularly bizarre here: An object with no internal heat source that is surrounded by a very good reflector just cools more slowly than one not surrounded by a good reflector. An object with an internal heat source can indeed get quite hot if surrounded by a very good reflector, because this reflector essentially insulates it, thus allowing the thermal energy to accumulate quite a bit until it reaches its steady-state. The latter, modulo the fact that greenhouse gases really absorb and emit rather than reflecting, is the rough picture of what actually is happening on Venus (and, to a much lesser degree, on Earth).
davidmhoffer says:
David, I hope you would agree on further reflection that this is a false equivalence. While you and I may disagree on whether the climate sensitivity is likely to be high enough to be a significant danger, I know that I for one would make a distinction between my belief that the scientific evidence points to at least a moderate climate sensitivity (> 2 K per doubling, say) and my belief that the greenhouse effect does not violate the 2nd Law. The former is still within the realm of reasonable scientific discourse, while the latter is basically an incontrovertible scientific fact.
It is important to distinguish between what we essentially KNOW for sure and what we think the weight of the current scientific evidence shows.
Ira,
Thanks for your explanation with the cash analogy. Analogies can be useful as a way of explaining something, but does yours fairly represent what is actually happening in the real world?
In your analogy Miss Chicken (clearly a relative of Chicken Little) gets $500 on each new day, gives all the cash she has to Mr Wall and gets half back. According to this analogy more heat (dollars) is coming in than is going out. Therefore the heat must add up until equilibrium is reached. It all sounds very plausible. (If it were not, then nobody would believe in it.)
But back in the real world can you transfer energy like wads of cash? Can you put it in the bank? Can a body which is constantly irradiated give up all its thermal energy and then get half of it back? The fallacy is in comparing thermal energy, which flows according to a difference in temperature, to successive transfers of money.
Argument by analogy can be misleading. On this and other threads the restriction of the flow of water out of a bath with the taps on is often used to demonstrate the principle that a blockage will raise the level of the water, so therefore a radiant blockage will raise the heat of the Earth. However, that analogy is incomplete because it does not take account of the energy in the flow of the water to the taps. If, for example, that water is supplied from an adjacent tank, the level of the water cannot by higher than the tank. Once that level is reached impeding the flow or even putting in the plug will make no difference.
A better analogy, I would argue, is a pipe through which water flows from a reservoir. If the exit from the pipe is below the water level in the reservoir the water will flow through the pipe. High to low just like the transfer of heat from warm to cold. With no height difference, there is no flow and water level remains the same. If you partly block the pipe the water will still flow through, but none will be returned to the reservoir. If you completely block the pipe, nothing happens. None of the water returns to the reservoir. The water can only be returned to the source if energy is supplied either by raising the pipe above the level of the reservoir or pumping the water back up.
In the constant irradiance models used to demonstrate the greenhouse effect, the Sun is pouring in a fixed quantity of watts m2 at all times. If the flow of heat from the Earth to space is blocked (as the water is blocked in the pipe) that heat cannot flow back heating the Earth even more because it does not have sufficient energy to do so – there is a temperature difference to overcome.
Anyway – to return to Ira’s analogy.
Mr Wall can hand back dollars to Mrs Chicken and the wealth can accumulate. But you cannot sum radiant energy like dollars. Ira says no cash has been created in his analogy – but it has been accumulated. In Ira’s analogy if Mr Wall returns all Miss Chicken’s money (reflection) she will accumulate it at $500 a day. But thermal energy does not accumulate like money that is not spent. It does not build up in the form of photons buzzing around under a radiative barrier until they burst through and restore a fictitious equilibrium. Heat cannot flow without a temperature difference. Thus the heated blackbody chicken in our make-believe oven cannot double its energy by its own emissions being absorbed and re-emitted from the oven walls. The chicken remains at a constant temperature which is as high or higher than the surrounding walls of the oven.
One slight addition to Rich Monroe’s comments on IR active gases.
Asymmetric diatomic molecules will also absorb/emit IR radiation. For example, CO, has significant IR absorption. N2 & O2 do not have significant absorption because they are symmtric (although molecules with different isotopes (eg N14-N15) are slightly asymmetric and have slight absorption)
The smoking gun of CO2 induced warming is that the warming has been primarily within the troposphere and not higher.
“Case 2 – A chicken being heated by an internal energy source (say, a radioactive chicken) at a constant power of, say, 100 W. In this case, all the radiation emitted by the chicken would be reflected by the perfect reflector and end up being absorbed by the chicken. The chicken would indeed get hotter and hotter indefinitely”.
Thanks for the replies. I’m not an expert (far from it) but this topic just interests me. But I find it difficult to accept that a 100w power source could heat anything above 100w. But maybe I’m wrong. It would be great if this could be done as our energy problems would be solved.
I will continue to debate alarmists in various ways. Few understand or are interested in the science even to a small degree so I tend to avoid this and focus on reduced living standards (due to higher energy costs) for no benefit whatsoever. If the science is discussed I use any tool available including the slayer viewpoints if appropriate.
Richard E Smith says: April 5, 2011 at 10:32 am
Analogies can be useful as a way of explaining something, but does yours fairly represent what is actually happening in the real world?
You are quite correct that this analogy is fairly simplistic. We could improve on it by saying “Miss Chicken is charged a progressive tax based on how much total money she has (corresponding to progressively more energy being emitted as the temperature goes up). At some level — say $10,000 in her account — that tax rate is $500. Every day she is paid $500, so if her account is above $10,000 she will be losing money; if her account is below $10,000 she will be gaining money. …” But then we would find new limitations, and have to add on more and more “corrections”.
Of course, at this point it would be better to discuss the ACTUAL energy flow. This analogy has already been pushed beyond the limit where is is providing insights and instead it is throwing up roadblocks when we try to use it.
It’s kind of like expecting your globe to not only show where various countries are, but to also have oil reserves under the surface that you could find.
Tim – look at the AGW Energy Budget as Ira has depicted it and as I linked to in Trenberth diagram. It claims that the the SOLAR energies of Visible, and the two shortwave either side of UV and Near IR are what heat the Earth, converting to heat energy, which is the upwelling Thermal IR.
None of these are felt as heat, ergo, they are not in themselves heat energy, heat energy is Thermal IR. The AGW Energy Budget says that non-Thermal energies are heating the Earth and converting to Thermal IR. How?
Remember, UV barely penetrates the epidermis on skin, it does not raise the temperature of the body further than the outer thin epidermis. Visible light is less intense, it is also not hot, but simple Light energy. It does not raise the temperature of the body, it is not felt as heat. Ditto Near IR. Near IR is not hot. It is not felt as heat, it is not thermal, it does not raise the temperature of the body, it penetrates the body further than Visible. Thermal IR, the heat we feel from the Sun, penetrates further, warming up the body. It is Thermal IR which warms up organic matter.
If you are saying that Thermal IR is only 1% of downwelling, and therefore you say it can be ignored in the Energy Budget, I am saying that means that it is the 1% Thermal IR which is doing all the heating of the Earth, and the Solar energies UV,V,NR, are insignificant in the scheme of things.
Either way, the AGWScience Energy Budget is a load of choose your favourite smelly mess, these Solar energies are incapable of raising the temperature of the Earth, of organic matter. They are incapable of converting into the heat energy as Trenberth states to upwell as this massive amount of Thermal IR.
For example, UV may penetrate a little, a millimeter or two, any more intense and it would burn up everything. It’s energy is extremely limited in producing any heat. Visible light’s energy is not hot, it does not heat things up. Think of the lamp designed to produce mainly blue light for the initial growth of plants! Near IR is not hot, it is able to penetrate deeper in organic matter, it too is non-invasive, it does not raise the temperature of organic matter, it does not convert to Thermal IR. It is used in IR cameras because it reflects off the subject as does visible light, penetrating a bit deeper than Visible light, but still, not producing, not “converting to heat energy” of the Trenberth AGW claim.
So, UV a little on the surface, Visible and Near IR not anything, then, how are these converting to heat energy, producing all that huge amount of Thermal IR claimed in the AGW EB? How??? So that’s the first most important question here because it establishes principle.
Take a thousand or as many as you like remote controls, shine them into your bath full of cold water, tell me how long it takes before it heats up so you can take a bath. NASA page, Near IR is not hot.
Just what is it contributing among the Solar energies of AGWEB in this claim that it is these energies which are converting to heat energy and upwelling in this huge amount heating the Earth globally? In traditional established science it is the Thermal IR energies which are converting to heat.
Do you see the problem I’m having in this? There’s no scientific logic here, the properties of these energies are not able to do what is being claimed for them. What is being claimed for them according to Ira here, is that they are thermal energies. If they are thermal energies that means they are Thermal IR.
So, that’s the first thing that has to be junked. The only thermal energy is Thermal IR, the heat energy of established traditional science.
Therefore, for example, all the descriptions by AGW that these solar energies penetrate into the ocean and heat it up are b*ll*cks, these can’t even heat our bodies let alone hundreds of meters down in the ocean.
So, this is my objection to the AGWScience Energy Budget. The claim that it’s these Solar energies of UV,Visible and NrIR which are converting to heat in organic matter, the Earth.
Prove this. You can’t. Neither can all the AGWScience propaganda. What it is doing here is simply lying. By attributing to Solar the known physical properties of the IR that is capable of converting to heat. It’s this lie, this basic premise of AGW, that I am demanding to have proved.
Until that is sorted, it is pointless to explore further what is happening in real life or in the depiction of the rest of the AGWScience Energy Budget, such as it grabbing more longer ums for its claim of Near IR.
Traditionally then, by established science, it is the IR that by conversion creates heat which is called Thermal IR, or simply Heat, heat energy. Wherever it begins, the energies that do not convert to heat are not Thermal. Near IR is not thermal and this is established as fact in traditional science, that’s the cut off point, and likewise Visible light is not thermal and UV is not thermal – we do not feel these as heat, because they are not converting, do not convert to heat.
I really don’t want to get distracted from this particular point, my objection and question how are these Solar energies converting to heat as claimed by AGW as per Trenberth, because this is crucial to the AGW claim and it goes against all established science, and I should be grateful if you would concentrate on it only.
I hope that is better explained, if you’ve managed to work your way through it. No doubt if I had more experience I could have set it out more precisely mathematically/scientifically… but, sticking to English in describing concepts etc. should be more than adequate, as the adage goes, if you can’t explain your hypothesis to your cleaning lady then you don’t understand it. I’m working on improving my English. How am I doing?
“But I find it difficult to accept that a 100w power source could heat anything above 100w. But maybe I’m wrong. It would be great if this could be done as our energy problems would be solved.”
First of all, you are a little confused on the meaning of “100 W”. You heat things above a certain TEMPERATURE, not above a certain power. 100 W might heat a filament to 2000 C; it might heat an insulated tank of water to a 60 C; it might heat an un-insulated tank of water to 30 C.
As to the second part, this can and is being done to help with energy problems — it is called adding insulation. With good insulation I can heat and cool me home with 1/2 or 1/10 the energy of an un-insulated home.
“It claims that the the SOLAR energies of Visible, and the two shortwave either side of UV and Near IR are what heat the Earth, converting to heat energy, which is the upwelling Thermal IR. ”
One step at a time. There is no point in looking at the rest of your post until we clarify what you mean here.
When you say “heat the earth”, do you mean
1) the whole earth on the diagram (the surface and the atmosphere and the oceans)?
1a) I contend that 98% of solar energy traveling through space toward earth is between about 0.25 um and 4.0 um. Said another way, roughly 10 % is UV, roughly 40% is visible and 50% is IR (and only a small amount of that is >3 um which is traditionally called “thermal IR”).
Further, I contend, that other power sources (notably geothermal & cosmic microwave background radiation & non-(visible/IR/UV) EM radiation) do not provide a significant amount of power to the earth as a whole.
I agree that “SOLAR visible/UV/IR provide 99% of the energy that heats the earth.”
DO YOU DISAGREE with any of this? If this solar energy is not what heats the earth as a whole, then what is your hypothesis?
2) do you mean “the surface of the earth (excluding the atmosphere)”?
2a) The diagram clearly shows that only ~168 W/m^2 of power to the surface is directly from the sun, while 324 W/m^2 is from “thermal IR” from the atmosphere.
DO YOU DISAGREE with any of this? How then can you claim the diagram shows that solar energy is the only source of power to the earth?
PLEASE choose (1) or (2) (or both) and answer, preferably with numbers. Or choose something else that you mean by “earth” and explain how the diagram relates to power to/from this “earth”
Also, you say “heat energy is Thermal IR”.
Googling “thermal infrared” gives these among the first hits:
“Thermal infrared radiation refers to electromagnetic waves with a wavelength of between 3.5 and 20 micrometers. ”
http://www.geog.ucsb.edu/~jeff/115a/remote_sensing/thermal/thermalirinfo.html
“MWIR [3-8um] and LWIR [8-15 um] is sometimes referred to as ‘thermal infrared.’ ”
http://en.wikipedia.org/wiki/Infrared
Both of these suggest that “thermal IR” is only loosely defined, but applies above ~3 um.
DO YOU DISAGREE? If so, give a definition of what wavelengths you think are “thermal IR”?
A precise definition of “heat energy” would also be appropriate. Or is it identical to whatever definition of “thermal IR” you just gave?
RJ says:
I don’t know what it means to “heat anything above 100w”. The temperature that something equilibrates to is given by the balance of the energy in and the energy out. Watts is a measure of energy per unit time, so if you have an input power of 100 W, the total energy of the system will (in the absence of any losses) just continue to increase its energy indefinitely. If you input the energy for a million years, you would have input ~3.15 x 10^15 J. That’s a lot of energy!
Of course, in the real world, objects do lose energy with time, e.g., via radiation. However, how quickly such energy loss occurs depends on how well-insulated the object is from its surroundings. I think you understand this intuitively. You certainly wouldn’t tell me that a person could walk out naked in -40 C weather and not get hypothermia. The person is generating thermal energy via metabolism (a typical rate being about 100 W). If the person bundles up, that 100 W will be sufficient to keep their body temperature at normal levels; however, if they are naked, it will not be sufficient. [The human body, of course, can adjust its metabolism to some degree as necessary to prevent hypo- or hyperthermia, as well as changing other things like dilation of the blood vessels and emitting perspiration in order to change the transfer of heat away from the body, but only within limits.]
Hans says:
In regards to the thermal radiation from the earth: Yes, it does help warm the sun (relative to the case where the earth is not present to absorb and re-emit some of the radiation received from the sun). However, as was pointed out the effect is infinitesimal, both because the earth only intercepts a tiny fraction of the sun’s energy and because the sun then only intercepts a tiny fraction of the energy that the earth emits.
As for how the greenhouse effect of the earth affects the sun: That is a more complicated question. At the end of the day (i.e., in radiative balance), the Earth system (meaning earth + atmosphere) must emit the same amount of energy back out into space as it receives, which (in the absence of a change in albedo for solar radiation) is the same whether or not there is a greenhouse effect on the earth. The greenhouse effect just means that the earth’s surface temperature has to be higher in order for this to be accomplished.
So, my first reaction would be that the greenhouse effect of the earth has no effect on how much radiation the earth emits toward the sun. However, really the amount of energy that the earth emits in both cases has to be the same only when averaged over the various cycles like the seasonal cycle and the diurnal cycle. Take the diurnal cycle as an example: If the greenhouse effect changes the amount of radiation that the day side of the earth emits relative to the night side of the earth, then the amount of radiation that the earth receives from the sun could in fact be affected.
But, all of these are ridiculously small effects in the grand scheme of things as far as the sun is concerned.
Tim, says:
I agree that “SOLAR visible/UV/IR provide 99% of the energy that heats the earth.”
DO YOU DISAGREE with any of this? If this solar energy is not what heats the earth as a whole, then what is your hypothesis?
I’m demanding that you prove it. You’re the one with the hypothesis…
2a The diagram clearly shows that only ~168 W/m^2 of power to the surface is directly from the sun, while 324 W/m^2 is from “thermal IR” from the atmosphere.
DO YOU DISAGREE with any of this? How then can you claim the diagram shows that solar energy is the only source of power to the earth?
Because that’s the explanation. YOU’VE JUST SAID IT. That this SOLAR, WHICH YOU HAVE JUST SAID IS 99% OF THE ENERGY WHICH HEATS THE EARTH. It is this according to the diagram what is converted into heat energy, thermal IR, and radiated back into the atmosphere.
You have said that no other sources are of any significance. Don’t you even listen to yourself?
RJ;
But I find it difficult to accept that a 100w power source could heat anything above 100w. But maybe I’m wrong. It would be great if this could be done as our energy problems would be solved.>>>
You continue to be confused. In every example given to you, 100 watts goes into the system as a whole, and 100 watts comes out. Check the numbers. In my oven/chicken example, 500 watts goes into the chicken, and 500 watts comes out of the oven. Not only CAN this be done, it IS done, and in NO WAY solves our energy problems.
You are confusing how much energy is flowing in the system at any one time with where it is CONCENTRATED at any one time.
At equilibrium, energy out = energy in.
The step I think you are missing is that brief time in between starting the beam of energy in, and REACHING equilibrium. Watts are actually joules/second. So using my original example, let’s do the steps again, but this time we’ll track the joules as well. Again, in reality this would be a smooth curve, not instant stepts, but the prinicipal is identical. (Calculus is just a way of reducing each step to a nearly infinitesimal size to get a more accurate answer)
Start = Oven and chicken at room temperature.
Beam = 200 watts = 200 joules per second.
Each step takes 100 seconds.
Step 1 (1 to 100 seconds)
Chicken is radiating 0 watts = 0 joules /second
Chicken (from beam) 200 joules/sec * 100 seconds = 20,000 joules
Chicken (from oven) = 0 joules/sec * 100 seconds = 0 joules
Joules retained in Chicken = (0 +20,000 + 0) = 20,000
Step 1.5
Chicken rises in temperature until it is radiating 200 watts. Joules/second being retained falls to 0. So 200 watts are going in, and 200 watts are coming out (of the chicken) but 20,000 joules of energy are IN THE CHICKEN.
Step 2 (101 seconds to 200 seconds)
Chicken is radiating 200 watts = 200 joules/second * 100 seconds = -20,000 joules
Chicken (from beam) 200 joules/sec * 100 seconds = 20,000 joules
Chicken (from oven) 100 joules/sec * 100 seconds = 10,000 joules
Joules retained in Chicken = Step 1 + Step 2
= 20,000 + (-20,000 +20,000 + 10,000) = 30,000 joules
Step 2.5
Chicken rises in temperature until it is radiating 300 watts.
Oven absorbs 300 watts.
Oven rises in temperature until it is radiating 300 watts, 150 inward and 150 outward.
Step 3 (201 seconds to 300 seconds)
Chicken is radiating 300 watts = 300 joules/second * 100 seconds = -30,000 joules
Chicken (from beam) 200 joules/sec * 100 seconds = 20,000 joules
Chicken (from oven) 150 joules/sec * 100 seconds = 15,000 joules
Joules retained in Chicken = (Step 1 + Step 2) + Step 3
= 30,000 + (-30,000 +20,000 + 15,000) = 35,000 joules
Step 2.5
Chicken rises in temperature until it is radiating 350 watts.
Oven absorbs 300 watts.
Oven rises in temperature until it is radiating 300 watts, 150 inward and 150 outward.
So if you continue the infinite series:
Beam 200w 200w 200w 200w…. 200w
Oven 0w 100w 150w 175w…. 200w
Energy Balance. Out = In
But, while equilibrium of 200 out and 200 in was being established:
Chicken (w) 0w 200w 300w 350w 375w… 400w
Joules retained 20,000 30,000 35,000 37,500…. 40,000 joules
Do you see now what has happened? There is a lag time for the oven to reach equilibrium and radiate 200 watts. As it rises in temperature, the joules/sec going into the chicken from the beam stay the same. So until the oven increases in temperature to the point it is radiating 200 joules/sec to the outside, the joules going into the system have to build up…in the chicken.
If the chicken was sitting on an open counter, there would only be a Step 1. The chicken would retain 20,000 joules and then would be at equilibrium. From 101 seconds on, no more joules retained than radiated.
After equilibrium is established, there’s more joules in the oven chicken than in the counter chicken. Now shut the beam off, let’s say after 1,000 seconds and let everything cool off to room temperature again. There is an imbalance at this point in terms of the joules and where they are. For both chickens, 200 joules per second has gone in from the beam for 1000 seconds. What has come out and been radiated to the local area?
To local area from:
Counter chicken = (1,000 * 200) – 20,000
Oven Chicken = (1,000 * 200) – 40,000
Now we shut off the beam, and let everything cool back down to room temperature. That means what ever joules of energy are in the chicken now escape to the local area until both are back at room temperature.
To local area from:
Counter chicken = (1,000 * 200) – 20,000 +20,000 = (1,000*200)
Oven Chicken = (1,000 * 200) – 40,000 +40,000 = (1,000*200)
No joules of energy are created, lost, destroyed, or hidden. During the time period when a new equilibrium is established, the joules build up in the chicken. Stop the input of energy and the joules leak back out.
Richard E Smith says:
Indeed…See below.
Sorry…That analogy fails. It would work if when you “stopped up the pipe”, you were able to block the radiation coming from the sun to the earth. However, the radiation continues to come from the sun to the earth. (Hence, it is like a pipe where you are forcing a constant mass of water into the pipe each second and then asking how much water comes out the other end.) This causes the earth’s temperature to rise, effectively increasing the “pressure” in your water analogy until the flow out is again equal to the flow in. (If you could completely block the pipe with something that would not get dislodged ever, then the pressure would increase without bound. Of course, there is nothing that can withstand infinite force…and in the real system, there is no perfect insulation that would do this.)
That last sentence is complicated. (Yes, heat…a macroscopic thing…can’t flow from hot to cold, but the heat is determined by a balance of radiation passing in both directions, and, yes, the radiation going back can increase.)
But, if you are uncomfortable with radiation going back, just think of it this way: If you block some or all of the heat flowing out, you have more heat flowing in than flowing out, so the temperature rises until it is pushing the heat out so hard that you still get the same amount of heat flowing out as you have coming from the sun. So, in the final state, the heat flowing out is still the same as before but you need a higher surface temperature to obtain this flow. That is what we call the greenhouse effect.
Tim:
http://en.wikipedia.org/wiki/File:The_green_house_effect.svg
“About half the solar radiation is absorbed by the Earth’s surface”
“Absorbation solar radiation: 168 Watts per metre squared”
“Radiation is converted to heat energy, causing the emission of longwave (infrared) radiation back to the atmosphere”
Some of the infrared radiation [the upwelling after conversion] passes through the atmosphere and out into space”
“Outgoing [into space] infrared radiations: 240 Watts per metre squared”
“Some of the infrared radiation is absorbed and re-emitted by the greenhouse gas molecules.”
Doesn’t say how much that is.
However, amounts, for the moment, is a distraction to getting my questions answered, getting the proof I’m asking for.
This is the point:
So, prove that this Solar energy you say 99% heats the Earth is actually capable of doing so, actually capable of converting into heat energy, heating the Earth, and therefore capable of radiating out the thermal IR claimed.
Also, still waiting for Ira to prove that it’s these Solar energies we feel as heat from the Sun, that these are thermal.
These are two sides of one coin, asking proof from Ira is relevant to your proving that it’s these Solar energies which convert to thermal IR.
From tradition physics these Solar energies do not convert to heat.
Joel Shore said (in response to Hans):
Sorry…That should read
RJ says:
April 5, 2011 at 2:24 am
“But does energy work this way. Energy is more like a teacher (sun) passing knowledge to a student (earth). The student can only take in so much knowledge and can not increase the teachers knowledge by passing the same knowledge back. But the student can increase the knowledge of another student (CO2) with less knowledge etc.”
———————————————————————————————————;
Claes Johnson’s student/teacher analogy in his comments on computational black body radiation:
“We can also compare with a common teacher-class situation with an excited/high temperature teacher emitting information over a range of frequencies from low (simple stuff) to high (difficult stuff), which by the class is absorbed and re-emitted/repeated below a certain cut-off frequency, while the class is unable to emit/repeat frequencies above cut-off, which are in-stead used to increase the temperature or frustration/interest of the class. The temperature of the class can then never exceed the temperature of the teacher, because all coherent information originates from the teacher. The teacher and student connect in two-way communication with a one-way flow of coherent information.
The net result is that a warm blackbody can heat a cold blackbody, but not the other way around. A teacher can teach a student but not the other way around. The hot Sun heats the colder Earth, but the Earth does not heat the Sun. A warm Earth surface can heat a cold atmospheric layer, but a cold atmosphere cannot heat a warm Earth surface. A blackbody is heated only by frequencies which it cannot emit, but has to store as heat
energy.”
On more comment…
Richard E Smith says:
…Which is why those of us here who are arguing on the side of the correct science have actually solved the equations. We are not using analogies to try to determine what happens…We are using them to explain what we KNOW actually happens. This is a much safer way to use analogies.
Joel Shore says:
April 5, 2011 at 1:29 pm
Hans says:
…asking if the earth’s greenhouse effect and thermal radiation from the earth helping keep the sun warm, in which case it would in principle, but the effect would be such an infinitesimal amount that it would not be measurable.”
As for how the greenhouse effect of the earth affects the sun: That is a more complicated question….The greenhouse effect just means that the earth’s surface temperature has to be higher in order for this to be accomplished.
So, my first reaction would be that the greenhouse effect of the earth has no effect on how much radiation the earth emits toward the sun.”
Joel, Ira’s example of the soldering iron in the box results in a temperature raise of the source. And that is what you stated also, to maintain the power flow.
“Take an object, be it a soldering iron where electrical power is converted into heat or the earth that is absorbing radiation from the sun.
Now instead, try surrounding that object by a box or shell that absorbs some of the radiation. That surrounding shell will heat up and by virtue of having a nonzero temperature, it will emit radiation. Now the object will be receiving not only the power it was originally receiving but additional power from the radiating shell; there is no way this can be avoided. Hence, in order to reach a state where energy in = energy out, it will have to emit more power. It does this by raising its temperature. It’s really that simple.”
“No…It is impossible for it to be in equilibrium. It was in equilibrium at 400 K when it didn’t have the walls at whatever elevated temperature that they are at emitting radiation at it. How can it possibly remain in equilibrium now that it is receiving more energy? That’s mathematically impossible. If it receives more energy, it has to emit more energy…and it does this by increasing its temperature.”
“If there is no net energy flow away from the soldering iron, which is still plugged into the wall and converting electrical energy into thermal energy, what is it going to do? It is going to heat up until the heat leaving it does balance the thermal energy that it is generating! How could it do otherwise?”
” And, yes, the power does get smaller as the temperature of the shell increases…That’s the whole point. Now take that to its logical conclusion and you will understand why the temperature of the object must increase.”
Tim Folkerts made the logical conclusion that in principle this must also raise the temperature of the sun by an infinitesimal amount.
And so do I because any restriction reduces the flow and this can only be restored by a higher temperature, so I’m very surprised that you don’t conclude this without doubts.
I would also like Ira to give his thoughts on this, as he came up with the analogy.
Claes is spouting nonsense, as seems to be his custom. This is my favorite thing that Claes has written – Look at Equation (10.3) here: http://www.csc.kth.se/~cgjoh/ambsblack.pdf He admits this equation is correct but then claims the problem is with the interpretation and spouts the standard talking points about no back-radiation, one-way transmission from hot to cold, etc.
What is missing from all the mumbo-jumbo he writes is the fact that he has already lost the argument when he admits that Equation (10.3) is correct. It doesn’t matter how you interpret the terms in (10.3), e.g., if you consider the second term to represent “back-radiation” or not. It is a mathematical equation that gives the same mathematical solutions regardless.
In particular, it says that if T_2 is the temperature of the earth and T_1 of the surroundings, then in the case where the earth has an IR-transparent atmosphere, T_1 is the 3 deg background temp of space; however, in the case where the earth has an IR-absorbing atmosphere, T_1 is the temperature of that atmosphere. And, the equation tells you that the heat flow away from the earth in the former case is greater than the heat flow away from the earth in the latter.
Once you have that result, it is simply a matter of stating the steady-state condition for radiative balance at the surface (that this heat flow away equals the heat flow in from the sun)…and then what you find is a surface temperature T_2 that is higher as T_1 gets larger. I don’t care if you call the reason that this happens “back-radiation” or “mind control by aliens from the planet Xena”, the result of the mathematics is the same!
>>I agree that “SOLAR visible/UV/IR provide 99% of the energy
>>that heats the earth [surface & atmosphere as a whole].”
>I’m demanding that you prove it. You’re the one with the hypothesis…
Science develops a whole set of interconnected ideas. After a while these come to be accepted as “established science” (that presumably could be shown incorrect, but that would require significant upheaval).
* the “solar constant” of ~1370 W/m^2 is “established science”. Divide this by 4 to get the average over the surface of the earth = 343 W/m^2. Do you disagree with this part of “established science”? http://en.wikipedia.org/wiki/Solar_constant
* Planck’s law of BB radiation is “established science”. Do you disagree with this part of “established science”? http://en.wikipedia.org/wiki/Planck%27s_law
* The sun’s surface temperature of 5800 K is “established science”. Do you disagree with this part of “established science”?
If you accept these, then you have to accept the ratios given: ~10% UV; ~40% visible; ~48% “non-thermal” IR (0.7 – 3 um); ~2% “thermal IR” (>3um). [Or show by your own calculations where the error is.]
* That the earth reflects ~ 30% of the incoming energy (from the clouds and from the ground) is “established science”. Do you disagree with this part of “established science”? http://en.wikipedia.org/wiki/Albedo
* Conservation of energy is a cornerstone of science. Surely you can’t disagree with this.
Since solar energy comes in (342 W/m^2) and only some solar energy leaves, the rest MUST be added to the earth (which eventually leaves as thermal IR). The exact numbers can be discussed (Kiehl & Trenberth gives 168 W/m^2 into the surface and 67 W/m^2 into the atmosphere). The relative magnitude, however, has been determined by the “established science” above (not to mention various other experiments I could reference).
* Absorbed energy “warms” an object — once again “established science”.
I don’t know how many other ways to say this! All the established science fits the hypothesis that solar energy in the proportions I quoted warms the earth in the manner I suggested. You now need to show which part of this established science is wrong and where else the energy might be coming from.
Myrrh,
So, prove that this Solar energy you say 99% heats the Earth is actually capable of doing so, actually capable of converting into heat energy,>>>
What in heck makes you think it has to convert?
Your Armour of Density or Your Armour of Avoidance?
Energy is measured in joules.
Solar energy is measured in joules.
Heat energy is measured in joules.
A watt is just a joule per second.
UV can be measured in joules per second per area.
IR can be measured in joules per second per area.
Visible Light can be measured in joules per second per area.
ALL energy is measured in joules, no matter what frequency, and power is measured in watts no matter what frequency. There is nothing to convert from an energy perspective. The only thing that gets converted is the frequency at which the energy gets transmited.
Which has been explained to you about a thousand times.
Proof positive that your Armour of Density (or Avoidance as the case may be) is effective.
Joel Shore;
…Which is why those of us here who are arguing on the side of the correct science have actually solved the equations. We are not using analogies to try to determine what happens…We are using them to explain what we KNOW actually happens. >>>
And there lies the frustrating part of the discussion. We explain the math and get objections. We come up with analogies to try and explain the math that is beyond some people. More objections.
But the truth of the matter is that the equations reign supreme. They are used every day by engineers and many other professions to design everything from combustion engines to rockets to boilers. They are used to design nuclear power plants, air conditioners and sex toys. They are used to calculate the optimum processes for making potatoe chips, plastic bags, and satellites.
The equations work, they work precisely, and they work thousands of times every single day.
Period.
You continue to be confused. In every example given to you, 100 watts goes into the system as a whole, and 100 watts comes out. Check the numbers. In my oven/chicken example, 500 watts goes into the chicken, and 500 watts comes out of the oven. Not only CAN this be done, it IS done, and in NO WAY solves our energy problems.
Thanks. I can see that 100 watts goes into the oven and 100 watts leave. But 500 watts goes into the chicken and also leaves The 100 watts increasing to 500 watts is the bit I still have a problem with. But I might have a block on understanding this.
I still also have a problem with a colder body heating a warmer one. (although this has been discussed on these threads)
But its not my area of expertise so I will just leave it for now and come back to it at some later point. An interesting thread though.