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Post by radiant on Sept 17, 2009 12:05:47 GMT
Kiwi Thanks for providing another quote containing: Most of the atmosphere is made up of nitrogen and oxygen which do not significantly absorb infrared energy because their emissivity in this portion of the electromagnetic spectrum is exceptionally low. This means they also do not emit significant infrared |
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Post by hunter on Sept 17, 2009 12:58:23 GMT
Citing Garblick and Tosscheuschner should invoke a climate equivalent of Godwin's law I note the following response to the Gerlich and Tscheuschner paper seems wrong. arxiv.org/abs/0802.4324:A recently advanced argument against the atmospheric greenhouse effect is refuted. A planet without an infrared absorbing atmosphere is mathematically constrained to have an average temperature less than or equal to the effective radiating temperature. Observed parameters for Earth prove that without infrared absorption by the atmosphere, the average temperature of Earth's surface would be at least 33 K lower than what is observed. As i have explained above a none absorbing atmosphere will be a none emitting atmosphere that will take the earths surface heat to the upper atmosphere until equilibrium is established and there will be no obvious mechanism to return heat to the surface for cooling. Additionally the earth has a hot core that is cooled by radiation to outerspace. Hot or warm winds could easily keep the surface of the earth higher than people believe because it is only the very absolute top of the earths molecular solid surface that is radiating heat to space while the rest is being warmed slightly from below. If by day the earth heats to a few hundred degrees and by night it cools to a few hundred degrees what actually is the temperature of the earth just below the surface which experiences the average of this warm cold cycle and experiences the warming from below? Permafrost must have taken a period of more minus than plus for a number of years to freeze so far down. In a warm cold cycle that is not going to happen i would guess. You would just get an average of hot and cold with warming from below Meanwhile the oceans exist and so the whole dynamic of a none water based planet are rediculously unreal. If water was not evaporating from the oceans they would be warmer than if not. When water evaporates the heat is transported into the atmosphere. Some mechanism is required to cool the atmosphere for life to be possible and what would happen at the surface is not clear to me. I have to wonder if people have thought this topic thru properly before building their models of earth RE: Your comment that only the top layer of Earth's atmosphere is radiating to space: That is simply incorrect, or Earth's features would be invisible from space. |
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Post by nautonnier on Sept 17, 2009 12:59:16 GMT
Citing Garblick and Tosscheuschner should invoke a climate equivalent of Godwin's law I note the following response to the Gerlich and Tscheuschner paper seems wrong. arxiv.org/abs/0802.4324:A recently advanced argument against the atmospheric greenhouse effect is refuted. A planet without an infrared absorbing atmosphere is mathematically constrained to have an average temperature less than or equal to the effective radiating temperature. Observed parameters for Earth prove that without infrared absorption by the atmosphere, the average temperature of Earth's surface would be at least 33 K lower than what is observed. As i have explained above a none absorbing atmosphere will be a none emitting atmosphere that will take the earths surface heat to the upper atmosphere until equilibrium is established and there will be no obvious mechanism to return heat to the surface for cooling. Additionally the earth has a hot core that is cooled by radiation to outerspace. Hot or warm winds could easily keep the surface of the earth higher than people believe because it is only the very absolute top of the earths molecular solid surface that is radiating heat to space while the rest is being warmed slightly from below. If by day the earth heats to a few hundred degrees and by night it cools to a few hundred degrees what actually is the temperature of the earth just below the surface which experiences the average of this warm cold cycle and experiences the warming from below? Permafrost must have taken a period of more minus than plus for a number of years to freeze so far down. In a warm cold cycle that is not going to happen i would guess. You would just get an average of hot and cold with warming from below Meanwhile the oceans exist and so the whole dynamic of a none water based planet are rediculously unreal. If water was not evaporating from the oceans they would be warmer than if not. When water evaporates the heat is transported into the atmosphere. Some mechanism is required to cool the atmosphere for life to be possible and what would happen at the surface is not clear to me. I have to wonder if people have thought this topic thru properly before building their models of earth
Welcome to the 'heated' discussion that I have been having for some time. The Hydrologic Cycle - the evaporation of water and its condensation and freezing passing latent heat to the air and acting as one of the most powerful greenhouse (sic) gases on the way can explain the climate of the Earth. CO 2 is a minor player. It appears to me that the hydrologic cycle provides both negative and positive feedback keep the climate in a balanced state. However, there seem to be two states (attractors) in the climate system and the climate can flip from one to the other. I think that this may be due to ocean dynamics as much as for other reasons - see thread solarcycle24com.proboards.com/index.cgi?board=globalwarming&action=display&thread=847 |
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Post by radiant on Sept 17, 2009 13:12:16 GMT
I note the following response to the Gerlich and Tscheuschner paper seems wrong. arxiv.org/abs/0802.4324:A recently advanced argument against the atmospheric greenhouse effect is refuted. A planet without an infrared absorbing atmosphere is mathematically constrained to have an average temperature less than or equal to the effective radiating temperature. Observed parameters for Earth prove that without infrared absorption by the atmosphere, the average temperature of Earth's surface would be at least 33 K lower than what is observed. As i have explained above a none absorbing atmosphere will be a none emitting atmosphere that will take the earths surface heat to the upper atmosphere until equilibrium is established and there will be no obvious mechanism to return heat to the surface for cooling. Additionally the earth has a hot core that is cooled by radiation to outerspace. Hot or warm winds could easily keep the surface of the earth higher than people believe because it is only the very absolute top of the earths molecular solid surface that is radiating heat to space while the rest is being warmed slightly from below. If by day the earth heats to a few hundred degrees and by night it cools to a few hundred degrees what actually is the temperature of the earth just below the surface which experiences the average of this warm cold cycle and experiences the warming from below? Permafrost must have taken a period of more minus than plus for a number of years to freeze so far down. In a warm cold cycle that is not going to happen i would guess. You would just get an average of hot and cold with warming from below Meanwhile the oceans exist and so the whole dynamic of a none water based planet are rediculously unreal. If water was not evaporating from the oceans they would be warmer than if not. When water evaporates the heat is transported into the atmosphere. Some mechanism is required to cool the atmosphere for life to be possible and what would happen at the surface is not clear to me. I have to wonder if people have thought this topic thru properly before building their models of earth RE: Your comment that only the top layer of Earth's atmosphere is radiating to space: That is simply incorrect, or Earth's features would be invisible from space. If the atmosphere cannot radiate infra red because there are no greenhouse gases then the temperature will rise as altitude increases. So at the top of the atmosphere it would be very hot with almost no means to radiate heat and the only way to radiate heat would be from the surface of the earth to outerspace. |
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Post by socold on Sept 17, 2009 20:16:38 GMT
As i have explained above a none absorbing atmosphere will be a none emitting atmosphere that will take the earths surface heat to the upper atmosphere until equilibrium is established and there will be no obvious mechanism to return heat to the surface for cooling. Additionally the earth has a hot core that is cooled by radiation to outerspace. I think you have a point about the atmosphere being warmer but I still think such a planet would be emitting radiation of a blackbody 33K cooler than Earth. If the atmosphere cannot emit then it can only lose energy to the surface*. From ( www.windows.ucar.edu/earth/Atmosphere/images/earth_rad_budget_kiehl_trenberth_1997_big.gif) the atmosphere will be absorbing 67wm-2 solar energy and so it must be, at equilibrium, passing 67wm-2 net energy to the surface. I guess that must be by conduction. I don't know how warm the first foot of atmosphere would have to be to allow 67wm-2 conduction but I think you are right that it would require a far warmer atmosphere than present. But the surface would still absorbing 168wm-2 solar energy plus now it is also gaining 67wm-2 from the atmosphere. In total that is just 235wm-2 and so the surface temperature could not be higher than -19C and the Earth from space would appear to be emitting no more than 235wm-2 and have an effective temperature 33K below what ours does. *assuming it doesnt warm too much in which case it might start emitting significant shortwave energy into space |
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Post by radiant on Sept 18, 2009 2:54:11 GMT
As i have explained above a none absorbing atmosphere will be a none emitting atmosphere that will take the earths surface heat to the upper atmosphere until equilibrium is established and there will be no obvious mechanism to return heat to the surface for cooling. Additionally the earth has a hot core that is cooled by radiation to outerspace. I think you have a point about the atmosphere being warmer but I still think such a planet would be emitting radiation of a blackbody 33K cooler than Earth. If the atmosphere cannot emit then it can only lose energy to the surface*. From ( www.windows.ucar.edu/earth/Atmosphere/images/earth_rad_budget_kiehl_trenberth_1997_big.gif) the atmosphere will be absorbing 67wm-2 solar energy and so it must be, at equilibrium, passing 67wm-2 net energy to the surface. I guess that must be by conduction. I don't know how warm the first foot of atmosphere would have to be to allow 67wm-2 conduction but I think you are right that it would require a far warmer atmosphere than present. But the surface would still absorbing 168wm-2 solar energy plus now it is also gaining 67wm-2 from the atmosphere. In total that is just 235wm-2 and so the surface temperature could not be higher than -19C and the Earth from space would appear to be emitting no more than 235wm-2 and have an effective temperature 33K below what ours does. *assuming it doesnt warm too much in which case it might start emitting significant shortwave energy into space I am really quite interested to see how we can play around with this earth and see if we can agree on what the outcome is. So far though we have some things we dont seem to be agreeing on . 1. The earths surface is not a blackbody. Much of the earth is green. A fair bit is brown. Quite a few lakes are a distinctive blue due to i think suspended silicates. Ocean areas are often greens and blues due to myriad life forms. Then there are the white bits. 1A. The main problem with this earth is the exstreme daily temperature changes. If the earth does not absorb so strongly and does not emitt so strongly i am assuming these exstremes are modified. 2. At equilibrium in a none radiating atmosphere there is no net change in the atmospheric temperature over time. But by day part gets hotter and by night part gets cooler because the atmosphere is warmed and cooled by the earths changing temperature. So do you need to add a net contribution from the atmosphere to the earths irradiation? The earths temperature will just be what a correctly described emitter will be given solar radiation but the average earths temperature will be altered by the daily heat cycle as heat is transferred from the atmosphere to the colder earth. 3. There would still be forces at work to create winds and the winds would warm the earth at night by contact with the earths surface where winds were present at the earths surface 4. The issue about the atmosphere warming the earths surface at night is related to: A. how cold the earth will get at night emitting radiation to space while being warmed by the atmosphere, but the earth is for sure not a black body and B. how much cooler the atmosphere will be at the beginning of the day. 5. The earth has a hot core which has to be allowed for If you can rerun the calculations for an emitter that reflects the nature of the earths approximate emissivity i am interested in what temperature you arrive at. Can you clarify why you are describing the earth as a black body emitter please? |
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Post by kiwistonewall on Sept 18, 2009 7:09:22 GMT
In all cases, the important point is the equality between emissivity & absorption. With Air, IR is absorbed & emitted, and since it operates over the entire BB curve, it is far from insignificant, as was long understood before the age of post-modern unreason descended upon us. For those who still can think, please refer to: Spectral imaging of the atmosphere By G. G. Shepherd pg 10: "Thermal Atmospheric Radiation: Where an atmosphere is not truly black it can be considered gray. The gray-body emission from the atmosphere is given by the Stefan-Boltzmann equation, but multiplied by the emissivity. For a more detailed exposition of this, and atmopsheric radiation generally, the work by Salby (1966) may be consulted. By Kirchhoff's law the emissivity is equal to the absorptivity, so that an atmosphere that emits thermal radiation strongly will also absorb it strongly. Thus absorption cannot be ignored for thermal infrared radiation. As a measure of blackness of the atmosphere it is convenient to introduce the optical depth T(z) which is the integral of atmospheric density (rho) multiplied by the mass absorption coefficient k, integrated through the atmosphere to level z." (the formula follow - link to pages: books.google.com.au/books?id=E6TgvVv3OXsC&pg=PA10&lpg=PA10&dq=%22thermal+emission%22+measurements+of+Oxygen&source=bl&ots=ftyRMrMT4R&sig=yaQOhFFl8LdqFBs6NsDHgPoi8_c&hl=en&ei=2SWzSqSEPYKCswOqm_zRDA&sa=X&oi=book_result&ct=result&resnum=6#v=onepage&q=%22thermal%20emission%22%20measurements%20of%20Oxygen&f=falseFor this reason, the atmosphere as a whole acts as a thermal blanket. The GHG help to thermalise the atmosphere, but they have little (if any) additional effect. Water vapour & clouds massively effect the system as they change the optical depth of the atmosphere as well as other effects. The significant part of the blackbody curve is a very small part of the total infrared spectrum. In other parts of the infrared (closer to visible) the atmosphere is largely transparent. Thermal imaging cameras work at the frequencies higher than ambient IR absorption so are not effected. And.. Why Antarctica: For Earth bound IR astronomy you need dry and cold air to minimise the thermal noise in the atmosphere. 74.125.155.132/search?q=cache:Ee_VXAbh6qcJ:www.phys.unsw.edu.au/~mgb/Antbib/asapaper5.ps.gz+cooling+of+air+by+%22thermal+emission%22&cd=69&hl=en&ct=clnk&gl=au |
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Post by radiant on Sept 18, 2009 7:34:56 GMT
In all cases, the important point is the equality between emissivity & absorption. With Air, IR is absorbed & emitted, and since it operates over the entire BB curve, it is far from insignificant, as was long understood before the age of post-modern unreason descended upon us. For those who still can think, please refer to: Spectral imaging of the atmosphere By G. G. Shepherd pg 10: "Thermal Atmospheric Radiation: Where an atmosphere is not truly black it can be considered gray. The gray-body emission from the atmosphere is given by the Stefan-Boltzmann equation, but multiplied by the emissivity. For a more detailed exposition of this, and atmopsheric radiation generally, the work by Salby (1966) may be consulted. By Kirchhoff's law the emissivity is equal to the absorptivity, so that an atmosphere that emits thermal radiation strongly will also absorb it strongly. Thus absorption cannot be ignored for thermal infrared radiation. As a measure of blackness of the atmosphere it is convenient to introduce the optical depth T(z) which is the integral of atmospheric density (rho) multiplied by the mass absorption coefficient k, integrated through the atmosphere to level z." (the formula follow - link to pages: books.google.com.au/books?id=E6TgvVv3OXsC&pg=PA10&lpg=PA10&dq=%22thermal+emission%22+measurements+of+Oxygen&source=bl&ots=ftyRMrMT4R&sig=yaQOhFFl8LdqFBs6NsDHgPoi8_c&hl=en&ei=2SWzSqSEPYKCswOqm_zRDA&sa=X&oi=book_result&ct=result&resnum=6#v=onepage&q=%22thermal%20emission%22%20measurements%20of%20Oxygen&f=falseFor this reason, the atmosphere as a whole acts as a thermal blanket. The GHG help to thermalise the atmosphere, but they have little (if any) additional effect. Water vapour & clouds massively effect the system as they change the optical depth of the atmosphere as well as other effects. The significant part of the blackbody curve is a very small part of the total infrared spectrum. In other parts of the infrared (closer to visible) the atmosphere is largely transparent. Thermal imaging cameras work at the frequencies higher than ambient IR absorption so are not effected. And.. Why Antarctica: For Earth bound IR astronomy you need dry and cold air to minimise the thermal noise in the atmosphere. 74.125.155.132/search?q=cache:Ee_VXAbh6qcJ:www.phys.unsw.edu.au/~mgb/Antbib/asapaper5.ps.gz+cooling+of+air+by+%22thermal+emission%22&cd=69&hl=en&ct=clnk&gl=au1. It is not possible to have spectroscopically dry air in the earths atmosphere from ground to outerspace. In the 'exstremely dry' air at Ridge 'A' Antartica at 13,000 feet, water content is sometimes as low as 0.10mm of liquid between the ridge and space. Other places at the pole are not as good with 0.25mm of water. The lower water justifies the move to Ridge A  Water is the main problem but there are thousands of other lines in the microwave and sub millimetre region they are interested in. (Molecular oxygen also emits in the microwave region 'quite strongly' at several lines and has a green visible spectra emission line - possibly visible if you look to the horizon at night, i am assuming these are relatively trivial amounts compared to say water. The night time green line is i believe being created at 100KM where more or less there is no atmosphere. As i said before we are talking about relative differences. Factors important for an astronomer maybe but not maybe for climatology ) 2. You also need to consider that a mixture of N2 02 and rare gases is not air. Such a mixture is Earths gases without Greenhouse gases, particles and animal and plant vapours. No doubt you have been to the blue mountains of Australia. Blued by gum vapours from the trees below. 3. Water in the atmosphere is a 'green house gas' for the purposes of any discussion of earths green house gases 4. There is no point talking about 'an atmosphere' as your book quotation begins unless you define the atmosphere. 'Atmospheres' may well refer to experimental atmospheres or atmospheres not found on earth. 5. I am talking about what would happen if earth had an atmosphere of only n2 02 and argon. What actually are you talking about? You have already several times confirmed that n2 and 02 do not emit significant IR radiation but you keep talking about air. Since you are based in melbourne and Michael Hammer is in Melbourne why not meet up with him and find out why he agrees with me please or explain to me why he is wrong. Why do you keep producing quotes like this: In all cases, the important point is the equality between emissivity & absorption. this?? 1.Atmospheric science: an introductory survey: The absorption spectra of the dominant species O2 and N2 exhibit a sparse population of absorption lines because these molecular species do not posess an electric dipole, even when they are vibrating. In contrast to the so called green house gases(notably h20 co2 03 and trace species2. Michael Hammer: Most of the atmosphere is made up of nitrogen and oxygen which do not significantly absorb infrared energy because their emissivity in this portion of the electromagnetic spectrum is exceptionally low. This means they also do not emit significant infrared  |
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Post by socold on Sept 18, 2009 18:46:19 GMT
The Earth's core provides negligible heat to the surface compared to solar radiation last time I looked it up.
I don't think splitting up the analysis into day, night etc is needed. We know how much solar energy is absorbed by Earth on average over an entire year and so know how much energy Earth must emit into space over an entire year to be in energy balance. So all we have to do is work out how annual average flows of heat between different components of the Earth can be arranged to make the surface as warm as it is.
I don't think it can be done unless the atmosphere is reducing heat loss into space, but you make a good point about the Earth surface maybe not being a blackbody. That might do it. I can't give a satisfactory answer for why I described the earth as a black body emitter. I've seen everyone else doing so so have assumed that's the case. Lame answer I know.
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Post by radiant on Sept 18, 2009 20:16:10 GMT
The Earth's core provides negligible heat to the surface compared to solar radiation last time I looked it up. I don't think splitting up the analysis into day, night etc is needed. We know how much solar energy is absorbed by Earth on average over an entire year and so know how much energy Earth must emit into space over an entire year to be in energy balance. So all we have to do is work out how annual average flows of heat between different components of the Earth can be arranged to make the surface as warm as it is. I don't think it can be done unless the atmosphere is reducing heat loss into space, but you make a good point about the Earth surface maybe not being a blackbody. That might do it. I can't give a satisfactory answer for why I described the earth as a black body emitter. I've seen everyone else doing so so have assumed that's the case. Lame answer I know. 1. The problem with the earths core is that if the earth is recovering from a global ice age that cold could have penetrated to great depth and now as the ice age becomes more and more distant the temperature gradient is recovering to reflect surface temperatures today. The same thing happens when you enter a cold brick house in cold weather and turn on the heating designed for that house where it might not come up to the designed temperature for two days as heat slowly warms the bricks and creates a temperature gradient that enables the heating in parts of the house to be less intense once established, such a process might have lags of thousands of years for the earth. Then there is the issue of hot spots moving to critical places like the greenland ice sheets and others areas like the cold ocean floors. We dont know the realities on these things i would say and can only speculate. 2. Day night differences might be important i am not sure. But what we get is a very warm atmosphere that can mainly only be cooled by warming the earth. And yes it can only be warmed by cooling the earth. 3. The none black body nature of the earth should make quite a difference as can be observed from how hot different surfaces get during the day. It is an obvious error to treat the earth like a black body i am thinking. But I have only just realised this makes the earth colder so it needs much more warming.  So now i am not sure what it all means  |
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Post by kiwistonewall on Sept 18, 2009 22:34:10 GMT
You confuse totally absorption & emission of blackbody radiation with spectral emission -
An analogy is a smoked glass window with scratches - The scratches totally block your view, but the % overall is low. The gray doesn't block your view, but the total optical depth of the gray is far more important that the scratches.
There is a fundamental failure to apply the basics of thermodynamics in your thinking.
Atmospheres provide the greenhouse effect by the blackbody equations.
If you had a cloud of oxygen and Nitrogen in space at 15C it would give off a pure blackbody radiation frequency curve. (In fact it would soon cool down to the background temperature of the galaxy since is radiates more than it receives. Based on your reasoning, such a cloud would stay warm for ever, as there would be no way for the heat energy to escape. (Let's assume the gas cloud was big enough to be held together by gravity!)l
ALL atmospheres work on this principle. Greenhouse gases just increase the efficiency of emission or absorption - but CANNOT change the fundamental fact - since the in & out is EQUAL, there can be no effect at equilibrium of any GHG.
Outside of equilibrium, they will have a dynamic effect, but the "proof" of the greenhouse effect by GHG is fundamentally flawed.
The dynamic solution is not solvable.
All we can do is look at data, and that also proves there is no GHG induced warming.
The greenhouse effect is a fundamental property of the optical depth of gases in the thermal region, and doesn't matter if the gas is H2, Argon, Sodium vapour or CO2.
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Post by radiant on Sept 18, 2009 23:11:13 GMT
You confuse totally absorption & emission of blackbody radiation with spectral emission - An analogy is a smoked glass window with scratches - The scratches totally block your view, but the % overall is low. The gray doesn't block your view, but the total optical depth of the gray is far more important that the scratches. There is a fundamental failure to apply the basics of thermodynamics in your thinking. Atmospheres provide the greenhouse effect by the blackbody equations. If you had a cloud of oxygen and Nitrogen in space at 15C it would give off a pure blackbody radiation frequency curve. (In fact it would soon cool down to the background temperature of the galaxy since is radiates more than it receives. Based on your reasoning, such a cloud would stay warm for ever, as there would be no way for the heat energy to escape. (Let's assume the gas cloud was big enough to be held together by gravity!)l ALL atmospheres work on this principle. Greenhouse gases just increase the efficiency of emission or absorption - but CANNOT change the fundamental fact - since the in & out is EQUAL, there can be no effect at equilibrium of any GHG. Outside of equilibrium, they will have a dynamic effect, but the "proof" of the greenhouse effect by GHG is fundamentally flawed. The dynamic solution is not solvable. All we can do is look at data, and that also proves there is no GHG induced warming. The greenhouse effect is a fundamental property of the optical depth of gases in the thermal region, and doesn't matter if the gas is H2, Argon, Sodium vapour or CO2. I think you need to consider what heat is and you need to consider why a dewar flask keeps things warm. Why doesnt this thing called heat radiate across the vacuum boundary put in place to inhibit conduction? Why is the dewar flask principal related to the low emissivity of mirrored silver so that the outer glass is not warmed by the inner glass? Put hot water in a glass and the outside gets hot. The heat is not felt on the outer glass of the dewar. en.wikipedia.org/wiki/Radiant_barrier Although reflective insulation is often thought of as a "mirror" to heat waves, a more accurate analogy is a material that is both "deaf" and "mute" to heat wavesIf man can slow down radiation emission why is it impossible for nature to do the same for unusually transparant gases? According to your theory the dewar flask must significantly emit thermal radiation no matter how it is constructed. I found your comment that an N2 atmosphere is not made of silver to be odd. You quote things like emissivity and then want to tell me these are irrelevant for N2 If N2 is present in space it will expand according to the energies of the molecules until there are only single molecules in space travelling with kinetic energy which has potential to energise or warm another atom if it reaches it. Also as i have repeatedly said and you repeatedly ignore i am talking about a relative difference. N2 has sparce absorption lines in the infra red band according to your reference so it will emit IR. But according to your references it is insignificant (compared to gases with an electric dipole) Blackbody radiation is an idea that is very useful. Radiation involves photons or packets or quanta. And all your atmospheric examples involve the peculiarities of water. And yet you continually ignore that simple fact. And yet for some reason you keep mentioning green house gases. I am not absolutely sure who is confused but for sure one of is or both of us are. Your comments about black bodies suggest you are missing something. Black body is a theoretical concept that is useful. There is no such thing as 'all bodies emit black body radiation' There is the theory and then there is the reality. Your own links show that at (ordinary) temperatures 02 and N2 do not significantly emitt thermal radiation Black body is a concept only. But it is useful. |
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Post by kiwistonewall on Sept 19, 2009 1:13:10 GMT
Someone is very confused. So you actually believe that blackbody radiation is only a concept? And that an O2 N2 gas cloud will NOT radiate a blackbody frequency curve, so would remain warm for ever?
There is no arguing with ignorance, and no point.
When truth is ignored for the sake of politics a new dark age is dawning!
Sad days indeed for humanity.
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wylie
Level 3 Rank
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Post by wylie on Sept 19, 2009 1:36:16 GMT
"Someone is very confused. So you actually believe that blackbody radiation is only a concept? And that an O2 N2 gas cloud will NOT radiate a blackbody frequency curve, so would remain warm for ever?
There is no arguing with ignorance, and no point.
When truth is ignored for the sake of politics a new dark age is dawning!
Sad days indeed for humanity. "
Kiwi,
If I am reading Radiant's posts correctly, he is saying that N2 and O2 (and in fact all gases) do NOT have a black body emission curve. I believe him to be flat out incorrect about that. However, perhaps there is some common ground in that the emissivity of gases can be quite low as compared to a "true black body emitter" (like solar plasma for example). Perhaps it would help to search out the emissivity of the common gases. The CO2 and water vapour absorption (and emission) can still be relevant against a low emissivity of N2 and O2 in the IR region.
Do you think that those emissivities are easily obtained?
Ian
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Post by radiant on Sept 19, 2009 5:59:08 GMT
"Someone is very confused. So you actually believe that blackbody radiation is only a concept? And that an O2 N2 gas cloud will NOT radiate a blackbody frequency curve, so would remain warm for ever? There is no arguing with ignorance, and no point. When truth is ignored for the sake of politics a new dark age is dawning! Sad days indeed for humanity. " Kiwi, If I am reading Radiant's posts correctly, he is saying that N2 and O2 (and in fact all gases) do NOT have a black body emission curve. I believe him to be flat out incorrect about that. However, perhaps there is some common ground in that the emissivity of gases can be quite low as compared to a "true black body emitter" (like solar plasma for example). Perhaps it would help to search out the emissivity of the common gases. The CO2 and water vapour absorption (and emission) can still be relevant against a low emissivity of N2 and O2 in the IR region. Do you think that those emissivities are easily obtained? Ian Ian, Kiwi has already supplied references to atest for the low emissivity of N2 and 02 so there is no dispute about that. Kiwis references show that N2 has 'sparce spectra in the IR absorption range' and N2 and 02 have 'negligible emissivity' and 'do not significantly emit IR radiation.' My own references show that 02 and n2 do not aborb or emit ir radiation at ordinary temperatures. There are a few gases like these. They are exceptions. Perhaps this is why you think i am flat out wrong? These gases emit at much higher temperatures They will cool down as i have explained to kiwi because they do have a few lines of emission of IR but this is an insignificant amount for our purposes of calculating heat transfer by radiation when other gases are much more efficient radiators. For example water. Therefore if at ordinary temperatures these gases are emitters as they must be if they behave like a black body which is black and absorbs all radiation and only emitts a spectra depending upon its temperature please find out for me what they are emitting. I found out so far that for astronomical purposes O2 has a green line and several microwave lines. These lines appear to arise from the stratosphere but since i dont have access to a research library my information is limited. Kiwi also no longer has access to a university library system so maybe you can help us please? Perhaps for example you can elaborate as to why you think i am flat out wrong to believe that n2 is not a black body emitter at ordinary temperatures. Kiwi thinks this is some kind of politically motivated game against the scientific truth for some reason??. Clearly i am emphasising that the planet has a massive amount of water. Clearly i am emphasising that science should prevail All of kiwis 'black body' examples of the atmospheres emission show the presence of water and why water is important in the atmosphere as a radiator of heat and other radiations. For example the reason for Antarctic microwave and submillimetre Astronomy is mainly because there is only .25mm of water above antartica sometimes. But kiwi gave as an example of the atmospheres 'black body radiation' as seen from earth when total cloud cover was present. Why did he do that It surely shows he is confused and denying some basic science even if i am also wrong somewhere. It would be really nice to get this resolved to all of our satisfactions somehow.  For example can you provide a definition of a black body other than the one i found in wiki and other internet sources, which might be wrong, that say this is 'an idealised or theoretical object' en.wikipedia.org/wiki/Black_bodywww.egglescliffe.org.uk/physics/astronomy/blackbody/bbody.htmlThanks |
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