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From: bill.sloman on 12 Dec 2008 08:41 On 11 dec, 21:46, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > On Thu, 11 Dec 2008 05:28:40 -0800,bill.slomanwrote: > > On 9 dec, 18:31, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > >> On Tue, 09 Dec 2008 07:02:51 +0000, Don Klipstein wrote: > >> > In <pan.2008.12.04.06.47.13.380...(a)REMOVETHISix.netcom.com>, Bill Ward > >> > wrote: > >> >>On Thu, 04 Dec 2008 03:35:12 +0000, Don Klipstein wrote: > > >> >>> In article <pan.2008.11.28.15.55.03.836...(a)REMOVETHISix.netcom.com>, > >> >>> Bill Ward wrote: > >> >>>>On Fri, 28 Nov 2008 02:26:40 -0800,bill.slomanwrote: > > >> >>>>> On 27 nov, 23:02, Whata Fool <wh...(a)fool.ami> wrote: > >> >>>>>> bill.slo...(a)ieee.org ÃÂ wrote: > >> >>>>>><SNIP to edit for space> > >> >>>>>> >You've misunderstood. The surface of the earth is ultimately > >> >>>>>> >cooled by radiation to outer space, but the "surface" that is > >> >>>>>> >cooled depends on the frequency that is being radiated. > > >> >>>>>> ÃÂ ÃÂ ÃÂ The frequency is determined by > >> >>>>>> temperature, isn't it? > > >> >>>>> A black-body radiator emits a wide range of frequencies. The > >> >>>>> centre of the range does move to higher frequencies as the > >> >>>>> temperature of the emitter gets higher, but it doesn't move all > >> >>>>> that fast. > > >> >>>>>> ÃÂ ÃÂ ÃÂ If the surface is moist, it will > >> >>>>>> likely be 20 degrees F cooler than a dry surface, > > >> >>>>> If the local relative humidity is less than 100%. Since the > >> >>>>> "surfaces" I was talking about are mathematical abstractions - > >> >>>>> essentially spherical shells around the earth located at various > >> >>>>> heights above the ground, this isn't a useful comment. > > >> >>>>>> ÃÂ ÃÂ ÃÂ And that doesn't mean that > >> >>>>>> particular surface is cooled less. > > >> >>>>> It seems that I haven't dumbed down my arguments anything like far > >> >>>>> enough, > > >> >>>>>> ÃÂ ÃÂ ÃÂ Your generalized statements about > >> >>>>>> the cooling of Earth seem to follow a pattern suggesting some > >> >>>>>> form of brainwashing. > > >> >>>>> It isn't usual to describe a tertiary education in science as > >> >>>>> brainwashing, but it is clear that my thinking has been exposed to > >> >>>>> influences that yours has not. > > >> >>>>>> >At frequencies where the > >> >>>>>> >atmosphere is transparent, this can be the surface that you > >> >>>>>> >stand on (when there aren't any clouds overhead). > > >> >>>>>> ÃÂ ÃÂ ÃÂ There is rarely frost on most > >> >>>>>> natural surfaces except for thin leaves, blades of grass and dark > >> >>>>>> surfaces with low coefficient of conductivity. > > >> >>>>> Irrelevant. > > >> >>>>>> >At frequencies that are absorbed (and re-radiated) by water > >> >>>>>> >vapour, this "surface" is fairly high in the troposphere, and > >> >>>>>> >for frequencies that are absorbed (and re-radiated) by carbon > >> >>>>>> >dioxide this "surface" is a good deal higher - 25% of the mass > >> >>>>>> >of the atmosphere (and 25% of the CO2) is up in the > >> >>>>>> >stratosphere. > > >> >>>>>> ÃÂ ÃÂ ÃÂ ÃÂ So there is confusion > >> >>>>>> about where the "surface" [is], or what the "surface" [is], > >> >>>>>> shades of Bill Clinton. > > >> >>>>> You clearly aren't following the argument. Each "surface" in this > >> >>>>> particular discussion is defined as the level at which a photon of > >> >>>>> a particular wavelenght first had an better than even chance of > >> >>>>> making it out into space without being absorbed and re-emitted or > >> >>>>> otherwise scattered. In principle this "surface" can be at any > >> >>>>> height in the atmosphere, depending on the particular wavelength > >> >>>>> being talked about. > > >> >>>>>> ÃÂ ÃÂ ÃÂ ÃÂ Does your last sentence > >> >>>>>> mean that carbon dioxide "cools" the stratosphere? > > >> >>>>> Quite the reverse. The carbon dioxide in the stratosphere absorbs > >> >>>>> infra-red radiation from the warmer troposphere and re-emits it > >> >>>>> with a spectrum that matches the roughly -55C temperature of the > >> >>>>> bulk of the stratosphere. > > >> >>>>That needs a little explanation. CO2 gas is not a BB radiator. > >> >>>> At the temperatures in question, the 15u band should be the only > >> >>>>radiation it can absorb or emit. How do you come to the conclusion > >> >>>>it emits in a -55C BB spectrum? Do you have a link supporting > >> >>>>that? > > >> >>> Peak wavelength of blackbody radiation at 218 K is a bit over 13 > >> >>> um (for > >> >>> power per unit area per unit wavelength bandwidth). > > >> >>Yes. > > >> >>> A 218 K blackbody has spectral power distribution, in terms of > >> >>> power per > >> >>> unit area per unit wavelength bandwidth, above half the peak from > >> >>> about 8.1 nm to about 24.1 um. > > >> >>Yes. > > >> >>> Looks like a 218 K blackbody emits 15 um at about 96% of its > >> >>> peak. > > >> >>Yes, and that's my point. CO2 can't radiate a blackbody spectrum, > >> >>because the bond energies don't match outside the 15u band. If they > >> >>can't absorb, how can they radiate? It's not a BB spectrum because > >> >>the upper and lower tails are missing. > > >> > I was merely claiming that CO2 does significant radiating in that > >> > nice wide 15um-peaking band. > > >> >>> The blackbody radiation formula is widely available. It is > >> >>> available in > >> >>> the "CRC Handbook" which is in the reference section of many, > >> >>> probably most libraries, most undergraduate college general physics > >> >>> texts, and certainly in at least one appropriate Wikipedia article.. > >> >>> Such as: > > >> >>>http://en.wikipedia.org/wiki/Planck%27s_law > > >> >>I also like the hyperphysics summary: > > >> >>http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2 > > >> >>http://hyperphysics.phy-astr.gsu.edu/hbase/bbrc.html#c4 > > >> >>> CO2's IR absorption feature of 15 um is actualy fairly wide and > >> >>> is strong at 13 um, and accounting for most atmospheric IR > >> >>> absorption within a few um of 15 um. > > >> >>Water is also active in that band, but is scarce in the stratosphere.. > > >> > http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif > >> > makes it look like CO2 is more active than water vapor, even at their > >> > degrees of presence in Earth's atmosphere as a whole. > > >> > GHGs play a significant role in the troposphere. > > >> But only radiatively. Water has latent heat. > > >> >>>http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif > >> >>>http://www.iitap.iastate.edu/gccourse/forcing/spectrum.html > > >> >>Surely you're not supporting Sloman's claim that cold CO2 gas can > >> >>radiate a blackbody spectrum, are you? > > >> > I think that was merely a poor choice of words on his part rather > >> > than a claim that CO2 has its radiation spectrum looking like that of > >> > a blackbody. > > >> I would hope so, but he missed several opportunities to clarify his > >> remarks. > > > You failed to understand a number of attempted clarifications. Don > > Klipstein is right about the poor choice of words - several of them were > > polysyllabic. > > Here's the exact exchange: Taken from a post in this thread dated 28th November 2008 at 16:55 (which may reflect my time-zone GMT+1). At present it is post 489 in the Google Groups list. > [Sloman] > [...] The carbon dioxide in the stratosphere absorbs > infra-red radiation from the warmer troposphere and re-emits it > with a spectrum that matches the roughly -55C temperature of the > bulk of the stratosphere. > > [Ward] > That needs a little explanation. CO2 gas is not a BB radiator. > At the temperatures in question, the 15u band should be the only > radiation it can absorb or emit. How do you come to the conclusion > it emits in a -55C BB spectrum? Do you have a link supporting > that? > > All you needed to say is that you didn't mean to imply it was a BB > spectrum, and that, yes, it radiates only in the allowed band. In terms that you were equipped to understand My response on the 29th November 2008 at 18:58. at present this is post 490. "I didn't say that it emitted a black body spectrum. It emits the same spectrum as any volume of carbon dioxide at 218K would, which is different from the spectrum emitted by warmer carbon dioxide. This follows from the second law of thermodynamics. The fact that the 218K spectrum is going to be different from the spectrum emitted by a warmer lump of gas depends on the proposition that the numbers of molecules occupying higher energy vibrational and rotational quantum states changes with temperature, and it is this distribution across the accessible quantised energy levels that dictates the shape of the emission spectrum. " This starts off by explicitly denies that it is a blackbody spectrum - which I wouldn't have had to spell out to anybody who knew anything about the subject. I can't see how you can complain that I failed to say that I "didn't mean to imply it was a BB spectrum". It is true that I didn't say "yes, it radiates only in the allowed band" because this doesn't happen to be true. The temperature of the emitting gas does determine how much radiation will be emitted at of the active wavelengths, and the emission from the asymmetric stretch at aound 4um will decrease more from room tmperature to -55C than the emission from the bending mode at 14um, but the 4um band isn't "forbidden"at any temperature, unlike the emissions from the symmetric stretch. I certainly wasn't going to say that CO2 at -55C could not absorb IR radiation at around 4u. That is equally false, and slightly more ridiculous. The shape of the absorbtion spectra won't be the same as is is a room temperature because a lower proportion of the molecules will be occupying the more highly excited rotational quantum levels, but the 4 um absorbtion will still be entirely allowed. The nature of your question revealed that you really didn't know what you were talking about, and made it difficult for me to take you seriously. Incidentally, your idea that I though that CO2 ever emitted black-body radiation comes from this paragraph "> The frequency is determined by temperature, isn't it? A black-body radiator emits a wide range of frequencies. The centre of the range does move to higher frequencies as the temperature of the emitter gets higher, but it doesn't move all that fast. " which was part of the answer to a post from Whata Fool to which you responded. For thise who know something about thermodynamics, this has exactly the same content as the second paragraph of my response above and is slightly more informative "This follows from the second law of thermodynamics. The fact that the 218K spectrum is going to be different from the spectrum emitted by a warmer lump of gas depends on the proposition that the numbers of molecules occupying higher energy vibrational and rotational quantum states changes with temperature, and it is this distribution across the accessible quantised energy levels that dictates the shape of the emission spectrum." but neither formulation proves to have been dumbed down enough for you to comprehend. Face it. You don't know what you are talking about, and your claims that I haven't answered your questions not only make it plain that you can't understand the answers, but also make it clear that you don't know enough to appreciate how thoroughly ignorant you are. -- Bill Sloman, Nijmegen -- Bill Sloman, Nijmegen
From: Bill Ward on 12 Dec 2008 11:51 On Fri, 12 Dec 2008 05:41:49 -0800, bill.sloman wrote: > On 11 dec, 21:46, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >> On Thu, 11 Dec 2008 05:28:40 -0800,bill.slomanwrote: >> > On 9 dec, 18:31, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >> >> On Tue, 09 Dec 2008 07:02:51 +0000, Don Klipstein wrote: >> >> > In <pan.2008.12.04.06.47.13.380...(a)REMOVETHISix.netcom.com>, Bill >> >> > Ward wrote: >> >> >>On Thu, 04 Dec 2008 03:35:12 +0000, Don Klipstein wrote: >> >> >> >>> In article >> >> >>> <pan.2008.11.28.15.55.03.836...(a)REMOVETHISix.netcom.com>, Bill >> >> >>> Ward wrote: >> >> >>>>On Fri, 28 Nov 2008 02:26:40 -0800,bill.slomanwrote: >> >> >> >>>>> On 27 nov, 23:02, Whata Fool <wh...(a)fool.ami> wrote: >> >> >>>>>> bill.slo...(a)ieee.org  wrote: >> >> >>>>>><SNIP to edit for space> >> >> >>>>>> >You've misunderstood. The surface of the earth is ultimately >> >> >>>>>> >cooled by radiation to outer space, but the "surface" that is >> >> >>>>>> >cooled depends on the frequency that is being radiated. >> >> >> >>>>>>    The frequency is determined by >> >> >>>>>> temperature, isn't it? >> >> >> >>>>> A black-body radiator emits a wide range of frequencies. The >> >> >>>>> centre of the range does move to higher frequencies as the >> >> >>>>> temperature of the emitter gets higher, but it doesn't move all >> >> >>>>> that fast. >> >> >> >>>>>>    If the surface is moist, it will >> >> >>>>>> likely be 20 degrees F cooler than a dry surface, >> >> >> >>>>> If the local relative humidity is less than 100%. Since the >> >> >>>>> "surfaces" I was talking about are mathematical abstractions - >> >> >>>>> essentially spherical shells around the earth located at >> >> >>>>> various heights above the ground, this isn't a useful comment. >> >> >> >>>>>>    And that doesn't mean that >> >> >>>>>> particular surface is cooled less. >> >> >> >>>>> It seems that I haven't dumbed down my arguments anything like >> >> >>>>> far enough, >> >> >> >>>>>>    Your generalized statements >> >> >>>>>> about the cooling of Earth seem to follow a pattern suggesting >> >> >>>>>> some form of brainwashing. >> >> >> >>>>> It isn't usual to describe a tertiary education in science as >> >> >>>>> brainwashing, but it is clear that my thinking has been exposed >> >> >>>>> to influences that yours has not. >> >> >> >>>>>> >At frequencies where the >> >> >>>>>> >atmosphere is transparent, this can be the surface that you >> >> >>>>>> >stand on (when there aren't any clouds overhead). >> >> >> >>>>>>    There is rarely frost on most >> >> >>>>>> natural surfaces except for thin leaves, blades of grass and >> >> >>>>>> dark surfaces with low coefficient of conductivity. >> >> >> >>>>> Irrelevant. >> >> >> >>>>>> >At frequencies that are absorbed (and re-radiated) by water >> >> >>>>>> >vapour, this "surface" is fairly high in the troposphere, and >> >> >>>>>> >for frequencies that are absorbed (and re-radiated) by carbon >> >> >>>>>> >dioxide this "surface" is a good deal higher - 25% of the >> >> >>>>>> >mass of the atmosphere (and 25% of the CO2) is up in the >> >> >>>>>> >stratosphere. >> >> >> >>>>>>     So there is confusion >> >> >>>>>> about where the "surface" [is], or what the "surface" [is], >> >> >>>>>> shades of Bill Clinton. >> >> >> >>>>> You clearly aren't following the argument. Each "surface" in >> >> >>>>> this particular discussion is defined as the level at which a >> >> >>>>> photon of a particular wavelenght first had an better than even >> >> >>>>> chance of making it out into space without being absorbed and >> >> >>>>> re-emitted or otherwise scattered. In principle this "surface" >> >> >>>>> can be at any height in the atmosphere, depending on the >> >> >>>>> particular wavelength being talked about. >> >> >> >>>>>>     Does your last sentence >> >> >>>>>> mean that carbon dioxide "cools" the stratosphere? >> >> >> >>>>> Quite the reverse. The carbon dioxide in the stratosphere >> >> >>>>> absorbs infra-red radiation from the warmer troposphere and >> >> >>>>> re-emits it with a spectrum that matches the roughly -55C >> >> >>>>> temperature of the bulk of the stratosphere. >> >> >> >>>>That needs a little explanation. CO2 gas is not a BB radiator. >> >> >>>> At the temperatures in question, the 15u band should be the >> >> >>>>only radiation it can absorb or emit. How do you come to the >> >> >>>>conclusion it emits in a -55C BB spectrum? Do you have a link >> >> >>>>supporting that? >> >> >> >>> Peak wavelength of blackbody radiation at 218 K is a bit over >> >> >>> 13 um (for >> >> >>> power per unit area per unit wavelength bandwidth). >> >> >> >>Yes. >> >> >> >>> A 218 K blackbody has spectral power distribution, in terms of >> >> >>> power per >> >> >>> unit area per unit wavelength bandwidth, above half the peak from >> >> >>> about 8.1 nm to about 24.1 um. >> >> >> >>Yes. >> >> >> >>> Looks like a 218 K blackbody emits 15 um at about 96% of its >> >> >>> peak. >> >> >> >>Yes, and that's my point. CO2 can't radiate a blackbody spectrum, >> >> >>because the bond energies don't match outside the 15u band. If they >> >> >>can't absorb, how can they radiate? It's not a BB spectrum >> >> >>because the upper and lower tails are missing. >> >> >> > I was merely claiming that CO2 does significant radiating in >> >> > that nice wide 15um-peaking band. >> >> >> >>> The blackbody radiation formula is widely available. It is >> >> >>> available in >> >> >>> the "CRC Handbook" which is in the reference section of many, >> >> >>> probably most libraries, most undergraduate college general >> >> >>> physics texts, and certainly in at least one appropriate >> >> >>> Wikipedia article. Such as: >> >> >> >>>http://en.wikipedia.org/wiki/Planck%27s_law >> >> >> >>I also like the hyperphysics summary: >> >> >> >>http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2 >> >> >> >>http://hyperphysics.phy-astr.gsu.edu/hbase/bbrc.html#c4 >> >> >> >>> CO2's IR absorption feature of 15 um is actualy fairly wide >> >> >>> and is strong at 13 um, and accounting for most atmospheric IR >> >> >>> absorption within a few um of 15 um. >> >> >> >>Water is also active in that band, but is scarce in the >> >> >>stratosphere. >> >> >> > http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif >> >> > makes it look like CO2 is more active than water vapor, even at >> >> > their degrees of presence in Earth's atmosphere as a whole. >> >> >> > GHGs play a significant role in the troposphere. >> >> >> But only radiatively. Water has latent heat. >> >> >> >>>http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif >> >> >>>http://www.iitap.iastate.edu/gccourse/forcing/spectrum.html >> >> >> >>Surely you're not supporting Sloman's claim that cold CO2 gas can >> >> >>radiate a blackbody spectrum, are you? >> >> >> > I think that was merely a poor choice of words on his part >> >> > rather than a claim that CO2 has its radiation spectrum looking >> >> > like that of a blackbody. >> >> >> I would hope so, but he missed several opportunities to clarify his >> >> remarks. >> >> > You failed to understand a number of attempted clarifications. Don >> > Klipstein is right about the poor choice of words - several of them >> > were polysyllabic. >> >> Here's the exact exchange: > > Taken from a post in this thread dated 28th November 2008 at 16:55 (which > may reflect my time-zone GMT+1). At present it is post 489 in the Google > Groups list. > >> [Sloman] >> [...] The carbon dioxide in the stratosphere absorbs infra-red >> radiation from the warmer troposphere and re-emits it with a spectrum >> that matches the roughly -55C temperature of the bulk of the >> stratosphere. >> >> [Ward] >> That needs a little explanation. CO2 gas is not a BB radiator. At the >> temperatures in question, the 15u band should be the only radiation it >> can absorb or emit. How do you come to the conclusion it emits in a >> -55C BB spectrum? Do you have a link supporting that? >> >> All you needed to say is that you didn't mean to imply it was a BB >> spectrum, and that, yes, it radiates only in the allowed band. > > In terms that you were equipped to understand > > My response on the 29th November 2008 at 18:58. at present this is post > 490. > > "I didn't say that it emitted a black body spectrum. It emits the same > spectrum as any volume of carbon dioxide at 218K would, which is different > from the spectrum emitted by warmer carbon dioxide. > > This follows from the second law of thermodynamics. The fact that the 218K > spectrum is going to be different from the spectrum emitted by a warmer > lump of gas depends on the proposition that the numbers of molecules > occupying higher energy vibrational and rotational quantum states changes > with temperature, and it is this distribution across the accessible > quantised energy levels that dictates the shape of the emission spectrum. > " > > This starts off by explicitly denies that it is a blackbody spectrum - > which I wouldn't have had to spell out to anybody who knew anything about > the subject. > > I can't see how you can complain that I failed to say that I "didn't mean > to imply it was a BB spectrum". It is true that I didn't say "yes, it > radiates only in the allowed band" because this doesn't happen to be true. > > The temperature of the emitting gas does determine how much radiation will > be emitted at of the active wavelengths, and the emission from the > asymmetric stretch at aound 4um will decrease more from room tmperature to > -55C than the emission from the bending mode at 14um, but the 4um band > isn't "forbidden"at any temperature, unlike the emissions from the > symmetric stretch. > > I certainly wasn't going to say that CO2 at -55C could not absorb IR > radiation at around 4u. That is equally false, and slightly more > ridiculous. The shape of the absorbtion spectra won't be the same as is is > a room temperature because a lower proportion of the molecules will be > occupying the more highly excited rotational quantum levels, but the 4 um > absorbtion will still be entirely allowed. Will it absorb a significant amount in this context? It looks way out on the tail of the BB spectrum. > > The nature of your question revealed that you really didn't know what > you were talking about, and made it difficult for me to take you > seriously. No, I think you saw it as an opportunity to try to intimidate me, which never works. > > Incidentally, your idea that I though that CO2 ever emitted black-body > radiation comes from this paragraph > > "> The frequency is determined by temperature, isn't it? > > A black-body radiator emits a wide range of frequencies. The centre of > the range does move to higher frequencies as the temperature of the > emitter gets higher, but it doesn't move all that fast. " > > which was part of the answer to a post from Whata Fool to which you > responded. For thise who know something about thermodynamics, this has > exactly the same content as the second paragraph of my response above > and is slightly more informative > > "This follows from the second law of thermodynamics. The fact that the > 218K spectrum is going to be different from the spectrum emitted by a > warmer lump of gas depends on the proposition that the numbers of > molecules occupying higher energy vibrational and rotational quantum > states changes with temperature, and it is this distribution across the > accessible quantised energy levels that dictates the shape of the > emission spectrum." > > but neither formulation proves to have been dumbed down enough for you > to comprehend. Your assumption is incorrect. I was simply trying to see if there was some good reason behind your attempt to complicate the relatively simple issue that CO2 is not a black body emitter. Apparently there wasn't. > > Face it. You don't know what you are talking about, and your claims that > I haven't answered your questions not only make it plain that you can't > understand the answers, but also make it clear that you don't know > enough to appreciate how thoroughly ignorant you are. I'm ignorant of a lot of things. I try to learn from those who know more and teach those who know less. Your approach seems to be to try to intimidate others by bringing in extraneous, irrelevant issues to stroke your own ego. But since you are such a self-evident expert in the fine details of spectroscopy, perhaps you could give us a quantitative answer to the original issue: What fraction of a -55C blackbody spectrum does CO2 absorb near the 15u band, what fraction is absorbed near the 4.7u band, and what fraction is not absorbed? Assume upper troposphere temperatures and pressures. Can you do that? Just estimate it as best you can.
From: bill.sloman on 12 Dec 2008 13:35 On 12 dec, 17:51, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > On Fri, 12 Dec 2008 05:41:49 -0800,bill.slomanwrote: > > On 11 dec, 21:46, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > >> On Thu, 11 Dec 2008 05:28:40 -0800,bill.slomanwrote: > >> > On 9 dec, 18:31, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > >> >> On Tue, 09 Dec 2008 07:02:51 +0000, Don Klipstein wrote: > >> >> > In <pan.2008.12.04.06.47.13.380...(a)REMOVETHISix.netcom.com>, Bill > >> >> > Ward wrote: > >> >> >>On Thu, 04 Dec 2008 03:35:12 +0000, Don Klipstein wrote: > > >> >> >>> In article > >> >> >>> <pan.2008.11.28.15.55.03.836...(a)REMOVETHISix.netcom.com>, Bill > >> >> >>> Ward wrote: > >> >> >>>>On Fri, 28 Nov 2008 02:26:40 -0800,bill.slomanwrote: > > >> >> >>>>> On 27 nov, 23:02, Whata Fool <wh...(a)fool.ami> wrote: > >> >> >>>>>> bill.slo...(a)ieee.org ÃÂ wrote: <snip> > >> >> > I think that was merely a poor choice of words on his part > >> >> > rather than a claim that CO2 has its radiation spectrum looking > >> >> > like that of a blackbody. > > >> >> I would hope so, but he missed several opportunities to clarify his > >> >> remarks. > > >> > You failed to understand a number of attempted clarifications. Don > >> > Klipstein is right about the poor choice of words - several of them > >> > were polysyllabic. > > >> Here's the exact exchange: > > > Taken from a post in this thread dated 28th November 2008 at 16:55 (which > > may reflect my time-zone GMT+1). At present it is post 489 in the Google > > Groups list. > > >> [Sloman] > >> [...] The carbon dioxide in the stratosphere absorbs infra-red > >> radiation from the warmer troposphere and re-emits it with a spectrum > >> that matches the roughly -55C temperature of the bulk of the > >> stratosphere. > > >> [Ward] > >> That needs a little explanation. CO2 gas is not a BB radiator. At the > >> temperatures in question, the 15u band should be the only radiation it > >> can absorb or emit. How do you come to the conclusion it emits in a > >> -55C BB spectrum? Do you have a link supporting that? > > >> All you needed to say is that you didn't mean to imply it was a BB > >> spectrum, and that, yes, it radiates only in the allowed band. > > > In terms that you were equipped to understand > > > My response on the 29th November 2008 at 18:58. at present this is post > > 490. > > > "I didn't say that it emitted a black body spectrum. It emits the same > > spectrum as any volume of carbon dioxide at 218K would, which is different > > from the spectrum emitted by warmer carbon dioxide. > > > This follows from the second law of thermodynamics. The fact that the 218K > > spectrum is going to be different from the spectrum emitted by a warmer > > lump of gas depends on the proposition that the numbers of molecules > > occupying higher energy vibrational and rotational quantum states changes > > with temperature, and it is this distribution across the accessible > > quantised energy levels that dictates the shape of the emission spectrum. > > " > > > This starts off by explicitly denies that it is a blackbody spectrum - > > which I wouldn't have had to spell out to anybody who knew anything about > > the subject. > > > I can't see how you can complain that I failed to say that I "didn't mean > > to imply it was a BB spectrum". It is true that I didn't say "yes, it > > radiates only in the allowed band" because this doesn't happen to be true. > > > The temperature of the emitting gas does determine how much radiation will > > be emitted at of the active wavelengths, and the emission from the > > asymmetric stretch at aound 4um will decrease more from room tmperature to > > -55C than the emission from the bending mode at 14um, but the 4um band > > isn't "forbidden"at any temperature, unlike the emissions from the > > symmetric stretch. > > > I certainly wasn't going to say that CO2 at -55C could not absorb IR > > radiation at around 4u. That is equally false, and slightly more > > ridiculous. The shape of the absorbtion spectra won't be the same as is is > > a room temperature because a lower proportion of the molecules will be > > occupying the more highly excited rotational quantum levels, but the 4 um > > absorbtion will still be entirely allowed. > > Will it absorb a significant amount in this context? It looks way out on > the tail of the BB spectrum. The broadband spectrum is all about emission. The absortion extinction coefficients of the lines around 4 um won't look much different. > > The nature of your question revealed that you really didn't know what > > you were talking about, and made it difficult for me to take you > > seriously. > > No, I think you saw it as an opportunity to try to intimidate me, which > never works. That would be a paranoid delusion on your part. I obviously assumed that you understood more about the subject than you do. but that's a long way from intimidation. > > Incidentally, your idea that I though that CO2 ever emitted black-body > > radiation comes from this paragraph > > > "> The frequency is determined by temperature, isn't it? > > > A black-body radiator emits a wide range of frequencies. The centre of > > the range does move to higher frequencies as the temperature of the > > emitter gets higher, but it doesn't move all that fast. " > > > which was part of the answer to a post from Whata Fool to which you > > responded. For thise who know something about thermodynamics, this has > > exactly the same content as the second paragraph of my response above > > and is slightly more informative > > > "This follows from the second law of thermodynamics. The fact that the > > 218K spectrum is going to be different from the spectrum emitted by a > > warmer lump of gas depends on the proposition that the numbers of > > molecules occupying higher energy vibrational and rotational quantum > > states changes with temperature, and it is this distribution across the > > accessible quantised energy levels that dictates the shape of the > > emission spectrum." > > > but neither formulation proves to have been dumbed down enough for you > > to comprehend. > > Your assumption is incorrect. I was simply trying to see if there was > some good reason behind your attempt to complicate the relatively simple > issue that CO2 is not a black body emitter. Apparently there wasn't. Since what I wrote was aimed providing an easy guide to the way the emissions of gaseous CO2 (which is obviously not a black-body radiatior) had to change as its temperature decreased, I find it difficult to understand why you are so enthusiastic about pushing the straw man proposition that someone might be dumb enough to think that gaseous CO2 was a blackbody radiator. The second law of thermodynamics does require the emission spectrum to change in such a way that a lump of gaseous CO2 at -55C would remain in thermal equilibrium with a blackbody radiator/absorber at -55C, but this does not carry any implication that gaseous CO2 is a blackbody radiator. > > Face it. You don't know what you are talking about, and your claims that > > I haven't answered your questions not only make it plain that you can't > > understand the answers, but also make it clear that you don't know > > enough to appreciate how thoroughly ignorant you are. > > I'm ignorant of a lot of things. I try to learn from those who know more Or so you claim. In practice you ignore any information that points out where your arguments fall over. > and teach those who know less. Not a large catagory, on the evidence available. >Your approach seems to be to try to intimidate others by bringing in extraneous, irrelevant issues to stroke > your own ego. The extra information may look irrelevant and intimidating to you, but you don't know much, so your opinion on its relevance is worthless, and you don't - in any event - seem to be intimidated by information you can't exploit to your own advantage, since you cheerfully ignore it. Your speculation about my need to stoke my own ego does strike me as some kind of projection (one of your favourite lines, but that's what projection is all about) but you are free to believe whatever makes you feel good, no matter how stupid it makes you look. > But since you are such a self-evident expert in the fine details of > spectroscopy, perhaps you could give us a quantitative answer to the > original issue: > > What fraction of a -55C blackbody spectrum does CO2 absorb near the 15u > band, what fraction is absorbed near the 4.7u band, and what fraction is > not absorbed? Assume upper troposphere temperatures and pressures. To do that in a useful way I'd need the detailed infra-red absorbtion spectrum of CO2 at -55C and lower stratosphere pressures - a digital spectrum giving extinction coefficients and line widths for all the active lines. I'm fairly sure that this information exists and is available - climate modellers refer to it from time to time - but I've been looking for it recently and haven't been able to find a search string that gets me anything like it. Once I had that, the rest would be pretty trivial. This is not to say that I'd take on the project if I got the spectral information. At present my only motivation do the job would be to satisy your idle curiousity, and since it is perfectly obvious that you wouldn't care what the answer was and wouldn't have clue what it meant in any larger context, it isn't exactly compelling. And don't bother claiming that I'm bluffing. Your fuss about the "blackbody" issue is an utterly transparent bluff, and it hasn't worked. You already look like a pretentious idiot, and trying to persist with that game isn't going to make you look any better. -- Bill Sloman, Nijmegen
From: bill.sloman on 12 Dec 2008 13:41 On 11 dec, 21:26, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > On Thu, 11 Dec 2008 04:56:18 -0800,bill.slomanwrote: > > On 11 dec, 04:16, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > >> On Wed, 10 Dec 2008 15:45:08 -0500, Whata Fool wrote: > >> > Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > > >> >>On Wed, 10 Dec 2008 06:10:34 -0800,bill.slomanwrote: > > >> >>> On 9 dec, 01:32, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > >> >>>> On Mon, 08 Dec 2008 06:36:08 -0800,bill.slomanwrote: > >> >>>> > On 8 dec, 03:02, Whata Fool <wh...(a)fool.ami> wrote: > >> >>>> >> Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: > > >> >>>> >> >On Sun, 07 Dec 2008 05:29:26 -0800,bill.slomanwrote: > > >> >>>> >> >> On 7 dec, 09:25, Whata Fool <wh...(a)fool.ami> wrote: > > > <snip> > > >> > Bill, what is needed is a calculation of the thermal energy > >> > in a square meter column of atmosphere, to see how long it takes to > >> > cool the whole column by radiation. > > >> We already know it will cool at the same rate the sun is heating it, > >> about 240W/m^2, and will do so at a radiation temperature of about 255K. > > >> What we don't know is how or if the surface temperature and the vertical > >> distribution of temperature is affected by 390 ppmv of CO2 in the > >> presence of an excess of water in the system. > > > You and Whata Fool don't know. Better informed investigators have a rather > > clearer idea. > > But you don't. At least not one you can explain. Isn't it frustrating to > be so sure of yourself and yet be so completely unable to explain why? I'm used to it. I can deal with stupidity, and I can cope with people who can't understand because they don't want to. I spent most of my careeer in industry, and coping with obstructive bosses is rahter more demanding that putting up with pretentious nitwits in user-groups. -- Bill Sloman, Nijmegen
From: Bill Ward on 12 Dec 2008 16:39
On Fri, 12 Dec 2008 10:35:42 -0800, bill.sloman wrote: > On 12 dec, 17:51, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >> On Fri, 12 Dec 2008 05:41:49 -0800,bill.slomanwrote: >> > On 11 dec, 21:46, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >> >> On Thu, 11 Dec 2008 05:28:40 -0800,bill.slomanwrote: >> >> > On 9 dec, 18:31, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >> >> >> On Tue, 09 Dec 2008 07:02:51 +0000, Don Klipstein wrote: >> >> >> > In <pan.2008.12.04.06.47.13.380...(a)REMOVETHISix.netcom.com>, >> >> >> > Bill Ward wrote: >> >> >> >>On Thu, 04 Dec 2008 03:35:12 +0000, Don Klipstein wrote: >> >> >> >> >>> In article >> >> >> >>> <pan.2008.11.28.15.55.03.836...(a)REMOVETHISix.netcom.com>, Bill >> >> >> >>> Ward wrote: >> >> >> >>>>On Fri, 28 Nov 2008 02:26:40 -0800,bill.slomanwrote: >> >> >> >> >>>>> On 27 nov, 23:02, Whata Fool <wh...(a)fool.ami> wrote: >> >> >> >>>>>> bill.slo...(a)ieee.org  wrote: > > <snip> > >> >> >> > I think that was merely a poor choice of words on his part >> >> >> > rather than a claim that CO2 has its radiation spectrum looking >> >> >> > like that of a blackbody. >> >> >> >> I would hope so, but he missed several opportunities to clarify >> >> >> his remarks. >> >> >> > You failed to understand a number of attempted clarifications. Don >> >> > Klipstein is right about the poor choice of words - several of them >> >> > were polysyllabic. >> >> >> Here's the exact exchange: >> >> > Taken from a post in this thread dated 28th November 2008 at 16:55 >> > (which may reflect my time-zone GMT+1). At present it is post 489 in >> > the Google Groups list. >> >> >> [Sloman] >> >> [...] The carbon dioxide in the stratosphere absorbs infra-red >> >> radiation from the warmer troposphere and re-emits it with a >> >> spectrum that matches the roughly -55C temperature of the bulk of >> >> the stratosphere. >> >> >> [Ward] >> >> That needs a little explanation. CO2 gas is not a BB radiator. At >> >> the temperatures in question, the 15u band should be the only >> >> radiation it can absorb or emit. How do you come to the conclusion >> >> it emits in a -55C BB spectrum? Do you have a link supporting that? >> >> >> All you needed to say is that you didn't mean to imply it was a BB >> >> spectrum, and that, yes, it radiates only in the allowed band. >> >> > In terms that you were equipped to understand >> >> > My response on the 29th November 2008 at 18:58. at present this is >> > post 490. >> >> > "I didn't say that it emitted a black body spectrum. It emits the same >> > spectrum as any volume of carbon dioxide at 218K would, which is >> > different from the spectrum emitted by warmer carbon dioxide. >> >> > This follows from the second law of thermodynamics. The fact that the >> > 218K spectrum is going to be different from the spectrum emitted by a >> > warmer lump of gas depends on the proposition that the numbers of >> > molecules occupying higher energy vibrational and rotational quantum >> > states changes with temperature, and it is this distribution across >> > the accessible quantised energy levels that dictates the shape of the >> > emission spectrum. " >> >> > This starts off by explicitly denies that it is a blackbody spectrum - >> > which I wouldn't have had to spell out to anybody who knew anything >> > about the subject. >> >> > I can't see how you can complain that I failed to say that I "didn't >> > mean to imply it was a BB spectrum". It is true that I didn't say >> > "yes, it radiates only in the allowed band" because this doesn't >> > happen to be true. >> >> > The temperature of the emitting gas does determine how much radiation >> > will be emitted at of the active wavelengths, and the emission from >> > the asymmetric stretch at aound 4um will decrease more from room >> > tmperature to -55C than the emission from the bending mode at 14um, >> > but the 4um band isn't "forbidden"at any temperature, unlike the >> > emissions from the symmetric stretch. >> >> > I certainly wasn't going to say that CO2 at -55C could not absorb IR >> > radiation at around 4u. That is equally false, and slightly more >> > ridiculous. The shape of the absorbtion spectra won't be the same as >> > is is a room temperature because a lower proportion of the molecules >> > will be occupying the more highly excited rotational quantum levels, >> > but the 4 um absorbtion will still be entirely allowed. >> >> Will it absorb a significant amount in this context? It looks way out >> on the tail of the BB spectrum. > > The broadband spectrum is all about emission. The absortion extinction > coefficients of the lines around 4 um won't look much different. > >> > The nature of your question revealed that you really didn't know what >> > you were talking about, and made it difficult for me to take you >> > seriously. >> >> No, I think you saw it as an opportunity to try to intimidate me, which >> never works. > > That would be a paranoid delusion on your part. I obviously assumed that > you understood more about the subject than you do. but that's a long way > from intimidation. > >> > Incidentally, your idea that I though that CO2 ever emitted black-body >> > radiation comes from this paragraph >> >> > "> The frequency is determined by temperature, isn't it? >> >> > A black-body radiator emits a wide range of frequencies. The centre of >> > the range does move to higher frequencies as the temperature of the >> > emitter gets higher, but it doesn't move all that fast. " >> >> > which was part of the answer to a post from Whata Fool to which you >> > responded. For thise who know something about thermodynamics, this has >> > exactly the same content as the second paragraph of my response above >> > and is slightly more informative >> >> > "This follows from the second law of thermodynamics. The fact that the >> > 218K spectrum is going to be different from the spectrum emitted by a >> > warmer lump of gas depends on the proposition that the numbers of >> > molecules occupying higher energy vibrational and rotational quantum >> > states changes with temperature, and it is this distribution across >> > the accessible quantised energy levels that dictates the shape of the >> > emission spectrum." >> >> > but neither formulation proves to have been dumbed down enough for you >> > to comprehend. >> >> Your assumption is incorrect. I was simply trying to see if there was >> some good reason behind your attempt to complicate the relatively simple >> issue that CO2 is not a black body emitter. Apparently there wasn't. > > Since what I wrote was aimed providing an easy guide to the way the > emissions of gaseous CO2 (which is obviously not a black-body radiatior) > had to change as its temperature decreased, I find it difficult to > understand why you are so enthusiastic about pushing the straw man > proposition that someone might be dumb enough to think that gaseous CO2 > was a blackbody radiator. The second law of thermodynamics does require > the emission spectrum to change in such a way that a lump of gaseous CO2 > at -55C would remain in thermal equilibrium with a blackbody > radiator/absorber at -55C, but this does not carry any implication that > gaseous CO2 is a blackbody radiator. > >> > Face it. You don't know what you are talking about, and your claims >> > that I haven't answered your questions not only make it plain that you >> > can't understand the answers, but also make it clear that you don't >> > know enough to appreciate how thoroughly ignorant you are. >> >> I'm ignorant of a lot of things. I try to learn from those who know >> more > > Or so you claim. In practice you ignore any information that points out > where your arguments fall over. > >> and teach those who know less. > > Not a large catagory, on the evidence available. > >>Your approach seems to be to try to intimidate others by bringing in >>extraneous, irrelevant issues to stroke >> your own ego. > > The extra information may look irrelevant and intimidating to you, but you > don't know much, so your opinion on its relevance is worthless, and you > don't - in any event - seem to be intimidated by information you can't > exploit to your own advantage, since you cheerfully ignore it. Your > speculation about my need to stoke my own ego does strike me as some kind > of projection (one of your favourite lines, but that's what projection is > all about) but you are free to believe whatever makes you feel good, no > matter how stupid it makes you look. > >> But since you are such a self-evident expert in the fine details of >> spectroscopy, perhaps you could give us a quantitative answer to the >> original issue: >> >> What fraction of a -55C blackbody spectrum does CO2 absorb near the 15u >> band, what fraction is absorbed near the 4.7u band, and what fraction is >> not absorbed? Assume upper troposphere temperatures and pressures. > > To do that in a useful way I'd need the detailed infra-red absorbtion > spectrum of CO2 at -55C and lower stratosphere pressures - a digital > spectrum giving extinction coefficients and line widths for all the active > lines. I'm fairly sure that this information exists and is available - > climate modellers refer to it from time to time - but I've been looking > for it recently and haven't been able to find a search string that gets me > anything like it. > > Once I had that, the rest would be pretty trivial. > > This is not to say that I'd take on the project if I got the spectral > information. > > At present my only motivation do the job would be to satisy your idle > curiousity, and since it is perfectly obvious that you wouldn't care what > the answer was and wouldn't have clue what it meant in any larger context, > it isn't exactly compelling. > > And don't bother claiming that I'm bluffing. Your fuss about the > "blackbody" issue is an utterly transparent bluff, and it hasn't worked. > > You already look like a pretentious idiot, and trying to persist with that > game isn't going to make you look any better. Oh come on. You can't even do a rough estimate? How close can you get? Enough to show you're not bluffing? Apparently not. http://upload.wikimedia.org/wikipedia/commons/7/7c/Atmospheric_Transmission.png I'm guessing, by simply looking at the relevant spectra, that CO2 would absorb around 20-30% in the 15u band, and less than 5% in the 4.7u band, leaving 65-75% unabsorbed. Your bluff is called. Is the graph wrong? What are the real numbers, if you actually know? |