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From: Don Klipstein on 9 Dec 2008 02:02 In <pan.2008.12.04.06.47.13.380842(a)REMOVETHISix.netcom.com>, Bill Ward wrote: >On Thu, 04 Dec 2008 03:35:12 +0000, Don Klipstein wrote: > >> In article <pan.2008.11.28.15.55.03.836887(a)REMOVETHISix.netcom.com>, Bill >> Ward wrote: >>>On Fri, 28 Nov 2008 02:26:40 -0800, bill.sloman wrote: >>> >>>> 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. >> 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. - Don Klipstein (don(a)misty.com)
From: Don Klipstein on 9 Dec 2008 02:09 In <pan.2008.12.04.08.02.57.92862(a)REMOVETHISix.netcom.com>, Bill Ward wrote: >On Thu, 04 Dec 2008 03:45:45 +0000, Don Klipstein wrote: > >> In article <pan.2008.11.30.21.41.11.102553(a)REMOVETHISix.netcom.com>, Bill >> Ward wrote: >>>On Sun, 30 Nov 2008 07:28:18 -0800, bill.sloman wrote: >>> >>>> On 29 nov, 21:38, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >>>>> On Sat, 29 Nov 2008 09:58:21 -0800, bill.sloman wrote: >>>>> > On 28 nov, 16:55, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >> <SNIP deeper levels of quotation> >>>>> >> That needs a little explanation. Â CO2 gas is not a BB radiator. >>>>> >> Â At the temperatures in question, the 15u band should be the >>>>> >> only radiation it can absorb or emit. Â How do you come to the >>>>> >> conclusion it emits in a -55C BB spectrum? Â Do you have a link >>>>> >> supporting that? >>>>> >>>>> > 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. >>>> >>>> What I should have said here is that the radiation it does emit has the >>>> same intensity as a blackbody radiator would emit at that temperature. >>>> >>>> This follows from the second law of thermodydnamics - if it wasn't so a >>>> blob of CO2 surrounded by a blackbody would end up at a temperature >>>> other than that of the blackbody. >>>> >>>>> You said, "a spectrum that matches the roughly -55C temperature of the >>>>> bulk of the stratosphere", not a "218K CO2 spectrum". >>>> >>>> Same thing. >>> >>>Isn't the CO2 absorption/emission spectrum a band, not a BB distribution? >>>In part of your previous post (which you snipped) you linked to this: >>> >>>http://www.wag.caltech.edu/home/jang/genchem/ir_img7.gif >> >> That appears to be a sampling of a layer of CO2 representing less CO2 >> than one has to pass through from surface to outer space. >> >> Another version of CO2 IR spectrum is at: >> >> http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif >> http://www.iitap.iastate.edu/gccourse/forcing/spectrum.html >> >>>It doesn't look like a BB to me. Are you having trouble keeping your >>>stories straight again? >> >> But CO2 is close to blackbody within some range of wavelengths where >> emission is close to peak of a 218 K blackbody. And the range does >> widen somewhat when there is more CO2 in the atmosphere. > >Look at this graph: > >http://upload.wikimedia.org/wikipedia/commons/7/7c/Atmospheric_Transmission.png > >Now please tell me if you think the CO2 absorption spectrum (3rd graph) is >similar to the 210K blackbody emission spectrum line in the top graph. I did not claim that - I merely claimed (using maybe better words now than before) that CO2 in the atmosphere radiates close as well as a blackbody does within the 15um-peaking band. The 210K spectrum does indeed have its peak close to CO2's 15 um band, so CO2's 15 um band will absorb and radiate some very significant amount at 210K. >Assuming you agree they are different, please explain how CO2 bonds >could emit in wavelengths they can't absorb. > >>>>> > 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. >>> >>>The "lump" would need to absorb and emit just enough to stay in thermal >>>equilibrium. Why would the general spectrum suddenly change? What you >>>are saying doesn't make sense to me. Please explain. >>> >>>>> Outside the 15u band? Â How much difference is there between the >>>>> energy in the spectra at the two temperatures? >>>> >>>> http://en.wikipedia.org/wiki/Black_body >>>> >>>> work it out for yourself. >>> >>>Let me rephrase: I don't think there's a significant difference. Show >>>why you think there is. Start by showing why you think it's a BB >>>distribution. >> >> CO2 acts fairly like a blackbody at wavelengths within the 15 um band. >> 15 um is a wavelength where a blackbody has spectral power distribution >> about 96% of peak. > >It appears to me both tails of a 210K blackbody spectrum are missing >(looks like about half the total area). Cold CO2 is not a black body - >it's a narrowband source. I was merely saying that CO2 is a significant absorber and radiator at 210 K. - Don Klipstein (don(a)misty.com)
From: Don Klipstein on 9 Dec 2008 02:12 In article <7gpgj495m2jks6qhj2vu6boee3h4p3hflb(a)4ax.com>, Whata Fool wrote: >Bill Ward <bward(a)REMOVETHISix.netcom.com> wrote: <And I snip to that point> >>The context is cooling of the stratosphere by CO2. Explain the >>significance of your comment. > > Please say it isn't so, CO2 cooling the atmosphere is a horror, >because there is and will be more CO2 all the time. > > With temperatures running 15 degrees below normal every day, >and more snow cover than seen in 10 years, any additional cooling >of the atmosphere is the horror, not Hawaii weather in Paris. GHGs cool the stratosphere and warm the lower troposphere and warm the surface. - Don Klipstein (don(a)misty.com)
From: Don Klipstein on 9 Dec 2008 02:18 In <pan.2008.12.04.08.24.48.144247(a)REMOVETHISix.netcom.com>, Bill Ward wrote: >On Thu, 04 Dec 2008 04:30:18 +0000, Don Klipstein wrote: > >> In <pan.2008.12.01.00.23.21.593448(a)REMOVETHISix.netcom.com>, B. Ward said: >>>On Sun, 30 Nov 2008 18:02:11 -0500, Whata Fool wrote: >>> >>>> Bill Ward <bward(a)REMOVETHISix.netcom.com> wrote: >>>> >>>>>On Sun, 30 Nov 2008 07:28:18 -0800, bill.sloman wrote: >> <And I snip most previously quoted material to edit for space> >>>>>> >>>>>> What I should have said here is that the radiation it does emit has >>>>>> the same intensity as a blackbody radiator would emit at that >>>>>> temperature. >>>>>> >>>>>> This follows from the second law of thermodydnamics - if it wasn't so >>>>>> a blob of CO2 surrounded by a blackbody would end up at a temperature >>>>>> other than that of the blackbody. >>>>>> >>>>>> <SNIP response to snipped point> >>>>> >>>>>Isn't the CO2 absorption/emission spectrum a band, not a BB >>>>>distribution? In part of your previous post (which you snipped) you >>>>>linked to this: >>>>> >>>>>http://www.wag.caltech.edu/home/jang/genchem/ir_img7.gif >>>>> >>>>>It doesn't look like a BB to me. Are you having trouble keeping your >>>>>stories straight again? >>>> >>>> He is confusing me, doesn't the AGW consensus claim that AGW has >>>> caused the stratosphere to cool to a lower than normal temperature? >>>> >>>>>The "lump" would need to absorb and emit just enough to stay in thermal >>>>>equilibrium. Why would the general spectrum suddenly change? What you >>>>>are saying doesn't make sense to me. Please explain. >>>> >>>> Haven't all measurements shown that the stratosphere has cooled, >>>> and that added CO2 concentration [AGW] caused it? >>>> >>>>>>> Outside the 15u band? Â How much difference is there between the >>>>>>> energy in the spectra at the two temperatures? >>>>>> >>>>>> http://en.wikipedia.org/wiki/Black_body >>>>>> >>>>>> work it out for yourself. >>>>> >>>>>Let me rephrase: I don't think there's a significant difference. Show >>>>>why you think there is. Start by showing why you think it's a BB >>>>>distribution. >>>> >>>> That page contains the following sentence; >>>> >>>> "This is the black body temperature as measured from space, while the >>>> surface temperature is higher due to the greenhouse effect." >>>> >>>> I claim, and strongly suggest that thinking scientists must >>>> understand >>>> that statement does not represent the true physics, because it ignores >>>> the probability that an N2 and O2 (78 + 20) atmosphere would be hotter >>>> than at present without GreenHouse Gases. >>>> >>>> Unless somebody can explain how N2 and O2 could cool after being >>>> warmed by solar energy and convection from the surface. >>> >>>I suspect the equatorial to polar temperature gradient would invoke >>>convection bands that would tend to equalize the temperatures by >>>conduction to the surface. The nighttime surface would be colder then >>>the adjacent atmosphere, the daytime would be hotter and, "on the >>>average", it looks to me like the (lower) atmosphere still might be >>>warmer than the surface, because of the day/night asymmetry in >>>convection. >> >> That does indeed occur. >> >>>I think adding GHG's with no latent heat would overall cool the >>>atmosphere and warm the surface via the nighttime IR blanket effect. >> >> That is indeed true. >> >>> But I also think that on Earth, latent heat transport by water >>>overwhelms any IR warming by CO2 >> >>>If someone has a lucid explanation showing otherwise, I'd like to see it. >> >> Could well be greater, without negating significance of warming of >> surface and lower levels of the atmosphere by CO2. Also consider that >> significant heat transport by atmospheric movement is not latent heat. > >But transport of water vapor is, by definition. When the WV condenses, >the latent heat has been transfered from wherever it evaporated. > >If there is a significant cooling contribution from water vapor, it >wouldn't take much negative temperature feedback in the water cycle to >compensate for the hypothetical ~1.5W/m^2 "forcing", from anthropogenic >CO2. Except that moving heat around the world does not cool it. Or are you talking about the latent portion of heat convected upwards? >> Just as an example of an extreme - cyclones of baroclinic nature (the >> "usual extratropical cyclone") where water vapor presence is low. Such >> things do occue in central and northern Canada in mid and late winter, >> when water vapor presence is low enough to not account for much heat >> movement. Such things do occur in desert areas. > >"Dust devils"? Dust devils are not baroclinic - those are convective, generally from surface to mere hundreds of meters above. Baroclinic cyclones are the big ones showing up on weather maps. >> They even occur on Mars without a cloud anywhere. >> >> I remember a demonstration by a Sunday School teacher showing >> baroclinic cyclones and baroclinmic events in general forming without >> latent heat - in a big pot of water on a record player turntable, with >> red food dye dropped in over the circumference, and blue dye dropped in >> at the center - and then heat the circumference with a propane torch. >> Baroclinic events result in global or regional convection and heat >> transport across latitudes through the otherwise-barrier of local lapse >> rate being short of allowing local vertical convection. > >That's some Sunday school. I'm envious. - Don Klipstein (don(a)misty.com)
From: Don Klipstein on 9 Dec 2008 02:23
In article <p2kgj4ppvnkeocqk0ddfqqclh7avkp0u67(a)4ax.com>, Whata Fool wrote: >bill.sloman(a)ieee.org wrote: > >>On 4 dec, 13:43, Whata Fool <wh...(a)fool.ami> wrote: >>> Not only that, but just the cooling of the solid surface by the >>> air in early morning and evaporation of the dew or frost may be a lot >>> more than the "forcing" averaged over 24 hours. >> >>All of which happens well below the effective emitting altitude, and >>is consequently irrelevant to the greenhouse effect. That is still radiational cooling. Adding GHGs increases the amount of absorptions/reradiations for radiated heat to escape from surface to space, and that will reduce radiational cooling of the surface. > The real "greenhouse effect" is in the energy transferred to the >N2 and O2 by convection with the surface, and on the planet with GHGs, >by molecular collisions with them. Yes indeed, effect of GHGs is to warm the N2 and O2 in the lower troposphere by warming the lower troposphere, and to cool the N2 and O2 in the stratosphere by cooling the stratosphere. <SNIP beyone here to edit for space> - Don Klipstein (don(a)misty.com) |