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Post by radiant on Oct 19, 2009 17:15:00 GMT
Radiant, you appear to have based your posts on the belief that the liquid water absorption profile is a good reflection of the absorption of water vapour. Here are two more papers of observational evidence for the water vapour "window" in the 8-13 micron region that suggests that this assumption is wrong: The Quarterly Journal of the Royal Meteorological Society Volume 99 Issue 421 A study of the continuum absorption within the 8-13 m atmospheric window A. C. L. Lee The above says significant exchange of radiatio occurs near the surface which would be impossible if the water vapour absorbed all the radiation in less than a mm of equivalent amount of water. Certainly, remote sensing (presumably from space) would be impossible. This study was done from a tethered balloon presumably to measure the radiation from earth in exceptionally clear atmospheric conditions. These conditions happen when water vapour is very low.The next study was observations over a distance of 1-1.5km in the atmosphere over the same spectral region. Other than it being further evidence that an atmosphere with a significant amount of water vapour is not opaque to radiation in the IR region, the paper is not that relevant to the discussion. Measurements of Lorentz air-broadening coefficients and relative intensities in the H216O pure rotational and v2 bands from long horizontal path atmospheric spectra Curtis P. Rinsland, Aaron Goldman, Mary Ann H. Smith, and V. Malathy Devi Applied Optics, Vol. 30, Issue 12, pp. 1427-1438 doi:10.1364/AO.30.001427 www.opticsinfobase.org/ao/abstract.cfm?uri=ao-30-12-1427which studies the spectral region: Kitt Peak was selected in 1958 as the site for a national observatory after a 3-year survey that included more than 150 mountain ranges across the U.S. At an altitude of 6875 ft and located in the middle of the Sonora Desert,You seem unable to grasp the nature of the science of IR measurement due to the problems of water vapour
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Post by icefisher on Oct 19, 2009 17:32:15 GMT
Also you cannot ignore the fact that we *do* have CO2, and it will emit in its own bands because it is excited by collision far more often than it is excited by absorbing a photon. So if you like, the ocean emissions warm the water vapour via radiation. The water vapour passes energy to the atmosphere via collisions. The CO2 is warmed along with the rest of the atmosphere and emits at 15 microns. Indeed the thermal conductivity of O2 and N2 is about 70% higher than CO2. And of course water is about a 1000% higher than 02 and N2. That together with the fact there is about 250,000% more of those gases than CO2 in the atmosphere one would be led to believe the vast majority of heat goes into the relatively IR inactive gases. The only question that needs answering is the relative radiative cooling of the dominant atmospheric gases versus CO2 in a number that goes to an accuracy of at least 4 or 5 decimal points. Can that even be done? Most of the work on emissivity I have seen is struggling to pick the first decimal point and calculated values seem to underestimate observed values from spectra analysis. . . .suggesting that the radiative models are not complete. . . .certainly too inaccurate to reliably estimate the forcing of increased CO2. Seems to me what we are seeing billions of dollars poured into is most like a large number of LSD addled minds effectively standing around reading tea leaves. Probably time to issue all these guys a shovel and have them do something productive. I noticed today that NASA broke its multiple month consecutive record of providing the biggest outlier in the ENSO prediction competition by failing to provide a new model run for the current month to the NOAA ENSO prediction unit. Top spot was taken over by their sister unit, COLA CCSM3 (funded by NASA), the same group that has been breaking NASA's failure runs for sometime now with displays of ineptitude on their own part, including the month prior to the most recent 6 month string of abysmal attemts to predict ENSO. Seems to be a pattern. . . .substituting bristle cone pines with Yamal 061 and a dose of Mannian upside down multi-variate analysis methods mixed in to fine tune shapes. . . .they proliferate well and show up in these predictions too. NASA is making a true A$$ of itself these days. Its about time to throw the bums out.
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Post by steve on Oct 19, 2009 17:50:52 GMT
Radiant You seem intent in ignoring the obvious. Why do the papers talk about the well-known window between 8 and 13 microns that can be used for remote sounding if it doesn't exist!? Further: The balloon was tethered and in one flight did not reach above 950mbar. The locatiion of the flight was central England in Autumn. Not known for its dry air. Profiles were taken in condition of cloud, but were rejected because of difficulty measuring temperature, not because of difficulty taking a profile. I thought you'd pick up on this, but 7000 feet is not that high. There is plenty of water vapour around. In the following you have to remember that relative humidity is being shown: cleardarksky.com/c/KittAZkey.html
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Post by steve on Oct 19, 2009 17:53:37 GMT
Icefisher Thank you for letting me have something to giggle at as I log off and go back to my chores
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Post by radiant on Oct 19, 2009 18:06:18 GMT
Radiant You seem intent in ignoring the obvious. Why do the papers talk about the well-known window between 8 and 13 microns that can be used for remote sounding if it doesn't exist!? Further: The balloon was tethered and in one flight did not reach above 950mbar. The locatiion of the flight was central England in Autumn. Not known for its dry air. Profiles were taken in condition of cloud, but were rejected because of difficulty measuring temperature, not because of difficulty taking a profile. I thought you'd pick up on this, but 7000 feet is not that high. There is plenty of water vapour around. In the following you have to remember that relative humidity is being shown: cleardarksky.com/c/KittAZkey.htmlYour own link tells you what you need to know. The line, labeled Transparency, forecasts the transparency of the air. Here 'transparency' means just what astronomers mean by the word: the total transparency of the atmosphere from ground to space. It's calculated from the total amount of water vapor in the air. It is somewhat independant of the cloud cover forecast in that there can be isolated clouds in a transparent air mass, and poor transparency can occur when there is very little cloudThere is no window when water is present. It is called cherry picking - just all of your links where you seek to remove the influence of water vapour in quantity. You tell me a few km of distance thru air are significant and that shows me something and i point out it is at over 6000 feet and you say it is not significant
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Post by radiant on Oct 19, 2009 18:20:53 GMT
Icefisher Thank you for letting me have something to giggle at as I log off and go back to my chores if you look up the thermal conductivity of n2 02 and C02 you will notice Icefisher is more or less correct for those gases. Gases can behave in ways that are not obvious. Tyndall observed that hydrogen conducts heat as well as a metal. A white hot element of platinum with a current flowing thru it was observed to be totally dull when surrounded with Hydrogen Thermal conductivity of gases seems to be related to their ability to move rapidly. C02 is a molecule with significant mass relative to N2 and 02. It is for reasons like this it is very difficult to model the behaviour of matter with simulations.
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Post by icefisher on Oct 19, 2009 22:18:34 GMT
Icefisher Thank you for letting me have something to giggle at as I log off and go back to my chores if you look up the thermal conductivity of n2 02 and C02 you will notice Icefisher is more or less correct for those gases. Thermal conductivity of: water .6 w/m.k o2 .02424 w/m.k n2 .024 w/m.k co2 .01465 w/m.k
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Post by radiant on Oct 20, 2009 4:10:39 GMT
if you look up the thermal conductivity of n2 02 and C02 you will notice Icefisher is more or less correct for those gases. Thermal conductivity of: water .6 w/m.k o2 .02424 w/m.k n2 .024 w/m.k co2 .01465 w/m.k Icefisher You referred to 'those gases' Water vapour has a similar thermal conductivity to C02 users.wpi.edu/~ierardi/FireTools/water_vapor.html
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Post by steve on Oct 20, 2009 7:57:56 GMT
It was the picture of heat being somehow sucked out of the CO2 and into the O2 and N2 that amused me, not the stuff about thermal conductivity.
That said, the conductivity figures back up what I said about conductivity being small compared with radiation and convection.
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Post by steve on Oct 20, 2009 8:17:12 GMT
So you think that air in central England in September is dry. And air at a mere 6000 feet is dry (despite evidence from a forecast link of humidity in the mid 50s with moderate temperatures).
There is currently a time on the forecast where humidity is 65-70% (yellow) and temperature is 41F-50F (green) and transparency is Transparent "Dark blue". So you are wrong in your interpretation. (I don't actually know what wavelengths they are talking about so the forecast could be irrelevant anyway).
I now have 3 satellite plots, two papers in optics journals, one book result all backing up my suggestion that you are incorrect in assuming that water vapour is all powerful. And I haven't even tried very hard.
You have said that obs from space do not extend far into the spectrum, but as I made clear, the two spectra in the Nature paper extends far enough to see the edge of the CO2 spectral band, but not the whole band.
So please go ahead and cherry pick me some recent information that says contrary to the above observations, and that perhaps criticise those metrologist meteorologists for talking about the "well known" window of 6-13 microns.
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Post by radiant on Oct 20, 2009 12:44:28 GMT
So you think that air in central England in September is dry. And air at a mere 6000 feet is dry (despite evidence from a forecast link of humidity in the mid 50s with moderate temperatures). There is currently a time on the forecast where humidity is 65-70% (yellow) and temperature is 41F-50F (green) and transparency is Transparent "Dark blue". So you are wrong in your interpretation. (I don't actually know what wavelengths they are talking about so the forecast could be irrelevant anyway). I now have 3 satellite plots, two papers in optics journals, one book result all backing up my suggestion that you are incorrect in assuming that water vapour is all powerful. And I haven't even tried very hard. You have said that obs from space do not extend far into the spectrum, but as I made clear, the two spectra in the Nature paper extends far enough to see the edge of the CO2 spectral band, but not the whole band. So please go ahead and cherry pick me some recent information that says contrary to the above observations, and that perhaps criticise those metrologist meteorologists for talking about the "well known" window of 6-13 microns. There is no dry air anywhere on earth The driest known air from the surface to space is at ridge 'A' antarctica at 0.25mm of water minimum. The next driest is around dome c which is 3 times wetter. Then comes places like mountain observatories in the South American Andies. 'Dry air in the atmosphere' is relatively dry. There is no dry air in the atmosphere. Air at 50,000 feet can be enormously wet. Observatories are picked for unique features that give them opportunities to be exceptionally dry 'often' or 'usually' but not all the time as this is impossible. Do i really need to explain this to you?? If you are genuinely interested in learning then produce the 3 satellite plots in easy to read form on a page and we can discuss them and everybody can learn what they are saying. The atmospheric window appears to be a lesser region of emission where some spectral lines can get thru sometimes depending upon earthly conditions. All your links are saying this. If not you need to explain why. So far you think dryer air is irrelevant - or do you?. I am not sure what you believe or why you believe it or say it. And there is no point referring to a forcast without producing a link to what you are referring to. This is an internet based conversation. I have gone to great lengths to supply data to support my point of view. At this point in time i am inclined to think you are just confused rather than being crooked but you need to be clearer what you are saying and i will then do my best to discuss it with you. If you persist in this stupidity of thinking you are superior to me when i am a 54 year old graduate in applied analytical chemistry i am not likely to find it very amusing for long.
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Post by steve on Oct 20, 2009 14:37:55 GMT
Let me summarise where I think we are:
My understanding of your position is that you say that the absorptivity of water vapour and water are similar, and very high over the part of the spectrum emitted by the earth, which would mean that infrared transmission through much of the atmosphere is constrained only by levels of water vapour.
I think this is incorrect. There is plenty of information about observations of the 6-13 micron "window" done at the earth's surface in places with normal amounts of water vapour. People have considered it worthwhile to build IR telescopes for this region of the spectrum on mountains that are only 4400 metres high. Yes, for astronomy, higher is better because water vapour apparently has a continuum spectrum in the 6-13 micron band, but 4400 is below half of the atmosphere and is therefore below half of the CO2.
I have for the most part expressed no strong opinions, and have merely put up links to research and books that suggests your opinion is wrong. If you want to be critical, then calculate the precipitable water content of the atmospheres over which the measurements in the paper have been done. I think the amounts are substantially more than the millimetre of water that you think will absorb all relevant IR.
If you persist in thinking that your opinion does not deserve questioning, when it quite clearly differs from the opinion of infrared astronomers, weather observers and climate scientists, then possibly you should have done some post-graduate study and learnt to deal with challenges to your intellect and learning. I am qualified enough not to be impressed by qualifications alone.
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Post by radiant on Oct 20, 2009 17:24:47 GMT
Let me summarise where I think we are: My understanding of your position is that you say that the absorptivity of water vapour and water are similar, and very high over the part of the spectrum emitted by the earth, which would mean that infrared transmission through much of the atmosphere is constrained only by levels of water vapour. I think this is incorrect. There is plenty of information about observations of the 6-13 micron "window" done at the earth's surface in places with normal amounts of water vapour. People have considered it worthwhile to build IR telescopes for this region of the spectrum on mountains that are only 4400 metres high. Yes, for astronomy, higher is better because water vapour apparently has a continuum spectrum in the 6-13 micron band, but 4400 is below half of the atmosphere and is therefore below half of the CO2. I have for the most part expressed no strong opinions, and have merely put up links to research and books that suggests your opinion is wrong. If you want to be critical, then calculate the precipitable water content of the atmospheres over which the measurements in the paper have been done. I think the amounts are substantially more than the millimetre of water that you think will absorb all relevant IR. If you persist in thinking that your opinion does not deserve questioning, when it quite clearly differs from the opinion of infrared astronomers, weather observers and climate scientists, then possibly you should have done some post-graduate study and learnt to deal with challenges to your intellect and learning. I am qualified enough not to be impressed by qualifications alone. My position is that i think tyndalls observations about 97% of emissions of hot water vapour in a flame of almost 6000F being absorbed by 1mm of water at 60F means something about the absorbances of the different states of waters. The following paper i provided shows that humans are still rapidly learning about the spectra of water vapour: bernath.uwaterloo.ca/media/240.pdfThe guy is sponsored by NASA and appears reputable. He says: Water vapour is crucial for the energy balance of the earth.2 Not only is it the most important absorber of out-going thermal radiation (greenhouse gas) but water is responsible for about 70% of the atmospheric absorption of in-coming solar radiation.156 There is a major problem in our understanding of this balance because the calculated average atmospheric absorption is about 25% (25 W m–2) less than observed.156,157 Water is the obvious suspect for this missing absorber. In atmospheric science the line parameters that are collected together in the HITRAN158 and GEISA159 databases are widely used for the computation of atmospheric transmission. It has been suggested that errors in the water line intensities,160,161 missing weak water lines,162 water dimers,163 water continuum164 and clouds165 are all possible contributors to the missing absorber problem. Several groups are re-measuring, extending and improving the water line parameters114–116,166 in the near infrared, visible and near UV. Interestingly, Mlawer et al.167 claim that there is no missing molecular absorber but that aerosol scattering is not quite correct in the atmospheric transmission models (see also Lubin et al.).168 The calculation of atmospheric transmission requires more than just line positions and intensities. Nearly as important are the pressure broadening coefficients due to air, self-broadening coefficients, air-induced line shift parameters and the temperature dependence of the air-broadening parameters. The temperature dependence of the absorption line intensities can be deduced from the known lower state energies and a reliable partition function. Although much data on water has been accumulated, the situation is still far from satisfactory and a number of groups are working on the problem.114–116,166,169,170 This type of measurement is plagued by systematic errors so that large numbers of carefully recorded and analysed spectra by different groups are required. One of the major experimental and theoretical problems in the atmospheric spectroscopy of water is the continuum. When atmospheric infrared spectra are simulated by a collection of lines that are each represented by a Voigt lineshape function (the convolution of a Gaussian from Doppler broadening and a Lorentzian from pressure broadening10) the results are in poor agreement with long path observations.If we go back to the title of the paper we read: The spectroscopy of water vapour: Experiment, theory and applications Tyndall was an experimental scientist who then used what he observed to make guesses Other scientists take the observations of others and their guesses and use maths and theory to construct reality. If you like, it is my Radiant observation versus Kiwis theoretical concepts. Obviously the modelers are theoreticians who rely on people like the author above to build meaningful spectra of the earth. 4000 metres is very high in terms of atmospheric visibility due presumably to water vapour in high concentration at the surface. I was able to observe a volcanic eruption in great detail while at 5500 feet when the volcano was over 200km from me. I was not the first person to spot it but the event was striking even from that huge distance and of course we can see the most distance stars when we look directly upwards but generally we cannot see very far thru the lower earths atmosphere because of atmospheric effects which can be plant vapours or water. When at 22000 feet the mountains at 12000 feet below seem crystal clear. At the surface we judge distances based on the amount of blueness but at altitude there is no obvious blueness even at 200km distance. Tyndall said that humid days were characterised by a bluer sky - i have no idea if that is right but it fits and the guy seemed to be good at observing. The blue mountains near sydney are blue because of gum trees however. The astronomers are up there to avoid water they say. It is a relative thing rather than an absolute thing. When i see evidence of a window or see it written in a spectroscopic paper i will think there is such a thing as an atmospheric window at the surface of the earth in ordinary conditions of humidity. Edit: 1. Bernath link changed as subscription required
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Post by nautonnier on Oct 21, 2009 7:59:33 GMT
And of course while all these treatises on the head of a pin about radiative absorption are interesting it should also not be forgotten that while CO2 happily scatters IR, water absorbs and changes state then rides in the convection past all the aborbption layers until it changes state again and releases the heat. Such convection and state change carries MUCH MORE heat to the tropopause than radiation.
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Post by steve on Oct 21, 2009 8:52:36 GMT
And of course while all these treatises on the head of a pin about radiative absorption are interesting it should also not be forgotten that while CO2 happily scatters IR, water absorbs and changes state then rides in the convection past all the aborbption layers until it changes state again and releases the heat. Such convection and state change carries MUCH MORE heat to the tropopause than radiation. Water doesn't carry much energy to the tropopause. Clouds are the evidence that water vapour has dumped its energy. Since clouds still have a lot of water vapour in and around them, what process is responsible for the further flux of energy towards space? Hmmm...
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