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From: Don Klipstein on 8 Dec 2008 00:20 In article <pan.2008.12.02.08.15.18.250571(a)REMOVETHISix.netcom.com>, Bill Ward wrote: >On Tue, 02 Dec 2008 05:28:18 +0000, Don Klipstein wrote: > >> In article <sfaqi41dau09mn1jdb9508t3f2t2hsj9ba(a)4ax.com>, Whata Fool wrote: >>>Eeyore <rabbitsfriendsandrelations(a)hotmail.com> wrote: >>> >>>>bill.sloman(a)ieee.org wrote: >>>>> >>>>> You should note that the infra-red spectra of both carbon dioxide and >>>>> water vapour absorb are line spectra, and the lines aren't all that >>>>> wide (though this does depend on atmopsheric pressure and temperature >>>>> - search on "pressure broadening") and they don't overlap to any great >>>>> extent, which allows both gases to make independent contributions to >>>>> the greenhouse effect. >>> >>> Sloman resumes the AGW discussion of spectra, with no numbers >>>showing flux rates. Water vapor has some pretty wide bands, CO2 much >>>more narrow. >> >> Cite? >> >> Also, CO2 has absorption at wavelengths where water vapor has little to >> none, to an extent giving CO2 9-26% of total "greenhouse gas effect". >> >>>>> There's also the point that the vapour pressure of water in the >>>>> stratosphere is pretty low, because the stratosphere is cold, and >>>>> carbon dioxide does more of the greenhouse work up there than it does >>>>> below the tropopause. >>> >>> Water has a very low boiling point in the stratosphere because >>>the pressure is low, does that make the vapor pressure high or low? >> >> The water vapor pressure in the stratosphere is low due to low >> temperature. >> >>> The stratosphere is cold, so the net energy transfer from the >>>surface to the stratosphere is upward, and the energy transfer to space >>>is great. >> >> Increased presence of greenhouse gases actually cools most of the >> stratosphere. That would increase lapse rate - which would mean a >> negative feedback mechanism. >> However, there are a few positive feedback mechanisms, including >> surface albedo (increases heat reception from the Sun) > >Isn't that related to ice melting? Yes. > Most of the cooling is at low latitudes where there's not much ice. Most of the cooling by vertical convection is at low latitudes, and increase of GHGs will warm the surface less there than elsewhere. Much warming of the tropics will depend on warming elsewhere, since significant cooling of the tropics is achieved by advection to cooler ragions of the world by largely horizontal atmosphere movements and ocean currents. >What other positive feedback mechanisms are you referring to? Surface albedo change by ice melting is a major positive feedback mechanism in parts of the world where there is ice to melt - and there is usually not a lot of convection there. Those parts of the world are cooled mainly by radiation. >> - so lapse rate increase instead raises the altitude of the tropopause. >> (Temperature difference between surface and stratosphere has to >> increase by about 3.5 degrees F in areas of the globe having >> convection to raise the tropopause by a mere 1,000 feet.) > >Another way to look at it is that the estimated 0.7K difference in surface >temperature can be corrected by a 200 foot change in the tropopause. The >tropopause naturally varies from ~30000' at the poles to ~45000' at the >heat equator. > >http://www-das.uwyo.edu/~geerts/cwx/notes/chap01/tropo.html > >It also says: "In other words, cold conditions lead to a lower >tropopause, obviously because of less convection..." > >I would assume the reverse is also true, that warm conditions cause more >convection, which leads to a higher tropopause. That is true. >Perhaps you could explain your comments more clearly by referring to the >graphs and text in the above link. You have made some logical leaps I'm >not sure I follow. >I also ran across the following related link which looks pretty good, >although I've only briefly skimmed it. I'm going to dig a little deeper >into it. > >http://www-das.uwyo.edu/~geerts/cwx/notes/notes.html > <SNIP to point of CO2 achieving 9-26% of GHG effect> >> CO2 has GHG effect in the range of 9-26% of the total GHG effect. > >You keep saying that, but I haven't seen your explanation of how you >derived it. What assumptions did you make, and what mechanisms are >involved? The 9-26% figure is easily obtainable from web searching. One source is the Wiki article on greenhouse gases. The mechanisms are CO2 having IR spectral features where water vapor does not. <SNIP from here> - Don Klipstein (don(a)misty.com)
From: Bill Ward on 8 Dec 2008 00:45 On Sun, 07 Dec 2008 21:02:17 -0500, Whata Fool wrote: > Bill Ward <bward(a)REMOVETHISix.netcom.com> wrote: > >>On Sun, 07 Dec 2008 05:29:26 -0800, bill.sloman wrote: >> >>> On 7 dec, 09:25, Whata Fool <wh...(a)fool.ami> wrote: > [snip] >>>> Apparently atmospheric radiation is a big part of the total >>>> IR radiation flux, and could that mean the atmosphere radiation >>>> controls the temperature, not the surface radiation? >>> >>> Some of the infra-red radiation emitted by the ground and the ocean >>> surfaces goes straight through the atmosphere (when the sky is clear) >>> but the rest is repeatedly emitted and readsorbed by the greenhouse >>> gases as it makes it way up through the amosphere; >> >>Where there is water vapor and clouds, the atmosphere should behave as a >>nearly black body of warm gas and convect accordingly. A steady state >>should be reached where the heat radiated from the top is equal to the >>heat coming into the bottom, else the bottom gas temperature would >>increase and force convection to transport more heat to maintain >>equilibrium. You can't "retain heat" in a gas without raising its >>temperature. >> >>> the height that it has to get to before it gets a clear shot at open >>> space eventually determines the temperature at ground level. >> >>That I agree with. How much CO2 and water respectively have to do with >>that is the question. > > > You should not agree with it, the temperature at ground level can > be all time record world highs in a desert valley, and not because of more > water vapor or CO2, or the temperature can be all time record lows at the > South Pole and not because of less water vapor or CO2. The point I'm agreeing with is that the earth must radiate the same energy it receives from the Sun, as a blackbody at about 255K. If you take a lapse rate downward from the level at which that occurs, you should arrive at the surface temperature. Of course, there are questions regarding the altitude at which that occurs, the lapse rate to use, and the net feedbacks involved. In the presence of an excess of H2O,It still isn't clear to me how anyone can claim 390ppmv of CO2 will significantly affect the surface temperature until those questions are answered. Ice core data shows CO2 following temperature for several hundred thousand years. To me, it seems unlikely that has suddenly reversed. I don't believe climate models as currently implemented have any credibility at all in answering those questions. If anyone has any specific, meaningful explanations, I'd be happy to see them. > In fact, the big changes in temperature occur with wind shift, > and that has very little to do with water vapor or CO2. > > All that can really be said about water vapor and CO2 is that > the atmosphere is cooler because of them, because GHGs cool the > atmosphere. At least in the daytime.
From: Don Klipstein on 8 Dec 2008 02:20 In <pan.2008.12.03.05.51.11.802525(a)REMOVETHISix.netcom.com>,B. Ward wrote: >On Wed, 03 Dec 2008 04:14:23 +0000, Don Klipstein wrote: > >> In <pan.2008.11.26.21.52.54.243812(a)REMOVETHISix.netcom.com>, Bill Ward >> said: >>>On Wed, 26 Nov 2008 07:52:48 -0800, bill.sloman wrote: <I snip to edit for space arbitrarily on level of quotation/citation, without snipping perfectly accurately on basis of degree of quotation> >>>> Don't be silly. I was being rude about the phrase "water and water >>>> vapor IR radiation plus phase change _moderate_ the temperature" which >>>> is total nonsense, as the Venus example demonstrates. >>>> >>>> You also need to apologse for not knowing what you are talking about. >>>> >>>>> Just say how N2 and O2 could cool after daytime heating and >>>>> I will go away. >>>> >>>> They emit and absorb in the infra-red just like water and carbon >>>> dioxide; because they are symmetrical molecules the transitions are >>>> forbidden, but pressure broadening/intermolecular collisions means that >>>> the transitions happen anyway, albeit much less often than with >>>> asymmetrical molecules. >>> >>>I think we need a link for that. It would mean N2 and O2 are GHGs. >> >> I suspect to some extremely slight extent they actually are. > >Can you tell us why you suspect that? Perhaps a link to some data? On that point, I am feeling challenged to find links supporting a contention that N2 and O2 have IR absorption spectrum features having any significance at "earthly temperatures". Considering only global average surface temperature of 288-289 K, a blackbody has spectral power distribution over 1% of peak over wavelengths from about 3.4 um to about 66 um. Going so far as .1% of peak spectral power distribution of a 288 K blackbody, the wavelength range is about 2.95 um to close to 100 um. Source: The "blackbody formula". I have strong doubt that the massive amounts of O2 and N2 in the atmosphere completely lack any infrared spectral features in or shortly outside such a range. <SNIP from here on basis of low level of content to show as quoted less than twice> - Don Klipstein (don(a)misty.com)
From: Bill Ward on 8 Dec 2008 02:58 On Mon, 08 Dec 2008 03:35:34 +0000, Don Klipstein wrote: > In article <pan.2008.11.27.19.50.55.98497(a)REMOVETHISix.netcom.com>, Bill > Ward wrote: > >>On Thu, 27 Nov 2008 07:50:47 -0800, bill.sloman wrote: >> >>> On 27 nov, 06:32, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >>>> On Wed, 26 Nov 2008 17:09:40 -0800, bill.sloman wrote: >>> >>>> > On 26 nov, 22:17, Bill Ward <bw...(a)REMOVETHISix.netcom.com> wrote: >>>> >> On Wed, 26 Nov 2008 07:53:11 -0800, bill.sloman wrote: >>>> >> > On 26 nov, 12:28, Whata Fool <wh...(a)fool.ami> wrote: >>>> >> >> Eeyore <rabbitsfriendsandrelati...(a)hotmail.com> Â wrote: >>>> >>>> >> >> >bill.slo...(a)ieee.org wrote: >>> <snip> >>> >>>> As you put it up thread, "the stratosphere isn't functioning as an >>>> insulator." >>>> >>>> If the stratosphere is transparent, and there is an excess of >>>> convective capacity in the troposphere (driven by the lapse rate), how >>>> can trace amounts of CO2 affect surface temperatures? Â If >>>> convection is sufficient to get latent heat to the tropopause, where >>>> it can radiate from cloud tops, etc, it has a clear shot at 3K deep >>>> space. Â The tropopause is there because it represents the top of >>>> the convective mixing layer. Because of increasing UV heating, the >>>> stratosphere has an inverted lapse rate, which prevents convection. >>>> Â >>> >>> You seem to have set up a straw man by claiming that you can slice the >>> atmosphere into three layers - >>> >>> - the trophosphere where heat transfer is only by convection >>> >>> - a very thin tropopause which does all the radiation >>> >>> - the stratosphere which does nothing >>> >>> which - unsurprisingly - leads you to incorrectly conclude that CO2 can >>> do anything. >> >>Where did I say the radiation all comes from a thin layer? You must be >>misinterpreting the concept of effective radiating altitude. >> >> >>>> >> IR radiated from the surface would be quickly absorbed by WV, >>>> >> clouds, CO2, and other GHGs, and at 500W/m^2 would be overwhelmed >>>> >> by the 10's of kW/m^2 available from convection of latent heat. >>>> >>>> > Clouds scatter infra-red radiation rather than absorbing it. as do >>>> > the greenhouse gases, but that's enough to sustain a thermal >>>> > gradient. >>>> >>>> Surely you're not proposing the lapse rate is sustained by outgoing >>>> IR. All the sources I've seen say the troposphere is due to >>>> convection, not radiation. Â Can you find one to the contrary. >>> >>> Don't have to. Convection and transport as latent heat both decrease >>> rapidly as you move up through the troposphere, and radiation >>> progressively takes over, becoming responsible for 100% of the heat >>> transfer by the time you get to the tropopause. This is clearly implied >>> by what I wrote earlier (which is why I've not snipped it). >> >>So you don't really understand convection or radiation. If you did, you >>might see that radiation could not generate a "thermal gradient". >>Radiation tends to equalize temperatures, you know. It's described by all >>that second law stuff you must have somehow skipped over. > > Radiation alone can generate a thermal gradient. That seems to me to be against the second law. Radiation is only observed to transfer heat from hot to cold. That tends to equalize temperatures, reducing thermal gradients, not generating them. Otherwise, you could simply set up a radiation field which generates a thermal gradient, then run a heat engine off the hot and cold sides, violating conservation of energy. > Suppose the atmosphere completely lacked convexction and advection, > was transparent to solar radiation but had GHGs. > > Solar radiation comes in and heats the surface. The surface radiates > longer wavelength radiation. The longer wavelength radiation from the > surface gets absorbed and re-radiated many times before it gets out of > the atmosphere. Another way of looking at that is that from the surface up, each successive layer radiates to the layer immediately above via the Stephan Boltzman T^4 relationship between emitter and receiver. The downward "reradiation" is basically a virtual effect, because it can never transfer energy from cold to hot. The upper layer absorbs the photon, converts it to heat, then repeats the process to the next layer up, and so on. When you integrate the layers over some vertical distance, you have the transfer function from the surface to that point. All energy going into the system must either emerge from the top, or remain as sensible heat somewhere in the system, subject to convection upward whenever it becomes warmer then the air immediately above it. Energy can't be "trapped". At some level, the air will be at 255K, and that altitude/pressure determines the surface temperature via the lapse rate(s). At least that's the way it looks to me. I think the radiation models are getting all wrapped around the axle because they attempt to account for "downward radiation" that can't actually have any physical effect. Cold objects simply can't transfer heat to hot objects. Entropy must increase. > There needs to be a temperature gradient in order to achieve heat > transport, even in such a "radiation layer". I would expect that gradient to be set by the adiabatic lapse rate due to the pressure variation with altitude. >The Sun actually has such a layer outside the core where heat transport >is by radiation absorbed and re-radiated many times, rather than by >convection. There is a temperature gradient in order for heat transport >to be upward. Any given parcel of gas radiates a little more upward than >it receives from above, and receives a little more from below than it >radiates downward. To me, that looks more complicated than it needs to be. There's hot gas, heated by conduction from beneath, radiating to space. Unless, of course, it's plasma, in which case it doesn't really apply to Earth. >>The lapse rate is set by gas laws. Convection occurs because warm air >>is less dense than cold air, so it rises, expands, and adiabatically >>cools, still maintaining a higher temperature than its surroundings. It >>continues up until it reaches an altitude where the air around it is >>slightly warmer (the lapse rate changes) than its adiabatic temperature, >>where it releases its excess energy and stops, moving the lapse rate >>toward adiabatic. > > Except most of the atmosphere has lapse rate less than adiabatic due > to: > > 1. Radiational cooling of the surface (some radiation from the surface > gets pretty far - ever read the sky with a non contact thermometer?). > > 2. Many areas have lower atmospheric air coming from somewhere else > cooler and/or upper atmospheric air coming from someplace else warmer. All the atmosphere doesn't need to be involved, just enough to maintain the observed cooling. >>If the air rises to its dewpoint temperature, WV condenses, releasing >>latent heat and giving the rising parcel a boost. Go out and watch a >>cumulus cloud and you can see the flat bottom at the condensation >>altitude, and the energetic billowing of the cloud upward from the >>latent heat release. The principle is scalable, that's why thunderstorms >>can billow up well into the stratosphere, yielding the "anvil" shape. > > The top of the anvil is the tropopause. I guess so, by definition, but sometimes they get pretty high: http://blogs.trb.com/news/weather/weblog/wgnweather/2008/07/highest_thunderstorm_tops.html <begin excerpt> In the Chicago area, garden-variety summer thunderstorms develop to heights between 35,000-45,000 feet, but the tops of severe thunderstorms here can approach 60,000 feet and in extreme cases 70,000 feet. The top of the thunderstorm that produced the Plainfield tornado on Aug. 28, 1990, towered to 65,000 feet. The tallest thunderstorms on Earth have been documented in the tropics where tops have been measured to about 75,000 feet, building more than 14 miles up into the atmosphere. <end excerpt> > > Also, most cumulus clouds don't become thunderstorms but stop growing > with their tops in the lower half of the troposphere. There are also > plenty of clouds other than cumulus, much of them formed by air rising > gradually while moving mainly horizontally. Granted, not all clouds have to cool equally. They don't have to if enough are unusually effective. > Sometimes the lapse rate is a close match to the adiabatic lapse rate > (the dry one at altitudes lacking clouds, and the wet one at altitudes > having them). More often it is less. But surface heating will generally tend to increase convection, won't it? >>>> > Convection becomes progressively less potent as air pressure and >>>> > thus density declines with height, and as the partial pressure of >>>> > water vapour declines with decreasing temperature as it climbs up >>>> > through the tropopause, so the amount of energy transferred as >>>> > latent heat falls away with height in the same sort of way. >> >>See above, then consider what happens when an airplane encounters a TS >>at 20000 feet. IR doesn't disassemble aircraft in flight. There's >>plenty of energy in convection, even at altitude. > > Yes, there are little spots where vertical convection causes > considerable release of energy. Most heat transfer throughout the > atmosphere is otherwise - advection and radiation, especially advection. How do we know that, other than Trenberth's precipitation assumption? >>Now why did you try to hide what I was responding to? You should know >>that won't work. >> >><unsnip> >> >>>> At night, convection stops, but cooling is not required at night. >>>> Convection kicks in during the day, when cooling is needed. >>>> >>>> I don't see how radiative cooling is even necessary below the cloud >>>> tops, since there's plenty of cooling capacity from convection. >>> >>> And there's solar energy availalbe to fuel it. >> >><end unsnip> >>> >>>> Exactly. It's a heat engine, with water as the working fluid. It >>>> cools the surface by using solar energy to convect latent heat to the >>>> cloud tops, from which it radiates as a black body to deep space. >>>> Â Cloud shadows are a strong, easily observable negative >>>> temperature feedback, since they cut off surface heating as the >>>> clouds develop. >>>> >>>> >> Once the energy reaches the tropopause, as you imply, it's a >>>> >> pretty straight shot to 3K deep space, since there's not much >>>> >> atmosphere left to absorb IR. >>> >>> 25% of the mass of the atmosphere lies above the tropopause, and 25% >>> of the CO2. There's very little water vapour in the stratosphere - at >>> -55C any water around is ice. >> >>You need to keep your stories straight: >> >>Up thread, on: Wed, 26 Nov 2008 07:53:11 -0800 (PST) >> >>You said: >>"Sure. Most of the mass of the atmosphere - about 90% - is below the >>tropopause. But the stratosphere stretches out quite a long way." >> >>Do you always adjust the facts to match your argument? How do you expect >>to retain any credibility? > > Looks like he did do a bit of research or learning on that matter > recently - although in parts of the world (the tropics) the tropopause > is indeed over almost 90% of the atmosphere. Doesn't most of the surface cooling occur in the tropics? > Elsewhere the tropopause > is lower. In the "middle latitudes" the tropopause is indeed close to > the 250 mb level on average, though varying. How much surface cooling occurs in the mid-latitudes? > Water vapor is mostly in the troposphere Wouldn't that be mostly in the lower troposphere? > whether the stratosphere has > 10% or 25% of the mass of the atmosphere. CO2 in the stratosphere > counts for something, especially in the areas of the world where the > tropopause is lower. > >>>> >> Perhaps it's easier to see if you look at the lapse rate as >>>> >> bounded at the top by the effective radiating temperature, and >>>> >> consider the surface temperatures as derived from that and the >>>> >> adiabatic lapse rate. >>>> >>>> > This approach doesn't make it easy to see how increasing levels of >>>> > greenhouse gases produce more greenhouse warming. >>>> >>>> Correct. Â Now show me how greenhouse warming is supposed to work, >>>> in view of the inconsistencies I've pointed out. >>> >>> This was a pedagogic point. I didn't intend to suggest that CO2 wasn't >>> an effective greenhouse gas, merely that this wasn't a way of looking >>> at what was going on that was helpful in letting you see where the >>> greenhouse effect is going on. >> >>So where is your explanation of how greenhouse warming is supposed to >>work, in view of the inconsistencies I've pointed out? >> >>>> CO2 isn't effective in the troposphere, because radiation is swamped >>>> by the convective transfer required to maintain the lapse rate. >>>> Â CO2 isn't effective in the stratosphere, partly because there's >>>> so little left, and partly because it would actually cool by >>>> radiating IR at the higher stratospheric temperatures. >>>> >>>> So where is the CO2 causing global warming? >>> >>> CO2 is not effective at the bottom of the troposphere, but it becomes >>> progressively more effective as you climb up through the troposphere >>> towards the tropopause. >>> and presumably exerts most of its effect in the upper layers of the >>> troposphere, where - incidentally - there isn't much water vapour >>> left, since it freezes out as the air gets higher and colder. >>> >>>> > Convective heat >>>> > transfer normally stops at the tropopause - though energetic >>>> > thunder- heads can go higher for a while - and slows down a lot >>>> > before it gets to the tropopause, so presumably the greenhouse >>>> > effect is mainly active in the upper layers of the troposphere. >>>> >>>> Which is above most of the atmosphere, and dry, so the postulated >>>> positive feedback from WV also looks highly unlikely. >>> >>> Only if you persist in thinking that everything has to happen in an >>> infinitely thin layer, which isn't a realistic model (which might not >>> matter if it gave the right sort of answer, which it doesn't), nor - >>> more important - a useful model, >> >>First, the thin layer bit is yours - I never even implied it. >> >>Second, apparently you think a model is only useful if it, "(gives) the >>right sort of answer". Yet you continue to prattle on about radiative >>transfer models even though you admit they would only be useful in a >>limited region at the top of the troposphere. > > Or anywhere that the lapse rate is short of adiabatic. There are >plenty of times I have no convection from the ground to air higher up, >and my non-contact thermometer gets a much lower reading for the sky than >it does for the ground. How much surface cooling occurs at your latitude? <snip dead text>
From: Whata Fool on 8 Dec 2008 03:08
don(a)manx.misty.com (Don Klipstein) wrote: >In article <pan.2008.11.29.05.43.32.198332(a)REMOVETHISix.netcom.com>, Bill >Ward wrote in part: [snip] >>Just keep in mind you can't actually heat a hot source from a cold >>target. All you can do is slow the rate of cooling of the hot source. The >>sky is cold, the surface is hot. > > GHGs will slow the cooling by making outgoing radiation from the surface >absorbed at a lower, warmer level, which radiates half its radiation >downward. [snip] > - Don Klipstein (don(a)misty.com) Do you mean "cooling of the surface", meaning the solid or liquid surface rather than the lower atmosphere? If N2 doesn't radiate much in longwave, then any cooling is faster than almost no cooling at all. All the atmospheric radiation physics is interesting, but we have a few men claiming life on Earth could suffer displacement or death if the increased CO2 causes a slower cooling of the lower atmosphere. If there was no radiation cooling of the lower atmosphere without any GHGs at all, is there some mystical way that more GHGs can cause slower cooling than 100 years ago. I am well aware of the temperature records and averaging, but physics works the same way all the time, and with zero GHGs equaling zero cooling, doesn't GHGs mean cooling, and more GHGs mean more cooling, and less GHGs mean less cooling. Statements that are not consistent are confusing. |