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Post by northsphinx on Jul 15, 2009 20:21:06 GMT
Of course must our planet be in radiation balance. Or just about at least. But the incoming shorter wave radiation is absorbed mainly at the surface and the outgoing long wave is from the ground as well as from higher up in the atmosphere, as from top of clouds. The average greenhouse effect of our atmosphere is about 32 K at the earth surface. Depending on many things. Translate that into height instead. The difference in height between average incoming height of the absorbation level and average height of the outgoing radiation level. That is about 3265 m in dry air with an dry lapse rate of 9,8 K/1000m and about 6530 m in humid air, with wet lapse rate of 4,9 K/1000m. Far from TOA. In fact a very common cloud top altitude. And it is probably much depending on cloud top altitude. Not only but at large very depending on it.
But the radiant balance work from top to bottom of the atmosphere not the other way. People seems to forget that. IF the average clouds tops would be at lower altitude would the temperature of the cloud be higher and radiation would increase until the unbalance is settled. Resulting in a colder surface. If the cloud top rise in altitude will the temperature of the cloud be lower and thereby decrease the outgoing radiation. To balance this will the atmosphere under the cloud became warmer. This is not an issue of temperature at a certain altitude, is is about the altitude where radiation is in balance.
To cool the earth into an ice-age would a low cloud regime do the work. And the opposite. To heat the world would high clouds do the work. As jet contrails.
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Post by nautonnier on Jul 15, 2009 20:23:33 GMT
The idea that you can take a system as complex as the earth's atmosphere, and with a few equations prove anything at all, is to me ludicrous. It's ludicrous to me that you think the earth loses heat by cconvection at the TOA. There is no experimental data that shows that when you add x amount of CO2 to the atmosphere at current concentrations, There is plenty of experimental data which shows the amount of IR transmission/absorption through an atmosphere with varying amounts of CO2. These experiments provide very strong support for the validity of the IR transmission equations. <i> ....Otherwise, IMHO, your theory and equations prove absolutely nothing. </i> It's not my theory or my equations. Perhaps you should take up your complaint with Richard Lindzen or Roy Spencer or Jack Barrett. They all subscribe to the basic theory. If you think they are wrong you need to explain why, but I suspect the problem lies with your understanding. “ It's ludicrous to me that you think the earth loses heat by cconvection at the TOA.”A nice little strawman for you to chortle into your beer about…. I am sure that you don’t think that is what JimG was saying. The convection from the surface carries heat to the tropopause past most of the CO2 in the atmosphere. Not only that of course but the hydrologic cycle ensures that a lot of heat is also carried in the form of latent heat in water state changes, and eventually at or near the tropopause the water gives up more heat as latent heat of fusion and the resultant ice crystals reflect >100wm -2 of INCOMING energy back out to space. This is called a NEGATIVE feedback as it only occurs when the surface is above a certain temperature threshold (SoCold does not believe in these feedbacks). Now you say are they ‘permanent’? Well over here we call this season ‘Hurricane Season’ every year - year in year out June to November, in the Indian continent its called ‘the monsoon’. These severe convective events carry huge amounts of energy from the surface to the tropopause (I can give you citations if you wish but its far far more than you would expect). In some areas of the tropics such as Belize the convective rainfall is so consistent you can ‘set your clock’ by it. These events are thus cyclical with varying periodocities and their strength is proportionate to the surface and atmospheric temperatures. The larger of these of course are the Hadley Cells that cause the tradewinds these together with the convection in the Indian Ocean area and off the coast of the Americas are the initiators for the La Nina and El Nino events that you are so keen on. It is CONVECTION that causes the ENSO and the SOI etc. So You will have to admit there is some effect from CONVECTION on the radiation leaving the TOA. Or then again perhaps you don’t – its so much easier maths to use Stefan Boltzmann and talk about doubling CO2 in the atmosphere and how that is bound to cause a rise in temperature. As JimG states there is NO empirical evidence to support AGW.
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Post by steve on Jul 15, 2009 20:41:00 GMT
Jim, If you increase the amount of CO2 in the atmosphere, then the amount of radiation into space will (all things being equal) reduce. The TOA balance will be lost. That's Myrhe for you. To regain the balance, you have to change the atmosphere so that it radiates more energy into space. If you increased the temperature of the atmosphere, then this would increase the amount of radiation to space. or: If you could reduce the amount of some clouds (the ones that keep heat in) and increase the amounts of others (the ones that reflect away sunlight) you could regain balance without changing the surface temperature much. If you could make the atmosphere drier, you could regain balance without changing the surface temperature much (because you've reduced an important greenhouse gas) If you could increase the amount of ice in mid-latitude and tropical glaciers you could regain balance without changing the surface temperature much (if the ice reflects away more sunlight). And there are many other configurations of the earth which would retain a similar surface temperature while retaining the energy balance after doubling CO2. But which configuration is most likely? "If you increase the amount of CO2 in the atmosphere, then the amount of radiation into space will (all things being equal) reduce. The TOA balance will be lost. That's Myrhe for you."Steve the problem that Jim is pointing out is that all things are NOT equal. Nautonnier, Most of the above was about all the possible things that are not equal, so I don't need you to tell me that. But Jim has never really reflected back the understanding that you can very reasonably calculate the so-called "forcing" from doubling of CO2 prior to then wondering about what the result of that forcing will be. You are getting this wrong. These clouds exist now. They existed in 1750. They will exist in 2100. They will be a negative feedback if their numbers increase as a result of warming. They will be a positive feedback if their numbers decrease as a result of warming. The surface will warm, but so will the rest of the atmosphere, so an increase in convection and an increase in these clouds is not a given. The theory does not have tunnel vision. People are spending their lives studying the potential changes of clouds as a response to warming. You appear to be the one with all the weight on one end of the seesaw by assuming that any feedback will be a negative feedback. I don't think Jim has pointed that out at all. And what else does all this convection carry? More water vapour. What is water vapour? A greenhouse gas. Yes the response should be examined to see if it will restore balance. No there isn't much evidence that it will. [irony]Obviously this extra convection pumping the heat away is what has led to the fact that satellite observations of the tropical mid-troposphere show it warming at a faster rate than at the surface[/irony]
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Post by jimcripwell on Jul 15, 2009 20:51:11 GMT
nautonnier writes "As JimG states there is NO empirical evidence to support AGW."
Thanks for the support. You are absolutely correct. And the same sort of logic goes for conduction. I dont think we can emphasise enough that there is no hard measured experimental data that quantifies how much effect adding CO2 to current levels, has on temperature. One can theorise that it must have some effect, but the key question is how much? We dont know, and without the required experimental data, it is simply not physics to claim that AGW is based in science. It is not. AGW was, is, and always will be (until there is this experimental data), a hypothesis with no science to support it.
A minor point. It is JimC, not JimG.
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Post by glc on Jul 15, 2009 21:53:14 GMT
One can theorise that it must have some effect, but the key question is how much? We dont know, and without the required experimental data, it is simply not physics to claim that AGW is based in science. It is not. AGW was, is, and always will be (until there is this experimental data), a hypothesis with no science to support it.
Jim
The forcing due to changes in CO2 can be calculated to a fair degree of accuracy. Your argument now appears to hinge on the feedback. That, however, is a separate issue. Lindzen and Spencer think it will be low (or negative). Others think it will be high.
Nautonnier
I'm not sure what your argument is. The energy emitted to space from the highest levels of the atmosphere is centred around the 15 micron wavelength, i.e. the CO2 absorption band. That is why we see a funnel in emission spectra plots. This indicates the temperature at which emission occurs. There is very little water vapour at these altitudes. At sea level the mean molecular ratio of H2O to CO2 is ~23. At an altitude of 10Km the ratio is about 0.2.
Northsphinx
The difference in height between average incoming height of the absorbation level and average height of the outgoing radiation level. That is about 3265 m in dry air with an dry lapse rate of 9,8 K/1000m and about 6530 m in humid air, with wet lapse rate of 4,9 K/1000m. Far from TOA.
True. Most of the emittance takes place at the atitudes you mention but not all. CO2 emittance is from much higher in the atmosphere (~220K). Changes in CO2 concentration will alter the radiation balance just as your change in altitude of clouds will.
We know CO2 concentration is increasing. What about the clouds? Do you have some information that I am not aware of. Is there a study which shows that average height of clouds has increased. Is there a mechanism to explain this.
You are right that this will affect global temperatures but so will increased CO2.
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Post by socold on Jul 15, 2009 22:26:43 GMT
I seem to remember a post recently where someone cited decreasing cloud cover in recent decades as a possible explaination for recent warming.
I not sure if the idea that clouds can both explain recent warming and also be a giant net negative feedback is consistant. As far as I can think right now, if they are a large negative feedback then they would have acted to dampen recent warming which rules them out as explaining it.
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Post by glc on Jul 15, 2009 22:44:11 GMT
Northsphinx
Having thought about it a bit more I'm slightly intrigued by your post. Are you just speculating or is there some solid research behind your comments.
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Post by northsphinx on Jul 15, 2009 23:48:43 GMT
....... True. Most of the emittance takes place at the altitudes you mention but not all. CO2 emittance is from much higher in the atmosphere (~220K). Changes in CO2 concentration will alter the radiation balance just as your change in altitude of clouds will.
We know CO2 concentration is increasing. What about the clouds? Do you have some information that I am not aware of. Is there a study which shows that average height of clouds has increased. Is there a mechanism to explain this.
You are right that this will affect global temperatures but so will increased CO2. The net radiance balance have to be the same. The radiation will be from several "sources" where as You state most of it is from lower altitudes than CO2 high altitude. Again: Most of the radiation is from lower altitudes. If the atmosphere is heated in this lower altitudes of any reason will the outgoing radiation outside CO2 band = most of the radiation increase due to higher temperature. The altitude where CO2 emits out in space at 220K is very telling. It is the temperature of the coldest part of the atmosphere. It is the tropopause in the tropics about. In fact top of the clouds in the tropics. It is warmer both under and above this 220K "layer" and also at higher latitudes. what is that telling you? It tells me that the CO2 220K signature is a measurement of the atmospheres coldest temperature. It tells me that the famous CO2 signature is only working in the tropics tropopause. Strange indeed. Especially since there is CO2 in the entire atmosphere. My answer to this is that the CO2 signature are only "visible" behind the water vapor signature if the atmosphere is dry enough. As it is at about 220K. At higher temperatures is water vapor much more efficient and hide the CO2 signature.
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Post by jimcripwell on Jul 16, 2009 0:44:53 GMT
glc writes "The forcing due to changes in CO2 can be calculated to a fair degree of accuracy."
We have been through this before; it is a matter of the English language. What is your definition of "calculated"? So far as I am concerned, "calculate" only applies when you have an exact formula. I can calculate how much money I owe the government at income tax time. So far as any attempt to determine the forcing of CO2, the correct word is "estimate". And you completely misinterpret what my point is. My point is that it is impossible to measure what effect an increase of CO2 from current levels has on temperatures; to get any experimental data. Without such a measurement any estimates from non-validated models, or equations or whatever, are absolutely meaningless. No measurement means no physics. And that means no science. Period.
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Post by glc on Jul 16, 2009 7:50:21 GMT
My point is that it is impossible to measure what effect an increase of CO2 from current levels has on temperatures; to get any experimental data. Then "your point" is wrong. We have experimental data and we have well established physical equations. The experimental data supports the equations and vice versa. Without such a measurement any estimates from non-validated models, or equations or whatever, are absolutely meaningless. What do you mean. The equations are validated. Are you suggesting that Beer-Lambert and Schwarzschild have been dreamt up by someone at NASA. Jim - We can calculate the light absorption in a tube of CO2.
- We can conduct an experiment to show that the calculation is true.
- We can change the concentration of CO2 and repeat the experiment.
- We can repeat the calculations each time and show that the absorption measured is exactly as predicted by the calculation.
- We can apply our calculations to the atmosphere.
- We can use emission spectra viewed from space to measure almost exactly the emission at each wavelength.
- We can use lots of different spectra which consist of varying amounts of water vapour to show that the equations are robust.
We can, therefore, measure to a significant degree of accuracy the amount of absorption that will result from an increase in CO2. At this point we don't care about anything else. The fact that this might change or that might change is irrelevant. That is for later discussion. You are quite definitely not ready for this. You need to start from the beginning, Jim. Look up "Beer Lambert" with particular reference to the measurement of absorption/transmission through an absorbing layer. The Schwarzschild transfer equation is, effectively, just an extension of Beer-Lambert. No measurement means no physics. And that means no science. Period. No comment.
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Post by glc on Jul 16, 2009 8:32:09 GMT
Northsphinx
Re: Your last post (Yesterday at 6:48pm)
I agree with everything you say apart from this bit:
It tells me that the CO2 220K signature is a measurement of the atmospheres coldest temperature. It tells me that the famous CO2 signature is only working in the tropics tropopause. Strange indeed. Especially since there is CO2 in the entire atmosphere.
That's not quite what 'it' [emission spectrum] tells me. All it says to me is that a large proportion of energy in the CO2 band is finally emitted to space at ~220K. It doesn't tell us anything about what was absorbed in the CO2 band at 280K, 260K, etc. Nor does it tell us the amount of energy emitted by water vapour which is later absorbed by CO2. All we actually see is what is finally emitted to space.
Yes - there is some overlap between CO2 and water vapour and I accept more CO2 will not produce a significant increase in absorption at lower altitudes. But, as CO2 increases it will increase the concentration at higher altitudes, which will in turn will increase the average height of the emitting layer which will mean more is being emitted from a colder region of the troposphere (and a warmer region of the stratosphere). The result being the troposphere should warm while the stratosphere cools.
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Post by steve on Jul 16, 2009 9:52:22 GMT
I seem to remember a post recently where someone cited decreasing cloud cover in recent decades as a possible explaination for recent warming. I not sure if the idea that clouds can both explain recent warming and also be a giant net negative feedback is consistant. As far as I can think right now, if they are a large negative feedback then they would have acted to dampen recent warming which rules them out as explaining it. socold, firstly, I think nautonnier's 100W/m^2 figure relating to clouds is about the difference between normal clouds and the difference between no clouds at all. So his figure is not a "forcing" figure in the normal (climate research-speak) definition. But different clouds do have different effects. Tropical cumulous clouds reflect away sunlight. So more of these causes cooling. Low stratus clouds, on the other hand, let in a lot of sunlight and stop heat escaping. More of these, during the day in a warm place, cause warming. But more of these in a cold place at night don't make that much difference. Other convective clouds can have different effects if there is a change of rate of formation when the sun rises - the quicker they form, the more cooling they produce etc. So it's quite complicated.
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Post by jimcripwell on Jul 16, 2009 11:05:49 GMT
glc writes "What do you mean. The equations are validated. Are you suggesting that Beer-Lambert and Schwarzschild have been dreamt up by someone at NASA."
What I am trying to explain to you is why it is useless to try and convince me that AGW has some basis in science. I have often referred to the Kelvin Fallacy. I am sure you know what I am referring to. You can do all the estimates and everything else you like, but until you carry out the actual experiment whereby CO2 from current levels, is added to the atmosphere, and then you measure what the resulting temperature rise is, you have not proved that AGW is real. And this experiment cannot be done.
Please note. I am not arguing that AGW is not a very good hypothesis, with lots of science to support it. What I object to is our politicians spending heaven knows how many dollars on a problem which has not been, and cannot be, proven to exist.
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Post by socold on Jul 16, 2009 12:24:54 GMT
I am reminded of certain Creationists who state they won't accept the Theory of Evolution is science until someone can show a monkey turning into a man in a lab. Anything else they claim is not observational evidence and therefore not science.
They write fossils off because they need "interpretation" to understand them. And apparently "interpretation" is not science.
I suspect it's a deliberate ploy to set the bar so ridiculously high so that they can easily hand wave away any of the evidence.
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Post by northsphinx on Jul 16, 2009 12:47:41 GMT
The CO2 220K signature is very important and is probably the key for understanding the atmosphere greenhouse effect. Which in my view have nothing to do with CO2 levels. The answer of some basic question may help: 1. Why is the CO2 emitting from this temperature or height? 2. Why is it the coldest part of the atmosphere? My answer is based of the same basics as Your but I draw another conclusion. You wrote: "All it says to me is that a large proportion of energy in the CO2 band is finally emitted to space at ~220K. It doesn't tell us anything about what was absorbed in the CO2 band at 280K, 260K, etc. Nor does it tell us the amount of energy emitted by water vapor which is later absorbed by CO2. All we actually see is what is finally emitted to space. " I see it as CO2 band is only measurable when water vapor is not around. Which is my answer for question no 1. The remaining and largest part of the IR signature is H20 close to cloud temperatures. Once again: CO2 signature is only measurable when H20 is not there. That is about 220 K to have dry air which is in the tropical tropopause when dry air stop convection up-wards. In polar region is the tropopause about 230 K, yes warmer, due to the fact that convection do not manage to drive the tropopause higher in altitude. The atmosphere is WARMER higher up. And still not have ANY impact in ordinary Earth radiant balance. That led us to question no 2. Why is it the coldest part of the atmosphere? Because here is the temperature level where H20 is drying out. Without H20 no convection and without convection very low heat-flux. Above is it warmer but still not measurable in CO2 signature because there is no heat-flux by convection. Convection that lift energy with help of water in the atmosphere to a higher altitude but lower temperature. The CO2 signatures show us just the temperature where the atmosphere convection driven by H20 stops. And that is fairly constant because 220 K is the temperature for dry air. More interesting for climate studies may be to measure the altitude of dry air. Not the temperature through CO2 signatures. If the altitude increase will the earth be warmer due to the gas laws. During glacial periods have there been a dry climate compared with today wich probably lowered the dry altitude and by that cooled or maintained a cold regime for thousands of year.
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