Greenhouse Thermodynamics and Water Vapor

Anthony Watts has
uncovered some data
from the NOAA website that appears to show water vapor levels have been decreasing for the last sixty years.

Strangely, a number of recent peer-reviewed publications claim that water vapor is increasing:

Water Vapor Feedback is Rapidly Warming Europe

Elevated surface temperatures due to other greenhouse gases have enhanced water evaporation and contributed to a cycle that stimulates further surface temperature increases, according to a report in Geophysical Research Letters. The research could help to answer a long-debated Earth science question about whether the water cycle could strongly enhance greenhouse warming.

The following paper finds a positive trend but contradicts the findings over Europe.

Trends and variability in column-integrated atmospheric water vapor

The main region where positive trends are not very evident is over Europe, in spite of large and positive trends over the North Atlantic since 1988.

The following also finds positive feedback:

Enhanced positive water vapor feedback associated with tropical deep convection : new evidence from Aura MLS

The moistening of the upper troposphere by deep convection leads to an enhanced positive water vapor feedback, about 3 times that implied solely by thermodynamics.

Is water vapor increasing or decreasing? Is feedback positive or negative? The graph below by Ken Gregory shows a clear decreasing trend at all atmospheric levels.

Water vapor levels are another worrisome variation between the ‘consensus’ view as represented by the IPCC reports and real world data.

The decline in water vapor with an increase in greenhouse gases is one clear prediction of Miskolczi’s theory of semi-transparent atmospheres. In contrast, decline in water vapor is not predicted by the theory of infinity thick atmosphere which maintains that temperatures increase for every incremental increase in greenhouse gases, and in fact the ‘consensus’ is that water vapor increases in a positive feedback loop.

Miskolczi states:

Since the world oceans are virtually unlimited sources and sinks of the
atmospheric water vapor (optical depth), the system – depending on the time
constant of the different energy reservoirs – has many ways to restore the
equilibrium situation and maintain the steady state global climate. For
example, in case the increased CO2 is compensated by reduced H2O, then the
general circulation has to re-adjust itself to maintain the meridional energy
flow with less water vapor available. This could increase the global average
rain rate and speed up the global water cycle resulting in a more dynamical
climate, but still the energy balance equations do not allow the average surface
temperature to rise. The general circulation can not change the global radiative
balance although, changes in the meridional heat transfer may result in local or
zonal warming or cooling which again leads to a more dynamical climate.
Note that there are accumulating evidence of long term negative surface
pressure trends all over the southern hemisphere, (Hines et al., 2000), which
may be an indication of decreasing water vapor amount in the atmosphere.

Miskolczi concludes:

On global scale, however, there can not be any direct water vapor feedback mechanism, working against the total energy balance requirement of the
system. Runaway greenhouse theories contradict to the energy balance
equations and therefore, can not work.

One should not be surprised. It has been proven mathematically that “Most Published Research Findings Are False”.

Update: Anthony Watts posts a followup post containing graphs showing rising specific humidity at the surface, and falling humidity at the higher (greenhouse relevant) altitudes. The obvious questions is why do the esteemed climate scientists above create the impression in their publications that increasing water vapor levels are proof of an increasing greenhouse effect? It’s very worrying.

  • Nick Stokes

    Strangely, a number of recent peer-reviewed publications claim that water vapor is increasing:

    Well, David, those publications got it right. And Miskolczi and Watts got it wrong. Anthony plotted some stratospheric water content figures, and thought they were for the whole atmosphere. At this site you can see the specific humidity at various levels of the atmosphere. At the lower levels (eg 1000 mb), which is where most of the vapor is, it has been increasing. Anthony’s plot was at the 300 mb level, where water is scarce.

  • Nick Stokes

    Strangely, a number of recent peer-reviewed publications claim that water vapor is increasing:

    Well, David, those publications got it right. And Miskolczi and Watts got it wrong. Anthony plotted some stratospheric water content figures, and thought they were for the whole atmosphere. At this site you can see the specific humidity at various levels of the atmosphere. At the lower levels (eg 1000 mb), which is where most of the vapor is, it has been increasing. Anthony’s plot was at the 300 mb level, where water is scarce.

  • http://landshape.org/enm admin

    Thanks for that Nick. I also note that the graph above is relative humidity not specific humidity. Specific humidity is a measure of absolute water vapor, and relative humidity is relative to saturated levels at a given temperature. However the levels water vapor has supposedly increased are very small, and the levels they need to fall globally to compensate for CO2 increases are very small. I wonder about the reliability of observations of this very small effect?

    Another water vapor issue that I wanted to look into the Miskolczi claim that the widely quoted
    K-T model requires water vapor to be much less than its actual level.

    In Kiehl and Trenberth (1997) the USST-76 atmosphere was used for the
    estimation of the clear-sky global mean D E and OLR . To make their
    computed OLR consistent with the ERBE clear-sky observations, they reduced
    the tropospheric water vapor amount by 12%, to about 1.26 prcm.

    Due to the low water vapor column amount in the USST-76 atmosphere
    the clear-sky estimates of the global average Ts , Ed , and Eu are irrealistic.
    The flux transmittance is over estimated by 33% and for example Ed is under
    estimated by about 31 W m-2. The ERBE clear-sky OLR may also have a 6.5%
    positive bias. Although Eqs. (4) and (8) are satisfied, this discrepancy indicates
    that the USST-76 atmosphere does not represent a real radiative equilibrium
    temperature profile and should not be used as a single-column model for global
    energy budget studies.

  • http://landshape.org/enm admin

    Thanks for that Nick. I also note that the graph above is relative humidity not specific humidity. Specific humidity is a measure of absolute water vapor, and relative humidity is relative to saturated levels at a given temperature. However the levels water vapor has supposedly increased are very small, and the levels they need to fall globally to compensate for CO2 increases are very small. I wonder about the reliability of observations of this very small effect?

    Another water vapor issue that I wanted to look into the Miskolczi claim that the widely quoted
    K-T model requires water vapor to be much less than its actual level.

    In Kiehl and Trenberth (1997) the USST-76 atmosphere was used for the
    estimation of the clear-sky global mean D E and OLR . To make their
    computed OLR consistent with the ERBE clear-sky observations, they reduced
    the tropospheric water vapor amount by 12%, to about 1.26 prcm.

    Due to the low water vapor column amount in the USST-76 atmosphere
    the clear-sky estimates of the global average Ts , Ed , and Eu are irrealistic.
    The flux transmittance is over estimated by 33% and for example Ed is under
    estimated by about 31 W m-2. The ERBE clear-sky OLR may also have a 6.5%
    positive bias. Although Eqs. (4) and (8) are satisfied, this discrepancy indicates
    that the USST-76 atmosphere does not represent a real radiative equilibrium
    temperature profile and should not be used as a single-column model for global
    energy budget studies.

  • Jan Pompe

    Nick

    Anthony’s plot was for specific humidity up to 300 mb not at 300mb. At 1000mb for both the results are different as one might expect but relative humidity has also shown a decline in recent years, depending on where you look of course and finally 300 mb is still in the troposphere ~8km.

  • Jan Pompe

    Nick

    Anthony’s plot was for specific humidity up to 300 mb not at 300mb. At 1000mb for both the results are different as one might expect but relative humidity has also shown a decline in recent years, depending on where you look of course and finally 300 mb is still in the troposphere ~8km.

  • kuhnkat
  • kuhnkat
  • Carl W

    Maybe I’m wrong, but I seem to recall Miskolczi writing (or saying) that changes in atmospheric water vapor content to counteract increased CO2 would be too small to be measured.

  • Carl W

    Maybe I’m wrong, but I seem to recall Miskolczi writing (or saying) that changes in atmospheric water vapor content to counteract increased CO2 would be too small to be measured.

  • http://www.friendsofscience.org Ken Gregory

    Dave, it is important to be clear if you are referring to relative or specific humidity. The plot on Anthony Watts blog is of specific humidity at the 300 mb level. (No, it is not “up to 300 mb”)

    Your statement that Anthony’s plot “appears to show water vapor levels have been decreasing for the last sixty years.” isn’t correct as he only shows it decreasing at the 300 mb level. Specific humidity generally has been increasing resulting is a positive water vapor feedback. The authors of the reports you quote falsely believe that the CO2 increase caused the increase in water vapor, but they are wrong. The atmosphere already had an infinite supply of greenhouse gases available in the form of water vapor from the oceans, but took only up a portion of the amount the atmosphere could hold. The relative humidity at 300 mb in only 38%. So adding some man-made CO2 to an infinite supply has almost no effect on the strength of the greenhouse effect. The Sun caused global warming during the 20th century, amplified by a positive water vapor feedback, causing specific humidity to increase at altitudes below 500 mb.

    If there was no change in CO2 concentrations we would expect relative humidity to remain about constant. The increasing CO2 causes relative humidity to fall, especially at the 400 mb and 300 mb level, as this is at the characteristic emission level. Changes of humidity near the surface has little effect on the strength of the greenhouse effect as the high level of water vapor already captures most of the long wave-length radiation. The decreasing relative humidity at 300 and 400 mb due to increasing CO2 levels allows more heat to escape to space, partially offsetting the increase of the greenhouse caused by the Sun.

    In general, the Sun’s increased activity has caused an increase in specific humidity, partially offset by CO2 which causes a decrease in relative humidity.

  • http://www.friendsofscience.org Ken Gregory

    Dave, it is important to be clear if you are referring to relative or specific humidity. The plot on Anthony Watts blog is of specific humidity at the 300 mb level. (No, it is not “up to 300 mb”)

    Your statement that Anthony’s plot “appears to show water vapor levels have been decreasing for the last sixty years.” isn’t correct as he only shows it decreasing at the 300 mb level. Specific humidity generally has been increasing resulting is a positive water vapor feedback. The authors of the reports you quote falsely believe that the CO2 increase caused the increase in water vapor, but they are wrong. The atmosphere already had an infinite supply of greenhouse gases available in the form of water vapor from the oceans, but took only up a portion of the amount the atmosphere could hold. The relative humidity at 300 mb in only 38%. So adding some man-made CO2 to an infinite supply has almost no effect on the strength of the greenhouse effect. The Sun caused global warming during the 20th century, amplified by a positive water vapor feedback, causing specific humidity to increase at altitudes below 500 mb.

    If there was no change in CO2 concentrations we would expect relative humidity to remain about constant. The increasing CO2 causes relative humidity to fall, especially at the 400 mb and 300 mb level, as this is at the characteristic emission level. Changes of humidity near the surface has little effect on the strength of the greenhouse effect as the high level of water vapor already captures most of the long wave-length radiation. The decreasing relative humidity at 300 and 400 mb due to increasing CO2 levels allows more heat to escape to space, partially offsetting the increase of the greenhouse caused by the Sun.

    In general, the Sun’s increased activity has caused an increase in specific humidity, partially offset by CO2 which causes a decrease in relative humidity.

  • kuhnkat

    Ken states:

    “If there was no change in CO2 concentrations we would expect relative humidity to remain about constant.”

    Are you saying that the relative humidity does not change based on air temperature, water temperature, atmospheric pressure, winds, irradiation…?

    Why is the chart labeled “up to 300 mb” (I believe Anthony and his bloggers decided this meant 0-300mb as opposed to 900-300mb) if they didn’t mean it?? Did the NOAA guys make an error??

  • kuhnkat

    Ken states:

    “If there was no change in CO2 concentrations we would expect relative humidity to remain about constant.”

    Are you saying that the relative humidity does not change based on air temperature, water temperature, atmospheric pressure, winds, irradiation…?

    Why is the chart labeled “up to 300 mb” (I believe Anthony and his bloggers decided this meant 0-300mb as opposed to 900-300mb) if they didn’t mean it?? Did the NOAA guys make an error??

  • Nick Stokes

    Kuhnkat asks: “Why is the chart labeled “up to 300 mb”…?”
    The chart originates at this interactive site . If you go there, you’ll see that it allows you to plot any of a large number of datasets, which you choose from a pull-down list. The one Anthony chose is called “Specific Humidity (up to 300 mb only)”, and that is the name that appears on the axis. It’s just part of the system; if you choose “Pressure”, the axis is labelled “Pressure”.

    You also choose a level, and Anthony chose 300 mb. This is not marked on the graph. It should be. Whoever designed it probably thought that you’d know, because you just entered that data. But the graph may have a longer life.

    On relative humidity, there’s a general expectation that it will remain about constant because it reflects a balance between evaporation and precipitation which will continue to exist as temperature increases. Ken Gregory says that GCM models assume that constancy; this isn’t true. They model evaporation and precipitation, and the approximate constancy is an observation, not an assumption.

    For radiative processes, specific humidity is the quantity that matters. It’s equivalent to the ppm of CO2 etc. Relative humidity is only important if phase change is part of trhe process.

  • Nick Stokes

    Kuhnkat asks: “Why is the chart labeled “up to 300 mb”…?”
    The chart originates at this interactive site . If you go there, you’ll see that it allows you to plot any of a large number of datasets, which you choose from a pull-down list. The one Anthony chose is called “Specific Humidity (up to 300 mb only)”, and that is the name that appears on the axis. It’s just part of the system; if you choose “Pressure”, the axis is labelled “Pressure”.

    You also choose a level, and Anthony chose 300 mb. This is not marked on the graph. It should be. Whoever designed it probably thought that you’d know, because you just entered that data. But the graph may have a longer life.

    On relative humidity, there’s a general expectation that it will remain about constant because it reflects a balance between evaporation and precipitation which will continue to exist as temperature increases. Ken Gregory says that GCM models assume that constancy; this isn’t true. They model evaporation and precipitation, and the approximate constancy is an observation, not an assumption.

    For radiative processes, specific humidity is the quantity that matters. It’s equivalent to the ppm of CO2 etc. Relative humidity is only important if phase change is part of trhe process.

  • Anonymous

    Nick, Do you have an explanation for the whats seems to be a significant fall in relative humidity then?

    On relative humidity, there’s a general expectation that it will remain about constant

  • http://landshape.org/enm David Stockwell

    Nick, Do you have an explanation for the whats seems to be a significant fall in relative humidity then?

    On relative humidity, there’s a general expectation that it will remain about constant

  • Jan Pompe

    Nick

    “The one Anthony chose is called “Specific Humidity (up to 300 mb only)”, and that is the name that appears on the axis.” and ” This is not marked on the graph.”

    I think that’s a bug in the system you get the same label, which is the text of the chosen variable, irrespective of the the pressure level chosen. As well as being the label of the y-axis it is on the title where I think it should be showing the level of analysis along with the chosen latitudes and meridians. We can’t tell from the chart itself what the level was. If you put a level

  • Jan Pompe

    Nick

    “The one Anthony chose is called “Specific Humidity (up to 300 mb only)”, and that is the name that appears on the axis.” and ” This is not marked on the graph.”

    I think that’s a bug in the system you get the same label, which is the text of the chosen variable, irrespective of the the pressure level chosen. As well as being the label of the y-axis it is on the title where I think it should be showing the level of analysis along with the chosen latitudes and meridians. We can’t tell from the chart itself what the level was. If you put a level

  • Nick Stokes

    Jan, I completely agree

  • Nick Stokes

    Jan, I completely agree

  • http://www.friendsofscience.org Ken Gregory

    Anthony Watts didn’t create the graph, he just used it. That is why he misinterpreted the “up to 300 mb”. If you read the UPDATE part of his post your will see that based on my comments he agrees that the data is at the 300 mb level.

    I am saying that with global warming from increased Sun activity or lower albedo and constant CO2 concentration, global average relative humidity at each altitude would be constant.

    Nick Stokes says:
    Ken Gregory says that GCM models assume that constancy; this isn’t true. They model evaporation and precipitation, and the approximate constancy is an observation, not an assumption.

    Yes, I agree. I don’t mean to suggest someone types in relative humidity = constant into the computer code. I said in my write-up “Relative humidity = constant (or various parameters to achieve the same effect.) Is this O.K?

    They model evaporation and precipitation to achieve an almost constant relative humidity. This is based on short term observations of temperature changes. During these observations CO2 concentrations are approximately constant, so these observations only hold true over periods when CO2 does not change much. It is invalid to extrapolate these observations to long term periods with increasing CO2. Just MHO! I am not an expert on climate models!

    See http://www.friendsofscience.org/assets/documents/The_Saturated_Greenhouse_Effect.htm

    I added plots to show the predicted hot spot and the radiosonde actual data, rather than assume everyone knows about this.

    BTW, I made the graph used in the lead post long before I saw Anthony’s post.

  • http://www.friendsofscience.org Ken Gregory

    Anthony Watts didn’t create the graph, he just used it. That is why he misinterpreted the “up to 300 mb”. If you read the UPDATE part of his post your will see that based on my comments he agrees that the data is at the 300 mb level.

    I am saying that with global warming from increased Sun activity or lower albedo and constant CO2 concentration, global average relative humidity at each altitude would be constant.

    Nick Stokes says:
    Ken Gregory says that GCM models assume that constancy; this isn’t true. They model evaporation and precipitation, and the approximate constancy is an observation, not an assumption.

    Yes, I agree. I don’t mean to suggest someone types in relative humidity = constant into the computer code. I said in my write-up “Relative humidity = constant (or various parameters to achieve the same effect.) Is this O.K?

    They model evaporation and precipitation to achieve an almost constant relative humidity. This is based on short term observations of temperature changes. During these observations CO2 concentrations are approximately constant, so these observations only hold true over periods when CO2 does not change much. It is invalid to extrapolate these observations to long term periods with increasing CO2. Just MHO! I am not an expert on climate models!

    See http://www.friendsofscience.org/assets/documents/The_Saturated_Greenhouse_Effect.htm

    I added plots to show the predicted hot spot and the radiosonde actual data, rather than assume everyone knows about this.

    BTW, I made the graph used in the lead post long before I saw Anthony’s post.

  • Nick Stokes

    Nick, Do you have an explanation for the whats seems to be a significant fall in relative humidity then?
    David, no, I don’t. Again, I would de-emphasise RH as a measure in the upper atmosphere, because there water is just a gas like any other, and SH is the thing to track. At sea level, RH is fairly steady, as you’d expect, because it reflects air-sea equilibrium. That equilibrium is the basis for expecting RH to be reasonably constant. Since sea-level has been warming, the SH goes up, as observed. So the query really becomes, why is the SH increase at sea level apparently diminishing at higher altitudes, even becoming a decrease at 300 mb?

    I don’t know. The earlier (1950-80) values might be not very accurate. As with all these things, we’re asking a lot of readings that were gathered in another time for a different purpose.

  • Nick Stokes

    Nick, Do you have an explanation for the whats seems to be a significant fall in relative humidity then?
    David, no, I don’t. Again, I would de-emphasise RH as a measure in the upper atmosphere, because there water is just a gas like any other, and SH is the thing to track. At sea level, RH is fairly steady, as you’d expect, because it reflects air-sea equilibrium. That equilibrium is the basis for expecting RH to be reasonably constant. Since sea-level has been warming, the SH goes up, as observed. So the query really becomes, why is the SH increase at sea level apparently diminishing at higher altitudes, even becoming a decrease at 300 mb?

    I don’t know. The earlier (1950-80) values might be not very accurate. As with all these things, we’re asking a lot of readings that were gathered in another time for a different purpose.

  • http://landshape.org/enm admin

    Hi Nick, thanks, taking the time to acknowledge what you don’t know is appreciated, as one could easily ‘move on’ on this media. I would have to check the data and read some of the papers before I came to any position on it, but there are some interesting variations and contradictions in the literature to follow up.

  • http://landshape.org/enm admin

    Hi Nick, thanks, taking the time to acknowledge what you don’t know is appreciated, as one could easily ‘move on’ on this media. I would have to check the data and read some of the papers before I came to any position on it, but there are some interesting variations and contradictions in the literature to follow up.

  • http://landshape.org/enm admin

    Bill Illis (in comments) claims in Anthony Watts posts a followup that:

    It is no wonder than no climate researcher has published a paper using all of this data.

    Is that true?

  • http://landshape.org/enm admin

    Bill Illis (in comments) claims in Anthony Watts posts a followup that:

    It is no wonder than no climate researcher has published a paper using all of this data.

    Is that true?

  • kuhnkat

    Sorry for carrying bogus info. The “up to 300mb” apparently refers to SPECIFIC HUMIDITY MEASUREMENTS BEING AVAILABLE UP TO 300mb for the tool.

    Nick, thank you for the info.

  • kuhnkat

    Sorry for carrying bogus info. The “up to 300mb” apparently refers to SPECIFIC HUMIDITY MEASUREMENTS BEING AVAILABLE UP TO 300mb for the tool.

    Nick, thank you for the info.

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  • Nick Stokes

    David,
    I noted your update. In looking at Anthony’s plots, you need to take note of the vertical axis scales. The range at 1000 mb is .45 gm/kg; at 300 mb it is .045 gm/kg, ten times less. The decrease at high altitudes is much less than the increase at low altitudes.

    Of the esteemed authors you listed, the second, Trenberth et al, does not mention feedback in the abstract, and is mainly concerned to say that the accuracy of this reanalysis data is not high over the oceans. I expect he is right. The third paper is about AURA data.

  • Nick Stokes

    David,
    I noted your update. In looking at Anthony’s plots, you need to take note of the vertical axis scales. The range at 1000 mb is .45 gm/kg; at 300 mb it is .045 gm/kg, ten times less. The decrease at high altitudes is much less than the increase at low altitudes.

    Of the esteemed authors you listed, the second, Trenberth et al, does not mention feedback in the abstract, and is mainly concerned to say that the accuracy of this reanalysis data is not high over the oceans. I expect he is right. The third paper is about AURA data.

  • http://landshape.org/enm admin

    Nick, I am interested in how these various apparently contradictory statements can be reconciled. They are talking about different things explaining some of the variation.

    However, Trenberth states in the abstract that “… is consistent with the assumption of fairly constant relative humidity”. The figure above shows, on the same scale of relative humidity, a strong decline at all levels (except possible the surface).

  • http://landshape.org/enm admin

    Nick, I am interested in how these various apparently contradictory statements can be reconciled. They are talking about different things explaining some of the variation.

    However, Trenberth states in the abstract that “… is consistent with the assumption of fairly constant relative humidity”. The figure above shows, on the same scale of relative humidity, a strong decline at all levels (except possible the surface).

  • Nick Stokes

    Well, David, the first thing is to say again that Trenberth doesn’t have much faith in the older NCEP humidity values over ocean, and he’s presumably using some other data. I think he’s also talking about a more recent period.

    But if you do insist on talking about global RH, you should pay attention to where the water is. If you were to talk about a global figure, you would weight the RH by water amount. So the low level values are more important.

    I don’t think there’s really much for you to get stuck into here. There is a general expectation that the cycle of evaporation and precipitation of water will just scale up as the average vapor pressure rises with temperature, leaving RH fairly constant. But it’s not propounded as a law that is used for prediction. It’s said that GCM’s also predict that RH would be fairly constant. But that is a qualitative description; if you want to falsify something, you’d have to track down the actual GCM numbers, and look carefully at the available data and its quality.

  • Nick Stokes

    Well, David, the first thing is to say again that Trenberth doesn’t have much faith in the older NCEP humidity values over ocean, and he’s presumably using some other data. I think he’s also talking about a more recent period.

    But if you do insist on talking about global RH, you should pay attention to where the water is. If you were to talk about a global figure, you would weight the RH by water amount. So the low level values are more important.

    I don’t think there’s really much for you to get stuck into here. There is a general expectation that the cycle of evaporation and precipitation of water will just scale up as the average vapor pressure rises with temperature, leaving RH fairly constant. But it’s not propounded as a law that is used for prediction. It’s said that GCM’s also predict that RH would be fairly constant. But that is a qualitative description; if you want to falsify something, you’d have to track down the actual GCM numbers, and look carefully at the available data and its quality.

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  • http://landshape.org/enm admin

    Hi Nick, I am only talking about RH because clear statements are made in the abstract that appear contradicted by the data. The assumption of constant RH also seems important, as shown in the IPCC AR4 here

    “In the absence of large changes in relative humidity, the observed warming of the troposphere (see Section 3.4.1) implies that the specific humidity in the upper troposphere should have increased.”

    I am not after falsification. I am not sure that its an achievable goal. My approach is to look at the way evidence is used. As a preliminary observation, there seems to be a pattern in this area of deprecating observations that do not fit the assumptions of GCMs, and RH is a prime example. That is not a falsification in itself, but the inconsistency in the story downgrades the evidence for warming due to enhanced greenhouse effect (EGE) provided by the models, I think.

    Better evidence would be provided if the models had a consistent story between themselves, and with the observations. There are a number of areas where almost all thue models are at variance with the observations, important to evidencing EGE the upper troposphere where temperature and RH contradict them. Of course, models are wrong in lots of ways and you expect refinements. Its a problem though when you draw faulty conclusions as a result.

    But I don’t want to take this OT to GCMs. The LBL codes are also of major importance, particularly in this upper-atmosphere issue.

  • http://landshape.org/enm admin

    Hi Nick, I am only talking about RH because clear statements are made in the abstract that appear contradicted by the data. The assumption of constant RH also seems important, as shown in the IPCC AR4 here

    “In the absence of large changes in relative humidity, the observed warming of the troposphere (see Section 3.4.1) implies that the specific humidity in the upper troposphere should have increased.”

    I am not after falsification. I am not sure that its an achievable goal. My approach is to look at the way evidence is used. As a preliminary observation, there seems to be a pattern in this area of deprecating observations that do not fit the assumptions of GCMs, and RH is a prime example. That is not a falsification in itself, but the inconsistency in the story downgrades the evidence for warming due to enhanced greenhouse effect (EGE) provided by the models, I think.

    Better evidence would be provided if the models had a consistent story between themselves, and with the observations. There are a number of areas where almost all thue models are at variance with the observations, important to evidencing EGE the upper troposphere where temperature and RH contradict them. Of course, models are wrong in lots of ways and you expect refinements. Its a problem though when you draw faulty conclusions as a result.

    But I don’t want to take this OT to GCMs. The LBL codes are also of major importance, particularly in this upper-atmosphere issue.

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  • http://danhughes.auditblogs.com Dan Hughes

    FWIW, Manabe and Wetherald in this paper from 1967 presented and used an empirical correlation for relative humidity (RH). The values are for use in global-average calculations. The approach assigned 0.77 as the RH at the surface.

    If I have correctly evaluated the equation here’s is what I get for relative humidity for several values of pressure.

    Pressure RH
    (mb) (-)
    1013 0.77
    925 0.70
    850 0.64
    800 0.60
    700 0.53
    600 0.45
    400 0.29
    300 0.21
    200 0.14
    100 0.06

    These are eyeball-grade values, I did not bother to interpolate in the table that I built.

    The values are pretty good relative to those in the plot, except at high altitude.

  • http://danhughes.auditblogs.com Dan Hughes

    FWIW, Manabe and Wetherald in this paper from 1967 presented and used an empirical correlation for relative humidity (RH). The values are for use in global-average calculations. The approach assigned 0.77 as the RH at the surface.

    If I have correctly evaluated the equation here’s is what I get for relative humidity for several values of pressure.

    Pressure RH
    (mb) (-)
    1013 0.77
    925 0.70
    850 0.64
    800 0.60
    700 0.53
    600 0.45
    400 0.29
    300 0.21
    200 0.14
    100 0.06

    These are eyeball-grade values, I did not bother to interpolate in the table that I built.

    The values are pretty good relative to those in the plot, except at high altitude.

  • http://danhughes.auditblogs.com Dan Hughes

    re: #24

    I forgot to note that the pressure and temperature distributions in the atmosphere above the surface are based on the usual lapse-rate model with surface temperature = 288.15 K and pressure = 101325.0 Pa.

  • http://danhughes.auditblogs.com Dan Hughes

    re: #24

    I forgot to note that the pressure and temperature distributions in the atmosphere above the surface are based on the usual lapse-rate model with surface temperature = 288.15 K and pressure = 101325.0 Pa.

  • Kyle Littler

    From #18:

    “In looking at Anthony’s plots, you need to take note of the vertical axis scales. The range at 1000 mb is .45 gm/kg; at 300 mb it is .045 gm/kg, ten times less. The decrease at high altitudes is much less than the increase at low altitudes.”

    That’s how it looks at the extremes, but for the range from 700-400 mb the decrease is a bit bigger, and this pressure range corresponds to a much greater altitude range than the region where specific humidity is decreasing. However, since atmospheric density is lower at higher altitudes ( http://www.auf.asn.au/metimages/atmosdensity.gif ), a change in specific humidity at higher altitude corresponds to a smaller change in actual water vapor concentration. With all this in mind, you can’t really tell whether the graphs suggest a net increase or decrease in the total amount of water vapor in the atmosphere just by eyeballing it; somebody would have to take the source data and do some actual number-crunching on it.

  • Kyle Littler

    From #18:

    “In looking at Anthony’s plots, you need to take note of the vertical axis scales. The range at 1000 mb is .45 gm/kg; at 300 mb it is .045 gm/kg, ten times less. The decrease at high altitudes is much less than the increase at low altitudes.”

    That’s how it looks at the extremes, but for the range from 700-400 mb the decrease is a bit bigger, and this pressure range corresponds to a much greater altitude range than the region where specific humidity is decreasing. However, since atmospheric density is lower at higher altitudes ( http://www.auf.asn.au/metimages/atmosdensity.gif ), a change in specific humidity at higher altitude corresponds to a smaller change in actual water vapor concentration. With all this in mind, you can’t really tell whether the graphs suggest a net increase or decrease in the total amount of water vapor in the atmosphere just by eyeballing it; somebody would have to take the source data and do some actual number-crunching on it.

  • http://www.friendsofscience.org Ken Gregory

    I remind you that a change in the amount of water vapor at high altitude is much more important to the greenhouse effect than the same change at low altitude.

    Box 8.1 of 4AR Chapter 8 page 632 states:

    “The radiative effect of absorption by water vapour is roughly proportional to the logarithm of its concentration, so it is the fractional change in water vapour concentration, not the absolute change, that governs its strength as a feedback mechanism. Calculations with GCMs suggest that water vapour remains at an approximately constant fraction of its saturated value (close to unchanged relative humidity (RH)) under global-scale warming (see Section 8.6.3.1). Under such a response, for uniform warming, the largest fractional change in water vapour, and thus the largest contribution to the feedback, occurs in the upper troposphere.”

  • http://www.friendsofscience.org Ken Gregory

    I remind you that a change in the amount of water vapor at high altitude is much more important to the greenhouse effect than the same change at low altitude.

    Box 8.1 of 4AR Chapter 8 page 632 states:

    “The radiative effect of absorption by water vapour is roughly proportional to the logarithm of its concentration, so it is the fractional change in water vapour concentration, not the absolute change, that governs its strength as a feedback mechanism. Calculations with GCMs suggest that water vapour remains at an approximately constant fraction of its saturated value (close to unchanged relative humidity (RH)) under global-scale warming (see Section 8.6.3.1). Under such a response, for uniform warming, the largest fractional change in water vapour, and thus the largest contribution to the feedback, occurs in the upper troposphere.”

  • Franko

    Different special effects create the complexity. Stores heat at the surface, increases air bouyancy, insulation by inversion, rise to form clouds, block in and out, give up heat, dissolve CO2, and rain to the surface.

    Lower humidity, less rain, less CO2 transported from high to surface. Both greenhouse gasses decrease at the top. How does this effect altitude versus temperature ?

  • Franko

    Different special effects create the complexity. Stores heat at the surface, increases air bouyancy, insulation by inversion, rise to form clouds, block in and out, give up heat, dissolve CO2, and rain to the surface.

    Lower humidity, less rain, less CO2 transported from high to surface. Both greenhouse gasses decrease at the top. How does this effect altitude versus temperature ?

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    Who knows where to download XRumer 5.0 Palladium?
    Help, please. All recommend this program to effectively advertise on the Internet, this is the best program!

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