In a new GRL paper, Svensmark et al., claim that liquid water content in low clouds is reduced after Forbush decreases (FD), and for the most influential FD events, the liquid water content in the oceanic atmosphere can diminish by as much as 7%. In particular, they argue that there is a substantial decline in liquid water clouds, apparently tracking a declining flux of galactic cosmic rays (GCR), reaching a minimum days after the drop in GCR levels. The implication would be that GCR can affect climate through modulating the low-level cloudiness. The analysis is based on various remote sensing products.
The hypothesis is this: a rapid reduction in GCR, due to FD, results in reduced ionization of the atmosphere, and hence less cloud drops and liquid water in low clouds. Their analysis of various remote sensing products suggest that the opacitiy (measured in terms of the Angstrom exponent) due to aerosols reaches a minimum ~5 days after FD, and that there is a minimum in the cloud liquid water content (CWC) minimum occurring ~7 days later than the FD. They also observe that the CWC minimum takes place ~4 days after the fine aerosol minimum (the numbers here don’t seem to add up).
The paper is based on a small selection of events and specific choice of events and bandwidths. The paper doesn’t provide any proof that GCR affect the low clouds– at best -, but can at most only give support to this hypothesis. There are still a lot of hurdles that remain before one can call it a proof.
One requirement for successful scientific progress in general, is that new explanations or proposed mechanisms must fit within the big picture, as well as being consistent with other observations. They must also be able to explain other relevant aspects. A thorough understanding of the broader subject is therefore often necessary to put the new pieces in the larger context. It’s typical of non-experts not to place their ideas in the context of the bigger picture.
If we look at the big picture, one immediate question is why it should take days for the alleged minimum in CWC to be visible? The lifetime of clouds is usually thought to be on the order of hours, and it is likely that most of the CWC has precipitated out or re-evaporated within a day after the cloud has formed.
In this context, the FD is supposed to suppress the formation of new cloud condensation nuclei (CCN), and the time lag of the response must reflect the life time of the clouds and the time it takes for new ultra-fine molecule clusters (tiny aerosols) to grow to CCN.
Next question is then, why the process, through which ultra-fine molecule clusters grow by an order of ~1000 to become CCN, takes place over several days while the clouds themselves have a shorter life time?
There is also a recent study in GRL (also a comment on May 1st, 2009 in Science) by Pierce and Adams on modeling CCN, which is directly relevant to Svensmark et al.‘s hypothesis, but not cited in their paper.
Pierce and Adams argue that the theory is not able to explain the growth from tiny molecule clusters to CCN. Thus, the work by Svensmark et al. is not very convincing if they do not discuss these issues, on which their hypothesis hinges, even if the paper by Pierce and Adams was too recent for being included in this paper.
But Svensmark et al. also fail to make reference to another relevant paper by Erlykin et al. (published January 2009), which argues that any effect on climate is more likely to be directly from solar activity rather than GCR, because the variations in GCR lag variations in temperature.
Furthermore, there are two recent papers in the Philosophical Transactions A of the Royal Society, ‘Enhancement of cloud formation by droplet charging‘ and ‘Discrimination between cosmic ray and solar irradiance effects on clouds, and evidence for geophysical modulation of cloud thickness‘, that are relevant for this study. Both support the notion that GCR may affect the cloudiness, but in different aspects to the way Svensmark et al. propose. The first of these studies focuses on time scales on the order of minutes and hours, rather than days. It is difficult to explain how the changes in the current densities taking place minutes to hours after solar storms may have a lasting effect of 4-9 days.
There are many micro-physical processes known to be involved in the low clouds, each affecting the cloud droplet spectra, CWC and the cloud life times. Such processes include collision & coalescence, mixing processes, winds, phase changes, heat transfer (e.g., diffusive and radiative), chemical reactions, precipitation, and effects from temperature. The ambient temperature determines the balance between the amount of liquid water and that of water vapour.
On a more technical side, the paper did not communicate well why 340 nm and 440 nm should the magic numbers for the remote sensing data and the Angstrom exponents, calculated from the Aerosol Robotic Network (AERONET). There are also measurements for other wavelengths, and Svensmark et al. do not explain why these particular choices are best for the type of aerosols they want to study.
For a real effect, one would expect to see a response in the whole chain of the CCN-formation, from the smallest to the largest aerosols. So, what about the particles of other sizes (or different Angstrom exponents) than those Svensmark et al. have examined? Are they affected in the same way, or is there a reason to believe that the particles grow in jumps and spurts?
If one looks long enough at a large set of data, it is often possible to discern patterns just by chance. For instance, ancient scholars thought they found meaningful patterns in the constellations of the stars on the sky. Svensmark et al. selected a smaller number of FDs than Kristjansson et al. (published in 2008) who found no clear effect of GCR on cloudiness.
Also, statistics based on only 26 data points or only 5 events as presented in the paper is bound to involve a great deal of uncertainty, especially in a noisy environment such as the atmosphere. It is important to ask: Could the similarities arise from pure coincidence?
Applying filtering to the data can sometimes bias the results. Svensmark et al. applied a Gaussian smooth with a width of 2 days and max 10 days to reduce fluctuations. But did it reduce the ‘right’ fluctuations? If the aerosols need days to form CCNs and hence clouds, wouldn’t there be an inherent time scale of several days? And is this accounted for in the Monte-Carlo simulations they carried out to investigate the confidence limits? By limiting the minimum to take place in the interval 0-20 days after FD, and defining the base reference to 15 to 5 days before FD, a lot is already given. How sensitive are the results to these choices? The paper does not explore this.
For a claimed ‘FD strength of 100 %’ (whatever that means) the change in cloud fraction was found to be on the order 4% +-2% which, they argue, is ‘slightly larger than the changes observed during a solar cycle’ of ~2%. This is not a very precise statement. And when the FD only is given in percentage, it’s difficult to check the consistency of the numbers. E.g. is there any consistency between the changes in the level of GCR between solar min and max and cloud fraction and during FD? And how does cloud fraction relate with CWC?
Svensmark et al. used the south pole neutron monitor to define the FD, with a cut-off rigidity at 0.06GV that also is sensitive to the low-energy particles from space. Higher energies are necessary for GCR to reach the lower latitudes on Earth, and the flux tends to diminish with higher energy. Hence, the south pole monitor is not necessarily a good indicator for higher-energy GCR that potentially may influence stratiform clouds in the low latitudes.
In their first figure, they show a composite of the 5 strongest FD events. But how robust are these results? Does an inclusion of the 13 strongest FD events or only the 3 leading events alter the picture?
Svensmark et al. claim that the results are statistically significant at the 5%-level, but for the quantitative comparison (their 2nd figure) of effect of the FD magnitude in each of the four data sets studied, it is clear that there is a strong scatter and that the data points do not lie neatly on a line. Thus, it looks as if the statistical test was biased, because the fit is not very impressive.
The GRL paper claims to focus on maritime clouds, but it is reasonable to question if this is true as the air moves some distance in 4-9 days (the time between the FD and the minimum in CWC) due to the winds. This may suggest that the initial ionization probably takes place over other regions than where the CWC minima are located 4—9 days afterward. It would be more convincing if the study accounted for the geographical patterns and the advection by the winds.
Does the width of the minimum peak reveal time scales associated with the clouds? The shape of the minimum suggests that some reduction starts shortly after the FD, which then reaches a minimum after several days. For some data, however, the reduction phase is slower, for others the recovery phase is slower. The width of the minimum is 7-12 days. Do these variations exhibit part of the uncertainty of the analysis, or is there some real information there?
The paper does not discuss the lack of trend in the GCR of moderate energy levels or which role GCR plays for climate change. They have done that before (see previous posts here, here, and here), and it’s wise to leave out statements which do not have scientific support. But it seems they look for ways to back up their older claim, and news report and the press release on their paper make the outrageous claim that GCR have been demonstrated to play an important role in recent global warming.
A recent analysis carried out by myself and Gavin, and published in JGR, compares the response to solar forcing between the GISS GCM (ER) and the observations. Our analysis suggests that the GCM provides a realistic response in terms of the global mean temperature – well within the bounds of uncertainty, as uncertainties are large when applying linear methods to analyse chaotic systems. The model does not include the GCR mechanism, and the general agreement between model and observations therefore is consistent with the effect of GCR on clouds being minor in terms of global warming.
As an aside to this issue, there has been some new developements regarding GCR, galaxy dynamics and our climate (see the commentary environmentalresearchweb.org) – discussed previously here.
Roy Spencer does not agree
http://www.drroyspencer.com/2009/07/new-study-in-science-magazine-proof-of-positive-cloud-feedback/
“Roy Spencer does not agree”
And why does that matter?
He is quite willing to debase the science merely because it clashes with his religious beliefs.
Which leaves it trivially simple for him to do the same if the science goes against his political beliefs.
Re “proof” vs “support for hypothesis”, I cringed with #40 and #42 (with the same disclaimer). But I do understand where it comes from.
As Doug Bostrom noted above (#41), Svensmark has a record of exaggerating in press releases and popularizations the conclusions that can be drawn from his research. An egregious example from his “Cosmoclimatology” article:
By these standards the press release for the recent article is almost restrained, but it does claim the new research “validates 13 years of discoveries that point to a key role for cosmic rays in climate change”. The point in the post, I think, was to point out that this body of work does not amount to the solid theory its author claims.
The Svensmark et al article under discussion does not, I think, so much validate their argument as try to patch a hole in it, a hole left by the absence of significant cloud response to Forbush events in the Slo*an/Wolfendale and (with local exceptions) Kristjánsson et al studies.
Howard S. (#51), Spencer does not agree with what? If you are referring to the Dessler paper referenced in #50 (the only time Spencer’s name has come up in the thread), that’s not the one Spencer discusses in the post you linked to. Read before you paste?
Phil. Felton
8/3 9:17 AM
To “nonsense”:
a) “The amount of moisture in the atmosphere is expected to increase in a warming climate (Trenberth et al., 2005) because saturation vapour pressure increases with temperature according to the Clausius-Clapeyron equation.”
b) “The water vapor feedback was first proposed by Manabe and Wetherald (1971). They noted, using a one-dimensional model, that keeping relative humidity fixed led to a doubling of the response to increasing CO2. The point was that the same relative humidity at a higher temperature meant more water vapor, given the Clausius-Clapeyron Relation. However, the Clausius-Clapeyron Relation refers to the saturation vapor pressure, and the atmosphere is not saturated. Nevertheless, existing models behave as though relative humidity were, indeed, fixed.”
I have left out the attributions, trying for a moment to stay away from the ad homs. Here comes a non-rhetorical question: What are we to make of these competing arguments?
[Response: What competing arguments? – gavin]
Mark, ‘he’s religious therefore’ isn’t a good science argument. Let’s look at the published science, not focus nearsightedly on the people pointing to the science.
Of course the blog headline (” … proof …?”) exaggerates the blog text (“… The authors cautiously speculate that this might be evidence of positive cloud feedback. …”).
But again it’s easy to get distracted.
Ignore the man’s religion, for the moment.
Ignore his semi-pro denial blog, for the moment.
Sure you can attack based on those. But it ain’t science.
Look at the paper in Science first. Spencer does provide a link to the whole paper as published there as a PDF, which lets people like me without journal access read it.
Let’s read it, eh?
Then look for comments by scientists who understand it.
_Then_ blow it all off authoritatively.
Just sayin’. The exercise of going through all the steps in order is a good example to set for the next reader.
Otherwise you sound like you’re dismissing what he’s pointing to because of his religion.
Look! The moon, not the finger pointing at the moon.
I need help with a denier argument. What’s the fallacy here?
Would an atmosphere without greenhouse gases be non-adiabatic? The equation for adiabatic gamma is just g / cp, which wouldn’t be much different in a 100% oxy-nitro atmosphere than it is now. Why wouldn’t a 90-bar nitro-oxy atmosphere on Earth result in a much hotter surface through this mechanism? I know there’s a fallacy here but I can’t put my finger on it. Help!
[Response: It’s putting the cart before the horse. The key constraint is what the emitting temperature is (not dependent on CO2) and at what level it is at (very dependent on CO2). From that you can use the adiabat to estimate what the surface temperature should be (assuming a well-mixed troposphere). For instance, with no greenhouse gases, it doesn’t matter what the mass of the atmosphere is because the surface is the emitting level and thus will be close to the blackbody temperature. – gavin]
Well, let’s all go over there to his site and engage him in healthy scientific debate …
Before doing so, though, can someone tell me what
means?
To: “What competing arguments? – gavin”
“…saturation vapour pressure increases with temperature.”
vs.
“However, the Clausius-Clapeyron Relation refers to the saturation vapor pressure, and the atmosphere is not saturated.”
“Competing” may not be the right word. “Contrasting”, perhaps.
[Response: Both statements are true. I still don’t get your point. – gavin]
“Mark, ‘he’s religious therefore’ isn’t a good science argument”
No, it isn’t.
Which is just as well that I didn’t MAKE that argument, isn’t it.
Try reading it again.
Someone who is willing to set aside the science if if goes against their beliefs is not being a scientist.
“It’s typical of non-experts not to place their ideas in the context of the bigger picture.” You flunk right there. 0/20
> comments closed
It means they’re open elsewhere. The Clement et al. paper has already been much commented on. Have a look:
http://www.google.com/search?q=Clement+Science+cloud+feedback+pacific+2009
There is a rebuttal to your recent paper on solar signature in the temperature record at Pielke Sr:
http://climatesci.org/2009/08/03/nicola-scafetta-comments-on-solar-trends-and-global-warming-by-benestad-and-schmidt/
Would be interested in your comments, there is an invititation for reply
Hank #50
I think Lucia does a good job of explaining how GCM’s can be invalidated during a time period much less than 100 years.
I encourage you to go to the “blackboard” at http://rankexploits.com/musings/ if you are confused on how that can be true.
Thanks
Ed
Walter,
It is true that Clausius-Clapeyron only tells you the maximum saturation pressure allowed, which is why people are so concerned with the constancy of relative humidity. If R.H. is constant, then water vapor increases scale linearly with Clausius-Clapeyron.
BPL, the surface temperature from the greenhouse effect is Ts = Te + (lapse rate)*(emission height). The emission height is not anywhere near 48 km, and it doesn’t even make sense to use the dry adiabat over the whole Earth, or to multiply a value that serves good in the troposphere by the depth of the entire atmosphere.
Chris, thanks.
So, what’s your take on, “Nevertheless, existing models behave as though relative humidity were, indeed, fixed” and the inference that it is not fixed. Is the constancy of relative humidity in the climate well understood in your opinion?
Edward, sorry, Lucia hasn’t convinced people like Tamino who know a lot more about statistics than I do. That’s my criterion, because . As an amateur reader, I’m far too easily fooled if I take stuff on blogs to be reliable. If it’s publishable, it’ll be published, after hard argument.
By the way, the definition of “proof” refers to “validation”, while the definition of “validate” refers to “proof”, the congruence of the words depending on the context of their use.
Read this and see how it scans:
“The paper is based on a small selection of events and specific choice of events and bandwidths. The paper doesn’t provide any validation that GCR affect the low clouds– at best -, but can at most only give support to this hypothesis. There are still a lot of hurdles that remain before one can call it a validation.”
Svensmark claimed that his recent article has validated (proved) his earlier claims, while Rasmus says he has not proved (validated) that. Nothing to cause hyperventilation, surely; the word “proof” was clearly not being used in a mathematical context.
Proof:
http://www.merriam-webster.com/dictionary/proof
Use meaning 1a, 1b or 3.
Walter (# 67),
//”So, what’s your take on, “Nevertheless, existing models behave as though relative humidity were, indeed, fixed” and the inference that it is not fixed. Is the constancy of relative humidity in the climate well understood in your opinion?”//
The constancy of relative humidity is not an assumption, it’s an observation and emergent property in model results (see Soden et al 2002 concerning the Pinatubo response; Soden et al 2005 on satellite observation. Also check the discussion by Dessler and Sherwood 2009 and references therein). Some work suggests very slight declines in R.H. (e.g., Minschwaner et al. 2006, although this analysis is confined to a small area over the whole troposphere and not averaged over a broad layer) but it is not very much to overwhelm the Clausius-Clapeyron influence which makes water vapor feedback both positive and significantly so.
There is now considerable evidence that the water vapor feedback is being assessed pretty much correctly in state-of-the-art AOGCM’s and that observational results are not compatible with a neutral or only slightly positive water vapor feedback. As such, your questions, as stated, are hypothetical.
Have you guys seen the propaganda at ilovemycarbondioxide.com? They get C02 p-chem wrong, they get thermodynamics wrong, they consider C02 w/o considering water vapor, they get the paleoclimate half wrong and they dismiss real experimental data.
Just FYI – one of my trips to Scripps in the past year revealed in discussion that the relative humidity was still around 80%, even though moisture in the atmosphere was increasing. I thought it was interesting.
“Nevertheless, existing models behave as though relative humidity were, indeed, fixed”
Well, mine would be it really doesn’t get all that much different from 80% here in the UK even if it’s raining.
Convective lift will remove water from a moist adiabat. Orographic lift will do the same.
I guess that these effects ensure that humidity never gets close to 100% very long. But then again, there’s a lot of water about on the surface of the earth, so it’s unlikely to get lower than, oh, 30% anywhere either. Not for long, anyway.
re your post in #59, they are not contrasting: as temperature goes up, the available H2O content goes up, but the possible containable H2O content before saturation goes up too.
Hence they do not contrast or compete.
This paper demonstrates an effect on low level clouds due to GCR, whilst it doesnt “prove” anything, it highlights the need for further research. We should be open minded and give the theory credit. Surely if GCR do effect clouds this needs to be incorporated in GCM’s to try and ascertain this impact of this natural effect.
I also note from the IPCC reports that cloud behaviour is an area of great uncertainty in GCM’s and we dont even know the sign of cloud feedbacks (some papers suggest negative, some positive). Hence there is room for everyone to work together here. Its not about predicting large warming and blaming it on man, its about science and understanding the climate correctly and replicating the natural effects correctly, so any anthropogeic influence can be correctly measured.
I note the comment about GISS apparently replicating cloud behaviour reasonably, however, If I recall correctly, that paper also highlighted none of the other models replicated cloud behaviour correctly. So the models are still a long way off being correct in this area. If there was one model that was right, why do we need all the others?
Link to full paper for those interested:
http://docs.google.com/gview?a=v&q=cache:k3yiHsNVc1cJ:www.wzforum.de/forum2/file.php%3F0,file%3D11877
Re #63, Nicola Scafetta has posted here before and has been spoken to by RC, they were less than impressed with the work. Any reason to change that impression I wonder?
[Response: No. Stay tuned. – gavin]
Howard S. writes:
First, google “Clausius-Clapeyron relation.” Then read these:
Brown, S., Desai, S., Keihm, S., and C. Ruf, 2007. “Ocean water vapor and cloud burden trends derived from the topex microwave radiometer.” Geoscience and Remote Sensing Symposium. Barcelona, Spain: IGARSS 2007, pp. 886-889.
Dessler AE, Zhang Z, Yang P 2008. “Water-Vapor Climate Feedback Inferred from Climate Variations.” Geophys. Res. Lett. 35, L20704.
Philipona, R., B. Dürr, A. Ohmura, and C. Ruckstuhl 2005. “Anthropogenic greenhouse forcing and strong water vapor feedback increase temperature in Europe.” Geophys. Res. Lett., 32, L19809.
Santer, B. D, C. Mears, F. J. Wentz, K. E. Taylor, P. J. Gleckler, T. M. L. Wigley, T. P. Barnett, J. S. Boyle, W. Bruggemann, N. P. Gillett, S. A. Klein, G. A. Meehl, T. Nozawa, D. W. Pierce, P. A. Stott, W. M. Washington, M. F. Wehner, 2007. “Identification of human-induced changes in atmospheric moisture content.” Proc. Natl. Acad. Sci., 104, 15248-15253.
Lastly, stop talking about “proof.” Mathematics or formal logic deals in proof, not science. Science is induction, not deduction. It deals in evidence and its findings are always, to some extent, provisional. But when a theory has the vast mass of evidence behind it that AGW has, it becomes perverse to withhold at least provisional assent.
Edward writes:
Lucia used an “IPCC trend” which the IPCC itself didn’t use, used two small a standard deviation, and “proved” a straw man argument was incorrect, using the wrong (inappropriate AR(1)) model to handle autocorrelation in the residuals. It did nothing to “invalidate GCMs.”
Gavin, Chris, thanks. That helps.
But in a 90-bar nitrogen-oxygen atmosphere, what would the temperature be like? I assume the ground (for purposes of argument, let’s assume no clouds and an albedo of 0.306 at the surface) would be at 254 K. But cp for nitro-oxy would still be about 1004 J/K/kg, g would still be 9.80665 m/s^2, and thus the adiabatic lapse rate would still be about 9.8 K/km. Persisting at that level would take the air temperature to absolute zero at an altitude of 26 km in an atmosphere that might be 50 km or so high. Obviously that’s impossible, so the lapse rate must change somewhere, but why? What would it actually be? I’m sorry if I seem obtuse but I’m still not getting something. I need to understand this to argue against this guy’s posts convincingly.
Hank #68
It’s not up to Lucia to convince Tamino, it’s up to the data to support the predictions of the models. It won’t take 100 years to see if the models are “validated”. Recent data does not seem to be matching up with the model predictions.
Barton Paul Levenson
(sorry for my english but your answer is very interesting)
to get the real lapse rate equal to the adiabatic lapse rate, the atmosphere must be stirred.
There must be convection to stir the atmosphere.
And to get convection there must be heat loss in the upper layer of the troposhere.
For such a thing there must be emitted IR towards the space.
And when we speak about IR , we speak automatically about greenhouse effect.
In another way, the greenhouse effect is the traduction of cooling rate of the atmosphere.
This cooling rate participates to the instability of atmosphere which favours convection, and dry adiabatic or moist adiabatic in the case of Earth.
Without cooling rate I think there is a very weak convection.
To resume I think that an 90 bars N2/O2 atmosphere should be very stratified and with a very weak lapse rate.
add to 82
When I said “cooling rate”, I wanted to say “radiative heating rate”.
In the case of greenhouse effect, the term “radiative heating rate” corresponds to a cooling.
Sorry, Edward; Barton sums up the problem. The point is to do work that’s publishable. It’s easy for somebody with a blog to convince others reading the blog that they’ve overthrown contemporary science. But most such claims won’t survive even the low bar of editorial review. Some will! We know it’s easy to get stuff published, somewhere, if not in a good journal then E’n’E.
—-
Anyone looked at this one? The wavelet tools seem to be getting a lot of use; I don’t pretend to understand the analysis.
http://indico.nucleares.unam.mx/getFile.py/access?contribId=1165&sessionId=39&resId=0&materialId=paper&confId=4
“… It seems then that GCR are modulating in some way both the AMO and SST (e.g. Fig. 3), and these in turn modulate in some way hurricanes as it can be seen from the Coherence wavelet analysis (e.g. Figs. 1-2) which confirms the conventional statement of hurricanes to be linked to warmer oceans. This is to a certain extent confirmed by the good coherence between GCR (10Be) and the number of hurricanes of magnitude-4 (Fig. 4). In contrast, the indicator of closed solar magnetic field (via SS) presents, within the COI, a lower and attenuated coherence with the terrestrial phenomena. It should be emphasized that we have put in evidence, for the first time from a Coherence wavelet study, the existence of fluctuations in the flux of GCR in the frequency of 30 ± 2 years, through the study of historical data (10Be). On the other hand ….”
30TH INTERNATIONAL COSMIC RAY CONFERENCE
On the trend of Atlantic Hurricane with Cosmic Rays
Proceedings of the 30th International Cosmic Ray Conference
Rogelio Caballero, Juan Carlos D’Olivo, Gustavo Medina-Tanco,
Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.)
Universidad Nacional Autónoma de México,
Mexico City, Mexico, 2008
Vol. 1 (SH), pages 785–788
I think the short answer is the temperature profile would be that which sustains the air pressure.
After all, if the atmosphere were to cool more than that which maintains the difference, it would collapse and heat up by that constriction.
Just like the pressure of the solar atmosphere.
I suspect such a planet would have wind problems similar to Trenco in the Lensman series…
“The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more, suggesting that an observed absence of warming of this duration is needed to create a discrepancy with the expected present-day warming rate.”
This is from “The State of the Climate 2008” Special Supplement to the “Bulletin of the American Meteorological Society” vol 90 no 8 AUG 2009
This would seem to me the statement that 15 years of no warming would cause the models some statistical problems. I could be reading this wrong of course and perhaps someone can point out where I am making my error.
[Response: Discussed in our last piece about what the IPCC models actually show. – gavin]
> Trenco
Good suggestion!
That’s one Ray Pierrehumbert could add, if he ever extends his article:
Science Fiction Atmospheres. R.T. Pierrehumbert. The University of Chicago. October 11, 2005.
http://geosci.uchicago.edu/~rtp1/papers/BAMS_SFatm.pdf
Barton, you would have a smaller or no lapse rate. It’s convective heat flow that produces (is sustained by) a lapse rate, and when all heat transport from surface to space is radiative, who needs convection? The stratosphere starts from ground level.
//The constancy of relative humidity is not an assumption, it’s an observation and emergent property in model results//
Thanks again, Chris, and would a fair paraphrase be that relative humidity is a strictly observed, macroscopic (regionally varying) property?
Why, then, do I see mention [below] of theoretical understanding and predictions? {I am not trying to contradict you, to be clear, but asking what I imagine to be a naive question.)
“Theoretical and modeling studies predict that relative humidity will remain approximately constant at the global scale as the climate warms.”
“However, observational evidence has been harder to come by, and the effect has been controversial. Much of that controversy can now be laid to rest, thanks to new observations and better theoretical understanding.”
And, perhaps asking too much for one post, do you have any concerns that:
“To date, observational records are too short to pin down the exact size of the water vapor feedback in response to long-term warming from anthropogenic greenhouse gases.”
re #88:
“Barton, you would have a smaller or no lapse rate”
Uhm, isn’t the dry adiabat a result of PV=nRT?
And the moist adiabat a result of condensation of H2O (which would occur for ANY vapour that has a gas transition within the temperature/pressure range in that atmosphere) dumping latent heat into the atmosphere if it is forced to rise without reducing the vapour pressure of its constituents.
And the tropopause is the result of O3-O2 transitions dumping energy. Not the height at which optical depth=1 in the IR. I’m pretty sure that that information is under the “start here” list of items to read up on.
It’s like we have turned back time here… Anyone remember reading this site before??
The effect of IR gas trapping is to make the earth warmer than it would be.
And that warmer earth would have a warmer surface temperature with the adiabat dropping temperature with height because of PV=nRT up until Ozone (or equivalent process) dumped a LOT of energy without needing a lot of material to soak it up as thermal energy, making the tropopause.
Being warmer, the air up until reaching that stasis would be at a greater height, so in so far as that generally warmer air is concerned, the IR trapping makes the atmosphere thicker, but in no significantly different way than the tropopause at the equator is higher than it is at the poles because the air is colder at the poles.
Weather results would be that the nighttime would be MUCH colder than daytime therefore the 500mb height (to give a level) would be much higher on the dayside than the night side.
Since the height difference of the 500mb height is cause for a thermal wind which is attempting to equalise the height of that pressure by moving air into it, you’d get terrible hurricanes.
But you would NOT get no lapse rate. You would have a stratosphere at whatever level the chemistry says UV light gets to dump lots of energy in (which may not happen: if O2 was much less common, there would be no stratosphere because where there is enough O2 to make O3 and absorb UV would happen where the atmosphere is dense enough that there would be no chance of an extra O+ coming along before losing the opportunity).
I *am* digging back to A level physical geography (~20 years old) and the work I’ve done since then to educate myself on what a weather model is modelling, but that’s pretty much what I remember the science being. And some of that is on this site under “start here”.
And Walter, RH at surface level is a common metric recorded. What that section is on about is anybody’s guess. But I would suspect you of quote mining there since it doesn’t match what I know to be true.
“Persisting at that level would take the air temperature to absolute zero at an altitude of 26 km in an atmosphere that might be 50 km or so high.”
BPL, there’s no need to get to absolute zero.
At some density, the gas laws break down: either because the molecular constituents are not point sources at high density, or because the mean free path and collision chances are too remote to make thermalisation a likely proposition (cf the “temperature” of a vacuum tube fluorescent compared with the 4000C “optical temperature” of a white light fluorescent).
So your 26-50km height is impossible but isn’t a feature of such an atmosphere, therefore is moot.
#79 Barton
I’m not clear what you are referring to as “IPCC trend” but Lucia was testing AR4 (not AR1) against the AR4 future projection for this century, she tested by merging the 5 major measurement groups (which Tamino did not to adjust for autocorrelation). Her result was falsification of the AR4 projection of 2C/century for the current decade. I agree with you that this does not “invalidate” CGM’s, however another 6-7 years of data might as Steve C puts it “cause the models some statistical problems”.
See discussion at link:
http://rankexploits.com/musings/2008/erhmm-its-the-ipcc-ar4-projections-that-are-falsified/
Thanks
Edward
How long will it be before this new natural phenomenon of the ocean and atmosphere being irreversibly at thermal equilibrium occurs?
… unless there’s a Yellowstone or Toba (re last part of 92) …
(PS I was not speaking precisely – not to imply that a smaller eruption would not also make a dent, or that 6 to 7 years is the magic number, or that the past decade’s trend is whatever)
Barton–
Your description of what I did is incomplete. I tested various temperature trends individually. (That is, GISSTemp alone, HadCRut alone etc.) Omce the data from individual runs became available, I tested the multi-model mean from the projections against the observations. Here’s a discussion of how long the multi-model mean has been outside the 95% confidence intervals using the method Santer used when rebutting Douglas’s paper on tropospheric tempeature trends.
http://rankexploits.com/musings/2009/model-mean-trend-rejecting-since-2001-for-a-year/
You can feel free to repeat it. All the data are available at the climate explorer.
The issue is not about a single clouds life time, this just distracts from the issue. It’s an effect on the cloud formation process, not a cloud itself. Hence it can have an effect over days, or even years.
If GCR were to allow low level clouds over the equator to form earlier each day (i.e. at lower temperature / humidity to norm), than the effect over time would lead to a reduction in SST and, in turn, a drop in average temperature. If the amount of incoming energy at the equator was reduced over a prolonged period of time, this would of course result in a reduction in global temperatures.
This supports the potential for a valid mechanism, and the solar cycle has been observed in base flows of large river catchments and flood frequency so there is certainly some effect on the climate other than simply changes to TSI, though exactly what effect this has is the key question. I also recall a recent paper that claimed (using climate models) the sun influenced ENSO, PDO etc…
Mark #90: but there would be no convection. An equithermal atmosphere would resist any packet of air from rising very far, even when heated by the ground. The atmosphere would be stable, like in a nighttime inversion. Dominant heat transport mechanisms would be conduction/diffusion, and any residual exchanges with the am-bi-ent radiation field. And that would maintain equithermality at around the black-body temperature.
If your picture were correct, it would produce a “refrigerator planet” ;-)
The ozone stuff doesn’t come in (assuming more than traces of oxygen, questionable as a planet without H2O and CO2 would be sterile) until very high up.
“For a claimed ‘FD strength of 100 %’ (whatever that means)”
The FD strength metric is plainly described in Section 2 of the paper.
#92 Edward :
Lucia did not falsify any projection for this century since this century has barely started. Another 6 or 7 years of data “might” lead to “some statistical problems” but might just as likely not. Time will tell. If it doesn’t, will the projection have been “dis-falsified” according to Lucia’s statistical methodology? Obviously not. “Falsification” on this basis is nonsensical.