Our WUWT thread on Antarctic Sea Ice Losses has spurred quite an interesting discussion. Dr. Robert G. Brown of the Physics Department at Duke University responds to a comment on ice albedo with a summary of water vapor action, the greenhouse effect, and the chaotic nature of the atmosphere. He ends with his view of why he’s not a betting man.
Well worth a read.
phlogiston: I do realise that over the Antarctic land mass albedo from surface snow is anomalously higher than that from cloud, since the snow presents such a pure white surface. However this is probably not the case for sea ice whose surface is more irregular and cracked with patches of dark sea in between.
The trouble is that water vapor is literally a two-edged sword. As vapor, it is the strongest greenhouse gas in the atmosphere by (IIRC) around an order of magnitude, so increasing water vapor can and does measurably increase the GHE — a lot, when considering dry air versus saturated air. In arid deserts, temperatures skyrocket during the day and plummet at night because of the absence of a water vapor driven GHE — CO_2 alone isn’t nearly enough to keep upward facing surfaces from rapidly losing their heat due to radiation. In very humid tropical climates, the nights are consistently warm because of the GHE.
However, water vapor is also the mediating agent for two major cooling mechanisms. One is the bulk transport of latent heat — sunlight and LWIR hit the sea surface and cause rapid evaporation of surface molecules of water. Wind blows over the ocean surface, stripping off water molecules as it goes. This evaporated water has a huge heat content relative to liquid water — the latent heat of vaporization. As the warm water vapor is carried aloft by convection, it carries the heat along with it. It also cools as it rides the adiabatic lapse rate upward, and further cools by radiating its heat content away (some of which returns to the Earth as GHE back radiation). Eventually the partial pressure of water vapor in the moist air becomes saturated relative to the temperature and the dew point is reached, making it comparatively probable that the water vapor will recondense into water. In order to do so, though, several things have to be “just right”. The water vapor has to be able to lose the latent heat of vaporization that it picked up at the water surface when it evaporated. The future water droplets have to be able to nucleate — which is a lot more likely to occur when there are ionic aerosols in the atmosphere as water (a polar molecule) is attracted to bare charge of either sign.
Once a water droplet is nucleated and grows past a critical size (that depends weakly on humidity and temperature) its surface becomes large enough that growth due to increased surface deposition outweighs loss due to surface evaporation, and the droplet stabilizes as a single droplet of condensation in a cloud or continues to grow to fall as rain. Either way the water, now high in the troposphere and hence through most of the optically opaque greenhouse layer, releases heat that is “short circuited” through the greenhouse mechanism and lost to space via radiation.
The cloud, as you note, has a very high albedo. High albedo means that it strongly reflects short-wave (e.g. visible) radiation without ever absorbing it and being heated by it. During the day, clouds outside of the polar regions act as a cooling agent, reflecting sunlight before it has a chance to reach the ground and lower troposphere to warm either one. During the day and the night, however, the cloud also acts as a powerful greenhouse blanket, directly reflecting LWIR as well as visible back down towards the Earth’s surface. In the tropics, daytime reflection wins by a landslide — reducing the incident sunlight by a huge fraction for a large fraction of the day beats the comparatively small modulation of surface radiative losses both day and night. In the temperate zone (again, IIRC) albedo still wins, but by a smaller and smaller margin as one creeps north (and in ways that are increasingly dependent on seasonal weather patterns — in the winter clouds can easily be net warming where in the summer they can be net cooling).
However — and this is key and the reason I’m replying to you — in the polar regions clouds are generally net warming, at least most of the year. You’ve already indicated some of the reasons — the polar regions are already often or permanently ice covered, and the gain in daytime albedo from clouds vs ice is not so great. The real problem, however, is that nighttime warming from the enhanced GHE from clouds scales with the fraction of the day that it is nighttime, and of course inside the arctic circles that can be as long as 100% of it. High albedo doesn’t cool when there is no incident sunlight to reflect, and even in the arctic summer, the sun comes in at a substantial angle so that direct solar warming is weak (so that clouds can reflect only a proportionally smaller amount of heat). A lot of polar temperature is determined by heat transport, not direct heating, explaining the substantial difference in mean temperatures of the North and South poles. In the north, there is substantial heat transport and heat exchange via the ocean; in central Antarctica there is only the atmosphere to carry heat in from the warmer latitudes and it just can’t do the job half as well.
That’s why I hesitated to assign a sign to the net feedback from any sort of local modulation of e.g. ocean-air humidity or sea ice coverage. The processes are COMPLEX and can have either sign, and they are NON-LOCAL as adding humidity in one place can increase albedo someplace else thousands of miles away is it finally concentrates enough to form clouds. A large part of the rain that falls over North Carolina comes up from the Gulf of Mexico maybe 1000 miles away. Some of it comes all the way over from the Pacific, where some of that might have originated in e.g. the growing El Nino. Heat from the tropical Pacific can be transported all the way to NC before it finally releases its heat and falls as rain, before it finally creates clouds that cause NC to cool after helping to greenhouse warm much of the surface area it crossed in between.
This is the kind of thing that the models are supposedly trying to model, but they perforce replace all of the small-length scale detail of this description with presumptive averages over cells 100-300 km square (where weather phenomena such as thunderstorms are order of 1 to 10 km square, where the details of front structure and development are much finer than this). They are excruciatingly tuned to aerosol levels and albedo — they have to be to stabilize anywhere near the correct/observed temperatures and preserve the central tenet that CO_2 causes X amount of baseline warming that is on average augmented by additional water vapor.
This last assumption is finally dying a quiet and well deserved death. AFAIK, it is due to Hansen, who in his original papers predicting disaster assumed universally positive water vapor feedback (and for no particularly scientifically motivated reason that I can see, hypothesized truly absurd levels of water vapor feedback that doubled or tripled the CO_2-only warming of his then very simple models). Naturally, some of the GCMs out there have built into them parametric assumptions that preserve this much “climate sensitivity” — total ACO_2 warming plus feedback, usually at the expense of an overdriven response to e.g. volcanic aerosols necessary to explain periods of global cooling and to keep the model from having a runaway exponential instability (because one has to have a mechanism that keeps positive feedback water vapor from causing increase of water vapor without bound just from FLUCTUATIONS in water vapor content or global temperature — the climate cannot be a biased random walk where every time the temperature goes up a bit, average water vapor increases and hence resets the Earth’s average temperature a bit higher unless a competing process can completely erase the gain when the temperature fluctuates down a bit).
At the moment, estimates of climate sensitivity are struggling to retain any net positive feedback from water vapor in the face of data that already solidly excludes the kind of absurd feedback levels Hansen originally hypothesized. Even the question of net negative feedback from water vapor, long considered to be anathema in climate science (except for a few mavericks who managed to publish papers suggesting that clouds could easily lead to net negative feedback through the dual mechanism of latent heat transport and modulation of albedo) is no longer completely off of the table. I don’t know that people will start to take it too seriously unless/until the Earth actually cools (several tenths of a degree, sustained, not just vary up or down or weakly downward trend) but obviously if this happened it would truly be the only likely catastrophe associated with global warming to all of those that have invested their professional careers, hundreds of billions of dollars of global wealth, and their political and/or scientific reputation on shaky claims in poor agreement (so far) with observational data.
IF there is a super-ENSO, perhaps it will help their arguments survive a bit longer, or perhaps it will truly kick up the temperature to where the models become believable again. Perhaps not. ENSO is not the only factor in climate evolution, and while it has been dominant for the last half century or so in mediating positive jumps as documented by Bob Tisdale, its ability to do so could easily be predicated by the phases and states of the other decadal oscillations, the state of the Sun, the state of baseline vulcanism, the immediate past climate history, and the price of tea in China. A chaotic nonlinear system can be quasiperiodic and apparently causal for a while and then for no computable reason change to an entirely different mode of behavior where a significant quasiparticle/process becomes insignificant and some other process becomes the critical driver. We could still watch as the developing ENSO discharges all that heat in such a way that it never manages to raise global average temperatures by much because of some confounding wave that causes the heat to be efficiently transported up and quickly lost rather than persisting to spread out over the globe at high altitude, or by a mere modulation of the winds that causes albedo over the warm(ing) patch to be higher than expected so that the delivery of solar energy to the ocean is effectively interrupted. It’s not like we can properly predict ENSO (although we can do pretty well with forward projective hindsight once an ENSO process has started).
No matter what, I expect the next year to be highly informative. If we have a super El Nino that heats the planet by 0.3C very rapidly, that certainly makes GCMs more, not less, plausible on average as it kicks global average temperatures at least in the right direction for them not to be as egregiously wrong as they currently appear to be. If it only kicks the temperature up by 0 to 0.1 C, and that only transiently so that temperature in a year are again pretty much flat relative to 1998-2000, it is very bad news for the models. If it fizzles altogether — short-circuited, perhaps, by the downhill side of solar cycle 24 that maybe be beginning and which will proceed with poorly predictable speed and which may or may not have a competitive local effect on the climate and produces no gain at all and cycles immediately into a cooling La Nina that augments any solar cycle cooling to actually drop global average temperatures, that too will be very informative.
Personally, I won’t even place a bet. I don’t think the climate is computable, which means that I think one is basically betting on the output of a (possibly biased) random number generator. I’d rather play Mumbledy-peg for money.
milodonharlani says:
They all take non-radiative effects, such as evaporation and convection and clouds into account.
No…Robert Brown mentioned runaway and Nick replied to explain how a positive water vapor feedback does NOT necessarily lead to runaway. It would only lead to runaway were it sufficiently strong and most people agree that it is not that sufficiently strong
Everyone agrees that clouds are challenging to model and that the biggest sources of uncertainty arise from uncertainties about the cloud feedback. That is not the same thing as the falsehoods that you expressed and continue to express.
Your argument doesn’t even make sense. Nowhere does it say that they don’t include clouds or don’t want to include clouds. The fact is that clouds are challenging for many reasons, but the most important is that there is a many orders of magnitude of length scales involved ranging from nucleation that occurs on length scales of microns to individual clouds that have length scales of, say, tens to thousands of meters, and then GCMs have a resolution considerably coarser than this, so cloud processes must be parametrized.
You are just expressing a bunch of paranoid rubbish that shows you have no clue how scientists work or think. If we were always worried about pleasing our paymasters, we would have gone into a more lucrative field like investment banking. The overwhelming majority of scientists do science because they have a desire to figure out how the world works to the best of their abilities.
A problem can arise when you mix ‘classical’ physics with quantum physics. Thermodynamics, specific heat and latent heat formulae have been derived by measurement and specific values for compounds have been assigned. All of these exclude radiation physics in their calculation. In other words, any radiation physics have been incorporated already to have completely functional real world outputs. Then some ‘bright spark’ starts adding radiation physics on top of what is already incorporated in classical physics. We simply say , with latent heat that a liquid vaporises and the amount of energy to do so = x. When you look at this through ‘quantum physics ‘ eyes you still come up with the same answer but the derivation is completely different. You are then dealing with energy levels and vibrational states etc. etc.. Care should be taken when mixing classical and quantum physics .
Robert Brown says:
Robert, you can’t truly believe this. After all, I think that you’d agree that we can predict the seasonal cycle pretty well. So, the question really becomes what aspects are computable and what are not. (Or, to what degree different aspects are computable.)
So, why do you believe predicting the response of the climate system to an increase in greenhouse gases is completely uncomputable and predicting the response to changes in the distribution of solar insolation (seasonal cycle) is? (I would grant you that the seasonal cycle allows us more rapid verification of our predictions, but does that really make the difference between something being computable or not?)
AlecM says:
And, yet, you can’t seem to find a physicist or a physics textbook that agrees with them, whereas we can provide you with many of both who disagrees with them. Why is this exactly?
Justthinkin said:
“Is the climate computable?
NO.
Next dumb question.”
Well say here is the reason we are told it is computable. If your can model climate you could model the stock market, no one present is trying to model the stock market because they found it was an epic failure years ago and was a waste of money, and that money was private money. They still model climate and it is a total failure and does cost lost of money but is taxpayers money, funny how when it not on your dime stupidity goes on and on of course I cannot blame them it been a profitable con game for the modelers..
a lot, when considering dry air versus saturated air. In arid deserts, temperatures skyrocket during the day and plummet at night because of the absence of a water vapor driven GHE
So when radiation is being supplied by the Sun, things get hotter due to the lack of water vapour as a GHG, but when there is no radiation coming from the Sun, things are hotter (or less cold) due to a radiative effect of water vapor as a GHG. Surely jungles would always be hotter than deserts if water vapor is a GHG, or maybe it is only a part-time GHG?
Maybe the difference between rock/sand versus vegitation/water at the surface is important as is the very high humidity that means we have a significant content of liquid water suspended in the atmosphere as droplets effectively increasing the mass of the atmosphere (atmosphere is “heavy”) although not the pressure.
Well rgb gives us another thought provoker.
Didn’t take long; first post even, for the fat to hit the shin.
Joeldshore gets a gold star today, along with Davidmhoffer, for giving us a short précis of whatever it was that AlecM penned at #1.
Since I am bilingual in English as well as Australian; I was sorely tempted to use my best Australian accent, and thesaurus, to expound my thoughts on AlecM’s highly informative piece.
Thank you Joel, and David for sparing me the need to embarrass the ladies present, with some of the better Aussie utterances, which we Kiwi, also master at an early age.
I generally agree with most of what rgb writes, including this present essay, but I do have some modifying views.
First off, I would point out, that water vapor, in the atmosphere, in daylight hours, absorbs a significant chunk of the near vis / IR in the incoming solar spectrum, longer than 700 nm, so that makes water vapor always a cooling influence, in that this energy then never reaches the surface as solar spectrum energy, which normally would go mostly into the deep ocean. The warming of the atmosphere that results from this, becomes an isotropic LWIR emission, which then does all the things rgb suggests, including some returning to the surface; “back radiation”; despite AlecM sitting there in his rocking chair forbidding it to do so.
A second nitpick, is that clouds only weakly reflect incoming solar energy; maybe 2-5%. It’s more than 2%, which is the normal incidence reflectance of water droplets, but the SW passes right on through the droplet, so you get an incoming, and an outgoing 2% reflectance from two surfaces of the droplet.
Mostly the droplet REFRACTS some 95% of the energy, into a wide angle beam, so two or three random refractions result in an essentially isotropic SCATTERING of that energy. It isn’t reflection; but it has about the same overall effect. So cloud albedo is refractive scattering, and not reflection.
Then there is the snow / ice albedo effect. Despite Kevin Trenberth’s assertion, TSI is about 1366 W/m^2, NOT 342. And with that blowtorch, even high incidence angle attenuated the snow surface readily melts, no matter the air temperature. Then refreezing occurs, and you get a glassy labyrinthine structure that is quite efficient at radiation trapping by total internal reflection.
So the diffuse reflectance of fresh snow quickly deteriorates, once the sun hits it, and instead of 80% “reflectance”, it rapidly gets down to more like 40%, and less. So by the time snow is 72 hours old, it is no longer such a high albedo item; maybe not even as high as ordinary green vegetation. It looks super bright to your eyes, but your eyes have a sophisticated gain control system, that completely disguises, exactly how dull the aged snow has become.
I may take the time to ray trace a spherical water droplet illuminated by a nearly collimated (0.5 deg. divergence) solar beam, using the full Fresnel polarized ray trace equations. You wouldn’t believe what it turns into after just one droplet.
I actually did exactly that, but for the cylindrical case. The question related to what was the best color for a fishing line, or at least the tippet, close to the fly, or lure. The results showed that a pure water clear line in the sun, produced a very bright line focus, that sparkled and flashed underwater, to scare the fish away. An acquaintance, who sits on the bottom of trout streams, breathing from a hose, (minimum bubbles) watching what fish do, actually managed to video those flashing streaks of focused sunlight close to the line, and it completely spooked wild trout. Result is, that a solid black line is far less spooky of fish, than a clear line. The don’t give a hoot about seeing your line; but the flashing lights totally spooks them.
Anyway, another essay to ruminate over Professor.
Many thanks RGB for this very illuminating explanation. You make it clear that climate on earth is all about one thing only – water, in all its phases. The example of an arid desert compared to one with a cloudy sky makes it obvious that water is not merely 2-3 times more effective than CO2 as a greenhouse gas – the difference must be more like 2-3 orders of magnitude.
@davidmhoffer: you wrote this about my arguments:
‘They are no such thing, they are pure bullsh*t, and when two PhD physicists from rather divergent points of view on the larger issues both say the opposite to the drivel you spout, the audience ought pay attention. Your yammering is distracting from the real physics being discussed, it is confusing to new comers to the discussion, and the pathetic whining about pyrgeometers is a regurgitation of the misinformation on the topic spouted by Doug Cotton and the Slayers. They’ve been banned from this forum, and you should be too.’
It’s clear you haven’t the faintest idea how to the counter standard physics so you wrote ‘whining about pyrgeometers’, then muddy the waters by introducing ‘the Slayers’. I never joined them because they too get some physics wrong. It’s easy to prove pyrgeometers measure Irradiance.
Put two, back to back, in zero temperature gradient: net IR signal is zero; it’s the vector sum of opposing Poynting Vectors for CO2 and H2O IR bands. The manufacturers state you need ‘back to back’ devices to measure net IR: http://www.kippzonen.com/Product/16/CGR-3-Pyrgeometer
Take one device away: net output jumps to say 400 W/m^2. Is this a real IR flux when you have just proved the flux at the centre point of the opposing pyrgeometers was zero? No professional makes that mistake The error arose thus: an optical pyrometer is a metal shield with a detector. The shield blocks off the radiation field from the back of the detector so it measures Irradiance in its view angle and, by calibration against a black body, temperature.
C. 50 years ago, a Meteorologist had the bright idea of using the output temperature of an optical pyrometer with an IR filter to give the S-B IR Irradiance. Pyrgeometers are calibrated against a cavity black body’s Irradiance, not a real energy flux. Their output signal is Irradiance.
Do you intend to persist in blustering with no real science? I got my PhD in Applied physics from imperial College a long time ago but I was the year prize winner and have lectured at a top university, so I am prepared to argue my case against all comers. Climate Alchemy must accept standard physics and that they got this bit wrong by copying Meteorology’s mistake.
Is what we DO know about the behaviour of water water cycle enough, it crudely modelled, to account for all global warming of the late 20h century without the actual need for it to be driven by anything other than the climate mechanism itself?
in the Stefan-Boltzmann equation. Finally, the earth is tipped, spinning, and in an eccentric and slowly varying orbit around the sun.
m, and 1 to 100 seconds, respectively. That is, a centimeter to a hundred meters describes things like local wind eddies, local wind gusts. There are a variety of things that happen on meso-scales — it isn’t like gusts of wind are sharply cut off at the length of a football field — with one of the most important ones being the length scales of convection in cumulonimbus (the size and convective scale of thunderstorms) with is 1000 to 10000 meters (1 to 10 km) with times of order 1000 seconds (around 15 minutes). Then one hits the synoptic scale (size of high/low pressure systems) which have lateral length scales of 1000 km and a vertical length scale (clipped) of 10000 meters with time scales of order 100,000 seconds — call it order a day. Finally, there are global, planetary motions — Hadley circulation, zonal streams — that have lateral scales of 10,000 km (basically, the order of the planetary circumference) and vertical scales of — surprise, 10000 meters, and times of 
seconds, call it 100 days.
neglecting drag, and something much, much more difficult to compute from first principles if we include drag (especially if it has an irregular shape) precisely because the Navier-Stokes equation for the drag coupling to an irregular shape is — not computable.
Probably not. As I said, it isn’t just water, it is albedo, it is indeed at least a small effect from CO_2, it is aerosols, it is (possibly) effects due to solar state, it is the thermohaline circulation of the ocean, it is land use changes (if you want anthropogenic climate change mechanisms, this is a big one as cutting down forests and replacing them with cities and parking lots is a major alteration in all sorts of surface properties). A major factor is the decadal oscillations and the quasi-stable circulation of air — anything that increases atmospheric mixing and transport of heat from tropics to the poles has a substantial heating effect because of the
Of course the climate is computeable.
The climate is a collection of long term statistics that we think are relevant to our lives. The amount of rain that will fall over land for example. This number is computeable. I dont even need a gcm to compute it. The question is this.
Is my number reliable enough to INFORM a decision.
Is it exactly computeable? I Dont know I have never seen
A proof that it isnt. Many words but no rigorous proof.
A proof that its not computable a rigorous proof ..well that would be a feat.
Steven, it is hard to know where to begin with this. First of all, the climate models are trying to solve not one, but two coupled Navier-Stokes equations, one for the atmosphere and one for the land. While it is true that there is no proof that the Navier-Stokes equation is in general solvable/computable, there is a Clay Millennium prize for the proof that it is:
http://www.claymath.org/millenium-problems/navier%E2%80%93stokes-equation
because (like the Riemann hypothesis and P=NP?) it’s a hard problem!
It isn’t made any easier by trying to solve it on an absurdly coarse spatiotemporal resolution. The Kolmogorov scale:
http://en.wikipedia.org/wiki/Kolmogorov_microscales
or the length scale where the atmosphere transitions from laminar to turbulent flow is around 3 mm. You should read a few articles on computing turbulent systems with high Reynolds numbers — they openly state that they aren’t, and aren’t likely to ever be, computable at full resolution as the number of grid points required is truly absurdly large, and you need that full grid PER variable being computed in a coupled computation. Then the question is — and if you can answer it, a prestigious prize, fame and fortune await you — whether or not one can solve turbulent problems in anything like a reliable way with a clearly inadequate grid.
In the case of the atmosphere, we actually know some of the length/time scales. The smallest length/time scales are order of
This doesn’t begin to touch the oceanic scales. The thermohaline circulation is almost an order of magnitude larger in (wound up) lateral length, and has a time scale in centuries. Oceanic mixing times also occur on a dazzling array of length/time scales, with seasonal variations and things like ENSO with scales comparable to (but often much slower than) planetary length scales in the atmosphere.
The atmospheric gridding in GCMs is typically order of 100 km laterally, 1 km vertically, and order of a few minutes temporally. With that gridding, computations take an enormous amount of time on the world’s largest piles of computers — it is more or less at our computational capabilities. This gridding cannot compute anything at the small through meso scales. It is blind to gusts, thunderstorms, small eddies, butterfly wing flaps, and good sized weather fronts. Tornadoes never happen in a GCM — they can’t. The big question is whether or not all of the neglected, ignored, approximated, dynamics on all of these smaller scales is important in determining the correct long time evolution of the system. Note well that plenty of these neglected motions are important in transporting energy, and even more important in converting energy from one form to another. The neglected mm scales are key in the damping out of e.g. wind energy into heat, for example — they are (literally) the lengths where diffusion competes with viscosity driven mixing, and thunderstorm dynamics involve the rapid transport and dissipation of a great deal of energy.
If you think all of this dynamics can be neglected in solving the Navier-Stokes equation for a crazy-complex, absolutely enormous system, prove it. Mathematicians consider this to be a difficult problem whose solutions (numerical or otherwise) are little understood and hard/expensive to compute. They can’t even prove that solutions exist in the general case.
Finally, I have no idea what you mean when you say that you don’t even need a GCM to compute (for example) the amount of rainfall that will fall over land. You mean that if I give you a planet with a given pattern of mountains, oceans, orbital pattern atmospheric chemistry, axial tilt, solar state, and past history you can just look at it and tell me how much rainfall will fall on land? If so, well… no, I just gotta say that that’s crazy talk, I can’t even be nice about it. If you mean that we have records and you can look at rainfall patterns in the past and make a statistical extrapolation (a.k.a. — educated guess that the future will be “like” the past) to predict the future, you could be right, you could even arguably probably be right, but — read Taleb’s The Black Swan and learn humility. Besides, this is not computing the climate — any more than observing the time required to fall ten meters a dozen times is “computing” the time required to fall ten meters the thirteenth time when you guess that it will be about the same. Computing the time requires a viable mathematical/computable physical theory, validated by comparing computational results to many more than a dozen experiments, so that we can safely and moderately reliably compute that it should be
I do the following demonstration of this for students. Drop a sheet of printer paper from a height of (say) two meters, held vertically. Try to compute the way it will land, as in solve equations of physics to predict its trajectory. Personally, I don’t think it can be done, because it is impossible to determine or specify the initial conditions sufficiently accurately to make the answer computable. And the spread of possible answers empirically turns out to be nearly useless — it can land “anywhere” in a circle of radius maybe 3 meters. The big question is, is the climate a simpler problem than a dropped sheet of paper?
I don’t think so.
While you are “computing” land rainfall, please hindcast the Great Dust Bowl for me. Explain the Little Ice Age and subsequent global warming — without anthropogenic CO_2. Hindcast the Younger Dryas. Then I’ll believe you when you say “of course it is computable”.
rgb
In mathematics and computer science, chaos and non-computability have precise definitions.
These definitions do not necessarily contain implications of one for the other. See:
http://mulhauser.net/lib/research/tutorials/chaos/
In the context of Brown’s article, a term better than “non-computable” would be “intractable.” An intractable algorithm is computable, but in practice never realizable because of time/space constraints.
@rgbatduke: ‘Sigh. I’ve written so very much about this. So has Roy Spencer. So have all of the physicists who write on the list. Your assertion that back radiation does not exist is sheer nonsense, refuted by experiments as simple as buying an IR thermometer and pointing it up, refuted in spectroscopic detail by pointing an actual spectrograph up. If you want to see spectrographs provided by Ira Glickstein from various sources on WUWT, look here:….’
Sorry, an IR spectrometer measures the IR Irradiance in its view angle. This will vary with wavenumber but for the self-absorbed GHG bands, the amplitude is the black body level for the emission temperature. This is standard physics.
Turn the pyrometer upside down so it measures the signal from the Earth’s surface. It will measure the black body ‘bell curve’. This is standard physics.
Now do a line by line subtraction of the atmospheric signal from the surface signal. the difference spectrum is the real, net IR flux vs wavenumber. This is standard physics.
To claim as in the Trenberth Energy Budget that the atmospheric Irradiance adds to the real surfce net IR flux to make the black body surface Irradiance a real, net energy flux is not standard physics. it is to make a false assumption dating back to Arrhenius via Sagan.
It’s interesting to work out why Sagan made his mistake: he got the cloud physics for Venus wrong; ~80% of the SW energy backscatters in the top of the atmosphere so he overestimated SW penetration to the base by about 7x in his two-stream calculation.
Sorry, but you do no faze me on this. iI got my PhD at Imperial College and was first in my year. i’ve made pyrometers and spectrometers for on-line use. I do know my stuff! So do the people who make pyrgeometers: http://www.kippzonen.com/Product/16/CGR-3-Pyrgeometer
Scroll to the bottom and look at the back to back pyrgeometer which measures net IR flux!
AlecM says:
May 21, 2014 at 9:58 pm
>>>>>>>>>>>>>>>>>>>.
Anthony
The first time I ran into Doug Cotton on the web, I had no idea who he was and got into a full fledged argument with him. I soon discovered I was arguing with someone who just made up their own brand of physics and proclaimed it to be standard while failing to provide a single reference to any text book that supported his idiocy. I haven’t the time or patience to rebut this complete bullsh*t at the moment, I’ll leave it to Joel Shore and RGB who have both put him in his place already though he appears to not understand that’s what has happened.
That said, his latest tirade is, to the best of my recollection, verbatim Doug Cotton. I suspect AlecM is either Doug Cotton, or simply a misguided acolyte cutting and pasting from Doug Cotton’s drivel.
As always, your blog, your rules, but you know my opinion on this stupidity.
REPLY: Yes, I’ve considered that this is just another one of the dozen or so identities that Doug Cotton inhabits on his mission from clods, er slayers. But this comment is coming from the UK, not Australia. Might be John O’Sullivan under one of his sock puppet identities. Who knows? They are mostly interchangeable, language wise.
But problem solved by application of some off-topic troll slayer spray – Anthony
@joeldshore; you apparently assert standard physics claims an Irradiance is a real net energy flux. Where is that claim? Be very careful in your answer because every physics and engineering textbook states specifically that to predict net IR flux from a warmer to a cooler body, you use the difference of two S-B equations, corrected for emissivity, absorptivity and view angle.
The problem arises because units of irradiance and net flux are the same. However, the former is the implied energy flux to a sink at Absolute Zero. You prove this very easily. Imagine a single flat plate with an insulated back at a set temperature in a vacuum, close to and parallel to a second plate with insulated back at Absolute Zero. The heating power needed to keep the temperature of the first plate constant is its single S-B Irradiance, as is the cooling power for the second plate.
Now make both plates the same temperature; power input for each will fall to zero. Why? The net radiation field comprises standing monochromatic waves with zero (on average) Poynting Vectors. If there is a temperature difference, the standing waves have the amplitude of the cooler body and superimposed is a travelling wave with PVs equal to the difference between the source PVs.
Sorry, but I am simply stating standard physics and you can check it against any good textbook or engineering manual. The best primer is Chapter 3 of Perry’s Chemical Engineering Handbook, co-written by Hoyt. C. Hottell who first made real GHG emissivity measurements. Engineers like me have to get the sums right. Climate Alchemists apparently don’t…….:o)
AlecM;
Engineers like me have to get the sums right.
>>>>>>>>>>>>>>
Wow. Just a couple of comments upthread you were claiming to be a physicist. Top of your class. Now suddenly you are an engineer. Make up your mind.
@davidmhoffer: my bachelor’s degree is in engineering, my PhD is in applied physics. I do both and I have lectured in both. No-one of my generation accepts the claim that Irradiance is a net energy flux except to a sink at absolute zero.
“Thermodynamics, specific heat and latent heat formulae have been derived by measurement and specific values for compounds have been assigned. All of these exclude radiation physics in their calculation. In other words, any radiation physics have been incorporated already to have completely functional real world outputs. ”
This is true. The reason it works is that the microscopic details do not matter so much in such cases. It doesn’t matter if a particle itself travels from one part of the system to the other, carrying energy directly, then it collides with another one transferring a part of it (or even if it doesn’t do that), or instead, it uses some intermediary to do that, or an entire chain of intermediaries (can be another particle or why not, a photon in the IR spectrum – anyway, they do not collide like billiard balls, if you get the hint).
Particles that are identical can lead to some things that are not so intuitive. People like to label things. It’s not always a good way of thinking.
If you get compatible microstates, do the microscopic details matter from the macroscopic point of view? Nope.
“No-one of my generation accepts the claim that Irradiance is a net energy flux except to a sink at absolute zero.”
Why would anybody accept such a thing? Indeed, the pseudo science tries to fool people with the radiation going up and down and then again up and down and up and down… 🙂
What actually matters is the net value.
And this reminds me of this: http://www.drroyspencer.com/2010/08/help-back-radiation-has-invaded-my-backyard/
He somehow thinks that by measuring the sky temperature (which in fact is not a temperature, radiation originates from different points of the atmosphere, at different temperatures, and more, it doesn’t even have the black body spectrum, it’s quite different from it – by measuring a system which is not in thermal equilibrium one cannot claim he measures ‘a temperature’). Somehow he thinks that by showing different pseudo temperatures at different heights, he shows ‘greenhouse effect’. And if you look too much for confirmation rather than refutation, all you cherry pick is things that (appear to) confirm your preconceptions.
Let’s see what he has there: “My car thermometer was showing virtually no change.”
From this paragraph: “What was amazing was that driving down in elevation from my house caused the sky temperature reading to increase by about 3 deg. F for a 300 foot drop in elevation. My car thermometer was showing virtually no change. This pattern was repeated as I went up and down hills.”
It’s funny how some see a confirmation in something that is actually a refutation. The greenhouse effect is supposed to increase the temperature, isn’t it?
Let me state it clear: I’m not thinking that the pseudo-greenhouse effect is not real. It’s just not as described by the pseudo-science. The CO2 effect is lower than in the religion.
A nice exposition of the role of water and water vapor.
Just one point about something I have noticed before in climate-related discussion of condensation nuclei.
Practically all discussion I have seen focus on phase change of H2O from gas to liquid and liquid to gas as well as from liquid to solid and vice versa. But we know that phase change is possible directly from the solid to the gas (ablation) and gas to solid (sublimation).
The ice cap on Mt Kilimanjaro is periodically much reduce by ablation. The same can happen on the surface of continental glaciers.
What role does sublimation have at the top of the troposphere or lower stratosphed–phase change from gas to solid? Is a nucleus needed as Svensmark’s theory seems to require? Or can sublimation occur and then be followed by phase change from solid to liquid?
The process would be: water vapor to ice crystal to water droplet with no nucleating particle needed.
@Somebody: the Spencer cheap IR thermometer works by having an uncooled photoresistor which is exposed to a focused 8 to 14 micron band filter, ‘atmospheric window’, IR. This reduces the effect of relative humidity on the signal.
The device may work by measuring current for constant potential difference across the resistor or there may be a constant current source and voltage derived. This signal is then compared via a look up table to a black body calibrated signal and the temperature for best fit is then output in deg C or F. More expensive versions have an emissivity adjustment. they are designed to look at plane faced sources, e.g. walls.
Point it to the sky and because the IR signal is from non self-absorbed minor gases, its emission depth is quite large, perhaps 100s of meters, and that gives substantial cooling from lapse rate; c. 6.5 K/km. So, the surface of the sensor cools because net IR flux goes from it to the sky. The device was never calibrated for that use. Go higher and it measures a lower ‘temperature’ because the temperature difference, photoresistor to sky, is greater.
This is no quantitative evidence of ‘back radiation’, just that there is a net IR flux sensor to sky.
I’ve seen AlecM’s comments on a few blogs recently. As a lurking layperson I must say he argues with authority. If his claims re his credentials are true one would have to assume he bases his arguments on *some* level of knowledge, but it’s hard for me to know how much. His critics do much nay-saying but little actual criticism of the points he makes. I’d be interested in seeing a guest post by him discussing EXACTLY what he claims with solid arguments addressing his points… That way he can make his best argument and his critics can demonstrate clearly why he is wrong – if he is. Or else can someone address exactly what he says rather than the usual somewhat broad dismissals.
george e smith
“Then there is the snow / ice albedo effect. Despite Kevin Trenberth’s assertion, TSI is about 1366 W/m^2, NOT 342. And with that blowtorch, even high incidence angle attenuated the snow surface readily melts, no matter the air temperature. Then refreezing occurs, and you get a glassy labyrinthine structure that is quite efficient at radiation trapping by total internal reflection.”
That may be true in the US, which is after all almost all closer to the Equator than the pole. It is emphatically not true at higher latitudes, where the snow will stay loose for weeks or months. The surface melting you describe only happens when the temperature rises above zero or very late in winter when the sun is relatively high in the sky. Incidentally in Swedish which has almost as many words for snow as Inuit has special words for both these phenomena: “skarsnö” and “dagsmeja” respectively. If it always happened we wouldn’t need special words to describe when it does, would we?
Don’t we need to rethink all these feedbacks that climate science is based on. Don’t we need to start measuring them to see if they are accurate.
Water vapor is estimated to increase by 7.0% per 1.0K increase caused by GHGs initially. The Classius Clapyeron relation.
Clouds are supposed to decline by 3.3% per 1.0K increase caused by GHGs initially.
Okay stop right there. Water vapor up, clouds down. Some fancy atmospheric effects have to occur to get that to happen. I imagine, climate science can imagine this but it does seem illogical.
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Next, water vapor is only increasing by about 2.4%/K compared to surface temperatures, 4.5%/K compared to the lower troposphere temps and 3.7%/K compared to sea surface temperatures alone. Okay, Classius Clapyeron is not accurate.
Cut water vapor feedback down to 2.4%/K rather than 7.0%/K and CO2 sensitivity falls to 1.5C per doubling.
Clouds? According to the CERES data, the change in Earth’s energy imbalance is exactly the same number as the Net Cloud energy imbalance. Clouds run the whole climate according to CERES. There is no real trend in the numbers. Furthermore, the opposite impact should have felt in the ice ages. Clouds should have increased considerably at the same time that temps fell by 5.0C. Hansen did not build this into his climate model simulation of the ice ages so that makes him a fake.
Change cloud to Zero feedback and water vapor to 2.4%/K and the CO2 sensitivity is only 1.2C per doubling.
Does that sound about right?
That is very close to where real temperatures are tracking compared to GHG forcing.
I’ll simply add one more time (not in this thread, but the umpty-zillionth time for this list) that all of the comments about “sky radiation” (a “sky dragon slayer” tag line) come from a cosmically naive misconception of the way the GHE works.
Look, guys, if you are at all serious about learning this (as opposed to ranting about it and sounding astoundingly ignorant even as you inflate your sense of self-importance) beg, borrow, steal, copy, obtain from pirate bay, check out from a library, I don’t care how you do it get a hold of a copy of Grant Petty’s book “A First Course in Atmospheric Radiation”. I’ll make it really easy for you by including a link to the site where you can buy it for a whole $36 USD. Note that this is astoundingly cheap for a textbook — Petty uses Sundog for the same reason I use Lulu for my own textbooks — so I’d recommend going the honest route but that’s up to you.
http://www.sundogpublishing.com/shop/a-first-course-in-atmospheric-radiation-2nd-ed/
Then maybe — especially if you do indeed have some sort of physics education — we can all start using big boy concepts instead of butchered misstatements about designed-for-the-ignorant-public block diagrams of energy flux taken in isolation as if they apply to to a passive system.
When you obtain your legal or illegal copy, read through the single layer model in Chapter 6. Note that this model has only the barest handful of parameters — albedo, emissivity, short and long wave absorptivity. Note that the “model” consists of a direct statement of the First Law of Thermodynamics — writing the differential equation for heat flow that determines dynamic equilibrium of the open system. It therefore by construction does not violate energy conservation. Note second that the absorptivities that appear — which are split very crudely into “short” and “long” partitionings of the spectrum, but ultimately reflect the atmosphere’s differential absorptivity in the relevant parts of the spectrum of incoming sunlight vs outgoing blackbody radiation — appear in the ODE symmetrically, that is, they obey Kirchoff’s Law of Thermal Radiation — absorption is precisely balanced by emission. Consequently your “objection” that any theory where this is true cannot possibly produce net surface heating relative to the mean temperature that would have been obtained without the absorptive layer are moot. Finally, note that if one tracks the “heat” absorbed as it moves from reservoir to reservoir in the system, entropy change is either zero or positive at every point. Net heat never flows “from cold to hot”. That is not necessary to increase the equilibrium temperature of an externally heated system — all one has to do is slow the rate it cools, and the greenhouse effect no more violates the second law as it makes the Earth’s surface warmer than it would be without greenhouse gases than the insulation in my attic violates the second law as it makes my heated house warmer by retarding the rate of flow of that heat out of the walls of my house.
Until you do this — and I’m serious, you need to work through the actual differential equations and stop commenting on one or another box in a block diagram that attempts to crudely summarize the equilibrium flow — you are just making yourself look silly.
Even your comments on downward directed radiation — measurable, as I noted, with cheap instrumentation or measurable in detail with more expensive instrumentation — somehow completely neglects the fact that this downward directed radiative flux carries energy. Contemplate the radiative balance of the surface underneath with and without this flux. Hmm.
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