A SIMPLE, STRAIGHTFORWARD CASE STUDY:
DOES
“THE ATMOSPHERIC RADIATIVE GREENHOUSE EFFECT”
DO WHAT IT’S SUPPOSED TO DO?
First, what is the rGHE supposed to do?
It is supposed to make the surface below a radiatively active atmosphere warmer than if this particular kind of atmosphere weren’t there. By extension, one could claim – and this is after all what the ‘Anthropogenic Global Warming hypothesis’ is all about – that the stronger the rGHE, the stronger its warming effect.
Now, as far as I’m concerned, this is a prediction that should be possible to test. Or else, what good is it?
Again, what is the strictest definition of the rGHE? What is its ‘surface warming mechanism’ supposed to be, in the simplest of terms? We went through this in Part 1, where what was defined as the “greenhouse effect” of clouds was overwhelmed by their opposing “albedo effect”, leading to an overall – net – cooling effect.
It is found simply and solely in the reduction in outgoing radiative (LWIR) flux from the surface to the top of the atmosphere (ToA) – the surface flux minus the ToA flux. (The surface flux is calculated directly from the surface temperature (based on a blackbody assumption, through the Stefan-Boltzmann equation), while the ToA flux is rather estimated from actual measurements made by satellite-borne instruments.)
The prediction, then, would go as follows:
The larger the difference between temperature-calculated surface LWIR flux and satellite-measured ToA LWIR flux, the greater the atmospheric radiative greenhouse warming effect on the surface.
The underlying premise being, that all of the energy thus presumed to transfer from the surface to the atmosphere, but not in the end onwards from the atmosphere to space, is somehow ‘trapped’ inside the system, necessarily leading to warming.
(I’ve discussed earlier how this premise is fundamentally flawed in that it doesn’t distinguish between heat [Q] (the ToA flux) and radiation (the surface ‘flux’). Everyone agrees that (from basic thermodynamic principles) if Qin is kept constant, then if you reduce Qout, there will necessarily be warming from Qin energy piling up. But then it should also go without saying that you need to actually follow the ‘heat’ in and out, nothing else. And the radiative heat being transferred from the global mean surface of the Earth to the atmosphere above [23-33 W/m2] is much smaller than the ultimate atmospheric radiative heat flux escaping the ToA into space [195-220 W/m2]. There is absolutely no reduction in radiative Qout going on here. ### There is also another fairly obvious reason why this kind of linear, one-dimensional reasoning doesn’t work as soon as you widen your field of vision only a tad. But I will rather get to this one a bit later. Done digressing …)
Well, OK.
How, then, do we test the above prediction?
We test it against real-world observations. From the actual Earth system.
In order to do this, we will have to compare two fairly comparable regions of the global surface. They should both be situated inside the same general latitudinal band, preferably the tropical one. The general regional topographical properties, including mean altitude, should be fairly similar, preferably as featureless as possible so as not to create any obvious advective barriers. They also need to be outside the direct influence of ocean currents (which can act both relatively cooling and relatively warming, in the tropics, mostly cooling).
What we want to test is a situation where there are massive amounts of rGHE-enhancing constituents in the atmosphere vs. a situation where there are much less of the same – basically moist continental vs. dry continental conditions. Atmospheric water vapour and clouds are far and away the main variables controlling the variation in ‘strength’ of the rGHE as defined. In effect, the more WV and clouds in an atmospheric column, the larger the rGHE on the surface below.
It turns out that Africa is easily the best continent to work with in this regard. The Southeast Asia-Indonesia-North Australia region is way too heterogeneous, and there aren’t really any dry regions inside the tropics proper, while the tropical zone of South America sees way too much disparity between the steamy Amazon Basin in the east and the Andes plus the dry, cool Peru Current-influenced coastal regions in the west. Africa is clearly the continent with the most homogeneous topography and where the climate zones away from the equator can most easily be tracked simply according to latitude.
I have picked two fairly broad regions for comparison:
- The Sahara-Sahel region, a stretched-out latitudinal sector extending from the 14th to the 20th parallels north, and between 15 degrees west and 36 degrees east, covering a total area of ~3.62 million km2.
- The Congo Basin, a more blocky sector straddling the equator, extending from the 5th parallel north to the 6th parallel south, and between 10 and 27 degrees east, covering a total area of ~2.32 million km2.
Figure 1.
I’ve appraised the mean annual temperature of the Sahara-Sahel sector to be around 28.5 degrees Celsius (301.5K) (based on the map above, but also on selected meteorological stations, finally allowing for the differences in elevation across the region – yes, this is clearly a crude estimate, but likely not too far from the truth), while the same value for the Congo would be about 25 degrees (298K). This gives a mean spread in annual temperatures between the two sectors of ~3.5 degrees in favour of the former. This seems to agree well with the impression you get from simply eyeballing the map above – the Sahara-Sahel rectangle clearly seems to exhibit higher mean temps than the Congo rectangle by some 3-4 degrees on average.
Right. So according to the basic rGHE blackbody (Stefan-Boltzmann) assumption for upward surface LWIR, a temperature of 301.5 Kelvin would produce a radiative flux of ~468.5 W/m2, while one at 298 Kelvin would produce one at ~447 W/m2.
That’s 21.5 more W/m2 of LWIR coming off the ground – on average – in the Sahara-Sahel sector than in the Congo sector.
OK. Let’s have a look at the total LWIR flux emitted through the ToA above the two regions, then, as measured by CERES (and averaged by me):
Figure 2. The Sahara-Sahel region to the left, the Congo Basin to the right.
The ToA LWIR flux above the Sahara-Sahel is 55.1 W/m2 larger than the same above the Congo.
According to the rGHE way of seeing things, [468.5 – 279.8 =] 188.7 W/m2 worth of radiative energy has been ‘captured’ and ‘retained’ by the Saharan-Sahelian atmosphere on the way from the surface up to the ToA. The same number for the Congolese atmosphere would be: [447 – 224.7 =] 222.3 W/m2.
That is, the approximate average magnitude of the rGHE (as strictly defined) in the two sectors compared:
- Sahara-Sahel: 188.7 W/m2.
- Congo: 222.3 W/m2.
(Notice that both of these values are significantly higher than the global mean, which is about 155 W/m2.)
Meaning, the atmosphere above the latter region apparently ‘traps’ 33.6 W/m2 more of the original outgoing surface LWIR than the former. Which of course is to be expected. It is, after all, a much wetter atmosphere, containing a lot more H2O.
But the difference still doesn’t seem that big, does it? Well, the Sahara-Sahel sector isn’t, when it comes down to it, among the driest regions of Africa. First of all, it is fairly close to the equator, so there would be quite a lot of water vapour in the atmosphere at large to begin with, compared to colder, higher latitude regions. Also, at least its southern half, is to a varying extent affected by the African monsoon, which brings in a fair bit of moisture and precipitation during a short string of summer months. The reason I didn’t simply choose Sahara proper as my ‘dry sector’ is that it’s too far from the equator. Moving outward from 20 degrees of latitude sees the mean annual solar input dropping off fast (Figure 3 below), naturally affecting annual temperatures. The effect of this can readily be seen in the map in Figure 1 – north of 25 degrees, annual temps generally drop below the Congo mean, from this simple fact alone:
Figure 3.
Speaking of solar input.
We’ve established that the Sahara-Sahel region has a weaker rGHE than the Congo Basin, and still it’s 3.5 degrees warmer (we can reduce this to about 2.5 degrees after adjusting for the difference in mean altitude for the two sectors, the latter one being on average ~150 (100-200) m higher). Completely contradicting the rGHE hypothesis.
Could solar input account for this? This seeming contradiction? Since there is so much WV and such extensive cloud cover above the Congo relative to the Sahara-Sahel, could this create such a strong overall albedo effect as to (more than) offset the entire difference in rGHE for these two particular regions?
Well, let’s just have a look. What does CERES have to say about the matter:
Figure 4. Once again Sahara-Sahel on the left, Congo on the right.
A way out? I’m afraid not. Quite the contrary.
The middle (golden) curve in both of these diagrams is the net (absorbed) solar flux from the ToA down. It is about 20 W/m2 larger in the Congo sector than in the Sahara-Sahel sector. On average.
Observe the pretty interesting fact that the mostly cloud/atmosphere-based albedo over the Congo Basin is pretty much equalled by the mostly surface-based albedo of the Sahara-Sahel region. As confirmed here:
Figure 5.
So there is basically nothing to be gained (or lost, rather) for Congo over the Sahara-Sahel regarding total albedo.
The latter region should thus, according to the strictly linear, radiative logic of the rGHE hypothesis, heat less (from lower total mean solar input) and cool more effectively (from higher total mean LWIR output to space) than the former, and hence end up considerably cooler annually, probably by several degrees.
Yet we see the opposite! The Sahara-Sahel is 2.5 degrees hotter than the Congo (altitude-adjusted), on an annual basis. Even being ~15 degrees further from the equator.
Either way you look at it, that difference is pretty significant!
And what’s more, there is a clear and consistent pattern across the African continent underscoring this find. It is certainly not simply restricted to the two regions in question. Let’s bring back the temperature map of Africa from Figure 1:
Figure 6.
What do we see?
- Where are the hottest areas to be found? The latitudinal band boasting the highest mean annual temps is centred around the 16th to 17th parallels north of the equator, along the Sahara-Sahel transition zone. However, there is also an equally hot region on the Horn of Africa (Kenya, Somalia, Ethiopia), just north of the equator. These areas all combine generally dry, clear climates with a relative proximity to the equator.
- What pattern along the equator? The central and western equatorial region is cooler on average by several degrees than the eastern region (on the Horn of Africa), at the exact same latitude, the equator. How to explain this glaring discrepancy? It’s hard to do without pointing out the obvious: Dry in the east, wet in the west (Figure 7 below).
- Why is Sahara-Sahel hotter than more southerly West Africa? We see how generally low-lying West Africa (the stretch between Cameroon in the east and Guinea in the west), approximately between 5 and 12-14 degrees north, is considerably cooler than the Sahara-Sahel region to the north of it, even with West Africa being closer to the equator and at a lower mean elevation. How can this be? Well, precipitation, atmospheric moisture and cloud cover all taper progressively off moving from the equatorial Atlantic in the south to the Sahel belt in the north – from wetter to drier (Figures 7 and 8 below).
- What pattern in the south? Notice how the latitudinal band centred along the southern 17th parallel does not come with the same scorching temperatures as its northern counterpart. This is true all the way from the Angolan-Namibian border in the west to Madagascar in the east. There are three very simple reasons for this: 1) The western coastline is indeed dry and low, but also highly influenced by the cold, north-flowing Benguela Current (Figure 9 below); 2) The middle section is situated on the high plateau of Southern Africa, more than 1000 metres high (Figure 7 (r) below); 3) The coastal lowlands of Mozambique and Madagascar are not influenced by any cooling currents (Figure 9), but simply experience a much wetter climate than the lands at the equivalent latitude north of the equator (Figure 7 (l)).
Figure 7. Left: Annual precipitation patterns of Africa. Right: Elevations of Africa; the greener, the lower.
Figure 8. Left: Total precipitable water vapour in the atmospheric column. There is on average about three times as much TPW in the troposphere above the Congo Basin as above the Sahara-Sahel sector. Right: On top of this, there are also substantial amounts of water (in the liquid form) held within clouds. This map only shows mean cloud cover as seen from space; it does not take into account the total thickness of the cloud layers, which in the tropics is normally considerable. (Both maps borrowed from the JRA-25 Atlas.)
Figure 9. Absolute sea surface temps (SSTs) around Africa, the annual mean of 2013. (I checked several other years, and this is pretty close to the overall pattern; there are only minor variations from year to year.) A couple of interesting points: 1) Compare the SSTs outside the Horn of Africa in the east and around West Africa in the west, both just north of the equator – 26-27 degrees in the east vs. 27-29 degrees in the west, and still the continental Horn of Africa is hotter than West Africa by a degree or two (Figure 6); 2) The cool waters of the north-flowing Benguela Current is clearly visible along the west coast of Southern Africa; compare this with the warm waters of the Mozambique Channel in the east. (Map produced in the KNMI Climate Explorer.)
The pattern could hardly be any more telling: Wetter means cooler. Drier mean hotter. (Remember, these are annual mean temps, the sum of all highs and lows throughout the year. Equivalent to the +15°C mean for Earth’s global surface.)
There are two points to be made here:
- The simple definition of outgoing LW effect (“greenhouse effect”) vs. incoming SW effect (“albedo effect”) neglects a very important part of the equation, namely the atmospheric absorption of incoming solar, preventing it from ever reaching the surface as radiative heat.
- What I hinted at earlier, the fact that clouds/WV in an atmospheric column reduce final outgoing LWIR through the ToA to space, doesn’t necessarily translate into warming. Why? Because of something called ‘heat capacity’. The rGHE hypothesis seems to ignore this pretty basic phenomenon as well. More H2O in the atmosphere simply means that the atmosphere can hold more energy without getting warmer. Dry air heats much faster than moist air, because it can hold a lot less energy. Water vapour has almost twice the ‘heat capacity’ of dry air, liquid water (clouds) more than four times. What happens is simply this: WV/clouds absorb surface radiation, but take longer to pass an equal amount on, because they need to store more of the incoming to raise its temperature as much as dry air. So they give off less, but don’t warm more!
This leads us to the conclusion that, while there is no reason to believe that the outgoing LW effect of having H2O in the atmosphere will raise the temperature, the combined (reflecting/absorbing) H2O effect on incoming solar (both SW and LW) is definitely going to cool the surface.
This conclusion appears to be quite solidly backed up by this post’s (admittedly quick and superficial) empirical analysis. More H2O in the atmospheric column will make the surface cooler. There are no empirical observations from the real Earth system supporting the notion of a net radiative surface warming effect of having H2O in the atmosphere above. The net effect is most certainly cooling …
The original prediction read like this:
The larger the difference between temperature-calculated surface LWIR flux and satellite-measured ToA LWIR flux, the greater the atmospheric radiative greenhouse warming effect on the surface.
Maybe. Maybe not. Either way, it clearly doesn’t generate overall (net) surface warming. So what good is it?
What the rGHE proponents are in fact doing, is simply ignoring the larger ‘cooling’ effect of having a radiatively active atmosphere and focusing only on the smaller (alleged/assumed/postulated) ‘warming’ effect, and then claiming that this smaller (alleged/assumed/postulated) ‘warming’ effect is what makes Earth’s global mean surface temperature as balmy as it is.
Fail!
In the end, it’s all about letting the sunshine in 😉 Doing that, trumps all other effects.
Okulær 
Reblogged this on Tallbloke's Talkshop and commented:
.
Interesting read. Reblogged for discussion at the talkshop.
Thanks, Tallbloke 🙂
[…] […]
Gasses disapate heat. Our daily lives count on that fact. Hair dryers, car radiators, electric base board heat, etc.
[…] The Greenhouse Effect That Wasn’t (Part 2) – DOES “THE ATMOSPHERIC RADIATIVE GREENHOUSE EFFECT” DO WHAT IT’S SUPPOSED TO DO? […]
This discussion is more than engrossing with regard to current climate understanding. It is quite revealing with regard to antediluvian catastrophe climate. My special thanks for this forum and its investigative efforts!
Glad you like it, Jess 🙂
Forget the never-ending theoretical discussions. I can’t understand why some enterprising post-doc doesn’t set up a simple experiment with two insulated vertical chambers. One contains dry air. The other contains 100% CO2, roughly equivalent to all the CO2 in the vertical column of atmosphere of the same footprint as the column. Both have digital precision thermometers every foot or so, including at the lower surface. Have a small ventilation hole near the top, so the thing doesn’t explode. Subject both to the sun (preferably pointing the columns at the sun all the time) and see what happens over a day’s cycle, after the system settles down. By GHGE theory, the CO2 column would be hotter at every temperature point. I predict the opposite. It could be done for a few thousand bucks, in a few weeks, and would be definitive. What’s stopping them, except peer-pressure?
John,
I’ve been thinking of a similar experiment. A column about 7.3 feet or 2.2 meters of pure CO2 at atmospheric pressure should contain the equivalent of 400 ppm in the atmosphere. Maintaining the pressure without contaminating the experiment could be tricky. Another problem is that any heat collected by the CO2 will not be free to rise, as it does in the atmosphere.
Jamie and Adam from Mythbusters may be your only hope, John
That’s an interesting experiment. I don’t think it would show much. What I do know from doing IR spectroscopy is that the Standard atmosphere one will absorb less incoming solar than the pure carbon dioxide one and because you’re limiting air exchange, the carbon dioxide one will be warmer than the standard atmosphere one; provided that both columns contain the same heat capacity.
*argh, left off during the day. It would not surprise me that the night-time one both reach the same temperature, though radiative transfer theory says that the carbon dioxide one should cool off faster (final temp determined by heat capacity, I think).
Seems a good idea but it needs more thought. What are you going to insulate them with? Insulating material is not going to let the sun’s radiation through, so I don’t understand why you suggest this. Further, what are you going to use to make the chambers? Ordinary glass is said not to allow infrared radiation to pass through.
Simple experiments have been done using glass jars and Al Gore demonstrated this. It has been repeated by others and the results can be found on the internet. You can see it in the video on this site: https://principia-scientific.org/the-glass-jar-greenhouse-gas-experiment-problem/
I have done it at home but find there is no detectable difference in the temperatures. I put the jars in the sun. Other claim to get the same result.
There is also the famous experiment done by Prof Wood to demonstrate that trapped radiation in a greenhouse does not cause the temperature to increase. He used two model greenhouses, one with ordinary glass and one with rock salt which allows IR to pass through. You can find this on the internet.
There is another experiment that is supposed to replicate the experiment by Tyndall. It uses a glass tube first filled with air and then with CO2, a candle and a thermal camera. Here is a link to a YouTube video https://www.youtube.com/watch?v=Ot5n9m4whaw. Thermal cameras can be set up to detect gas leaks in industrial plant and this camera was set up to detect CO2. Hence it was no more then a magic trick. The person who set up the experiment gave away the secret on the internet.
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Thanks, Sadie, but I think I’m fine for now 🙂
Is Kristian about any longer?
An interesting aspect of this assessment of regional rGHE that I didn’t really mention in the post itself, is how there appears to be absolutely no balance between incoming and outgoing radiative flux through the ToA:
The Congo sector: 287.4 W/m2 IN – 224.7 W/m2 OUT = +62.7 W/m2
The Sahara-Sahel sector: 267.5 W/m2 IN – 279.8 W/m2 OUT = -12.3 W/m2
This should come as no surprise. We are after all looking only at regional systems here, not at the total (global) system. A large part of the energy absorbed (in fact, most of it) is moved internally by advection (oceanic and atmospheric circulation) between regions throughout the world before it is ultimately radiated back out to space. So this energy, while moving internally, would fall outside the particular radiative budgets of the two particular ‘subsystems’ discussed here.
Is this, then, the reason why the Congo region is cooler on average than the Sahara-Sahel region, despite having a much stronger rGHE as defined?
I could understand why rGHE proponents would want to claim this to be the case.
However, it won’t help their hypothesis trying to locate this ‘missing’ (non-radiated) energy …
The thing is, what happens in the equatorial belt? Over land? There is no significant advection close to the surface away towards the north or south. Air (and energy) is rather coming in from the north and from the south. Or it moves along the equator. If anything, at the surface, equatorial continental regions would on average get extra energy IN from surrounding regions, by advection from higher pressures towards the central low. That’s how the Hadley-Walker cells work. The overwhelming majority of the energy coming directly in from overhead (the Sun) would be shed straight back up, convected vertically towards the tropical tropopause, still comfortably within the same sector.
What happens in the equatorial belt is that there is convergence at the surface and divergence at the tropopause. The energy not being radiated away on its way up to the tropopause (inside the sector), will rather be radiated away from tropopause or near-tropopause level on its way north or south to the subtropics (outside the sector):
“Air convected to the top of the troposphere in the ITCZ [InterTropical Convergence Zone] has a very high potential temperature, due to latent heat release during ascent in hot towers. Air spreading out at higher levels also tends to have low relative humidity, because of moisture losses by precipitation. As this dry upper air drifts polewards, its potential temperature gradually falls due to longwave radiative losses to space (this is a diabatic process, involving exchanges of energy between the air mass and its environment). Decreasing potential temperature leads to an increase in density, upsetting the hydrostatic balance and initiating subsidence. The subsiding air warms (as pressure increases towards lower levels), further lowering the relative humidity and maintaining clear-sky conditions. However, although the subsiding air warms, it does not do so at the dry adiabatic lapse rate. Continuing losses of longwave radiation (radiative cooling) means that the air warms at less than the dry adiabatic lapse rate (i.e. some of the adiabatic warming is offset by diabatic cooling).”
http://www.st-andrews.ac.uk/~dib2/climate/tropics.html
As you can well read from the highlighted part (my emphasis) in the quote above, energy is definitely being brought out of the equatorial belt before it can be radiated to space. But it happens aloft, not significantly at the surface. It is brought to those regions, like the Sahara-Sahel sector, that end up radiating more to space than what they absorb from the Sun, the surplus energy brought in aloft from the ITCZ.
The absorbed solar heat is simply thoroughly shuffled internally within the Earth system before it is finally allowed to be reemitted to space.
The point I want to make is this:
If you want to argue that energy is being ‘trapped’ by gases and clouds in the troposphere, and that this somehow constitutes the rGHE, then you cannot also invoke the “energy being brought out of the region by other means offsetting a regional warming” argument, because then the energy you claimed to be ‘trapped’ and which would then (by rGHE logic) necessarily warm the troposphere and, consequently, the surface below, would not have been ‘trapped’ at all to begin with. It managed to get (‘radiatively undetected’) all the way from the surface up to the top of convection and only from there moving poleward and out of the region; at last radiated to space along the way. So your whole ‘warming mechanism’ would no longer be fit for purpose. It would no longer be at all.
You can’t have it both ways …
Hi Kristian,
I am the Norman from Roy Spencer that is responding to some of your posts.
I looked at CERES for the Surface Solar flux at the surface and I see a lot more than the 175 you have . It may be an annual amount and Sahara may have higher temps annually than the Congo but that would smear the effects of what is actually going on with the GHE. The Sahara is colder than the Congo during the Sahara winter months and much warmer in the summer so the overall annual mean may be higher but it would come from the summer heating period.
I gathered some CERES data and it does match what I am getting with the insolation data.
https://ceres-tool.larc.nasa.gov/ord-tool/srbavg
In the June plot the Sahara looks as if is receiving around 280 W/m^2 and the Congo between 200 to 225 W/m^2. My individual city sights were a little different but these are global fluxes.
It would show that the Sahara surface does receive much more solar energy at its surface then you would have to determine the reflected solar and subtract out what is available for actual heating.
From this graph
https://ceres-tool.larc.nasa.gov/ord-tool/srbavg
It looks like the June solar upward flux (all-sky) is about 25 W/m^2 difference favoring the Congo. But if you subtract 50 from 280 you get a surface absorbing 230 W/m^2 in Sahara in June but only 200 or less in the Congo it could even be lower. My calculations using other resources showed about 50 more W/m^2 in the Sahara in summer and hence greater heating (this was with the DWIR calculated into it, based on the two African cities used in your Roy Spencer post).
I like your work and hope you continue.
A note. I have seen about 4 or 5 posters on Roy Spencer that you complain that they do not understand your view or point. I am one of them. Maybe it is how you are presenting your material since a lot of physics trained people are taking your posts in ways you do not intend.
Hi, Norman.
To me it seems you’re forgetting that the relevant solar input variable isn’t the “Shortwave Flux Down”. It’s rather the “Net Shortwave Flux”, which is equal to “ASR, absorbed solar radiation” and to “solar heat” – the “Shortwave Flux Down” minus the “Shortwave Flux Up”.
Here I have specified the coordinates of my two regions: i) Sahara-Sahel (20-14N, 15W-36E), and ii) the Congo (5N-6S, 10-27E) and ticked off the CERES EBAF Ed2.8 Sfc “Net Shortwave Flux, All Sky” variable, in the “Surface Fluxes” box, and gotten these results back:
As you can see from these plots, the average solar heat flux (‘net SW’) at the surface is very much as high in the Congo as it is in the Sahara-Sahel region. And there’s much more of your “back radiation” in the Congo to boot (meaning a much smaller radiant heat loss). And still the surface T_avg in the Congo is lower by several degrees.
You have got to bear in mind, Norman, that for the postulated “radiative GHE”, only annual averages matter. It doesn’t matter if its hotter in summer or colder in winter, only the annual average counts for anything. It’s supposed to be a NET effect, after all.
Also, the “radiative GHE mechanism” is actually meant to be a ToA phenomenon, not a surface phenomenon. The surface is basically simply supposed to be warmed from the lapse rate ladder being pulled up as the “effective radiating level” moves higher.
Kristian
https://ceres-tool.larc.nasa.gov/ord-tool/imageGenerator?command=gridOnly&iminlat=50&imaxlat=129&iminlon=340&imaxlon=49&gridSize=1
https://ceres-tool.larc.nasa.gov/ord-tool/imageGenerator?command=gridOnly&iminlat=50&imaxlat=129&iminlon=340&imaxlon=49&gridSize=1
I still not sure what your data graphs are showing. I went to CERES and put in -20 West 50 East 40 North -40 South. This covers all Africa. I clicked on the visualize button to get many graphs. I scrolled down to the one with Total Net radiation (all solar and IR) All sky and scrolled through the months and it shows exactly what the temperature data shows for the two African cities (Kinshosa, Congo and Khartoum, Sudan). In the early months Kinshosa has more surface energy and as summer in the North approaches (Sudan) the energy balance goes toward this city and it ends much hotter during the summer. I also noticed that there is lots of variance for the larger areas you selected. So it would be hard to get good temperature data to compare for these regions unless you could overlay total net radiation and surface temperature.
I still think you miss the point of general GHE. If you removed the radiating gases you get very little downwelling IR and your Net upwelling IR would jump up considerably and the surface would really start to cool.
I am not sure about your statement “The surface is basically simply supposed to be warmed from the lapse rate ladder being pulled up as the “effective radiating level” moves higher.” Sounds a lot like Doug Cotton backward thought process. The lapse rate does not determine the surface temperature, the temperature of the lapse rate at any height is a product of the surface temperature. The starting point is the surface.
I will continue to try and understand you point. It seems very different than my understanding of physics. Not meaning mine is correct, I try to learn and create more correct understandings as I go.
I have an idea that the insulating properties of the atmosphere (slow heat transfer by conduction) may be the correct view of GHE. As you stated in a Roy Spencer post, if the upper atmosphere where the same temp as the lower the GHE would not exist as the energy would be leaving at the same rate as enters.
Norman, you say:
No, you’re missing my point. I’ve told you this before. I KNOW that if you somehow managed to turn the atmosphere into a completely non-participating medium (you wouldn’t, though), then there would be no apparent atmospheric “DWLWIR” to the surface, no matter how hot the atmosphere itself happened to be.
However, you would get the EXACT same result if the atmosphere had an effective absorptivity/emissivity equal to 1, but a temperature no higher than space (2.7K). The surface would then receive a ‘flux’ from its surroundings worth of 0.000003 W/m^2, effectively zero.
IOW, the effect of the “DWLWIR” on the surface radiant heat loss is indisputable, but its final temperature effect on the surface as a result of this isn’t. Since the magnitude of the “DWLWIR” is itself a direct radiative effect of the final temperature.
As I’ve pointed out to you now probably 10-20 times, you need BOTH mass AND radiative properties to enable the atmosphere to create a thermal effect on the solar-heated surface.
Can we PLEASE agree on this fact, Norman? I call it a “fact” because it is. It is not an opinion. Or a view of the world. It is just as plainly obvious that you need the atmosphere to have a TEMPERATURE as you need it to possess RADIATIVE PROPERTIES in order for it to be able to make a difference to the surface radiative budget.
If we can agree to this simple circumstance, then – and ONLY then – can we move on …
* * *
This particular post is about whether making the atmosphere *more* radiatively active (that is, from one positive (non-zero) level to a more positive one, NOT from the zero level to a non-zero one) will make the surface T_avg any higher. You assume it will, almost by default. Based on theory. The empirical evidence from the real world, however, clearly shows that such an assumption is invalid.
You’ve already seen the CERES plots of the average sfc solar input/heat (‘net SW’) in the Sahara-Sahel vs. in the Congo. The latter annually absorbs just as much solar heat as the former.
Here’s the “net total flux” (net SW in (radiant heat gain/Q_in) minus net LW out (radiant heat loss/Q_out)) for the two regions in question.
First, the Sahara-Sahel:
Then, the Congo:
It is evident from these plots that the surface net radiant heat (Q_rad in – Q_rad out) is *much* more positive in the Congo than in the Sahara-Sahel, in fact, the Congo has an extra radiant heat surplus of about 50 W/m^2 (+ ~65%) at the surface as compared to the Sahara-Sahel.
Furthermore, we already know from the main post that the radiative imbalance (SW in minus LW out) at the ToA over our two regions is vastly different: While the Sahara-Sahel imbalance is negative by 12.3 W/m^2 (more radiant heat OUT than IN), the Congo imbalance is strongly positive, by 62.7 W/m^2 (more radiant heat IN than OUT), a total difference in favour of the Congo of [12.3+62.7=] 75 W/m^2!
So how come the surface T_avg in the Congo is STILL lower than in the Sahara-Sahel by several degrees, Norman …!?
This SO obviously contradicts your assumption that if you only increase the atmospheric “DWLWIR” to the surface, thus reducing the surface (and the ToA) radiant heat loss (‘net LW’), then the surface T_avg has to go up, as if by physical necessity.
It is NOT a physical necessity, Norman! Real-world observations tell us it isn’t.
What part of the total system is it, then, once the atmosphere has become radiatively active, that will routinely baffle (as in ‘negate’) any further RADIATIVE attempt at producing extra warming? It’s called ‘atmospheric circulation.’
Hi Kristian
I’m the Snape from Spencer’s blog (not the wizard, in case you weren’t sure).
“Snape. You’re looking at the ToA. The surface temp is set … at the surface. The Sahara-Sahel and the Congo has the same average heat input (and output) to the surface.”
Looking at your research (very impressive), it looks like the radiative budget at the surface is similar to the TOA. The Congo’s surface absorbs more radiation than it emits, while the Sahara’s surface radiates more than it absorbs.
Am I confused?
So if I understand correctly, here is an analogy:
The Congo and Sahara each get a dime from the sun. The Congo then shares 2 or 3 cents with its neighbors. The Sahara STEALS 2 or 3 cents from its neighbors
and yet is only slightly warmer!
What’s the Congo’s secret? More energy is “trapped” and returned than in the Sahara. Warm rain and backradiation.
I don’t think the CERES data copies and pastes like some other sites. I don’t think the image address copied what I was viewing. Sorry.
What I do is simply download the graph of plotted data produced at the CERES site and create my own image file on my pc. Try doing that.
Welcome, Snape.
You ask: “Am I confused?”
It would appear so.
You can’t compare a regional surface budget and a regional ToA (or, tropopause, really) budget directly. They are fundamentally dissimilar.
You see, convection/advection only operate WITHIN thermodynamic systems, never BETWEEN. Which is to say, convection isn’t a heat transfer mechanism in the same way as conduction, radiation and evaporation/condensation are – it never brings heat across a system boundary, it only ever transports heat within the system, specifically a fluid system (gases, liquids). So we can’t include convection/advection in the surface budget, because the surface heat will have to be transferred (via conduction, radiation or via evaporation/condensation) to the air above before convection/advection can take hold in the first place.
At the regional tropopause, however, convection/advection basically bring in ALL the heat (barring a little bit of incoming solar), from below and/or from the sides (the adjacent regions). This is fully explained in the quote I linked to at Spencer’s blog:
“The point I want to make is this:
If you want to argue that energy is being ‘trapped’ by gases and clouds in the troposphere, and that this somehow constitutes the rGHE, then you cannot also invoke the “energy being brought out of the region by other means offsetting a regional warming” argument, because then the energy you claimed to be ‘trapped’ and which would then (by rGHE logic) necessarily warm the troposphere and, consequently, the surface below, would not have been ‘trapped’ at all to begin with. It managed to get (‘radiatively undetected’) all the way from the surface up to the top of convection and only from there moving poleward and out of the region; at last radiated to space along the way. So your whole ‘warming mechanism’ would no longer be fit for purpose. It would no longer be at all.
You can’t have it both ways …”
Nope. You are confused. This is exactly what DOESN’T happen. This exchange occurs only at altitude, not at the surface. At the surface, if anything, the situation is reversed. This is basic meteorology. Whenever there’s a low pressure at the surface, air masses are coming IN (convergence). This happens in the Congo. Whenever there’s a high pressure, like in the Sahara, and to a smaller extent in the Sahel, air masses move OUT and away (divergence). This is simply how the Hadley Cells work:
Equator (the Congo) – low pressure and convergence at the surface, high pressure and divergence at the tropopause;
Subtropics (Sahara-Sahel) – high pressure and divergence at the surface, low pressure and convergence at the tropopause.
However, it turns out the TOTAL surface heat budget (radiative+conductive+evaporative) is the same in both regions. But the RADIATIVE part is strongly reduced in the Congo compared to in the Sahara-Sahel. And STILL the latter is warmer on average by several degrees. Goes directly against the whole idea of warming being ‘forced’ by a reduction in the surface radiative heat loss from “more atmospheric back radiation”.
” So we can’t include convection/advection in the surface budget, because the surface heat will have to be transferred (via conduction, radiation or via evaporation/condensation) to the air above before convection/advection can take hold in the first place.”
What if Wichita, Kansas was -10 F, then a warm front moved in from the Gulf, raising the temperature to + 40 F?
That wouldn’t count? You think the warming had nothing to do with convection from an outside source, it was all internal?
*****
No matter how you spin it, the column of air above the Sahara is heated by neighboring areas (either at altitude or elsewhere). One way or another, that equates to a warmer surface.
That is NOT true of the Congo, just the opposite. So like I said, you’re trying to compare apples to oranges.
Remember all my “runners” moving back and forth on a field before eventually leaving? That was my clumsy attempt at a GHE metaphor. Here is the same idea, but clearly, eloquently expressed:
http://rabett.blogspot.com/2018/08/the-simplest-green-plate-effect.html?m=1
Snape, you say:
Hehe, in what way? I wonder
1) There is MUCH more “atmospheric back radiation” to the surface in the Congo (~400 W/m^2) than in the Sahara-Sahel (~350 W/m^2).
2) The environmental lapse rate, that is, the tropospheric temperature gradient from the surface up would be steeper over the Sahara-Sahel than over the Congo, the tropospheric column, after all, being much drier in the former region.
You’re not thinking this through, Snape. You’re only looking for easy “gotchas”. I’m sorry, but you won’t find any.
I have no idea what a heat budget means. It is an invention of climate scientists which enables them to declare a thermal equilibrium point wherever they want. It is how they generate the extra energy they claim is causing global warming. They ignore the real physics which is the law of conservation of energy and that applies everywhere.
Kristian
“1) There is MUCH more “atmospheric back radiation” to the surface in the Congo (~400 W/m^2) than in the Sahara-Sahel (~350 W/m^2).”
Yes. That and warm rain is how I think the Congo is able to maintain a mean temperature only a few degrees less than the Sahara, despite a significant convective deficit (keeping in mind the Sahara has a considerable convective surplus).
*******
That being said, humid air is lighter and more buoyant than dry air, so all else being equal, I agree the Sahara should be warmer than the Congo. And indeed it is.
“I agree the Sahara should be warmer than the Congo. And indeed it is.”
Except at night, when despite the atmospheric CO2 concentration being essentially identical to that in the Congo, the temperature in the Sahara can drop almost 50deg C and approach freezing point, whereas the midday-midnight temperature difference in the Congo is a few degrees at most.
The difference is of course due to the very large difference in humidity.
You’re still just making up things as you go along, Snape. You don’t really have any counterarguments at all. You’re simply not addressing the issue that is being discussed. Convection doesn’t enter the SURFACE heat budget equation. Please get that into your head.
Sahara-Sahel sfc: heat IN (Q_sw), 174 W/m^2; heat OUT (Q_lw+Q_cond+Q_evap), 174 W/m^2.
The Congo sfc: heat IN (Q_sw), 174 W/m^2; heat OUT (Q_lw+Q_cond+Q_evap), 174 W/m^2.
Here’s the gist of it all (read carefully and repeatedly until you understand):
“(…) what kind of effect on the average surface temperature would such a striking difference have? [That is, an average radiative heat loss from the surface 2-3 times smaller/less effective in the Congo than in the Sahara-Sahel.] If the radiant heat loss of the surface is that much reduced from having an atmosphere on top with a much higher level of IR opacity [much more “atmospheric back radiation” to the surface], then wouldn’t we expect this to somehow result in substantial surface warming? Wouldn’t the surface have to warm in this case so that the other available mechanisms [conduction and evaporation] are able to work at a higher level of efficiency, simply forced to [compensate] by the reduction in the radiative loss?
Isn’t this exactly the idea of how the “enhanced GHE” is supposed to force the surface to warm towards a new and higher equilibrium temperature, to make up for a reduction in radiative heat loss?
So how come the average surface temperature in the Congo is almost 3 degrees LOWER than in the Sahara-Sahel region!? With as much heat coming IN, but with much, much less radiant heat going OUT. Why hasn’t this circumstance forced the average surface temperature in the Congo to be much HIGHER than in the Sahara-Sahel? As per standard AGW ‘logic’.”
– – –
Please address what I’m actually saying, Snape. Not this nonsense of yours.
“Please address what I’m actually saying, Snape. Not this nonsense of yours.”
I’ve been trying to, Kristian, but it’s should be a give and take so we’re not just talking over each other. You wrote,
“So we can’t include convection/advection in the surface budget, because the surface heat will have to be transferred (via conduction, radiation or via evaporation/condensation) to the air above before convection/advection can take hold in the first place.”
I replied here, but got no answer:
“What if Wichita, Kansas was -10 F, then a warm front moved in from the Gulf, raising the temperature to + 40 F?
That wouldn’t count? You think the warming had nothing to do with convection from an outside source, it was all internal?”
Again, do you think Wichita heated itself by conduction?
*****
I do NOT think that increased backradiation MUST make a particular surface warmer. No need to bring up the Sahara.
If I bring a pot of water to a low simmer, then somehow increase the “backradiation” enough, I would expect the water to get hotter and boil.
What if I increased the backradiation even more? In that case, I WOULD NOT expect the water to get any hotter. Other mechanisms are at play. This is understood, so I wouldn’t change my view of the GHE.
But that’s exactly what you’ve done……found a situation where more backradiation didn’t produce a higher local temperature, and from that drawn a conclusion.
So my answer to this:
“Why hasn’t this circumstance forced the average surface temperature in the Congo to be much HIGHER than in the Sahara-Sahel? As per standard AGW ‘logic’.”
Other mechanisms are at play, which have overwhelmed the eGHE
Bottom line, the column of air above the Sahara suffers a net loss to space. That loss cannot be replaced internally, so it must therefore be heated by an external, terrestrial source. Your claim, then, is that this extra heat has no bearing on the surface temperature. Following that logic, if we removed the extra heat source, and the column cooled until a radiative equilibrium was reached, the surface temperature would be impervious.
Seems very dubious. Where is your evidence.
Radiation is not the same as heat transfer. Radiation only transfer heat when it travels from hot to a cold. The atmosphere does not heat the surface.
Snape, you write:
No, you very clearly haven’t. You’ve sought to redirect all attention away from the surface to the troposphere above. You’re specifically talking about the tropospheric budget when trying to justify the observed surface temperatures, without ever addressing the SURFACE budgets. I’m sure you’ve never in your life taken a course in thermodynamics, but still, it SHOULD be possible, upon several reminders, to grasp the basic setup of this problem. It has got NOTHING at all to do with how much air is coming in or moving out of the upper tropospheric column. That is irrelevant to this particular test. It ONLY has to do with how much heat is coming INTO and how much heat is moving OUT FROM the surface.
Snape, the Sahara/Sahel vs. the Congo comparison is about ANNUAL AVERAGES, not about occasional warm fronts moving in or out. The tropospheric temperature gradient in the Sahara/Sahel region starts at a surface temperature ~3 degrees higher than in the Congo, but climbs up a little bit steeper, so likely ends up at a tropopause temp (~16 km up) similarly lower. Somewhere in the middle range (+/- 8 km up), the tropospheric temperatures in both regions are equal, and so exchange no heat on average. Got that? If air generally moves from the Congo to the Sahara/Sahel at high altitude, it generally moves rather the OTHER way at low altitude, closer to the surface. This latter movement is much more relevant to the SURFACE temp/energy budget than the former.
The Hadley Cells work in a pretty complex manner over continental areas like Africa, but while the Sahara/Sahel region feeds vast amounts of hot, dry air masses in the direction of the equatorial areas around the Congo, picking up lots of moisture on the way, during extended periods of the year, the Congo never feeds the Sahara/Sahel with any substantial amounts of warm, moist air masses in return. So the net is clearly hot, dry air OUT OF the Sahara/Sahel and warm, moist air INTO the Congo. Close to the surface.
You can’t ‘win’ this discussion, Snape.
But this comparison was not made to test YOUR belief, Snape. It was made to test the “idea of an (anthropogenically) enhanced GHE as the cause of ‘global warming'”. Its core premise is, after all, that an increase in “atmospheric back radiation” (or, stated differently, and more correctly, a reduction in radiative heat loss from the surface) will and must cause surface warming. This is an absolute requirement for this idea to work at all. Which means, it fully relies on an “ALL ELSE BEING EQUAL” stipulation to be valid and true.
It can only work if everything apart from the increase in “atmospheric back radiation” (i.e. the reduction in surface radiative heat loss) is kept constant.
What we’re doing here is simply testing the validity of this stipulation. Does everything else, all processes, remain unchanged if we simply decide to change the composition of the atmosphere, that is, its immediate IR opacity?
Of course not. As reality explicitly and consistently shows us. If you change the water content of the tropospheric column, OTHER THINGS, OTHER PROCESSES, CHANGE WITH IT!
Which means, you can’t tell from just considering ONE single parameter out of many, the increase in the air’s nominal IR opacity (and the resulting increase in “atmospheric back radiation” to the surface/reduction in the surface’s radiative cooling rate) whether that surface will end up warmer or not.
But this is exactly what is done. One ASSUMES that simply changing the atmosphere’s IR opacity will and must, on balance, make the surface warmer, no matter what …!
Not local, Snape. Regional. Did you even read the post? This is a consistent pattern, not a special case for these two particular regions. A wetter troposphere is consistently associated with a cooler surface (on land, of course, where the surface doesn’t move, and away from ocean influence). Even though a wetter troposphere would always also be associated with more “atmospheric back radiation” to that surface.
But yes, it’s called EMPIRICAL TESTING OF AN HYPOTHESIS, Snape. How else would you test – on planet Earth – the claim that an increase in the atmosphere’s IR opacity will and must cause global surface warming? The only way you can do this on the same planet, is by comparing different regions with different atmospheric IR opacities, that is, in effect, different contents of water.
If you insist on testing the whole globe, and/or you insist on testing CO2 specifically, then you will have to compare the Earth with other celestial bodies out there. And I’m afraid the ‘hypothesis’ won’t fare much better then … For instance, in each cubic metre of Martian air above the global Martian surface, there are ~26 times (!) as many CO2 molecules as in each similar volume of terrestrial air. But is there a stronger “GHE” on Mars than on Earth because of this undeniable (and quite striking) circumstance? Nope. Quite the contrary! On Mars, the global T_s (~203K) is ~8K lower than the global T_e (~211K), which means the Red Planet has a NEGATIVE “GHE” as defined here on Earth (T_s (288K) > T_e (255K).
So how could we increase the “temperature-enhancing” effect of the Martian atmosphere on the global Martian surface from the current state? Would going from 96 to 100% CO2 concentration help? Er, no. The “GHE” is already negative. What we could and should do instead is pump it full of nitrogen, or oxygen, or argon, or carbon dioxide for that matter. Simply BULK UP ITS OVERALL MASS, WEIGHT AND DENSITY.
THAT’S what matters. THAT’S what makes the difference. Not the relative amount (percentage) of IR-active molecules in the atmosphere.
My point EXACTLY! You’re making my point, Snape. You’re explaining how REALITY works, not how the “AGW” logic works.
There is no radiative “GHE”. The atmospheric “temperature-enhancing” effect on the surface is a massive one.
Kristian
Is the surface of the Sahara warmer than the Congo because the air is drier, or is it warmer because it has an extra external heat source…..convection? That’s what I’m asking here.
You seemed to imply that convection DOESN’T COUNT as a means of heat transfer, so I brought up the Wichita scenario. You avoided answering on the grounds it was short term.
Short term or on a yearly average, does a net influx of warmer air count as a heat source? In other words, If an external input can raise the temperature of a city for a day, why not on a yearly basis?
*******
The Sahara surface has net radiative deficit, so why doesn’t it get colder? Even more confusing, it seems to have a convective deficit with neighboring areas (hot, dry, low level winds moving away).
So again, why does it have a steady temperature? If the answer is “warm air moving down the column”, then that air must, on average, be warmer than the surface winds leaving, in order to make up for the surface radiative deficit, right?
The problem with that, is the upper level of the column has a radiative deficit as well!
Let’s say we were studying the surface temperature of two columns of air in a lab. Same SWIR input to both, but one column has much more water vapor than the other. Which surface will be warmer?
Well, if you pointed a hair drier (an extra heat source) down at the surface of one of the columns, but not the other, it would ruin the experiment.
But we’re not doing this test in a lab, Snape. That’s the whole point. And that’s the mistake being done. It is assumed one can control all factors at play and then just change specifically chosen parameters. But that’s not how the real Earth system works.
No one is saying that the PRINCIPLE behind increased radiative insulation (reducing the radiative heat loss while keeping the heat input constant) is wrong. It is very much correct. It WOULD work. If all other factors remained unchanged during the reduction in radiative heat loss. Just like it would work if you reduced convection, and/or evaporative loss, and/or conductive loss.
The problem is the “All Else Being Equal” clause. All else is NEVER (!!) equal. And that’s why you need to TEST the claim of inevitable warming OUT THERE IN THE REAL WORLD, against real earth-system observations; not in a lab, not on paper, and not in a model.
Are you seriously claiming this is what happens in the Sahara-Sahel??!
There is no extra heat source anywhere, Snape. You need to rid yourself of this particular mind bug. The surface absorbs the heat it absorbs. From the Sun only. 174 W/m^2 in the Sahara-Sahel AND in the Congo. On average. But the surface in the Congo receives and absorbs MUCH more thermal radiation (DWLWIR) from the atmosphere on top than the surface in the Sahara-Sahel does. And STILL the T_s in the Congo is LOWER by several degrees. On average.
Snape, you wrote:
Convection is not an extra external heat source to the Sahara-Sahel surface, Snape. You’re entering *facepalm* territory, here. Where were you when the fundamental “Heat Moves From Hot To Cold Only” principle was explained in school.
The T_s in the Sahara-Sahel is of course higher than the T_s in the Congo, even with equal heat INPUT [Q_in(sw)] and with equal total heat OUTPUT [Q_out(lw)+Q_out(cond)+Q_out(evap)], 174 W/m^2 in all cases, because all heat loss mechanisms are not created equal, and because vertical convective power matters crucially. As these simple real-world observations show us.
IOW, evaporation and convection rule, not radiation. The average surface temp is set and controlled by solar input, evaporation rates and column convective power, NOT (!!) by the effectiveness of the radiative heat loss. It is completely overpowered and drowned out. In direct contradiction to what’s predetermined as ‘truth’ by standard “AGW theory”.
I’ve never stated (nor implied) any such thing. Convection is a potent means of heat transfer … WITHIN A FLUID. It is, however, NOT a means of heat transfer BETWEEN different thermodynamic systems. J.C. Maxwell pointed this out already in the 19th century. Convection is also a MASS transfer. It transfers energy by means of moving the (fluid) matter containing the energy.
Look, this is veeery simple. The only thing you need to do is follow the temperature gradient. Heat in nature only ever moves from HIGHER to LOWER temp. Convection is thus, as you should be able to gather, ALWAYS a transfer of (fluid) matter, but NOT always a transfer of heat. It only transfers energy in the form of HEAT from one place to another whenever the first place has a HIGHER TEMPERATURE than the next.
And so, there is very much a transfer of heat by way of convection UP AND AWAY from the surface BOTH in the Congo AND in the Sahara-Sahel, because the surface is hotter than the troposphere above it in both regions, and the tropospheric temperature gradient going up to the tropopause is NEGATIVE in both cases. So we naturally have upward vertical convection in both areas, responding to surface solar heating and steepening of the tropospheric temperature gradient during the day. However, in the Sahara-Sahel, the convection is mostly fairly dry (‘dry adiabatic lapse rate (DALR)’), while in the Congo it is distinctly moist all the time (‘moist adiabatic lapse rate (MALR)’), and therefore manages to go MUCH deeper (that is, higher up the air column). Equatorial deep moist convection is what drives the Hadley Cells.
I wrote about how these things work in this comment of mine (quite recently linked to for you to read; you apparently didn’t):
I quote:
* * * * * *
The thing is, what happens in the equatorial belt? Over land? There is no significant advection close to the surface away towards the north or south. Air (and energy) is rather coming in from the north and from the south. Or it moves along the equator. If anything, at the surface, equatorial continental regions would on average get extra energy IN from surrounding regions, by advection from higher pressures towards the central low. That’s how the Hadley-Walker cells work. The overwhelming majority of the energy coming directly in from overhead (the Sun) would be shed straight back up, convected vertically towards the tropical tropopause, still comfortably within the same sector.
What happens in the equatorial belt is that there is convergence at the surface and divergence at the tropopause. The energy not being radiated away on its way up to the tropopause (inside the sector), will rather be radiated away from tropopause or near-tropopause level on its way north or south to the subtropics (outside the sector):
“Air convected to the top of the troposphere in the ITCZ [InterTropical Convergence Zone] has a very high potential temperature, due to latent heat release during ascent in hot towers. Air spreading out at higher levels also tends to have low relative humidity, because of moisture losses by precipitation. As this dry upper air drifts polewards, its potential temperature gradually falls due to longwave radiative losses to space (this is a diabatic process, involving exchanges of energy between the air mass and its environment). Decreasing potential temperature leads to an increase in density, upsetting the hydrostatic balance and initiating subsidence. The subsiding air warms (as pressure increases towards lower levels), further lowering the relative humidity and maintaining clear-sky conditions. However, although the subsiding air warms, it does not do so at the dry adiabatic lapse rate. Continuing losses of longwave radiation (radiative cooling) means that the air warms at less than the dry adiabatic lapse rate (i.e. some of the adiabatic warming is offset by diabatic cooling).”
http://www.st-andrews.ac.uk/~dib2/climate/tropics.html
As you can well read from the highlighted part (my emphasis) in the quote above, energy is definitely being brought out of the equatorial belt before it can be radiated to space. But it happens aloft, not significantly at the surface. It is brought to those regions, like the Sahara-Sahel sector, that end up radiating more to space than what they absorb from the Sun, the surplus energy brought in aloft from the ITCZ.
* * * * * *
Kristian
I’ll respond to the comments you made little by little, over the course of a day or two, ok?
You wrote,
“There is no extra heat source anywhere, Snape. You need to rid yourself of this particular mind bug. The surface absorbs the heat it absorbs. From the Sun only. 174 W/m^2 in the Sahara-Sahel AND in the Congo. On average.”
From the sun only? On a yearly average, the Sahara’s surface radiates more than it absorbs from the sun. So if the sun is its only heat source, why doesn’t it get colder?
“I’ve never stated (nor implied) any such thing. Convection is a potent means of heat transfer … WITHIN A FLUID. It is, however, NOT a means of heat transfer BETWEEN different thermodynamic systems.”
Are you just playing games here, Kristian? I’m talking about convection between columns of air……….the same fluid.
Obviously “air” does not convect heat through the actual air/surface boundary. That’s where conduction comes in.
Irrelevant to begin with, since when we compare “surface” temperatures between two locations on land, it’s actually the air temperature ~ 2 meters above the ground that’s being measured.
“Well, if you pointed a hair drier (an extra heat source) down at the surface of one of the columns, but not the other, it would ruin the experiment.”
This is speculation based on deduction. If the Sahara surface is on average hotter than its neighbors, it likely has a convective LOSS of heat laterally (i.e., warm, near surface winds moving outward to other areas).
If It also has a RADIATIVE deficit, then again, why doesn’t it get colder?
Do you think it conjures up the energy lost? Geothermal maybe?
****
You made an observation that supports the idea that the Sahara “column” is heated at high altitudes, which then equates to warmer temperatures below (compared to otherwise):
“As you can well read from the highlighted part (my emphasis) in the quote above, energy is definitely being brought out of the equatorial belt before it can be radiated to space. But it happens aloft, not significantly at the surface. It is brought to those regions, like the Sahara-Sahel sector, that end up radiating more to space than what they absorb from the Sun, the surplus energy brought in aloft from the ITCZ.”
“The larger the difference between temperature-calculated surface LWIR flux and satellite-measured ToA LWIR flux, the greater the atmospheric radiative greenhouse warming effect on the surface.” – your quote.
Hi Kristian,
It’s a bit like the Song et al. 2016 paper (DOI: 10.1038/srep33315), people looking at the difference between surface flux and OLR. I don’t have a problem with that. But that is a lousy measure of the greenhouse effect anyway, because the absolute number yielded by that difference is dependent on ASR and the value of the radiative imbalance, as well as bulk atmospheric emissivity. A much better measure of the intensity of the greenhouse effect is the ratio of surface flux to OLR, which is dependent only on the bulk atmospheric emissivity.
Your observations on OLR are all that is required to show that albedo is the driving mechanism of the increased surface flux. I don’t see why you need to challenge basic greenhouse theory, as if you need to prove greenhouse theory wrong in order to demonstrate your OLR-theory is right. There is no need. All you need to do is show that the bulk atmospheric emissivity of the atmosphere has not increased over the satellite era. Can we do that? (Hint: yes).
Best regards