Guest Post by Willis Eschenbach
There is an interesting new study by Lauer et al. entitled “The Impact of Global Warming on Marine Boundary Layer Clouds over the Eastern Pacific—A Regional Model Study” [hereinafter Lauer10]. Anthony Watts has discussed some early issues with the paper here. The Lauer10 study has been controversial because it found that some marine stratocumulus clouds decrease with increasing warming. This is seen as an indication that (other things being equal) clouds are a net positive feedback, that they will amplify any warming and make it even warmer. This finding has engendered much discussion.
I want to do a different analysis. I want to provide a theoretical understanding of the Lauer10 findings. Figure 1 shows the larger picture, within which Lauer’s results make sense. This is the picture of part of the Earth as a solar-driven heat engine.
Figure 1. Very simplified picture of the main driving loop of the tropospheric circulation. A large counter-rotating cell (a “Hadley Cell”) of air exists on each side of the equator. Energy enters the system mostly around the equator. Thunderstorms (shown with rain) drive deep convection currents from the surface to the upper troposphere. Some of the energy is transferred horizontally by the Hadley Cells to the area at 30N/S. There, some the energy is radiated out to space. A large amount of the radiation occurs in the clear dry desert regions. Other parts of the atmospheric circulation not shown.
Lauer10 is discussing the low cloud decks found off the western edges of the continents at around 30°N/S, as illustrated in Fig. 1.
Considering the earth’s climate as a heat engine can lead us to interesting insights. First, we can see how the heat engine works. The thunderstorms in the wet tropics convert some of the incoming solar energy to work. The work consists in part of moving huge amounts of warm air vertically. In the process, most of the moisture is stripped out of the air, producing the rain shown in Fig. 1. After rising, some of this now-drier air travels polewards. It descends (subsides) in the region around 30° north and south of the Equator. This dry descending air forms the great desert belts of the planet. The air then returns equator-wards to repeat the cycle.
A closed system heat engine (like the climate) needs some form of radiator to cool the working fluid before it returns to be recycled through the engine. In the climate, the areas around 30°N/S serve as the main radiators for this loop of the atmospheric circulation. There, excess energy is radiated to space.
Now, here’s the theoretical question:
What would we expect to happen to this flow system if there is an increase in the temperature?
The Constructal Law says that in such a case, a flow system like the climate will rearrange itself to “speed up the wheel”. That is to say, it will change to increase the throughput of the system. The system reorganizes itself to increase the total of work plus turbulence.
How can the circulation shown in Fig. 1 become more efficient and increase its throughput? There are not a whole lot of control points in the system. The main control points are the clouds at both the hot and the cool ends of the heat engine.
The Constructal Law suggests that as the system warms, two things would happen. First, there would be an increase of cumulonimbus (thunderstorm) clouds at the equatorial end of the system. This would increase the speed and volume of the Hadley circulation. Next, there would be a decrease of clouds in the area around 30° latitude. This would increase the amount of radiation leaving the system. These changes would combine to increase the total throughput of the system.
In that light, let us re-consider the results of Lauer10. What they show is that as more heat passes through the system, as expected, the clouds at the radiator end of the system decrease. This increases the amount of energy that can pass through the system in a given time. In other words, they are an expected result of the system warming.
Lauer10 appears to discount this possibility when they say:
The radiative effect of low marine clouds is dominated by their contribution to the planetary albedo as their impact on outgoing longwave radiation is limited because of the small temperature difference between cloud tops and the underlying surface.
I found this doubtful for a number of reasons. First, the cloud top for marine stratiform clouds is typically at an altitude of ~600-700 metres, and the cloud bottom is at around 400-500 metres. The dry adiabatic lapse rate (cooling with increasing altitude in dry air) is about 1°C per hundred metres. This puts the cloud base at around five degrees C cooler than the surface. Then we have 200 metres at the wet adiabatic lapse rate, that’s about another degree. Total of six degrees cooler at the cloud tops.
The annual average surface temperature at 30°N is about 20°C, which puts the cloud tops at about 14°C. While this doesn’t seem like a lot, it gives a blackbody radiation difference of about 30 W/m2 … hardly a “limited” difference. Even if it is “only” half of that, 15 W/m2, that is the equivalent of four doublings of CO2.
Next, the strength of the solar contribution at 30° latitude is only about 60% of equatorial sunshine. This is due to the greater angle to the sun, plus the greater distance through the atmosphere, plus the inherent increase in albedo with decreasing solar angle.
Next, there is a fundamental difference between equatorial clouds (cumulus and cumulonimbus) and the stratocumulus decks of the area at 30° latitude. This difference is ignored by the averaging, with which climate science is unfortunately rife.
The problem is that the timing of clouds is often more important than the amount. Consider someplace in the tropics that has say eight hours of clouds per day. If those clouds are in the afternoon, the reflection of the sunlight will dominate the effect of the clouds on radiation. The clouds will cool the afternoon, as we all know from our common experience.
If that same eight hours of clouds occurs at night, however, the situation is reversed. Clouds are basically an impervious black body to outgoing longwave radiation. Because of this, they increase the downwelling LW when they are overhead. During the day this is usually more than offset by the reduction in solar radiation.
But at night there is no sun, so the effect of night-time clouds is almost always a warming. Again this is our common experience, as clear winter nights are almost always colder than winter nights with clouds.
However, all of this is obscured by the averaging. In both the day and night cases above, we have the exact same amount of clouds, eight hours per day. At night the cloud warms the earth, during the day the same cloud cools the earth, and averages can’t tell the difference.
The relevant difference between stratocumulus at 30° latitude and the equatorial clouds is that the equatorial clouds die out and vanish at night. This allows for free radiation from the surface. The stratocumulus deck, on the other hand, persists day and night. This means that it has much more effect on radiation than equatorial cloud.
Finally, I think that there is a fundamental misunderstanding in their claim that the maritime stratocumulus cloud “impact on outgoing longwave radiation is limited” because of the small temperature difference.
It is true that between the upwelling longwave from the surface and from the low clouds is about 10% (30W/m). The temperatures are not hugely dissimilar. But the internal energy flows are very different under the two conditions (clear and cloudy).
Consider a night-time hour with cloud. The cloud is radiating through clear dry air above to space at something like 370 W/m2. In addition, the cloud is radiating roughly the same amount back to the surface, something like 370 W/m2. Meanwhile, the ocean surface is radiating (losing) around 400 W/m2.
So the ocean loses 400 and gains 370 W/m2, so it is losing 30 W/m2 in this part of the transaction.
Now take away the cloud for an hour. The surface is still radiating something like 400 W/m2, this time out to space. So the authors of Lauer10 are correct, there’s not much change in outgoing LW, “only” 15 to 30 W/m2. But what they are neglecting is that the ocean is no longer receiving 370 W/m2 of LW from the cloud. Instead, above the ocean is mostly dry air, which provides little downwelling radiation to the surface. In this case the surface itself is losing about 400 W/m2.
So despite having identical energy flows to space, these two conditions have two very different net internal energy flows. When the sky is clear, the ocean is losing energy rapidly. When it is overcast with marine stratocumulus, the ocean loses energy much more slowly. The difference in ocean loss is 370 W/m2, which is a large difference. That is why I don’t agree that the clouds make little difference to the radiation balance. They make a big difference to net energy flows (into and out) of the ocean.
And why are oceanic net energy flows important to the outgoing radiation? It is the long-term balance of these flows across the ocean surface that determines the oceanic (and therefore the atmospheric) temperature. As a result, small sustained imbalances can cause gradual temperature shifts of the entire system.
I think I notice the problem because of my training as an accountant. A small difference in the amount of payments can mask a huge difference in the source of those funds. And a small amount of income or expense adds up over time.
My conclusions?
1. I think it quite possible that Lauer’s findings are correct, that increased warming in the area of the persistent marine stratiform layers at 30°N/S leads to decreased clouds in those areas.
2. I think that Lauer’s finding are an expected effect when we consider the Earth as a heat engine operating under the Constructal Law. With increasing heat, the Constructal Law says the system will adapt by increasing throughput. Reduced cloudiness at the cold end of the heat engine is an expected change in this regard, just as we expect (and find) increased cloudiness at the hot end of the heat engine with increasing heat.
3. Of course, for this study to truly be science I need to insert the obligatory boilerplate. So let me note that mine is a preliminary study, that “further investigation is warranted”, that I could use a big stack of funds to do just that, that I will require a personal assistant to undertake the onerous task of archiving a few datasets per year, and that Exxon has been most dilatory in their payment schedule …
FURTHER INFORMATION
Constructal Law and Climate (Adrian Bejan, PDF)
The constructal law of design and evolution in nature (Adrian Bejan, PDF)
A previous post of mine on Constructal Law and Flow Systems
The constructal law and the thermodynamics of flow systems with configuration (Adrian Bejan, PDF)
Addendum before posting. After writing the above, I noted today a new paper published in Science (behind a paywall) entitled Dynamical Response of the Tropical Pacific Ocean to Solar Forcing During the Early Holocene, Thomas M. Marchitto et al. It is discussing one of the geographical areas that Lauer10 analyzed, the eastern Pacific off of Mexico. The abstract says:
We present a high-resolution magnesium/calcium proxy record of Holocene sea surface temperature (SST) from off the west coast of Baja California Sur, Mexico, a region where interannual SST variability is dominated today by the influence of the El Niño–Southern Oscillation (ENSO). Temperatures were lowest during the early to middle Holocene, consistent with documented eastern equatorial Pacific cooling and numerical model simulations of orbital forcing into a La Niña–like state at that time. The early Holocene SSTs were also characterized by millennial-scale fluctuations that correlate with cosmogenic nuclide proxies of solar variability, with inferred solar minima corresponding to El Niño–like (warm) conditions, in apparent agreement with the theoretical “ocean dynamical thermostat” response of ENSO to exogenous radiative forcing.
In short, their study reports that when the ocean gets warmer at the equator, it gets cooler at 30°N, and vice versa. They also find that this effect is visible on annual through millennial timescales. Unsurprisingly, this is not found in the GCMs.
Intrigued by the idea of a “ocean dynamical thermostat”, I read on:
Values in the middle of this range are sufficient to force the intermediate- complexity Zebiak-Cane model of El Niño–Southern Oscillation (ENSO) dynamics into a more El Niño–like state during the Little Ice Age (A.D. ~1400 to 1850) (3), a response dubbed the “ocean dynamical thermostat” because negative (or positive) radiative forcing results in dynamical ocean warming (or cooling, respectively) of the eastern tropical Pacific (ETP) (4). This model prediction is supported by paleoclimatic proxy reconstructions over the past millennium (3, 5, 6). In contrast, fully coupled general circulation models (GCMs) lack a robust thermostat response because of an opposing tendency for the atmospheric circulation itself to strengthen under reduced radiative forcing (7).
Now, consider this finding in light of Figure 1. Yes, it is a simple “thermostat” in the sense that as the equator heats up, the area around 30°N/S cools.
But in the light of the climate heat engine it is much more than that. The Constructal Law says in response to increased forcing the climate system will respond by increasing throughput. One way to increase the throughput of a closed cycle heat engine is to cool the radiator.
And that is exactly what their “ocean dynamical thermostat” is doing. By cooling the radiator of the climate heat engine, the engine runs faster, and moves more heat from the tropics. Conversely, when the earth is cooler than usual, the engine runs slower, and less heat is transported from the tropics. This warms the tropics.
I started this by saying that I would provide a theoretical framework within which the Lauer10 findings would make sense. I believe I have done so. My theoretical results were strengthened by my subsequent finding that Marchitto et al. fits the same framework. However, this is only my understanding. Additions, subtractions, questions, falsifications, confusions, expansions, and just about anything but conflagrations gratefully accepted.
Finally, testable predictions lie at the heart of science, and they are scarce in climate science. If I am correct, the kind of study done by Lauer et al. of the persistent stratocumulus decks in e.g. the Eastern Pacific should reveal that in the observations, changes in night-time cloud cover are greater than changes in day-time cloud cover. My check from the Koch brothers must have gotten lost in the mail, so I don’t have the resources for such a study, but that is a testable prediction. It would certainly be a good and very easy direction for Lauer et al. to investigate, they have the records in hand. Here’s their chance to prove me wrong …
My regards to all,
w.
References and Notes for the above quotations from Marchitto et al.
3. M. E. Mann, M. A. Cane, S. E. Zebiak, A. Clement, J. Clim. 18, 447 (2005).
4. A. C. Clement, R. Seager, M. A. Cane, S. E. Zebiak, J. Clim. 9, 2190 (1996).
5. K. M. Cobb, C. D. Charles, H. Cheng, R. L. Edwards, Nature 424, 271 (2003).
6. M. E. Mann et al., Science 326, 1256 (2009).
7. G. A. Vecchi, A. Clement, B. J. Soden, Eos 89, 81 (2008).
PS – Both papers, one discussing the atmosphere and the other the ocean, explicitly note that this thermostatic effect is not correctly simulated by the climate models (GCMs). The Marchitto paper is very clear about exactly why. It is because of one of the most glaring and under-reported shortcomings of the models. Here’s Marchitto again, in case you didn’t catch it the first time through (emphasis mine):
In contrast, fully coupled general circulation models (GCMs) lack a robust thermostat response because of an opposing tendency for the atmospheric circulation itself to strengthen under reduced radiative forcing (7).
Say what? Model circulation strengthens under reduced forcing?
In a natural heat engine, when you add more heat, the heat engine speeds up. We can see this daily in the tropics. As the radiative forcing increases, more and more thunderstorms form, and the atmospheric circulation speeds up. It’s basic meteorology.
In the models, amazingly, as the radiative forcing increases, the atmospheric circulation actually slows down. I might have missed it, but I’ve never seen a modeller address this issue, and I’ve been looking for an explanation since the EOS paper came out. Although to be fair the modellers might have overlooked the problem, it’s far from the only elephant in the model room. But dang, it’s a big one, even among elephants.
So yeah, I can see why the models are missing the proper thermostatic feedback. If your model is so bad that modelled atmospheric circulation slows down when the forcing increases, anything’s possible.
OHD, it is geometry. 1368 W/m2 times pi*r^2 is the number of Watts intercepted, and is distributed over how many square meters of the earth’s surface, remembering the earth is rotating. This gives the average: Intercepted Watts over total surface area. How would you define an average any other way? What is the ratio of surface area to intercepting area?
OHD says:
This just means that you don’t understand it. Watts per m^2 means how many watts are incident on a square meter of surface. The orientation of that surface is surely relevant to how much radiative power is incident on it per square meter. Imagine taking a (thin) square plate 1 m by 1 m. If the normal of the plate surface directly faced the sun then you would have 1368 W hitting the plate and the intensity would be 1368 W/m^2. If you now start rotating the plate, then I think it is not hard to understand that less and less power from the sun would hit the plate because it is intercepting less and less of the sun’s energy. In fact, in the limit where you had turned the plate by 90deg, it would be intercepting almost none of the energy because it would just present toward the sun one of its thin edges, a surface that has an area of its thickness times 1 m. The only way for the number of Watts hitting that plate to decrease as you rotate it is if the intensity in W/m^2 on the 1 m^2 of surface goes down as you rotate it. In fact, the only way for it to be consistent is if you multiply the value you get when the surface is perpendicular by the factor cos(theta). If you average the value of cos(theta) over a hemispherical surface, you find the average value is 1/2. This is where the additional factor of 1/2 comes from that you are missing.
We are not taking about reflection or albedo. You are the only one who brought this up. We are talking about how much radiation from the sun the earth intercepts. And, it is you, not us, who are imagining that things on the earth influence the sun as my above example with the plate illustrates. We are the ones who have a consistent mathematical description of reality.
Joel Shore, irrespective of how much of your plate is facing the unrestricted sunlight – even if it is just 1 mm² – the intensity of the radiation would still be 1368 W m². If you do not have that figure or data (1368 W m²) you cannot work out anything that relates to it. One square millimetre (1mm²) then would intercept 1.368 W in total.
The “Global Energy Flows W m²” plan I was talking about states quite plainly “Incoming Solar Radiation 341.3 W m²” It says nothing about averages and for that reason if that plan was the only data reference available to you, then how would you work out how much solar radiation would interfere with say an Earth orbiting satellite? Or, as our moon’s distance from the Sun is very similar to that of the Earth, how would you work out its total surface irradiance?
And Jim D the figure of 342 as an average over total surface area is the same for any sphere with the same incoming solar radiation (1368 W m ²). Let us take one that is easy to work out i.e. its radius = 6 m: Πr² = 113.09734 = size of interception disc.
Ok so now we know the incoming solar radiation is 1368 W m² (not as the plan says 341.3) so, 1368×113.09734 = 154717.16 W total intercepted which is to be divided with surface area of globe i.e.
Area of global (spherical) surface: 4Πr² = 452.38934 > > 154717.16/ 452.38934 = 342 which corresponds quite well to the “341.3 W m² of Incoming Solar Radiation” described in the plan. A plan which pays no attention to the fact that only half the planet’s surface area is exposed to sunlight at any one time and the plan does not have to as it definitely says: “Incoming Solar Radiation 341.3 W m²”
People who make up these plans simply cannot keep on confusing “Total Watts received by the total surface area” with “Incoming Watts per Square meter (W m²)”
But then again, what kind of scientists made that plan up and why?
Sorry Joel, wrong calculus, – too hastily done. – One square mm would receive or intercept 0.001368 Watts total. – I was definitely wrong there.
Sorry ohd
the old books (1972) give the solar constant as 1940 cal. per minute per square cm
(100 cm= 1meter)
I am sure if you work it out correctly you must get to the 342 W/m2
OHD,
I think you agree now that 342 W/m2 is the correct number to describe an average incoming solar radiation over the surface of the earth during a day, which is the only number that matters for the long-term energy balance, and you seem to have just misinterpreted some wording in a document.
Not really the only number; the dynamics are crucial. Most of the effective incoming hits very directly in the tropics, and drives many phenomena there, ranging from the Diurnal Bulge (a huge heated swelling of the atmosphere that tracks the sun about 2 hrs lagged as the planet rotates), to violent storms, to massive evaporation, etc. OTOH, the polar circles get little incoming, and radiate the heat they receive from atmospheric and oceanic currents and circulation on a continuous basis. In the temperate zones, major swings of mostly incoming to mostly outgoing on daily and seasonal bases.
To claim that all of this is adequately covered with the 342W/m^2/annum “average” is scientific, physical, and statistical nonsense.
Yes Jim D, I spent some time yesterday and earlier today looking up some other similar plans and I came across one by Kiehl & Trenberth (1997) that states quite clearly that it is showing Global Average Energy Flows and as the different values are very similar to the ones posted here in wuwt by Willis Eschenbach under Anthony’s title “Knobs” – it must also be averages –
I shall just have to say to you and all the other guys who got involved: I am sorry if I have been coming across as an ignorant and pesky knob. I was wrong —. But, then again, on the positive side – I have learnt a lot.
OHD
Henry P
There is no longer any difficulty for me to work out the average incoming solar radiation. I have studied a lot these past few days and I have found out how these clever climate scientists do it: They take the Solar Constant (S) and divide it by 4 and there you’ve got it. In one scientific article I looked up yesterday I read:
“So to be able to compare “apples and oranges”, when climate scientists talk about energy balance and the climate system they usually convert radiation from the sun into the effective radiation averaged across the complete surface of the earth. – This is simply 1367/4 = 342.”
Note; in the quote above S = 1367 Wm²
Well I figured some time ago that seeing that a time factor is brought in, and earth only receives 12 hours daylight per day, you would have to divide by 2. The remaining amount is only true when you are exactly at the equator. Going up and down from the equator dimishes the amount of radiation because of the angle. I accepted that that there is mathematical formula for that: you just have to divide again by 2 to get to the average of 342 w/m2 of any place on earth. But it is good to remember how we got here: you can figure out easily which place on earth gets most of the sun’s heat…. More north and south gets much less energy.
Joel Shore says on December 13, 2010 at 5:44 pm
You are correct. I was confused.
However, I like to think of it this way. If the sun does not hit perpendicularly to the surface, then one square meter of the Earth’s surface intersects less than one square meter of the incoming solar radiation. The amount received by each square meter of the Earth’s surface goes as you say: TSI * cos(theta) where theta is the angle between the normal and the incoming radiation.
“The oblique angle doesn’t have anything to do with albedo.”
I can see how that must be so for the Earth as a whole all other things remaining equal.
However if one were to shift the clouds latitudinally without altering total cloud quantities (or other cloud characteristics) would those same clouds increase global albedo if placed nearer the equator and decrease global albedo if placed nearer the poles due to the changed angle of incidence onto the clouds of incoming solar energy ?
Stephen,
I didn’t mean to imply that there was no interesting interactions between obliquity and albedo. What I was saying was simply that getting the 342 W/m^2 average incoming solar radiation from the 1368 W/m^2 solar constant does not involve any consideration of albedo…It’s just geometry.
OHD, to your credit you came here to learn. Some come here just to argue, and it is hard to tell one from the other at first.
Stephen Wilde, the latitude makes a difference because 100 sq. km of clouds at the equator blocks more incoming solar radiation than at higher latitudes, just due to the subtended angle. The area that matters for albedo is that relative to the sun’s viewpoint. This is irrespective of any additional reflectance you might get from a non-normal incidence angle, which I would think is secondary to the subtended angle effect.
Jim and Joel,
Thanks for the confirmation.
I’m thinking that such latitudinal cloud shifting could well affect affect albedo more significantly than any other factor.
Such shifting seems to be intimately connected to the changes from MWP to LIA to date for example.
Much more likely to be the answer rather than the alternative cosmic ray effect from Svensmark. As the cloud bands shift equatorward the length of the interface between air masses would increase due to the greater circumference giving air mass mixing over larger areas and a significant increase in cloudiness quite apart from the increase in blocked energy so the combined effect could well be substantial.
I haven’t seen such an effect discussed or even acknowledged anywhere other than in myt own blog contributions.
Hi Stephen!
to be fair I did mention your theory also in my own blog
http://www.letterdash.com/HenryP/more-carbon-dioxide-is-ok-ok
Do you have a own blog? What is your blog’s address?
What I had not realised until now (I have OHD to thank for that), even though I had known about this, (it just slipped my mind)
is that apart from the greater surface area being covered by (the same amount) clouds in the equator region, the amount of solar radiation is much bigger between the +30 and -30 latitudes then say between +30 and +90.
After I settled on that figure of 342/m2 I forgot that it is an average figure.
So, obviously, if you can prove a correlation of sun cycle activity with the movement of clouds more towards the equator versus more towards the poles, that would have a huge impact on earth’s albedo and earth’s subsequent cooling or warming.
I now have to update my own blog again……
Hi Henry, I don’t have my own blog. I just operate as a guest contributor mainly at Climaterealists.com where I have my own section and as a contributor to other blogs of my own choosing.
As regards proving a link between solar cycle activity and latitudinal jetstream variability I think one just has to watch things for a little longer.
The response of the air circulation to the recent solar quietness and in particular the development of such an extreme negative AO at around the same time should be a wake up call to everyone.
There has to be a link between solar activity and the solar vortices which then translates into a top down effect on the tropospheric air pressure distribution to affect cloud band positioning.
Some members of the climate establishment are still in denial. They say that it is just a matter of greater meridional movement rather than a change in net latitudinal position but that doesn’t make the phenomenon go away. Even if it is ‘only’ a matter of increased meridionality the result is just the same, namely longer strings of cloudiness around the planet penetrating more equatorward than was seen during the late 20th century warming period of a more active sun with a significant effect on global albedo altering energy input to the oceans and skewing the relative balance between El Nino and La Nina.
It’s obvious to me too and the idea has been developing in my mind since I first noted that the trend towards decreased meridionality started to fade away from about 2000 after having first become noticeable in the mid 70s when that warming spell began.
I don’t believe the top down solar effect is the whole story however. The solar cycles 18 and 19 were even more powerful than cycles 21, 22 and 23 but the jets were still fairly meridional then. Thus I have proposed an opposing bottom up oceanic modulating effect which is itself to some extent independently variable.
I think the logic is sound and I just have to wait for observations to prove my point. No adequate past data exists to resolve the issue because the independent variability of sun and oceans breaks the correlations frequently enough to make the effect largely disappear in the coarseness of past mulitidecadal data and the high variability of short term datsa. Nonetheless the effect remains clear on longer timescales such as from MWP to LIA to date.
The scale of the change in solar behaviour just recently has been a godsend in that it is large and dramatic enough fot its effects to become obvious over and above short term chaotic variability and the effects of other climate forcing processes.
So the simple fact is that the globe switches periodically from net warming to net cooling in response to changes in solar activity changing global albedo via cloudband redistribution. Meanwhile semi independent oceanic variability operates on the cloud bands as well for a modulating effect that obscures the solar effect except on century long timescales.
Hope you guys keep going back to this blog, as I have got more to learn about these “Global Energy Flows W/m² Plans”. By now I have concluded that all the ones I have seen that show values in W/m² are derivatives from Trenberth et al. Those that have values in percentages seem to come directly from NASA or to be copies there off. – I could, of course be wrong. But that does not really matter. They all show more or less the same things.
Of course when they say “Incoming Radiation 100%” it is even more confusing to realise that they are still talking about an average.
And furthermore it was difficult, for me to accept that the average for the Earth is the same as it would be for a ping pong ball behaving like the Earth does, in the same orbit. But having thought about it – it is all proportionate –
As I said , I do have more questions about these plans, but they re going to take some time to formulate, so I hope you do not go away while I am pondering.. Thanks.
Now back to what, at the moment is my “Hobby Horse”. I.E. “The Global Energy Flow M m²” plan, or plans. One such plan has been used by the IPCC to explain the Earth’s energy budget, so it must have been ‘peer reviewed’ and a countless number of people, among them many scientists, must have studied it.
So, after reading this post, please look at it once more and if you can, please explain to me where I go wrong.
I wish I could reproduce the “Global Energy Flow M m²” plan here but I cannot do that so I shall have to write down the various values. Hope you will all bear with me.
The values given in the particular plan that was posted here earlier by Willis Eschenbach will be used:
Incoming Solar Radiation in (all in shortwave) = 341.3 (341) W m².
Reflected by clouds, atmosphere and surface totals 101.9 (102) W m².
Absorbed by Atmosphere = 78 W m².
Absorbed by Surface = 161 W m².
That is all the incoming radiation accounted for.
Then, the rules say, to put it briefly; “what comes in must go out” and right enough 101.9 (102) W m² has already been reflected as shortwave and outgoing radiation (longwave) from all sources adds up to 238.5 W m² and if we add on the 0.9 W m² which seem to be permanently absorbed by the surface (possibly to become fossil fuels), then there it is – all a neat and tidy equilibrium.
So far I think I have understood it -but then it becomes very “Untidy” because in the Atmosphere there is written “Greenhouse Gases”.
As the total surface absorption of 161 Wm² can only be balanced by radiation from
17 Wm² thermals + 80 Wm² from evapo-transpiration + 64 Wm² from which must be surface radiation we have 161 Wm² emitted by the surface, directly and indirectly absorbed into the atmosphere + the 78 W m² from the Sun. to account for atmospheric temperatures. But as said earlier “all that is re-radiated back into space.”
Out of these untidy “Greenhouse Gases”(GHG) comes 333 W m² as “Back Radiation” and some kind of a circuit between the surface and the GHG seems to have been set up where 356 W m² (accounting for the Atmospheric Window of 40 W m²) is being re-radiated – but as 64 + 97 + 78 W m² have already been counted out/back into space in the “Tidy” bit. – I am somewhat at a loss here -. However my big question(s) is (are) not why are 333 and not 292 or even 94.5 W m² being re-radiated but how come no back radiation is ever reflected and by what ‘natural law’ do greenhouse gases operate as they seem to be able to radiate in one direction only. – Always downwards – As I see it, if they radiate 333 W m² in one direction, down to the surface, which at best can be only 50%, then they must radiate at least that amount (333 W m²) in the other direction – back into space. But they do not. So where does that energy come from? And where is it going?
Has a perpetual heat engine been set up, or does the “Greenhouse Effect” not exist at all? – Or am I missing the “blatantly obvious”.
In whatever case, one would think radiation from “Greenhouse Gases” must -just like any other travel out in all direction from the source and therefore also back to space. In which case this planet is getting rid of more energy than it receives.
OHD,
Search for Trenberth Energy Diagram using Google. That adds it all up for you. You missed that the 239 going out includes 169 from the atmosphere so, yes, the atmosphere radiates in all directions. The net radiation effect in the atmosphere is cooling, so the surface heat and evaporation provide energy to the atmosphere to balance that.
Yes Jim D, I may not have used the number 169 but I did not miss the value of 169 W m². As my posting seemed long enough as it was I did not see the need to subtract or separate out the 30W/m² from clouds + the 40 W/m² from the atmospheric Window from the 239 just to add them on again later. All the incoming shortwave radiation (except the reflected energy) went back into space via the Atmosphere as longwave radiation whether or not it came from thermals, direct absorption, latent heat (evapo-transportation) or surface radiation. It was the extra energy (shortwave radiation) created by the “GHG” I had a problem with. If I had switched it around to be an exact replica of the said energy flow plan I would still have been left over with longwave radiation or Watts per m² to spare. And still there is no answers to my questions (I shall now make the questions more specific):
1) Where do the Greenhouse gases get the energy from to radiate 333 W/m² back into space as well as towards the Earth’s surface?
2) Where on the plan does it show that an extra 333 W/m² is being radiated out to space?
3) As the answer to the above question 2) is “Nowhere” then – what qualities do the Greenhouse gases possess to enables them to send radiation in one direction (towards the surface) only?
These 3 questions I can find no answers to in any Trenberth Energy Diagram
All I can find, so far when I Search for Trenberth Energy Diagram is The Science of Doom site and all they say –so far-is: “The third important number, solar radiation absorbed into the climate system = 239 W/m2
This is simply 342 * (100% – 30%). You see slightly different numbers like 236, 240 – all related to the challenges of accurate measurement of albedo.
Some of the radiation is absorbed in the atmosphere, and the rest into the land and oceans.”
So that is easier still 341-30% = 238.7 But that does not answer my questions.
333 W/m² from back radiation must be directed one half towards the surface and the other half must be directed towards space. ( My reason for Question 2)
OHD,
Only 239 has to be radiated to space to balance the incoming total.
333 goes towards earth. The sum of these is supplied by the other arrows.
Did you look at the diagram? There is no reason the same amount has to go up as down. The top of the atmosphere is colder so it radiates less upwards than the bottom radiates downwards.
I think when considering the green house effect, what I think is often overlooked is that during the day water is evaporated. During the night or when the vapor gets colder, due to whatever reasons, most of that water vapor condenses again. When it condenses, it releases about 40 kJ per mole (=18 gr).
like I said, I am not sure, but logic would tell me that that heat is radiated in a circle around the molecules. That means 50% back to space and 50% to earth. I think it is this 50% back to earth that provides a large portion of the green house effect.
Jim D, you say: “Only 239 has to be radiated to space to balance the incoming total.”
Yes of course, that’s what I am saying too and I would even go further and say that that is all that can be radiated back to space.
You can be sure I am looking at the diagram which is right in front of me as I am writing this. The right hand arrow shows that there are an extra 333 W/m²
which have been generated somehow somewhere among the Greenhouse Gases and then are sent back to the surface as longwave Back Radiation.
I wanted an answer as to why radiation from these greenhouse gases do not radiate equally in all directions; i.e. 333 W/m² down towards the surface and therefore also 333 W/m² in all other directions, i.e. out to space?
Then the next arrow shows 396 W/m² total radiation leaving the surface. This total must, I assume, be composed from an absorbed/converted shortwave radiation of 64 W/m², which is left from absorbed shortwave after thermals and latent heat have been taken out + 333 W/m² from GHG. (We are not going to argue about 1 W/m ² as the discrepancy may be mathematical and due to “decimal exchanges”
A short way up on the right hand side of that arrow there is an Atmospheric Window where 40 W/m² bypasses the Greenhouse Gases which I can only assume is due to the length of radiation wave bands and must therefore all come from the converted shortwave radiation. But that only means that the 333 W/m² were created or generated from only 50 + 27 W/m² in the first place. How is it possible to create 333 W/m² from 77W/m²? – I have read somewhere that it is not supposed to be possible to create or to destroy energy.
Then you go on to say: “There is no reason the same amount has to go up as down.” Well, I have always been under the impression that there is a natural law about that as well which says something like this: “radiation is emitted equally in all direction from its source” Is that not a good enough reason, or am I wrong there as well?
And lastly you say: “The top of the atmosphere is colder so it radiates less upwards than the bottom radiates downwards.
That does not seem to bother the 239 W/m² part of shortwave radiation nor should it make any difference to the 333 W/m² part of radiation from an “all around back Radiation” nor to the other 356 W/m² of Surface Radiation. Yes, I know 64 W/m² out of that has already been counted into the 169 W/m² radiated back to space, but so has everything else that has been absorbed by the atmosphere. (78 +17+80+64= 239)