Be sure to read Part 1 first, now …
DEFINING THE rGHE THROUGH THE ERL.
How is the rGHE defined in the most basic way? If you have a planet with a massive atmosphere, the strength of its “greenhouse effect” is defined as the difference between its apparent planetary temperature in space and the physical mean global temperature of its actual, solid surface. The planet’s apparent temperature in space is derived simply from its average radiant flux to space, not from any real measured temperature. It is assumed that the planet is in relative radiative equilibrium with its sun, so is – over a certain cycle – radiating out the same total amount of energy as it absorbs.
If we apply this definition to Venus, we find that the strength of its rGHE is [737-232=] 505 K. Earth’s is [288-255=] 33 K.
The averaged planetary flux to space is conceptually seen as originating from a hypothetical blackbody “surface” or ‘radiating level’ somewhere inside the planetary system, tied specifically to a calculated emission temperature. This level can be viewed as the ‘average depth of upward radiation’ or the ‘apparent emitting surface’ of the planet as seen from space. Normally it is termed the ERL (‘effective radiating level’) or EEH (‘effective emission height’).
The idea behind the ERL is pretty straightforward, but does it accord with reality? The apparent planetary temperature of Venus in space is 231-232K, based on its average radiant flux, 163 W/m2. Likewise, Earth’s apparent planetary temperature in space is 255K, from its mean flux of 239 W/m2. In both of these cases, the planetary output is assumed to match its input (from the Sun), so one ‘simple’ method one could use to derive the apparent temperature of a planet is by taking the TSI (“solar constant”) at the planet’s (or moon’s) particular distance from the Sun, and multiply it with 1 – α, its estimated global (Bond) albedo, a number that’s always <1, finally dividing by 4 to cover the whole spherical surface. Determining the average global albedo is clearly the main challenge when going by this method. The most common value provided for Venus is 0.75, for Earth 0.296.
But does the resulting value really say anything about the actual planetary temperature? If the planet absorbs a mean radiant flux (net SW) below its ToA, then how this flux affects the overall system temperature very much depends on the system’s total bulk heat capacity. If it is large, the flux will have little effect, if it’s small, the flux will have a bigger effect.
Either way, what one tends to assume is that the planetary system needs to warm (that is, store up solar energy) until it has attained a temperature high enough for it to emit the same amount of energy per unit time as it absorbs: heat IN = heat OUT.
And in one way, this is of course correct.
The problem is to determine where this ideal ’emitting temperature’ is to be found. This is where the concept of the ERL comes in. And it is very much a ‘concept’ rather than a real ‘thing’. A planet’s energy budget, its heat balance with its surroundings (sun/space), isn’t really in itself tied to any single temperature. It only really concerns how much energy enters and thus how much energy needs to be expelled. It is only us humans and our mathematical devices that apparently feel the need to turn these fluxes or amounts of energy into specifically defined temperatures. We simply understand the concept of ‘temperature’ better than we understand the concept of ‘energy’. We feel temperatures, not energy. Temperatures are concrete, energy is abstract.
So we average the total amounts of energy exchanged into mean transfers, power density fluxes. We take all the energy and divide it by time and area and get a useful and easy-to-handle value: J/s/m2. The nice thing is, we can then enter this value into the Stefan-Boltzmann equation, describing the relationship between the surface temperature of an object and the potential thermal emission from that surface as a result of that temperature. And the operation of course works equally well both ways. One can just as easily find the object’s surface temperature from knowing the intensity of its thermal radiance. But, we will have to average …
So if we estimate that Venus at dynamic equilibrium with the Sun emits an average flux to space of 163 W/m2, then, without much ado, we can derive its apparent planetary temperature in space to be 231.5K. Perfoming the same calculation on Earth gives an apparent emitting temperature of 255K.
But what do these calculated temperatures actually signify? What are they? Are they real? Or are they just mathematical constructs?
Unless they can be connected directly to a global, isothermal blackbody surface somewhere within the planetary system, they are not real. They are just hypothetical quantities.
WHY IS THE rGHE ERL RAISED? WHAT IS IT SUPPOSED TO DO?
According to the rGHE hypothesis, a planet’s effective radiating level to space is lifted off the actual surface of that planet and into the massive atmosphere above it because this atmosphere, being IR-active, intercepts some of its thermal radiation meant for space, absorbing it down low and emitting it as its own from cooler air layers up high. The atmosphere is simply seen as the shell around the central sphere in Willis Eschenbach’s ‘Steel Greenhouse’ model. Before the atmosphere (the shell) is introduced, the planet’s (the central sphere’s) effective emitting surface to space coincides with its own. It both absorbs and emits the entire radiant flux from its heat source (the Sun) at its actual surface: 240 W/m2 IN, 240 W/m2 OUT. This is the lunar situation.
Then, as the atmosphere/shell is put in place around the planet/sphere, the planet is no longer directly connected with its surroundings. The atmosphere intervenes. It is basically ‘in the way’, the extended system’s new effective emitting surface to space. The central planet’s outward flux is now absorbed by the atmosphere, warming the atmosphere. The point is, the atmosphere needs to warm like this up to the point where it is able to emit an amount of energy per unit time to space to match the incoming flux from the Sun to the total system. Since the atmosphere is now the extended planetary system’s new effective emitting surface, absorbing the planet’s energy on the inside and emitting its own energy to space on the outside, and the system as a whole is still absorbing the same amount of energy from its heat source, the Sun, it follows that this balance is only reached at the point where the atmospheric temperature matches the planetary surface temperature before the atmosphere was emplaced.
So how is this supposed to work? The basic premise goes like this: The solid surface can only radiate one way – up. The atmosphere, on the other hand, absorbs only from below, but emits both up and down. Up to space and back down to the surface; the famous (or infamous) atmospheric “back radiation” or DWLWIR.
So if the shell, the atmosphere, absorbs 240 W/m2 from the planetary surface below, it emits only half to space (120 W/m2); the other half is recycled, back down to the surface it goes. So how can the ‘outer’ surface of the atmosphere shell warm so that it ends up radiating the 240 required W/m2 to space all by itself?
This is where we enter the warming stage of the rGHE-concocted internal amplifying radiative transfer loop of the atmosphere/surface system. The atmosphere is always returning half the flux from the surface, in turn feeding the atmosphere with ever more energy, until the ‘net’ flux between them equilibrates at 240 W/m2:
Energy absorbed by the surface (sun+atm) ⇒ sfc UWLWIR ≻ ≺ atm DWLWIR = Net LWsfc-atm
240 ⇒ 240 ≻ ≺ 120 = 120
240+120 ⇒ 360 ≻ ≺ 180 = 180
240+180 ⇒ 420 ≻ ≺ 210 = 210
240+210 ⇒ 450 ≻ ≺ 225 = 225
240+225 ⇒ 465 ≻ ≺ 232.5 = 232.5
240+232.5 ⇒ 472.5 ≻ ≺ 236.25 = 236.25
240+236.25 ⇒ 476.25 ≻ ≺ 238.125 = 238.125
240+238.125 ⇒ 478.125 ≻ ≺ 239.0625 = 239.0625
240+239.0625 ⇒ 479.0625 ≻ ≺ 239.53125 = 239.53125
In the new steady state, the sphere/planet, the old emitting surface to space, from an elevated temperature of 303.3K, emits 480 W/m2 to the atmosphere, the new emitting surface to space. At this time, the atmosphere emits 240 W/m2 down to the surface, but also significantly up (out) to space, from an equilibrated temperature of 255K.
As you can gather from this, the steady state ERL temperature is achieved by the parallel warming of the surface and the atmosphere, and the warming of the surface (and thereby of the atmosphere) is accomplished not by the reduced flux from the new extended system to space, but directly by the addition of more and more “back radiation” from the warming (absorbing/emitting) atmosphere.
The upshot: The ‘raised ERL’ model of the rGHE mechanism for ‘extra’ surface warming turns out to be nothing more than another and simply a bit more convoluted version of the “heating by back radiation” narrative.
When it comes down to it, you cannot get the surface to warm some more – the rGHE way – by any other means than increasing the atmospheric “back radiation”.
This is what the concept of the (raised) ERL is ultimately all about. The atmosphere absorbs IR from the surface. Hence it also emits IR back down to it. Warming it. It isn’t really about the upward radiation through the ToA at all. It’s about the downward radiation to the surface. Guy Callendar’s original “sky radiation” idea.
It’s this funny diagram all over again:
Figure 1. (Derived from Stephens et al. 2012.)
TWO DIFFERING VIEWS ON HOW TO ATTAIN A THERMAL EQUILIBRIUM
The imagined ‘internal amplifying radiative transfer loop’ of the rGHE hypothesis is actually just a misconstrued version of the real-world situation.
There simply is no continuous radiative transfer of energy going on inside the atmosphere, looping up and down and back and forth, warming in all directions, getting bigger with each cycle, during the energy buildup towards the new steady state.
There is only a storing up of internal energy. As in any real-world, warming thermodynamic system.
This is the key to understanding: There’s a distinct difference between energy being statically accumulated inside a warming thermodynamic system and energy being dynamically transferred between thermodynamic systems.
If you don’t get this distinction, you won’t understand what’s going on.
What the rGHE hypothesis is essentially saying is that, in the new steady state, the solar flux is finally once again given a free pass all through the system: Conceptually, 240 W/m2 come in to the surface, warming it; the 240 W/m2 then move out from the surface, cooling it back, and is absorbed by the atmosphere, warming it; the 240 W/m2 then finally move out from the atmosphere, cooling it back, and ends up in space, where it originally came from. The overall temperature at this stage will thus not change. It warms as the Sun shines, and cools back down when the Sun’s out of sight.
The point is that, in addition to this lossless ride of the solar heat through the Earth system, there is now a continuously (and constant) cycling loop of radiative energy transfer up and down between the surface and the atmosphere, absolutely necessary to maintain the steady-state temperatures enabling this equilibrated situation to last. This transfer loop, in the steady state, is really a zero-sum game*, but that doesn’t mean it can be removed in any way. If it’s removed, then the entire Earth system will freeze cold.
*480 W/m2 up from the sfc, of which 240 go straight to space (the ‘solar flux’ part) and 240 to the atm, after which the atm returns those 240 back to the sfc, adding it to its 240 W/m2 in from the Sun and enabling it to emit 480 W/m2 up to space and the atmosphere in combination. In this way, 240 W/m2 always moves up and down between the sfc and the atm, while at the same time an equal flux always escapes to space:
Figure 2.
The thing is, the orange internal atmospheric radiation loop in Figure 2 doesn’t really exist. It’s purely a figment of someone’s imagination. What exists is rather the statically stored ‘internal energy’ held within the thermal mass of the atmosphere system, giving it its steady-state temperature (and temperature distribution). There is no continuous thermodynamic zero-sum transfer game of radiative energy back and forth between the surface and atmosphere, keeping the temperatures up.
What the ‘radiationers’ perceive as the cause of the steady-state temperatures (the necessary, eternally cycling radiative transfer loop), is really just an apparent effect of those steady-state temperatures (actually caused simply by the storing up of ‘internal energy’). ‘Thermal radiation’ is called thermal radiation because it is the result of warmth, of temperature, not because it causes that warmth or temperature.
OUR PLANETARY NEIGHBOURS IN SPACE
We have talked about the apparent and/or potential ERL-driven rGHEs on Venus and Earth. We have yet to discuss Mars.
While Venus carries an enormously massive atmosphere, Earth’s is much more moderate in mass, density and pressure. Still, when compared to the Martian atmosphere, ours can practically be considered Venusian. Consider surface air pressure and density on the three neigbouring planets:
VENUS ……. sfc air pressure: 92 bar (92x) ………….. sfc air density: 66.5 kg/m3 (54.5x)
EARTH ……. sfc air pressure: 1 bar …………………….. sfc air density: 1.225 kg/m3
MARS ……… sfc air pressure: 0.0063 bar (/158) ….. sfc air density: 0.02 kg/m3 (/61.3)
So in a way, Earth’s atmosphere can be considered to be centred somewhere around the median point on a mass continuum between two extreme cases, the incredibly dense and heavy one on the one end and the incredibly thin and light one on the other.
VENUS
The apparent radiatively/rGHE-driven ERL on Venus (and on Earth) is in actual fact an illusion. When comparing Venus and Earth directly, we soon realise how the strictly radiative story of the Venusian atmosphere is first and foremost one about depriving the planetary system and its different levels, significantly the surface, of solar heat, and that it is simply the enormous mass of the Venusian atmosphere, making it so much denser and deeper than Earth’s, that forces the low pressure/density/temperature levels much higher up above the solid surface:
Figure 3. A crude schematic comparing the overall planetary systems of Venus (a)) and Earth (b)) and their main heat fluxes IN/OUT. Note in b) that Earth’s lower, solid line tropopause is the global average one (at 12 km and 200 mb), while the upper, dashed line tropopause is the Hadley-cell (tropical/subtropical) one (at 16-17 km and 100 mb). What you will notice is how the ‘average depth of atmospheric upward LW radiation’ (the ERL) – the lowermost end of the orange arrows – on Venus is located at/around the actual tropopause, made up of a thick blanket of clouds, while on Earth it is located much further down, deep within the airy troposphere, a difference thought to reflect the general levels of atmospheric IR-opacity of the two planets. At the same time, you will observe how the Venusian atmophere reflects and absorbs nearly all of the incoming radiant heat from the Sun (the yellow arrows), preventing 97.4% of the potential solar heat input from ever reaching the actual, solid surface at the bottom, while Earth’s atmosphere, on the other hand, does the same to only a moderate extent (preventing 44.4%). The final point to bear in mind is how much higher above the surface you need to go on Venus (60-64 km) to get to the 200-100 mb level (the tropopause) than on Earth, a reflection of the monstrous mass of the Venusian atmosphere compared to Earth’s, putting a 92,000 mb pressure on the surface where Earth’s atmosphere merely exerts a thousand (1013 mb on average).
If the Venusian atmosphere had the same mass as Earth’s, if Venus received the same solar input as Earth and its troposphere had the same lapse rate, then its troposphere would climb up to the 200 mb level (like on Earth and ‘real’ Venus), at initially the same altitude (~12 km) above the surface (same mass and assuming same tropospheric temperature and ignoring differences in chemical composition, like heavy CO2 (Venus) vs. light H2O (Earth)), and from there on up to ~50 mb would be the thick, global, isothermal tropopause cloud layer, practically emitting the planet’s entire flux to space. However, the required flux to put out would be much smaller than Earth’s, because the same cloud layer would also reflect a much larger portion of the incoming solar:
Figure 4. a) The radiative/convective situation on ‘terrestrial’ Venus (an atmosphere having the same general level of EMR-activity as ‘real’ Venus, but the mass of Earth’s atmosphere). At Earth’s distance from the Sun (1AU), 341 W/m2 comes in to ‘terrestrial’ Venus. Its atmosphere then reflects 67-68% of the incoming solar radiation (as compared to ‘real’ Venus: 75% (Figure 3)), letting only 110 W/m2 through, and proceeds to absorb 60% of the remaining downward flux (as compared to ‘real’ Venus: 90%), so that the actual, solid surface only receives 44 W/m2 of solar heat for it to absorb. Since ‘terrestrial’ Venus’s atmosphere is almost completely made up of CO2 (like on ‘real’ Venus), it can only absorb upward surface IR within its specific, pressure-broadened spectral bands. Meaning a lot will go straight through. This freely escaping surface IR, will not reach straight to space, though. It will move up to the haze or cloud layers high up in the troposphere, absorbed by these instead. Three things to notice when comparing ‘terrestrial’ Venus in a) with Earth in b): 1) The required LW output from the Earth system is 2.2 times as big as the Venusian one (240 vs. 110 W/m2); 2) the Venusian atmosphere being a ‘cloud emitter’ and Earth’s being an ‘air emitter’ means that the latter will have to collect its aggregate flux from a much deeper part of the atmospheric column, on Venus, everything from below is ultimately captured by the cloud lid at the top; 3) on Earth, the surface absorbs 165 W/m2 worth of solar heat, nearly four times as much as the surface of ‘terrestrial’ Venus, whereas a mere 24 W/m2 are shed by non-radiative processes on Venus (basically, conduction>convection), a flux 4-5 times as weak as the equivalent one on Earth, but exactly the same as Earth’s conductive loss. Either way, nothing in this setup points to any particular radiative effects forcing the surface of ‘terrestrial’ Venus to be warmer than Earth’s.
Which leads us to the titanic mass of the Venusian atmosphere. Its mechanism for surface warming will be revealed a bit further on. First, our other planetary neighbour, the small, red one …
MARS
What, then, goes on on a planet with a tenuous atmosphere such as the Martian one, where the gas molecules are relatively few and far apart?
I’ll cut right to the chase: The mean global surface temperature of Mars, according to the ‘Thermal Emission Spectrometer’ (TES) instrument aboard the ‘Mars Global Surveyor’ (MGS), and so now generally accepted by NASA, is ~210-211K (based on multiple-year measurements with no real trend observed, albeit slight interannual differences). Its central estimate is corroborated by the overlapping and succeeding investigations of the ‘Mars Climate Sounder’ (MCS) spectrometer aboard the ‘Mars Reconnaissance Orbiter’ (MRO), plus in situ surface measurements from various landers like Viking 1 and 2 and Pathfinder.
Since the mean TSI (“solar constant”) at Mars’s average distance from the Sun (1.52 AU) is ~587 W/m2 and the Red Planet’s mean global albedo appears to be ~0.235 (TES gives 0.232, MCS 0.239), this means the absorbed solar flux at the ToA would be ~112.3 W/m2 (equivalent to Earth’s 239 W/m2), which would again be associated with a planetary blackbody temperature in space (equivalent to Earth’s 255K) of … ~210-211K.
Now isn’t that quite an astounding coincidence!?
Mars’s ‘effective/apparent planetary emission temperature in space’ happens to be exactly equal to its ‘physical surface temperature’.
Recalling the rGHE equation:
Tsfc = Terl + (Γ*H). For Mars, this gives: 210K = 210K + (2.5 K/km * 0 km)!
The planetary ‘effective radiating level’ on Mars is coincident with the actual, solid planetary surface. It appears not to be raised one single metre off the ground!
How can this be?
Mars does after all possess a massive atmosphere lying on top of its solar-heated surface. It’s not impressively massive in any way, a mere 25 teratonnes where Earth’s is 5148. But it’s still there. And most importantly, it is significantly IR-active, made up of ~96% CO2. It does absorb outgoing radiation from the ground.
In fact, the Martian atmosphere contains a lot more CO2 than Earth’s atmosphere does. Each cubic metre of atmosphere above each square metre of Martian surface holds ~28 ~26 times (!) as many CO2 molecules as does a similar volume over a similar area on Earth. This would be equal to 10,400 ppm in our atmosphere, or 1.04% of it. Which is quite comparable to Earth’s average global atmospheric boundary layer content of all IR-active substances, mainly including water.
So how come our ERL is (allegedly) lifted 5-6 kilometers up in the air, while Mars’s stays firmly on the ground, when the total IR-opacity of the two atmospheres are in fact rather similar? Yes, water clearly absorbs wider across the EMR spectrum than what CO2 does, so Earth’s atmosphere would effectively be more IR-opaque than Mars’s. But that doesn’t explain why the Martian ERL apparently isn’t raised at all.
What makes the whole difference is of course the overall mass, the total molecular density of the atmosphere. Regardless of the specific content of actually IR-active constituents …
On Mars it is quite easy to show how silly the whole ERL concept really is. Because on Mars, the atmospheric IR window stands pretty wide open, the only significant absorber being CO2 (although aerosols/dust and the few tiny clouds do contribute):
Figure 5. Left diagram: From Bandfield et al. 2013 (Figure 1); Right diagrams: From Pierrehumbert 2011 (Figure 3b), caption stating: “The panel to the left shows a summer-afternoon emission spectrum for Mars observed by the TES instrument on the Mars Global Surveyor. Its accompanying temperature profile was obtained from radio-occultation measurements corresponding to similar conditions. (…) squiggly arrows on the temperature profiles indicate the range of altitudes from which IR escapes to space.”
I’ll exemplify how silly it might get.
Let’s assume that, of the incoming solar flux below the ToA (112 W/m2), about 15 are absorbed by the atmosphere and its dust particles. This leaves 97 W/m2 of incoming heat to be absorbed by the surface. So the surface also has 97 W/m2 to shed, as total heat.
Well, the surface holds a mean temp of 210-211K, so emits an UWLWIR ‘flux’ (its S-B-calculated radiance) of 112 W/m2. Of this, ~75 W/m2 is directly lost to space through the atmospheric window. Looks more like 95 W/m2 from the spectras in Figure 5? I agree. But let’s ignore that for now. Hopefully, you’ll see where I’m going with this.
The Martian surface absorbs a solar flux of 97 W/m2. It then emits 75 of these straight back out to space. The surface also loses some heat to the massive atmosphere above by way of conduction>convection; let’s assume it amounts to an average of 10 W/m2. This leaves [97-75-10=] 12 W/m2 to be transferred as radiant heat from the surface to the atmosphere.
97 IN, [75+12+10=] 97 OUT. Heat balance.
What, then, about atmospheric “back radiation”? Well, the surface, from its temperature (210-211K), emits 112 W/m2, but only [75+12=] 87 of them escape as radiant heat, so one would expect the atmosphere to make up the balance by providing a DWLWIR ‘flux’ of [112-87=] 25 W/m2. This way, the surface ends up absorbing a total radiant input of [97+25=] 122 W/m2, which is handled by emitting back out 112 W/m2 and losing the final 10 through non-radiative processes.
[97+25=] 122 IN, [112+10=] 122 OUT. Energy balance.
But what now of the atmosphere’s budget?
The atmosphere absorbs 15 W/m2 directly from the incoming solar, 10 via conduction>convection from the surface, and 12 through radiant heat transfer from the surface, a total of [15+10+12*=] 37 W/m2 (*UWLWIR 37 – DWLWIR 25). Since the surface, as we saw above, emits 75 of the system’s required aggregate flux of 112 W/m2 to space, it rests upon the atmosphere to shed the remaining heat, meaning, just those 37 W/m2.
But from where exactly? From what level? Or levels? Is this level (or are these levels) determined by the atmospheric IR-opacity? Or by its temperature? Or by both? Or by something else entirely?
Let the silliness begin.
The atmosphere absorbs heat from three different sources: 1) from solar SW radiation, 2) from surface LW radiation, and 3) from surface conduction>convection. Originally, three separate ‘batches’ of energy.
So, how high up must the energy transferred from the surface via conduction>convection (the 10 W/m2) go before it can be emitted to space?
If we follow ERL logic, it cannot escape until it has reached an altitude of ~38 km above the surface, the air layer holding an average temperature of 115K (assuming a Martian mean global environmental lapse rate of 2.5 K/km). One can only assume this is because the IR-opacity of the atmosphere won’t allow it to escape any sooner. Even though it’s 10 W/m2 already from the start, when moving out of the relatively ‘warm’ surface …
What about the 15 W/m2 in from the Sun? 33.2 km. The 12 W/m2 from surface LW? 36 km.
Does this make any sense? Or do we have to add all three batches together first and only then decide? 15+12+10= 37 W/m2. This is what (in this particular setup) the Martian atmosphere actually emits to space, after all.
So, does that mean the ERL is really situated about 20.4 km above the planetary surface?
If this were true, then Mars’s apparent temperature in space would be 150K rather than ~210-211. It’s not.
We might try to argue that the 150K is the apparent temperature of the Martian atmosphere, not of the planet as a whole.
But then we’re no longer talking about the planetary ‘effective radiating level’, the actual ERL as defined, are we? That’s the solid surface, after all, there’s no question about it. We’re only talking about the ‘average (or apparent) depth and temperature of atmospheric upward radiation’. Based solely on the Stefan-Boltzmann connection. We don’t know if this is physically the average depth of radiation. We only assume it to be so from our understanding/interpretation of the temperature-radiance relationship of blackbody surfaces. 37 W/m2 is simply the amount of energy the Martian atmosphere has to put out to space. And that’s all there is.
But how come the elevated ‘average depth and temperature of atmospheric upward radiation’ doesn’t raise in the least the solid surface temperature above the apparent planetary temperature on Mars? How come the fact that some of the surface IR is absorbed by the Martian atmosphere still doesn’t do anything at all in terms of forcing the surface temperature to be higher than the overall planetary one?
THOSE are the questions I would like for you to focus on. Because THOSE are the key to ulocking the mystery! The mystery of what really forces surface temps: atmospheric mass or radiation?
Let me give you a couple of clues:
From UniverseToday.com (June 2008): “Temperature of Mars”
“Mars follows a highly elliptical orbit, so temperatures vary quite a bit as the planet travels around the Sun. Since Mars has an axial tilt similar to Earth’s (25.19 for Mars and 26.27 for Earth), the planet has seasons as well. Add to that a thin atmosphere and you can see why the planet is unable to retain heat. The Martian atmosphere is over 96% carbon dioxide. If the planet had an atmosphere to retain heat, the carbon dioxide would cause a greenhouse effect that would heat Mars to jungle like temperatures.”
From Space.com (Aug 2012): “What is the Temperature of Mars?”
“Mars’s atmosphere is about 100 times thinner than Earth’s. Without a “thermal blanket,” Mars can’t retain any heat energy.“
(My bold.)
The first quote is the ‘funniest’. Author Jerry Coffey can’t seem to connect the dots of his own observations: Mars has such a thin atmosphere that it can barely retain any heat. This makes the Martian surface cold. The exceedingly thin atmosphere, however, is made up of 96% CO2. So if only the atmosphere were much thicker than it is, enabling it to retain heat (like the atmosperes of Earth and Venus), then the CO2 would all of a sudden cause the surface of Mars to heat! So not the acquired atmospheric thickness itself. Not its newfound ability to retain heat. No, its content of CO2 specifically, which already in its thin state is up to 96% (and thus 26 times the absolute concentration of Earth’s atmosphere!), but which is then apparently unable to heat anything. For some odd reason …
A classic example of the kind of mental contortions of self-deception that a steadfast ‘radiationer’ will perform in order to make his expected reality fit with reality itself. The never-ending effort to reduce his constantly recurring cognitive dissonance.
Tim Sharp at Space.com keeps it more honest. At least in what he writes.
The reason why there is no apparent raised ERL and hence no rGHE, as defined, on Mars, the reason why its atmosphere cannot radiatively raise its surface temperature above the planetary one, is very simple: The atmosphere is way too thin. It can barely retain any heat.
It doesn’t matter if 96% of it is CO2. It can do nothing as long as the bulk of the atmosphere remains as rarefied as it is.
Which naturally raises the question: If the atmosphere got thicker and the surface of Mars grew warmer as a result, would it then be the radiative properties of its CO2 molecules that caused the extra heating? Even though they apparently do nothing in the present state …
Think about it, and consider this:
THE (REAL) MECHANISM EXPLAINED
What will normally happen in Earth’s relatively dense IR-active atmosphere is the following (a crude, general description):
A CO2 molecule – for instance – in the near-surface air absorbs a 15 μm wavelength IR photon from the surface, is excited from having its energy content boosted, but collides almost immediately with a nitrogen (N2) or oxygen (O2) molecule, giving up its newly gained surplus energy to this one by conduction. In other words, it doesn’t get to reemit this energy in the form of another photon to fall back to its former state. It rather passes it on conductively by collision.
The denser the air, the harder it will be for the CO2 molecule to reemit rather than pass on the absorbed energy conductively, meaning, the higher the ratio of gained energy lost by molecular collisions to that lost by reemission events.
The N2 and O2 molecules (making up 99% of our bulk atmosphere) thus statistically ending up with this extra energy transferred from the surface, will help to maintain the overall temperature of the atmosphere by moving a little bit faster. They need to do this, because at the same time higher up the air column, other molecules are moving a little bit slower from losing energy to space. However, there is no balance to be obtained from air molecules moving faster and faster down low (from absorbing heat from the surface, the ‘hot reservoir’) and molecules moving slower and slower up high (from emitting heat to space, the ‘cold reservoir’), if there is no natural process to connect the two levels. Then the temperature difference between them would simply grow ever larger, the gradient from hot to cold ever steeper. A highly unstable situation that could never be sustained (simply not tolerated) within a massive volume of gas subjected to gravity and heated from below.
No, what will happen is of course this: The warmed air down low will become less dense (from the faster-moving molecules) and float up spontaneously to higher levels through natural buoyancy to equilibrate with its surrounding air masses, automatically keeping the steady temperature gradient in place. Likewise, only the other way around, the cooled air up high will become more dense (from the slower-moving molecules) and spontaneously start to subside in order to equilibrate at lower levels. In this way, the layers of air up through the column is always sure to be replaced (too warm by cooler, and too cool by warmer), the constant organised circulation or ‘turnover’ of air masses in the troposphere ensuring the stable distribution of energy and hence temperature from top to bottom. Radiative processes simply work to stimulate this natural turnover circulation, keeping it running smoothly and stably (through a net ‘warming’ tendency down low, and a net ‘cooling’ tendency up high).
In this way, the excess energy from the surface is certain to always ‘leak’ upward through the troposphere by the movement of the heated air itself.
High up in the atmosphere, the air density is much lower. In fact, already at 5 km up the atmospheric column, the air density is reduced to 60% of the surface value. At 10 km, it’s down to a third, and at 15 km the air is no more than ~15% as dense as it is at the surface. (Also, the air up there is colder, so the gas molecules travel more slowly through space.) This means that the CO2 molecules do not collide with other air molecules as often as further down, which means their chances of emitting in the form of a photon any surplus energy it might possess or acquire are better.
Most of the energy transferred from the surface (or the Sun) to the atmosphere as heat, is ultimately held by N2 and O2 molecules (ending there by way of diffusion/conduction), but since these molecules are not themselves able to effectively release this energy to space in the form of radiation, thus also letting the atmosphere cool back from the original absorption, they have to transfer their surplus energy (once again by way of collisions) to the actual IR-active constituents of the atmosphere, like CO2 (and, much more importantly, H2O), in order for these to do the job and rid the extended Earth system of it. This process is easier to accomplish the higher up the air column (down the pressure/density gradient) you get, for the reason mentioned just above.
What is the corollary of this?
Moving from the initial to the final (steady) state of warming, what the solid surface needs to do is feed and thereby fill the massive atmosphere above it with (internal) energy, up to the point where the atmosphere, functioning as the now extended planetary system’s new effective emitting surface to space, is able to radiate away as much heat as what the total system originally absorbed from the Sun.
* * *
I must once again stress the distinction between what is perceived (by the ‘radiationers’) as a continuous output of thermal radiation associated solely with the specific temperature of the air, and the temperature of the air itself. You can only ever tranfer energy away from a system in dynamic thermal equilibrium that at some point earlier has been transferred to it. What is radiated from the atmosphere (to space) is simply the energy previously absorbed from the Sun by the planetary system. The radiative output from the surface/atmosphere system to space is ONLY to match the solar input; no more, no less. The temperature of the system is related ONLY to its static content of internal energy. The only quantities acting as dynamic transfers to/from the system is the incoming ‘net SW’ and the resulting outgoing LW (‘OLR’) at the ToA. And that’s it.
Conceptually, one can view the ‘Sun>surface>atmosphere>space system’ as a grand energy conveyor belt, with solar SW radiation as the heat input (Qin) to the heating end (sfc), convection as the transporter of Earth’s resulting internal energy (U) from heating end to cooling end, and finally terrestrial LW radiation as the heat output (Qout) from the cooling end (tropopause).
Imagine an open tank brimful of water. This tank with all its water would represent our steady-state atmosphere and all its stored-up internal energy (enduing it with a steady-state temperature and temperature distribution).
If we were to connect a pipe to the bottom of the tank and open the valve to let the pipe supply the tank with, say, 240 new litres of water every minute (4 l/s), this would be equivalent to our Sun supplying our planetary system (conceptually via the solid surface) with an average energy (heat) input of 240 W/m2.
Where would the water added at the bottom go? It would become part of the total volume of water contained within the tank. However, at the same time, the tank would also necessarily – being brimful – overflow by the exact same amount of water from the top. The new bottom water would ‘push’ the old top water out. In this way, the total volume would never change, the outflow would always match the inflow.
This is effectively what goes on in our atmosphere in the steady state as well. As new heat from the Sun is added from the bottom of the atmosphere, the whole convective air column above shifts upward, ‘pushing out’ the exact same amount of heat from the top. In between is only the (rather slow) bulk movement of internal energy. The energy is always there, stored up, but it is never released to space unless there’s an extra ‘heat push’ from below.* Heat IN > gained (‘new’) internal energy at the bottom replacing lost (‘old’) internal energy at the top > heat OUT. A conveyor belt.
*No, energy released during the night is not energy released independently of an extra ‘heat push’ from below. The output simply always lags the input, the response is extended rather than direct (2+0 = 1+1 rather than 2+0 = 2+0), the terrestrial LW intensity can never match the daytime solar heat, but is more consistent, spread out in time, so still manages to expend the original gain over a full cycle.
* * *
So, at what point will the surface/atmosphere system stabilise (equilibrate)? At what time is enough energy ‘filling’ the system? In what state, in what condition or configuration will as much heat as what comes in be able to be emitted out as well?
The troposphere, the lowermost part of the atmosphere, in direct thermal contact with the solar-heated surface, inflates, its outer edge (the tropopause) lifting (it can move in no other direction) through the upward propagation of surface heat by bulk air movement. As this occurs, the troposphere is warmed and expands thermally, stretching the air column so that both the pressure and the density gradients become gentler, the scale height (H) would increase, meaning you would have to go higher from one specified pressure or density level to one reduced by a factor of ~2.72 (e). To provide some examples: If the surface temperature of Titan (Saturn’s largest moon, and the only moon in the solar system with a substantial atmosphere) happened to rise from its actual 94K to Earth’s 288, then its scale height would increase from 20.5 to almost 63 km! That is, you would all of a sudden have to move 63 rather than 20.5 km up into the atmospheric column, from the 1.47 1470 mb surface pressure, to reach the 541 mb level. On Venus, if you went from its actual surface temp of 737K to Earth’s 288, its scale height would drop from 15.8 to below 6.2 km, so even if the surface air pressure remained at 92 bar, the 34 bar level (first scale height) would be located almost 9 km closer to the ground.
If the Earth’s global surface cooled to 210K, then its first scale height (1013 – 373 mb) would go down from ~8.4 to 6.1 km, its second (373 – 137 mb) from 6.8 to below 5 km. In other words, rather than being ~15.2 km above the surface*, the atmospheric 137 mb pressure level would be located slightly above 11, more than 4 kilometres further down the column.
*In reality, Earth’s 137 mb pressure level is at ~14.2 km, not 15.2; the calculation above is after all pretty crude, not taking into account how the scale height changes with every increment of ascent, not just from one scale height to the next. The principle stands, though.
So how come Earth’s global surface isn’t at 210K rather than 288? If the tropopause itself stays at the same pressure level anyway, only further down?
Simply because in this state, the air column from surface to tropopause would be far too compressed. Just as much atmospheric mass would be contained between the two levels in the 210K scenario as in the 288 one, but would fill a vastly smaller volume. The air pressure (and density) gradient(s) would necessarily be quite a bit steeper in the cold scenario than in the warm. And the air density would increase significantly all the way from the surface to the tropopause, the root of its steeper exponential curve shifted to the right on the x-axis.
This situation would be an intolerable one; unstable and unsteady. The original solar heat could not be radiated away at an adequate level of efficiency from the Earth system (energy would still escape by radiation to space from every atmospheric layer, of course; just not at the required rate).
The system would have to warm in order to stretch the tropospheric column back out. Why? Because of the relatively high mean (column aggregate) frequency of molecular collisions preventing the absorbed surface heat from escaping in sufficient amounts per unit time by radiation to space, keeping it rather ‘locked away’ as molecular KE inside the conductive/convective thermal mass of the troposphere.
There will be a balance struck in this regard between gravity, atmospheric mass (pressure/density), atmospheric composition (molecular size), and temperature, sorting out the tropopause height in between them. Compositionally defined degree of IR-opacity does not enter this equation. A massive atmosphere is an IR-active one. If it weren’t, it couldn’t get rid of its absorbed heat.
Robinson and Catling (2014) has found an interesting relationship between the average tropopause height on planets/moons in our solar system possessing massive atmospheres and the atmospheric pressure at that height:
Figure 6. (Robinson & Catling’s Figure 1.)
This diagram suggests that this fairly narrow and strangely common general tropopause range (50-200 mb) is no coincidence at all. It happens to be centred around somewhat of a ‘universal’ atmospheric balance point between convection and radiation, establishing itself as high as the surface heat (or solar heat absorbed at depth) of a planet with a substantially massive atmosphere will need to go or be brought for it to be finally and adequately radiated to space, irrespective of the specific level of IR-opacity of this atmosphere as defined by the concentration of its actually IR-active species, rather depending simply on the overall pressure/density/temperature of the bulk air. What gives the atmosphere, or layers therein, their real IR-opacity is simply their total molecular density (directly associated (along with temperature) with the rate of molecule collisions).
Let’s just quickly relate this to Earth and to our two next-door sister planets, Venus and Mars.
At the 180-200 mb level in the atmosphere of Venus (~61 km) and Earth (~12 km), there is quite exactly the same amount of molecules in a cubic metre of air, although the terrestrial ones, being lighter than the Venusian ones, move a bit faster (even if the air at that level is actually colder, 235 K on Venus, 210 on Earth), while the Venusian ones (CO2) are bigger than the terrestrial ones (N2 and O2).
The crucial difference between Venus and Earth, though, is simply that, on Venus, the ideal atmospheric air density levels (60-65 km) consist of (is completely filled by) thick, nearly impenetrable and all-covering cloud layers, on Earth (10-15 km) mostly of pure air with only scattered clouds here and there. A dense, constant, global cloud blanket such as the Venusian one, being a fairly effective broadband (black/gray body) emitter, is able to radiate almost the entire planetary flux to space all by itself from a relatively shallow atmospheric stratum, quite closely related, in fact, to its physical temperature. There is no coincidence in the main Venusian cloud layers being situated where they are. Their height is an equilibrated one.
A single shallow layer of air is not itself capable of radiating the full flux of a cloud deck, even at the same temperature. Hence, an ‘air-emitting atmosphere’ needs to collect its aggregate flux from a far thicker portion of the column than what a ‘cloud-emitting atmosphere’ has to. This is in effect the difference between Venus and Earth (and Mars).
Finally, what about Mars?
On Mars, even the surface air density (and pressure) is way lower than the required value(s) for an effective planetary emitting “surface”. Still, that doesn’t mean the atmosphere isn’t radiating, that it can’t emit radiation to space. It does so all the way from the surface and several tens of kilometres up the column. After all, surface (and solar) heat is transferred to it, both radiatively and non-radiatively, so it naturally also has to get rid of it somehow. The tenuous Martian atmosphere radiating just doesn’t work to raise the apparent planetary emitting level (and thus temperature) off the ground, that’s the thing …
WHAT A LOAD OF EXTRA ATMOSPHERIC MASS WILL DO
Figure 7.
In Figure 7 we have doubled Earth’s atmospheric mass (a)), without changing its average degree of EMR-activity at all (still ~0.5%), to compare it with ‘real’ Earth (b)).
What will happen?
The two Earths are located at the same distance from the Sun, their rotation periods and their axial tilts are equal, their mean global tropospheric lapse rates are also set to be the same, considering that both planets’ gravity, atmospheric specific heat and release rate and distribution of latent heat from water condensing in the air column are also assumed to be the same.
The only difference is in the total mass of their atmospheres. At the planetary surface, the atmospheric pressure is doubled in Earth a). Its surface air density is also initially twice as high as on Earth b), but this could change with the temperature (thermal pressure). As you will observe, the tropospheric column in a), containing exactly two times as much atmospheric mass as column b), is far from twice as high in the initial state. In fact, while column b) is 12 km high (from the solid surface at 1000 mb to the global average tropopause at 200 mb), column a) is ‘only’ 4-5 km higher (from the solid surface at 2000 mb to the global average tropopause at 200 mb), quite exactly as high as the Hadley-cell (tropical/subtropical) tropopause on our present Earth. The reason for this is simply that both atmospheric pressure and density fall off exponentially, not linearly.
The solar input is the same, but the total reflectivity of the doubled atmosphere planetary system in a) will likely go up a little bit (potentially more layers of clouds). Also, the doubled atmosphere will likely absorb more of the ‘SW net’ down from the ToA, having a deeper column with a denser lower troposphere and more layers of cloud. It’s hard to appraise the exact amount, but it probably wouldn’t be a lot more, considering a substantial part would already be absorbed in the upper two thirds of the column, significantly by clouds (and ozone even above the tropopause). As you can see from Figure 7, I’ve increased the reflected portion from 101 to 111 W/m2 (global albedo up from 29.6 to 32.6%) and the atmospherically absorbed portion from 75 to 95 W/m2 (from 31.3 to 41.3%).
This means that the global surface of Earth a) on average absorbs a solar heat flux of 135 rather than one of 165 W/m2 (b)), and 230 W/m2 are what needs to go out to space through the ToA rather than 240.
Next stage: Getting the heat back out.
Doubling the mass, pressure and density of an atmosphere has implications for its IR absorption/emission profile. The surface thermal radiation will be absorbed across a shallower layer down towards the ground, which means less heat will move out from the surface in the form of radiant loss. At the same time, the LW emissions to space will be able to accumulate from a deeper column, so that the ERL will most likely be situated a bit farther below the tropopause on Earth a) than on Earth b).
In the end, though, these things will not matter all that much. What matters most is the extended depth of atmosphere that the doubled mass naturally provides. From the 200 mb level (the tropopause) and 12 km down, the pressure, air density and IR-opacity of the two columns are more or less identical and proceed along the same exponential course, assuming equal temperatures.
If you look once more at the two scenarios in Figure 7 above, you should be able to appreciate from this what will have to be the end result. The more massive atmosphere still has to get its surface heat up to the atmospheric pressure/density/IR-opacity levels from where it can be effectively radiated to space. This is still the upper two thirds of the tropospheric column, from the tropopause at 200 mb and maybe 10 km down. But since this section of atmosphere is now located much higher above the surface, and since the lapse rate is still the same, this will inevitably force the average surface temperature to rise significantly.
If the 249-250 K level in column b), its ‘average depth of upward radiation’ (ERL), corresponding to a BB emission flux to space of 220 W/m2 (the total atmospheric flux, added to the sfc atm window flux of ~20 W/m2) is at around 5.8-6 km above the ground, then the 247-248 K level in column a), its ERL, corresponding to a BB emission flux of ~213 W/m2 (atm flux + sfc atm window flux of ~17 W/m2), situated about a kilometre further down from the tropopause than in column b), would still be at around 9.5 km above the surface. Extrapolating the normal lapse rate down from this level would give an average surface temperature of [(9.5 * 6.5) + 247.5 =] ~309.5 K.* Compare this to the global average in Scenario b): 288K. That’s a 21.5 degree increase!
* * *
*It is important here to point out how it is the surface that warms first. It warms (solar energy accumulates) as long as it cannot get its heat out (convectively) as fast as it comes in (radiatively). It thus needs to warm the atmosphere above to thermally inflate and stretch it, up to the point where a radiative/convective equilibrium is achieved and able to be maintained. The radiative/convective equilibrium is what keeps the average tropospheric temperature gradient aligned with the adiabatic lapse rate in a dynamic steady state. Radiation heats at the bottom and cools at the top of the atmospheric column, so is working towards steepening the gradient. Convection counteracts this tendency, lowering the gradient back down, by moving heat from the heating end at the bottom (cooling it) to the cooling end at the top (warming it). Convection is simply tasked with bringing the surface heat from the planet’s ‘old’ emitting surface (the actual, solid one) to the ‘new’ at the top of the tropospheric column. The two contrary processes of radiation and convection thus find a balance in a so-called ‘radiative-convective equilibrium’, making sure that the observed average of the ever-fluctuating environmental lapse rate corresponds to the ideal, hypothetical adiabatic lapse rate, on Earth, 6.5 K/km.
Now, there are a couple of requirements for this particular balance to be found and maintained:
- The convective engine, bringing the energy from the heating (absorbing) end to the cooling (emitting) end, up through the troposphere, needs to be at a certain level of efficiency.
- The radiative cooling from the top of the troposphere (top of convection, really) also needs to be at a certain level of efficiency.
These two points are required in order for the extended planetary system to balance its (solar) input with its overall output. As much heat per unit time must exit as what enters. This is true for the system as a whole, but also significantly for the surface itself. The two are tightly connected.
But it is always the surface that warms or cools first! The troposphere just follows …
* * *
So, how would the surface heat budgets look?
On Earth b), at 288K, there is 165 W/m2 of incoming from the Sun, and 53 (radiant) + 112 (conductive+evaporative) W/m2 of outgoing terrestrial heat.
On Earth a), at 309.5K, there is 135 W/m2 of incoming from the Sun, perhaps ~35 W/m2 of radiant heat loss (significantly reduced from Scenario b)), and about 100 W/m2 of non-radiative heat loss.
What is worth noting here is that, although there is less heat moving out of the global surface via non-radiative processes on Earth a) than on Earth b), even with a considerably higher mean surface temperature, this is not a point of inconsistency. It’s an effect fairly easily attributed to the substantial increase in atmospheric pressure/weight and density at the surface, making it harder for the convective engine to run at sufficient speed (see previous post). A stronger ‘driving force’ is required to ‘push’ the surface heat out and up.
Remember now that the Venusian atmosphere is not 2x the mass of Earth’s, but 92x …!
Does this mean the massive atmosphere of Mars does nothing to force its solar-heated surface to be warmer than if the atmosphere weren’t there? Not quite. There is one more effect caused by the mass of an atmosphere that raises the average surface temperature of a planet: The evening out of temperature amplitudes. This effect is potentially larger than what you might at first think. It occurs also on Earth and Venus. In fact, the effect is much bigger there than on Mars, simply because their atmospheres are more massive. The pattern is pretty consistent:
Moon: no atmosphere – huge spatio-temporal temp swings > Mars: light atmosphere – pretty large swings > Earth: moderately massive atmosphere – moderate swings > Venus: extremely massive atmosphere – practically no swings.
The larger its surface temperature amplitudes, the colder a body can be on average and still maintain a radiative equilibrium between input and output. Courtesy of the ^4 exponential relationship between radiative output and temperature. When a surface fluctuates between being very hot and very cold, it radiates so much during the hot periods (or from the hot regions) that it can remain in the cold for a longer period of time (and keep larger areas cold) and still balance its budget. Hence, its average temperature drops.
Temperature swings (or spatio-temporal differences, rather) enable the surface of the body to put out more radiation than what its physical temperature average would suggest. The larger the differences (in space and time), the more it puts out relative to its mean temp. The Moon, for instance, puts out 3.5 times as much LW to space from its global surface over a year as what its actual average global temperature of 197K would imply.
What a massive atmosphere does, then, in more ways than one, is cutting down these amplitudes. It basically reduces the heating rates during the day and the cooling rates during the night. In addition, it spreads (circulates) the heat from warmer regions to cooler ones.
Cutting down the amplitudes means elevating the average global/annual surface temperature. In other words, Mars would be a colder world – on average – without its atmosphere, because its temperature swings would be even much larger than they are (closer to the lunar range).
Summing up:
The difference between the apparent planetary temperature in space and the average global temperature of the planet’s physical surface, is 505K on Venus, 33K on Earth and 0K on Mars. The more massive the atmosphere, the higher up the conceptual ERL (the effective planetary emitting “surface”) is pushed. On Mars it isn’t pushed up at all, because the air density already at the surface is low enough for the solar heat to escape to space at an adequate pace. On Earth, we have to move a few kilometres up to reach such levels, and on Venus we have to climb a few tens of kilometres.
It’s all really straightforward:
- The more mass in an atmosphere, the deeper its air column, and the higher up you need to go to find sufficiently thin layers of air. Hence, the ‘massive’ ERL is pushed up. Pulling the average surface temp up along with it …
Okulær 
Wow!
You really did a lot of work on this one.
I will have to read this a few more times to apriciate all the good work
Yes, the “atmospheric radiative greenhouse effect” is a harder idea to refute than what one would perhaps think. Because it’s so tightly coupled at all levels with the real warming mechanism. One simply tends to confuse the ‘mass’ effect with a ‘radiation’ effect. But the atmospheric mass is the actual force, the atmosphere’s radiative properties but a tool, one means to an end.
I have been explaining this at my own site and on multiple blogs for several years now.
Your narrative can be improved IMHO by mentioning that there is a separate adiabatic energy loop between surface and atmosphere which maintains hydrostatic equilibrium for an atmosphere suspended off the surface against gravity.
The ‘extra’ 33K above S-B is trapped at the surface in a constant conductive / convective energy exchange between surface and atmosphere and never gets out to space whilst incoming solar energy gets its free pass straight through the system.
Here is something that I have previously posted elsewhere. A bit long but highly relevant:
1. The ultimate defining error in the purely radiative theory of gases is a failure to recognise that for gases which are free to organise themselves along a density gradient within a gravitational field the amount of photon emission at a given temperature declines with gas density.
The reason is that conduction via collisional activity increases with density and as conduction increases so photon emission declines.
The same packet of kinetic energy cannot be both radiated and conducted at the same time.
Thus a surface at 288k at equilibrium with insolation and overlain by the mass of an atmosphere at 1 bar pressure will only emit photons at a rate commensurate with a temperature of 255k.
The other 33k is permanently trapped in a constant exchange of energy between molecules at that surface by way of conduction and convection.
The Dry Adiabatic Lapse Rate traces the decline in photon emission as compared to conduction as one goes deeper into the mass of a gaseous atmosphere.
At thermal equilibrium every molecule at the same height has a balance between conduction to its neighbours and conduction from its neighbours which is why they are all at the same temperature at that height. That is the point of hydrostatic balance where the upward pressure gradient force created by kinetic energy at the surface is equal to the downward gravitational force.
Only ‘ surplus’ kinetic energy is permitted to flow up or down by photonic emission which is why only 255k escapes from the top of Earth’s atmosphere.
If a molecules moves higher then photonic emission to space increases relative to conductive energy transfer and the molecule cools to a temperature commensurate with others at the same height.
If a molecule falls lower then photonic emission declines relative to conductive energy transfer and the molecule warms to a temperature commensurate with others at the same height.
Conventional accounts describe the reduction in the proportion of conductive energy transfer with height as the creation of potential energy because the process is reversible on descent so that potential energy can become sensible energy again during descent.
Let’s apply the above principles to the 15u emissions reduction in outgoing longwave radiation from surface to space.
CO2 molecules undoubtedly absorb and emit at the wavelength of 15u but there can only be net absorption of photons by a CO2 molecule that is below the height of hydrostatic equilibrium. If a molecule is at the correct height along the lapse rate slope for its ambient temperature then its ration of photonic energy emission or absorption is saturated. It can neither absorb more nor emit more photons because conduction to and from surrounding molecules has achieved its maximum rate at that temperature and mass density.
The remaining (photonic )portion of its energy transmission activity is accounted for by equal emission and absorption of photons.
Hydrostatic balance, by definition, involves conduction in and out being in balance at the same time as radiation in and out is in balance.
Therefore, at that point of hydrostatic balance radiation flows straight through from surface to space without interruption.
In effect, insolation at 255K gets a free pass straight through an atmosphere which is in hydrostatic equilibrium.
I first proposed that free pass concept in another article several years ago.
Since an atmosphere is densest at lower levels most 15u absorption by CO2 molecules is carried out by CO2 below the height of hydrostatic balance provided such CO2 molecules are too cool for their height along the lapse rate slope and are thus free to accept additional photonic energy. That is why the gap in emissions exists. 15u emission to space is reduced by CO2 absorption to a lower level than the rest of the wavelengths escaping to space.
That creates a potential imbalance in the overall hydrostatic balance around the absorbing CO2 molecule so convection increases speed to compensate.
The absorbed 15u wavelength disappears into potential energy which is invisible to thermal sensors but because the speed of convection has increased the surface becomes a fraction cooler as energy conducted from the surface is taken up faster than required for thermal equilibrium.
That 15u then reappears as sensible energy again at the surface beneath the nearest column of descending air and warms the surface back up to the original temperature.
Once back at the surface that kinetic energy is then free to radiate upward at the entire range of wavelengths and so can then escape to space.
Thus the proposed warming effect of CO2 has been cancelled by the convective adjustment.
The speed of convective overturning will always alter to the extent necessary to prevent radiative gases from changing surface temperature.
Bear in mind that since the whole process is based on mass rather than radiation we could never measure the miniscule changes in the rate of convective overturning from GHGs alone especially considering the huge variations caused by solar and oceanic cycles of activity.
As regards the matter of back radiation, note that increasing density towards the surface progressively reduces the amount of photonic emission so every time a photon travels down and is reabsorbed it becomes less likely to emit another photon downward because conduction increasingly takes energy out.
The net effect for the atmosphere as a whole is that back radiation from GHGs is dissipated into conduction before it reaches the surface.
Instead, the energy that would have been in the form of back radiation goes into the ascending convective column as potential energy and reappears at the surface again as kinetic energy beneath the nearest descending convective column.
That resolves the discrepancy between the standard Trenberth diagram and my proposals previously published elsewhere.
The kinetic energy that returns to the surface in adiabatic convective descent is exactly the same energy that Trenberth et al wrongly thought was returning to the surface via back radiation.
Stephen, thank you for your interest.
We do not agree on your adiabatic loop thing (the alleged return (?) of KE to the surface). Or on what an ‘adiabatic loop’ is in the first place. Or a simple ‘adiabatic process‘ for that matter. And I surely will not discuss it here now with you on my own blog. We will just have to agree to disagree on these issues, for I will obviously never convince you and you will definitely never convince me.
“This diagram suggests that this fairly narrow and strangely common general tropopause range (50-200 mb) is no coincidence at all. It is as high as the surface heat (or solar heat absorbed at depth) of a planet with a substantially massive atmosphere will need to be brought for it to be adequately radiated to space, irrespective of the specific level of IR-opacity of this atmosphere as defined by the concentration of its actually IR-active species, rather depending simply on the overall pressure/density/temperature of the bulk air. What gives the atmosphere, or layers therein, their real IR-opacity is simply their total molecular density (directly associated (along with temperature) with the rate of molecule collisions).”
Exactly right:
http://www.newclimatemodel.com/the-gas-constant-as-the-global-thermostat/
The same conclusion has been reached over at the hockey schtick:
http://hockeyschtick.blogspot.co.uk/2015/02/how-pressure-dependent-atmospheric.html?showComment=1424607553566#c6973546116993416760
I’ve been promulgating the same view since 2008:
http://www.newclimatemodel.com/greenhouse-confusion-resolved/
“It is that interruption in the flow of radiant energy in and out which gives rise to a warming effect. The warming effect is a single persistent phenomenon linked to the density of the atmosphere and not the composition. Once the appropriate planetary temperature increase has been set by the delay in transmission through the atmosphere then equilibrium is restored between radiant energy in and radiant energy out.”
and see here:
Click to access mae578_lecture_06.pdf
The radiative theorists have simply ignored established science relating to non radiative energy transfers.
One by one the various commentators are moving towards realisation and I commend Kristian for getting this far despite past disagreement with me over a detail or two.
Stephen, this is my point: It is not as simple as what the guy writing the HockeySchtick article makes it out to be. If it were, I wouldn’t have had to write these two posts at all.
The hidden point in this is that you have a reasonable explanaition for why some planets dont have an atmosphere.
Since planets are supposed to form the same way its always been a puzzle why some have an atmosphere and others not.
After a first reading of the last two posts, I think we are in substantial agreement but I would word it differently. (perhaps not as well as you — don’t know)
I can not see any “back-radiation warming” for various reasons. One reason is that the CO2 molecule is almost certainly going to give up its energy in a collision before it can radiate just as you point out. But what about in the upper atmosphere? There the CO2 molecule has a chance to radiate a photon out to space and also downwards. But what chance does the downwards photon have of reaching the surface anyway? And if it did, it would not warm the surface.
Long ago I concluded that it must be the mass of the atmosphere, the force of gravity, along with conduction/convection/advection that is the driving force of the planetary temperature.
I am led to believe that if I could magically double the force of gravity on this planet that the average temperature would rise.
I also am led believe that if I could magically raise CO2 levels substantially that nothing would happen.
I will re-read your two posts and see if I missed anything. (almost certain I probably did) 🙂
Thanks for your efforts ~ Mark
Mark,
I thank you for your patience. It has taken time to get here, I know.
As I told Stephen above, the reason it has taken such time is because the problem is actually not an easy one to solve. It is not as straightforward as Postma and others try to make it.
You say:
“I can not see any “back-radiation warming” for various reasons. One reason is that the CO2 molecule is almost certainly going to give up its energy in a collision before it can radiate just as you point out. But what about in the upper atmosphere? There the CO2 molecule has a chance to radiate a photon out to space and also downwards. But what chance does the downwards photon have of reaching the surface anyway? And if it did, it would not warm the surface.”
There isn’t any “back-radiation warming”. Because “back radiation” isn’t a distinct physical (thermodynamic) entity to begin with. It’s an apparent effect of atmospheric temperature.
However, the atmosphere being (much) warmer, thicker and weighing much heavier on the surface than space DOES force the solar-heated surface to be warmer on average than if the atmosphere weren’t there. This is a simple MASS insulating effect, not a radiation effect.
“I am led to believe that if I could magically double the force of gravity on this planet that the average temperature would rise.”
Most likely, yes.
“I also am led believe that if I could magically raise CO2 levels substantially that nothing would happen.”
Clearly not from any radiative effects, at least …
Kristian,
I’m certainly happy to agree to disagree since there is more we agree on than not.
Nevertheless, I would urge you to be clearer on how you think the mass effect works if there are no radiative gases.
If you have something better than my adiabatic loop then I’d be happy to discuss it with you if you are willing to do so.
Stephen, you say: “I would urge you to be clearer on how you think the mass effect works if there are no radiative gases.”
It doesn’t work if there are no radiative gases. On the other hand, there can be no massive atmosphere with no radiative gases. As explained in Part 1.
If there can be no atmosphere without radiative gases then it is a radiative effect and not a mass effect contrary to your contention.
What you are suggesting is that no solid material on a planetary surface could enter its gas phase without radiative gases already being present to cause it to convert from a solid to a gas.
Isn’t that an obvious contradiction ?
All one needs to make a solid convert to a gas is the correct amount of insolation to raise it to the temperature at which it changes phase to a gas.
Once it is a gas then there will inevitably be uneven surface heating around the sphere with densitry differentials in the horizontal plane and consequent convection.
Once you have any convection it moves mass both up and down equally and there you have the atmosphere in place.
No GHGs needed.
“If there can be no atmosphere without radiative gases then it is a radiative effect and not a mass effect contrary to your contention.”
Stephen. Read Part 1. If you have already done so, you need to read it again. It is specifically NOT a radiative effect. The EFFECT is massive. But radiative properties are essential as a TOOL for the atmospheric mass to cause the effect.
I’ve read Part 1 in some detail.
What you skate over is how to put a gaseous atmosphere there in the first place.
A gaseous atmosphere forms when solids at a surface are heated to a point where they phase change to a gas.
Only insolation or internally generated heat is required for that and not pre existing radiative gases.
Only continuing heat is required to keep the gaseous atmosphere aloft so as to avoid it cooling to a point where the phase change reverses.
GHGs are not required.
“A gaseous atmosphere forms when solids at a surface are heated to a point where they phase change to a gas.
Only insolation or internally generated heat is required for that and not pre existing radiative gases.”
And I’m not claiming that. Why do you assume I think radiative gases are needed for solids/liquids to change into gas? What does this have to do with anything?
“Only continuing heat is required to keep the gaseous atmosphere aloft so as to avoid it cooling to a point where the phase change reverses.
GHGs are not required.”
Yes, they are required for the surface-heated atmosphere to be able to cool to space.
I assumed that you think radiative gases are needed for solids/liquids to change to a gas because you said that without radiative gases there could be no ‘massive’ atmosphere. By ‘massive’ I assume you mean an atmosphere comprised of mass rather than a particulartly large or dense atmosphere.
Anyway,why does the surface heated atmosphere need to cool radiatively to space when it cools in any event from expansion with height ?
Furthermore that (adiabatic) cooling with height lowers the temperature which reduces radiation to space from any GHGs that might be present.
If there are no GHGs then rising air cools exactly as much as falling air warms and all radiation to space is achieved from the surface.
There is still a surface temperature enhancement above S-B because the convective overturning requires a store of kinetic energy (heat) at the surface to sustain it.
“I assumed that you think radiative gases are needed for solids/liquids to change to a gas because you said that without radiative gases there could be no ‘massive’ atmosphere.”
Huh!? If you have indeed read Part 1, then I fear you have gravely misunderstood it, Stephen. What I said was: “(…) there can be no massive atmosphere with no radiative gases”. If you’d read and understood my Part 1, you would’ve immediately seen what I meant: There can be no massive atmosphere that does not naturally contain IR-active substances.
Well I accept that since all matter (even non GHGs) has SOME radiative capability then you cannot have an atmosphere without radiative capability.
The trouble is that the rest of your Part 1 appears to suggest that it is the radiative capability that put the atmosphere in place initially and that the radiative capability is needed to keep it in place.
Neither of those propositions is correct for the reasons I explained above.
Well, it is not what it suggests. So, are we done with this bickering over privately misconstrued straw men?
It’s your site so we can stop there if you wish.
If radiative capability is not what provides the surface kinetic energy to keep the mass of the atmosphere suspended off the surface against gravity then what does ?
Do you have an alternative to PE being reconverted to KE within descending air masses ?
“If radiative capability is not what provides the surface kinetic energy to keep the mass of the atmosphere suspended off the surface against gravity then what does ?”
Solar heat.
Solar heat only gets you to 255K on Earth as per S-B.
You need to explain why the additional 33K remains stuck at the surface without radiating to space despite radiation, conduction and convection upwards.
It has to be returned to the surface somehow from within the convective overturning cycle.
AGW theory says it returns via downward radiation from GHGs whereas I say it returns as PE reconverted to KE in convective descent.
You seem to be proposing some other scenario but it isn’t clear what that is.
You say it isn’t any thermal effect at the surface from downward IR but rather the presence of atmospheric mass but you don’t say how the atmospheric mass has the effect you propose.
I provide an explanation involving adiabatic ascent and descent but you say that is wrong too.
You need to explain your alternative mechanism bevcause I don’t see it in either Part 1 or Part 2.
“You say it isn’t any thermal effect at the surface from downward IR but rather the presence of atmospheric mass but you don’t say how the atmospheric mass has the effect you propose.”
Yes, I do. The atmospheric mass makes it harder for the solar heat to get back out from the surface. By being warmer than space and by being thicker and heavier on the surface than space. Solar heat gets you as far as you want. On Venus it gets you to 737K. All you need is to increase the atmospheric mass.
Yes I agree with that, assuming insolation reaching the surface and the strength of the gravitational field stay the same.
Unfortunately you don’t say how you think additional atmospheric mass achieves that effect.
Conduction from surface to atmosphere causes convection that takes kinetic energy in excess of 255K upwards and in the process the rising air cools from expansion.It cannot just sit at the surface as you seem to propose because surface heating is always uneven and warmer lower density air always rises above higher density cooler air.
So why is the surface still at 288K ?
AGW theory says that downward radiation adds 33K to 255K.
I say that the surface cooling effect of upward convection is only effective in the first convective overturning cycle so during that first cycle the excess 33K is removed upward and the surface remains at 255K despite the insulating effect of the mass of the atmosphere.
On completion of the first convective cycle that 33K is being returned to the surface in descent and so then the surface temperature rises to 288K.
What is your alternative ?
You an’t just leave the warmed air at 288K at the surface because uneven surface heating around a sphere illuminated by a point source of light always leads to convection and a cooling temperature gradient with height even without GHGs.
“Unfortunately you don’t say how you think additional atmospheric mass achieves that effect.”
‘Unfortunately’, I do, Stephen. It is what these two posts (and the one preceding them) are about. What is the point in asking the very questions that these posts specifically set out to answer? Try reading and understanding before complaining about not finding the answers you seek. I’ve spent time writing these posts. So I find it an exceedingly unhelpful exerice having to explain it all over again to some person who can’t be bothered investing that extra bit of effort it takes to find out for himself. When it’s right there in front of him. In the text.
Well you seem to just be saying that atmospheric mass absorbs energy by conduction so that the Earth’s surface can get 33K warmer than 255K and more massive atmospheres lift the surface temperature even more which is fine as far as it goes.
The trouble is that convection then takes the extra 33K up and away and you say that GHGs radiate it to space to cause the cooling gradient with height so how do you still get the surface to 288K for Earth ?
That 33K has to get back down to the surface again somehow but you don’t say how (having excluded downward radiation and adiabatic warming in descent) or if I have missed that point could you please direct me to it.
Stephen, you say: “The trouble is that convection then takes the extra 33K up and away (…)”
No, it doesn’t. Look, it’s all in the two posts + the one preceding them. Convection takes up SURPLUS energy. In the steady state. That’s how the solar input is transported up and out of the system. Convection does not bring the atmosphere’s ‘internal energy’ up or down. That is held in place by the hydrostatic equilibrium. Surplus energy (externally transferred energy) disrupts the hydrostatic equilibrium. And we get convection. To even out the energy/temperature distribution again.
Okulaer,
I have re-read your two posts a couple of times. I can see nothing to quibble over — but I’ll try. 🙂
You wrote, “It is not as straightforward as Postma and others try to make it.” That is true enough. Postma spends a lot of time and effort telling us why it is not radiation warming the surface. I have missed it if he goes into any great detail over the exact way that the surface reaches the temperature it does. I don’t know what he would think of your last two posts, but doubt he would find much fault. Well other than, perhaps, the reference to Willis’ iron greenhouse which is not really important to this narrative anyway.
I know of about four different people who have taken a swing at explaining how this planet attains its temperature due to gravity, mass, conduction, convection, advection, radiation, and the sun. (I am probably leaving something out) I am not sure just who is spot on perfect, if anyone. I do know I think you are pretty close.
I can say, “well done”.
Appreciated 🙂
Water dominates temperature regulation on Earth within its liquid and vapour range. The atmosphere and surface radiation absorption, transmittance and reflectance can all be altered dramatically by the state of water in the atmosphere and the surface.
In arriving at the ERL there is an assumed value of global albedo. This is something that only exists mathematically in the same way as ERL only exists mathematically. The presence of water in the atmosphere and the surface can alter albedo dramatically and needs to be considered in any analysis of Earth’s temperature. As an example it is known that the so-called snowball earth is a stable state with the present level of solar insolation. Once the planet is all ice it stays all ice for a long time. Once the oceans are iced over they stay that way until geothermal effects and possibly very elevated levels of CO2 can unfreeze it.
These examples show how significantly water can alter how light is reflected from earth:
There is a risk of oversimplifying the complexity of climate in making mathematical constructs using assumptions that are also based on mathematical constructs.
Hi, Rick 🙂
Water is of course extremely important to Earth’s climate. However, it is much, much less important on other planets (and moons). And still we see the same general pattern of solar insolation and atm mass vs. tropopause height. On Titan, methane has almost the same climatic role as water on Earth. On Venus and Mars there is hardly any WV to speak of. And still we have Hadley circulation.
If earth was a black body with high thermal inertia and no atmosphere the average surface temperature would be 288C. If it was all water with ice caps having transparent atmosphere it would be 276C. If it was all ice with existing atmosphere the average temperature would be 203C.
The starting point to determine ERL is to assume an average global albedo. That value is highly dependent on the condition of water as mist or vapour in the atmosphere and water or ice on the surface.
Mass dominates over radiation in the troposphere because the convective mixing is more efficient than the radiative transfer in tending toward an isentropic state. However if the atmosphere was transparent its mass would have no bearing on the surface temperature. Water dominates the radiative properties of the atmosphere to give the value of albedo used to derive the ERL. It also has a significant bearing on the surface albedo as well given the large difference in radiative transfer between ice and water.
My point is that unless you can derive the albedo along with the factors that affect it you do not have a good model of Earth’s climate system or what the average surface temperature will be. From your analysis you can conclude that a slightly opaque atmosphere with a tropospheric zone will have a surface temperature affected to some degree by the mass of the atmosphere.
One factor I am certain of is that there is no strong correlation between rising CO2 in the atmosphere and cloud optical depth. Given the importance of cloud to global temperature it is a reasonable conclusion that CO2 in the atmosphere has little influence.
Rick, you say: “However if the atmosphere was transparent its mass would have no bearing on the surface temperature.”
This is not correct. See the ‘Addendum’ at the end of Part 1. A massive atmosphere will either way, transparent or opaque, naturally siphon off and capture some of the heat from the planetary surface originally (and ultimately) meant for space, and thus force the surface and the planet as a whole into a disequilibrium. This process is what necessitates an elevation of the mean surface temp.
You are not considering the case of an isothermal atmosphere in thermal equilibrium with the surface and pressure falling exponentially with height. In that case atmospheric mass has no bearing on the surface temperature.
In any case this is beside the point. To determine your mass based atmospheric effect you are starting with an assumed albedo. We can easily observe that albedo can vary significantly with the state of water in the air and on the surface. We know there are other factors like volcanic eruptions that also affect the albedo. I am not certain that trace amounts of CO2 cannot alter the albedo. Lack of correlations suggest it doesn’t.
Unless you can disconnect CO2 from albedo you cannot be certain that CO2 does not affect Earth’s surface temperature.
I agree that in the troposphere, as its name indicates, convective heat transfer dominates over radiative heat transfer.
“You are not considering the case of an isothermal atmosphere in thermal equilibrium with the surface and pressure falling exponentially with height.”
True. Because this is not a situation that could ever come to be. The atmospheric mass itself sees to that. If you read my Part 1, you will see how and why.
I will be more direct to my point.
In your diagram above you show 341W/sq.m average solar insolation and 240W/sq.m getting to the surface. How did you determine that 101W/sq.m was released from the atmosphere before arriving at the surface?
“How did you determine that 101W/sq.m was released from the atmosphere before arriving at the surface?”
I didn’t. I have no way of determining this myself. You need satellites. And you need full global coverage over time (over many diurnal and annual cycles). To find an average value. Earth’s global albedo is estimated by CERES to be ~0.3:
It might fluctuate around this value from year to year, it might even change somewhat over time. For instance, if the global albedo went from 0.3 to 0.31, Earth’s absorbed solar flux would be reduced by ~3.4 W/m2, quite close to the claimed total increase in ‘radiative forcing’ from a doubling in atmospheric CO2.
Anyway, the 0.3 figure seems to be a pretty well defined one as an overall average in our current climatic state. It’s hard to imagine it to be substantially different. So I’m not quite sure what you’re trying to argue, Rick.
The starting point of your analysis depends on average global albedo. It is not a given. It is a mathematic construct. It varies significantly over the globe. If the earth was all ice the albedo would be much higher and the globe would be much colder despite the presence of the atmosphere. Snowball earth is a possible state with the present level of solar insolation. Do your simplified analysis starting with an albedo of 0.7 and see what temperature you arrive at.
In the addendum to Part 1 you state:
“We hardly ever take our time to stop and think about what is actually being suggested here. We tend to just go along with it. In fact, we swallow it hook, line, and sinker. And from that point on, having accepted this basic premise of theirs, there is no escape.”
You are making the same error by accepting the mathematical construct of average global albedo as being an invariant; a given. It is far from it. Over the last two decades albedo has been increasing while CO2 has also been increasing:
http://isccp.giss.nasa.gov/climanal1.html
This goes counter to the positive feedback that climate models incorporate with regard to albedo.
Your analysis is meaningless in terms of determining the role of CO2 in the atmosphere unless you can be certain CO2 does not influence albedo. The climate modellers are not using the simplified analysis you suggest to predict warming by CO2. The circulation models are far more complex and certainly take into account the mass of the atmosphere. The coupled models include the mass of the oceans. The models have parameters to tune them to historical records then forecast future temperature. The forecasting models are not based on an effective radiation level or average global albedo.
Even if you convince warmists that atmospheric mass matters, which modellers already accept, and the radiative role of CO2 does not matter you have made no progress toward negating the theory that man made CO2 influences climate. You need to also be certain that CO2 can in no way affect global albedo because you take albedo as a constant and is your starting point.
“The starting point of your analysis depends on average global albedo.”
The starting point of any analysis of any planet’s heat budget depends on average global albedo, Rick. It is not a particular approach of my analysis. What do you suggest I do, then? Make up my own albedo? Not do any analysis at all, because the albedo apparently fluctuates too much? I still don’t get your objection …
“It varies significantly over the globe.”
Indeed it does. However, it does not vary significantly globally from year to year or even from 2000 to 2014 (as per the CERES data). In fact, it stays remarkably stable. There is clearly some internal regulation involved.
I am not discussing regional patterns, Rick. I’m discussing global averages. Like all global analyses do.
“You need to also be certain that CO2 can in no way affect global albedo because you take albedo as a constant and is your starting point.”
You do not prove a negative, Rick. That’s fundamental. You prove a positive. You need to be certain that CO2 does and can affect global albedo to any meaningful degree here on Earth. Are you? And if so, can you present any observational evidence …?
I’m even more interested to hear: Do you believe an increase in atmospheric CO2 would raise global albedo or lower it? And why? And how?
“I’m even more interested to hear: Do you believe an increase in atmospheric CO2 would raise global albedo or lower it? And why? And how?”
I do not have an opinion on whether CO2 alters albedo. The evidence I can muster suggests it doesn’t but my point is that the global circulation models assume it does and the model tuning parameters were determined from a data set of rising global temperature and rising CO2 so the albedo embodied in those models show a positive correlation. The IPCC and the so-called 97% have complete faith in the global circulation models.
The models also include parameters for positive feedback. One definite positive feedback is loss of sea ice, which is no longer reducing but it was a good story while it was reducing. There is strong evidence that phytoplankton blooms are a negative feedback as the gasses released seed clouds and this is significant in the southern ocean and near the land masses in the NH.
In my view the issue you must first address is your starting assumption with regard to albedo. Unless you can demonstrate that CO2 does not affect albedo you cannot prove that climate models are wrong in the short term. As the models are refined and recalibrated against more recent temperature data and ever rising man made CO2 the predicted temperature sensitivity to CO2 is falling but they are still predicting the temperature will rise due to man made CO2:
Click to access climate_sensitivity.pdf
I agree with your analysis on the basis that albedo is a given but I know it is not hence your analysis is on unstable foundation and proves nothing with regard to man made CO2 influencing global temperatures.
I have also correlated yearly lower troposphere temperature change against yearly global emissions and you can see it is not a convincing picture:
Click to access Temp_Correlate_YtoY.pdf
“Unless you can demonstrate that CO2 does not affect albedo you cannot prove that climate models are wrong in the short term.”
Well, that isn’t really my goal, anyway. I’ll leave that to others. What I’m attempting to do here is simply to show how it is an atmosphere’s total mass and not its species-specific radiative properties that necessitates and causes the enhancement of the average temperature of a solar-heated planetary surface.
What is interesting is how global albedo does affect (and to a large extent controls) a planet’s overall heat balance. Just look at Venus. It’s ALL albedo and atmospheric mass. It’s not the specific CO2-concentration at all. Same with Mars. So naturally, Earth would be no different. It is just easier to get fooled on Earth, tricked into thinking it might be CO2. It’s not. CO2 is the fly riding on the elephant’s back. It can do nothing of consequence.
You mentioned regional variations in albedo, and I kind of waved it off. There’s no real reason to. It does have the potential to be highly significant, in the short and medium term at least. Like from say 1850 to 2015. The thing is, if the Hadley-cell (tropical/subtropical) albedo went down for some reason over a period of decades to centuries, and the extratropical/polar albedo went similarly up, then the global albedo might remain fairly stable, but the Earth system would very likely store up energy (and thus warm), for the simple reason of how the solar heat travels through it. I’m not saying this is how things have really progressed from 1850 till today – no one has any data to tell one way or the other. But it could have been the case. And it would be completely natural. What would cause such a gradual shift? I have no idea. But the Sun seems a likely culprit. I have a nagging suspicion our mother star is much more of a string-puller than what we (and especially the IPCC) tend to give her credit for …
Anyway, Rick, if you feel so inclined, you could read some earlier posts of mine, addressing clouds (and WV) and their profound effect on Earth’s climate and energy budgets. It would be interesting to hear your opinion …:
I think this is the point of difference:
“Most of the energy transferred from the surface (or the Sun) to the atmosphere as heat, is ultimately held by N2 and O2 molecules (ending there by way of diffusion/conduction), but since these molecules are not themselves able to effectively release this energy to space in the form of radiation, thus also letting the atmosphere cool back from the original absorption, they have to transfer their surplus energy (once again by way of collisions) to the actual IR-active constituents of the atmosphere, like CO2 (and, much more importantly, H2O), in order for these to do the job and rid the extended Earth system of it. ”
It isn’t necessary to use the GHGs as a radiative intermediary to get the surface to cool to space.
If there are no GHGs the surface itself will radiate to space at 255K but also conduct and convect at 33K.
[okulaer: There is no physically effective way for the atmosphere to conduct back to the surface during the night the surplus energy it received and pulled up convectively during the day. You’re mixing up surplus energy (transferred heat) and internal energy. Atmospheric circulation takes the surplus energy up and away from the surface by the movement of air (convection) for it to be radiated to space from aloft; the air then falls back to the surface to pick up new surplus energy from the surface. (It never brings this energy back down!) This is how the climate engine works, Stephen.]
The surface needs to be at 288K in order to achieve both tasks simultaneously.
If there are GHGs then some radiates out from within the atmosphere but less then radiates out from the surface and the surface stays at 288K
If you were right about GHGs being necessary then the more GHGs present the cooler the surface would become yet we see from the example of Venus that that is not the case. The Venusian atmosphere is at a similar temperature to that of Earth at the same pressure and adjusted only for distance from the sun yet with vastly more GHGs than Earth,
[okulaer: *Sigh* No more from you, Stephen, until you can start addressing what I’m actually saying and not just presenting ever more of your twisted straw men.]
You have most of it right but go wrong on the need for GHGs.
It really is a matter of mass and mass alone but to see that you have to understand adiabatic uplift and descent as work being done with and against gravity and not surrounding molecules.
It may irritate you but I’m trying to help here.
[okulaer: No, you are not trying to help. You are trying to promote your own theory over mine. By deliberately misrepresenting the things I say. I’m afraid it ends here.]
Stephen Wilde says: June 24, 2015 at 10:20 am
“Most of the energy transferred from the surface (or the Sun) to the atmosphere as heat, is ultimately held by N2 and O2 molecules (ending there by way of diffusion/conduction), but since these molecules are not themselves able to effectively release this energy to space in the form of radiation, thus also letting the atmosphere cool back from the original absorption, they have to transfer their surplus energy (once again by way of collisions) to the actual IR-active constituents of the atmosphere, like CO2 (and, much more importantly, H2O), in order for these to do the job and rid the extended Earth system
What complete and total nonsense! the total sensible heat energy of this Earth’s atmosphere is trivial compared to the large transformation of insolation EMR power to the production of WV from airborne water condensate sunside, and the release of sensible heat nightside, to power EMR radiant exitance to space. No insolation power absorbed by this atmosphere is ever transferred to the surface as sensible heat, or any form of temperature! 🙂
Hi Will,
I was contacted by Hukseflux, to whom you had asked me to send a comment. Which I did because I thought you must work there. But no, they do not know you and I was only contacted because they were curious about my comments, which did not make much sense to them. And I am now curious of who you are and why you asked me to send my comment to what you had written to them.
Even though you find fault with me for not considering the opinions of others, would you please at least give me a little background about yourself and why you asked to send my comments to Hukseflux.
Have a good day, Jerry
Could you please reference where I asked you to send any comment to Hukseflux? I have not written to them in many years. I have used their products and recommend them if you need to make actual thermal flux measurements!
Hi Will,
Okulaer’s post of May 13, Your comment of May 20, 2015 at 8:04pm
Have a good day, Jerry
jerry l krause says: June 28, 2015 at 5:25 am
“Hi Will, Okulaer’s post of May 13, Your comment of May 20, 2015 at 8:04pm”
Ah! My “Please comment on:
http://www.hukseflux.com/product_group/heat-flux-sensors ……. All the best -will-”
My bad, I should have written “about” rather than “on”,
I had no idea you would treat “on” as “to”! sorry!!
That ad shows their flux measurement devices and how they work. They actually measure, via back to back thermocouples the Watts/m^2 through a known thermal resistance giving both magnitude and direction of thermal flux. Most who “measure” a lot, construct and calibrate similar devices to fit “that” set of circumstances. I will read the rest of your postings on that thread and respond on the current okulear!
All the best -will-
jerry l krause says: May 22, 2015 at 2:52 am
“So the fact is from this time to the next morning the surface is cooler than a portion of the atmosphere above.”
The only time I have noticed this inversion is when higher temperature air from elsewhere being less dense went over the surface boundary layer, and pritty much stopped any further exitance from the surface..
“The first commonly known fact was that the atmospheric temperature has never been observed to be lower than the atmosphere’s dewpoint temperature.”
That may well be true, but please state what causes any dew point temperature, which can be from 100o Celsius down to -40o Celsius.
“But I am very intrigued by the fact you, like Spencer, cannot see (understand) what the point of the dewpoint temperature is.”
Dew point is only a measure of the WV (H2O gas) in that part of the atmosphere as that gas condenses causing dew the latent heat is converted to sensible heat at the rate of 2400 J/g of H2O, as more and more dew forms the dew point will decrease in temperature somewhat. At least to -40oC the surface dew point itself cannot be lower than the surface temperature. Air very near the surface cannot be below the surface temperature, if it has any WV. Is that your point?
“Where did he learn that condensation could seemingly, quickly, reduce the vapor content of the air?”
Water vapor (the monomolecular gas form) condensing to airborne water condensate (clouds) or surface dew is the definition of condensation. Precipitation is not required. Perhaps you are not treating WV and airborne water condensate as different phases, with the airborne water condensate being a nonentity in the religion of meteorology!
jerry l krause says: May 23, 2015 at 10:58 pm
“Now be a gentleman and answer: What happens as the WV condenses?”
As the gas form of H2O condenses to a airborne water condensate (aerosol colloid) it releases from 2500 J/g to 2260 J/gm of latent heat, depending on temperature. Now be a gentleman and state where you ever taught chemistry?
“The observations are not fantasy. My reasoning (thinking) based upon them and accepted scientific laws is fantasy.”
The projected Meteorology or ClimAstrology has no science whatsoever and is “only” accepted by themselves, and the religious/political hangers on!
All the best -will-
@ okulaer
Due to the back and forth between you and Mr. Wilde I have become confused on one aspect of your position. So, I have a simple question.
What would happen in regards to the climate if the planet earth had an atmosphere of pure nitrogen? (yes, I know we would all be dead and it would be a moot point but still …)
Thanks.
Mark,
In my Part 1 I tried to explain why this could never be. Unless a pure N2 atmosphere became IR active through so-called “N2-N2 collision-induced absorption/emission” (CIA/CIE), a process which is highly relevant and operative on cold Titan (its atmosphere made up of 95-98.5% N2), if it were instead completely EMR inert and transparent, then the Earth system could never find a dynamic equilibrium between solar-heated surface and massive atmosphere, nor between itself and its surroundings (Sun/space). It could never reach a steady state. And so the atmosphere would’ve had to go.
What you’re doing by asking this question, Mark, is falling into the warmists’ trap. They crave these questions.
There can be no massive atmosphere that is not also thereby IR active! To necessitate (atm mass) > to enable (atm radiative properties) > to cause (atm mass).
“What you’re doing by asking this question, Mark, is falling into the warmists’ trap. They crave these questions.”
No, just curious is all. Kids ask me questions sometimes and so I get curious at what others say.
I have been told three different things over time. One — if the atmosphere were pure nitrogen then the planet would lose most of the atmosphere as it heated up and expanded and so was lost to space. And then two — that the surface would just radiate through the nitrogen without any difficulty. And then three — that conduction and convection would warm the nitrogen atmosphere and that any gas will radiate so it would radiate into space along with the surface radiation.
Since it is only a thought experiment, I have never really decided on one, two, or three. (and I have a forth that I came up with but have never really been confident of it)
Thanks for taking the time to respond. ~ Mark
Mark,
The surface would radiate through the nitrogen without any difficulty. If it didn’t absorb by N2-N2 CIA. And the nitrogen could definitely not radiate to space the heat it absorbed (non-radiatively) from the surface (if it didn’t emit by N2-N2 CIE). Most likely, neither CIA nor CIE would be effective enough as the sole mechanism at terrestrial temps (works well enough on Titan). So the only real option is that the atmosphere would gradually accumulate energy that it couldn’t rid itself of. Hence inflate and eventually erode into space. Of course, it’s all completely hypothetical. Such an atmosphere does not exist, and for good reason. What would likely happen is that IR-active substances would somehow form and/or leak into this atmosphere to let it radiate and thereby ensure an equilibrated state.
Jerry l Krause says: June 29, 2015 at 3:12 am
Jerry l Krause,
Please, please run up some mountain and throw yourself into the volcano,.
to cease your incessant Bull Shit!
All the best, -will-
okulaer,
Thanks for your thoughts on the hypothetical nitrogen atmosphere. And many thanks for your recent posts — I know that these things take a lot of effort and I highly doubt you are getting big money from the Koch Brothers to do it. 🙂
I look forward to the “executive summery” that you mentioned last post (or the one before perhaps).
~ Mark
Mark,
Remember that this planet is not a black-body not even a gray body with uniform emissivity angularly or spectrally. This atmosphere is not a surface,and the concept of cross sectional area really does not fit well with optical depth. No one knows, especially the incompetent ClimAstrologists!! The best guess is that the N2 would still have a pressure, density, and temperature gradient statically induced by gravitational force. The temperature of the whole mess must be whatever to radiate to space all absorbed insolation. The surface temperature would likely be much higher than present. That wonderful water keeps this Earth at exactly the “correct” temperature, ignoring whatever stupidity Earthlings may spout! OTOH Earthlings are very good at turni9ng over each leaf, looking for something, and continually learning, even if nothing there! Beware of those that claim to know!!
Will,
Amazingly enough, my personal guess (number 4) was something close to your guess. And I am well aware that we humans have a long, long way to go before we really know all there is to know about the weather machine on our planet. (first we have to stop with the CO2 delusion!)
Thanks for the help Will.
~ Mark
Hi Will,
This reply to your comments to me of June 28 is primarily for the information of others who might read your comments about previous comments of mine. For it seems obvious you do not think I am qualified to consider myself a scientist, so it seems anything I might write to clarify what I have previously stated will not be accepted by you as having any validity.
I am using a simple radiometer modified from the simple economical balloon-borne net radiometer which V. Suomi, D. O. Staley, and P. M. Kuhn (SSK) designed, constructed, and tested. (Quarterly Journal of the Royal Meteorological Society, vol 84, No. 360, Apr. 1958, pp. 134-141.) Will has called attention to a less simple, more expensive commercial net radiometer manufactured by Hukseflux Inc. Will has properly described the fundamentals of most commercial net radiometers and radiometers. The ‘raw’ outputs of the SSK net radiometer were two temperatures. One, the temperature of an upward facing absorbing-emitting (a-e) surface and the other the temperature of the downward facing a-e surfaces. These two a-e surfaces were thermally isolated from each other by the design of the radiometer and each a-e surface was thermally isolated from its environment by the heat transfer mechanisms of conduction and convection so that the temperatures of the a-e surfaces should be a radiation balance between the absorption of radiation and the emission of radiation. Then, from these temperatures the radiation flux being emitted could be calculated using the S-B Law. And of course, because of the absorption-emission balance this emitted flux was the flux of radiation being absorbed.
So the basic difference between commercial radiometers and my modified (the top one-half of the SSK net radiometer) is the ‘raw’ data which is output, one a radiation flux and the other a temperature. The fundamental point, which seems I have failed to clearly communicate, is that those who observe the downward LWIR radiation flux from a ‘cloudless’ atmosphere between sunset and sunrise with a commercial instrument, probably have never asked the following question about the radiance output of their radiometers: What would be the temperature of an ideal (or near ideal) black body which would emit their observed radiances? Whereas, with the modified SSK radiometer, it is this temperature which is directly observed.
So, if the radiance output, observed during the nighttime, by commercial radiometers is never converted to temperature, these observers can never observe that this temperature, which must calculated (or compared to a calculated chart) is less than the ambient atmospheric temperature of their radiometer’s environment. But based upon a multitude of observations is a reproducible observation if the condition of the sky is cloudless or even nearly so.
So based upon the consistent, reproducible, observation that the downward LWIR radiation from a cloudless sky cannot cause the temperature of the radiometer’s a-e surface to rise to the temperature of the instrument’s environment, I conclude that this downward LWIR radiation from the cloudless sky cannot be preventing the radiating surface of the earth from cooling further. So, I have to conclude there must be some other factor than any downward LWIR radiation from a cloudless sky which to preventing the radiating surface from cooling to the temperature of my ‘SSK’ radiometer’s a-e surface.
In Will’s other comment, he refers to the fact that I have drawn attention to the consistently observed fact that the atmosphere’s temperature has never been observed to be lower than the atmosphere’s dew (frost) point temperature. Which I consider to be another empirical scientific law. Hence, I consider this is one factor (the condensation of atmospheric water vapor to form dew, frost, or fog) which prevents the earth’s surfaces (and atmosphere in contact with these surfaces) from cooling to the temperature of my radiometer’s a-e surface at sunrise (given the cloudless sky condition).
The other factor which prevents the earth’s surfaces (and atmosphere in contact with these surfaces) from cooling to the temperature of my radiometer’s a-e surface at sunrise (given the cloudless sky condition) I cannot claim to have empirically observed as I have observed the formation of dew, frost, fog, which drastically slows cooling, before sunrise. For I have not yet made enough observations of an environment (both soil and atmosphere) that is so dry that the thermal inertia of the soil and the atmosphere prevents the surfaces and atmosphere from cooling, as if they were nearly perfect blackbodies, to near the atmosphere’s dew (frost) point temperature. So, while it is possible to find locations where it has been observed that atmospheric surface layer temperatures cool 40, or more, degrees Fahrenheit from a day’s high temperature to the next morning’s low temperature, one would have to document the sensible heat changes and surface temperature changes as they occurred during the night and use these observed temperatures to document the maximum amount of radiation that could have been ‘ideally’ radiated to space during this period of cooling.
But the fact that such extreme temperature oscillations have been observed to occur day after day is empirical evidence which seems to force a conclusion that the sensible heat which is being stored during the heating period of the day is being emitted during the cooling period of a day (24hr period).
Will and others, I have merely reported what I have observed and others have observed. From these observations I must conclude that the downward LWIR radiation, as observed, does not limit the minimum diurnal temperature; hence this downward LWIR radiation from a cloudless sky cannot cause the observed surface layer temperature, as commonly observed, to be any greater than it would be if there were no observed downward LWIR.
However, good science dictates that others must begin to make observations as I have. There must be collaboration. Side by side comparisons of the SSK radiometer must be made with commercial radiometers. I could go on what needs to be done but the empirical evidence is very few who participate on blogsites are actually experimentalists who even inspect the data being regularly generated by observations being made at many airports and the data being generated by atmospheric sounding which are being done every 12 hours at fewer locations, but still not a few, worldwide.
Have a good day, Jerry
jerry l krause says: June 29, 2015 at 3:12 am
“Will and others, I have merely reported what I have observed and others have observed. From these observations I must conclude that the downward LWIR radiation, as observed, does not limit the minimum diurnal temperature; hence this downward LWIR radiation from a cloudless sky cannot cause the observed surface layer temperature, as commonly observed, to be any greater than it would be if there were no observed downward LWIR”
There is no observed downward LWIR. . You fell for the scam, by the SCAMMERS, admit it! Your observations are fine. Your interpretation of what you were observing is not creditable! Your conclusions of what you think you were observing is completely biased by the scam
Please review your observations based on “no” upward or downward LWIR from/to the surface as such has never been detected, observed, nor measured. “Radiance” as a potential for thermal EMR flux is easy to measure in any direction. Actual measurement of thermal EMR flux is limited to special laboratories and equipment.
Hi Will,
What is keeping the temperature of my radiometer’s upward facing a-e surface from cooling still further, than what it does, below the ambient atmosphere’s temperature?
Have a good day, Jerry
The ambient atmosphere’s temperature does.
Hi Kristian,
The ambient atmosphere’s temperature does. Are you saying there is no radiation balance, absorption equal emission, occurring at the absorbing-emitting(a-e) surface? Are you saying that a-e surface is merely emitting to cold space the energy ‘leaking’ to it from its warmer environment? Except as I remember, you are a proponent of the greenhouse effect and there must be some downward LWIR radiation from a cloudless sky. Which I agree there is. But my observation is that there are other factors which limit the minimum temperature of the diurnal temperature oscillations.
Will’s claim, to which I am responding, is: “There is no observed downward LWIR radiation. However, if this is the case, how is it when the sky is overcast during the night that the temperature of the a-e surface and the temperature of the ambient atmosphere are the same. There must be the lack of something to explain a-e surface temperatures less than the ambient temperature or conversely to explain what causes the two temperatures to be the same..
But you are right, if the radiometer is failing to perform as advertised, the ambient temperature could prevent the a-e surface temperature’s from falling further.
Have a good day, Jerry
“Except as I remember, you are a proponent of the greenhouse effect (…)”
Am I? That’s news to me. Have you read anything of what I’ve been writing on this blog for the last year at all? Like the post your commenting on here for instance …
“(…) there must be some downward LWIR radiation from a cloudless sky.”
No. There mustn’t. Not to a warmer surface.
We’ve had this discussion before, Jerry. There is no point going through it again.
Hi Kristian,
I was mistaken when I stated that you were a proponent of the GHE. But now I am clueless why we seem to have disagreed.
If you go back in Roy’s post you will not find me debating if downward LWIR can warm water. This because I have never seen one atmospheric sounding over a sea surface which out of sight of land so I do not know if the atmosphere above the sea is always colder than the sea surface as most claim.
But atmospheric sounding over land surfaces near sunrise sometimes, and I might claim, there is always a temperature inversion if the sky is absolutely cloud free. So, at this time the LWIR radiation is being emitted by matter whose temperature is greater than that the surface. So your statement, “No, there mustn’t. Not to a warmer surface.”, does not hold.
And I since I have consistently reported that the during the nighttime the temperature of my radiometer’s absorbing-emitting surface is always colder than the atmospheric surface layer ambient temperature. So, there is always a warmer atmosphere above the a-e surface.
I will admit that sometimes, in my weaker moments, I will agree that this downward LWIR will slow the cooling because some of it, as I have just stated, comes from a portion of the atmosphere whose temperature is greater than the land surface below. However, my observations point to the fact that, even the cooling rate of the surface might be slowed, the fact there are other factors, given the clear sky condition which prevents the surface layer atmosphere from cooing to the temperature of the radiometer a-e surface.
When the atmosphere begins to cool before sunset, as it usually does, I claim that atmosphere begins to cool because surface in contact with the atmosphere has first cooler to a slightly lower temperature than the atmosphere in contact with it. This I claim is because condensed matter, but solid and liquid, has greater ‘radiation power” than does diffuse matter (a gas, the atmosphere). It is seldom mentioned that greenhouse gases emit due to the temperature of atmosphere. If you are interested I can refer you to two peer-reviewed articles whose observations that the temperature relationship of its emission is 6th instead of the 4th power of S-B Law for condensed matter.
Hopefully this somewhat resolves our problem. Which I am still uncertain what it really is.
Have a good day, Jerry
I do not know if our discussion has ever clearly defined that I have never claimed that a warmer surface detects
r
Kristian, I do not know how the last did not get removed as I attempted to compose my response. I had rejected what I had begun as not the best, properly defined, statement. Jeery.
Hi Kristian,
Roy did an actual experiment, a very good experiment if one’s ponders the results he reported. Jimc, according to my latest scan, is the only one has pondered the shield which was the sole purpose of the experiment. No one, except Roy, paid any attention to what Jimc wrote concerning the shield. Because Roy commented before I got my comment to Jimc composed, I quickly edited my comments and addressed them to Roy. Roy, and no one else, has responded to my questions which I asked Roy.
Then in Roy’s post about the experiment, Wayne responded to something I had written about Feynman. Wayne’s comments motivated me consider what Feynman had taught physics students about QED at Caltech the second year of their introductory physics course at all Caltech students had to take. As I have stated many times, I do not understand the physics; but I consider I understand what Feynman taught about the consequences of the physics. I will quote a portion of what he taught about the ‘emission and absorption of photons. (The Feynman Lecture on Physics, Vol III, pp 4:7,8)
“We have already discussed these rules in a somewhat different way in Chapter 42 of Vol. I, Equation (4.29) says that the probability that an atom will absorb a photon and make a transition to a higher energy state is proportional to the intensity of the light shining on it. But, as Einstein first pointed out, the rate at which an atom will make a transition downward has two parts. There is the probability that it will make a spontaneous transition /a/2, plus the probability of an induced transition n/a/2, which is proportional to the intensity of the light—that is, to the number of photons present. Furthermore, as Einstein said, the coefficients of absorption and of induced emission are equal and are related to the probability of spontaneous emission.” Etc. Feynman next considers the blackboy spectrum. I consider the apparent general failure to consider this in the context of the greenhouse effect is the reason for confusion and endless debate.
If you want to see further than others, you have to stand on the shoulders of giants.
Have a good day, Jerry
Kristian,
I can think of a way to explain power transfer between the difference in potential. Way to simple for me but may help for folk that just do not get “it”!
A 12 volt car battery 75% charged and a 6 volt motorcycle battery also 75% charged, negative terminals connected together. Connect a 6V 1A motorcycle tail-light lamp between the two positive battery terminals. Describe the result?
The 12 V battery at 1A provides 12 W of power, but the lamp only emits 6 W of light and other heat to be convected away. Where go the other 6 W? This is way to simple for describing EMR but can help folk consider just why the difference in potential must be considered, rather than the absolute 12 V. Space has an impedance but it is not dispersive of power as is that lamp! The 6 V battery still only gets 6 W. Thanks for reading!
Your article explains nicely why the temperature of Venus at the height of one Earth atmosphere is about the same as Earths temperature,and, the lapse rate above is the same as Earths.
Pretty much all pressure dependent and nothing else. Regards wayne
Hello Kristian,
I noted you posted this over at Judith Curry’s place.
Is there an online plotter for CERES data that generated this? It seems so based on the logo and the bottom “generated by” caption. However, I’ve been unable to locate it. Do you have a link?
Thanks in advance.
Hi Anthony,
Yes, there is: http://ceres.larc.nasa.gov/order_data.php
I know this is an old thread, but it seems like a logical place to continue discussions from other places ….
You say:
More correctly, all surfaces absorb and emit radiation from all directions. The surface has only one surface, so it only radiates upward (and absorbs downward radiation). The shell with a top surface and a bottom surface radiates both upward and downward. Nothing at all odd or mysterious here.
No, this is the wrong reasoning. If the shell emits 120 W/m^2 to space, it is purely because it has the proper temperature (214.5K) to do so. There is no reason at all that this must be 1/2 the surface radiation. And if the surface is radiating 240 W/m^, it is simply because it happens to be 255 K.
Why do you say this? In the original (no shell) system, there was an inward flux (sunlight) of 240 W/m^2 and and outward flux (thermal IR @ 255K) of 240 W/m^2, ie steady-state. The new system (adding the shell) still has an inward flux (sunlight) of 240 W/m^2 but a “reduced flux from the new extended system to space” of only 120 W/m^2. And initially when the shell is added, the surface is still absorbing 240 W/m^2 of sunlight but only radiating 120 W/m^2 thermal IR heat to the shell, so all of that extra 120 Joules per square meter per second is going to the surface. That sounds like a direct cause to me!
More precisely, 240W/m^2 of heat is continuously coming in (sunlight) and 240 W/m^2 of heat is simultaneously leaving (thermal IR to the cooler atmosphere), implying a steady temperature.
Similarly for the atmosphere, 240W/m^2 of heat is continuously coming in (thermal IR from the warmer surface) and 240 W/m^@ is simultaneously leaving (thermal IR to the cooler outer space), implying a steady temperature.
So? If you want to talk about “heat”, then there is heat of 240 W/m^2 leaving and arriving to/from both the surface and the atmosphere. OTOH, It might be handy to calculate the transfer from surface to atmosphere using sigma(303K^4 – 255K^4). It might even be handy to think of this as 480 W/m^2 of photons continuously heading generally upward and 240 W/m^2 of of photons continuously heading downward.
None of that violates any laws of physics.
From Spencer’s blog:
http://www.drroyspencer.com/2017/05/uah-global-temperature-update-for-april-2017-0-27-deg-c/#comment-246800
Norman says, May 15, 2017 at 9:03 AM:
Well, see, this is where the problem comes to light. When you explain it like this, you make it SEEM as if the IR energy from the surface is somehow transported up through the tropospheric column by way of a gradually diminishing radiative flux, in the sense that it somehow started out rather large (~398 W/m^2), but ends up much smaller (~240 W/m^2), traveling through ever-cooling layers of air.
However, this makes absolutely no physical sense. The only way this could be is if, at each incremental tropospheric level from surface to tropopause, the outward-moving radiative flux – NOT a radiant HEAT flux, mind you – would somehow ‘leave behind’ a tiny bit of its energy, thereby having its overall intensity slowly eroded as it ascends, while helping rather – via the very same process – to maintain the air temperatures on its way.
This is, however, NOT how it works. This is – again – mixing up cause and effect.
The photons that we “see” are NOT the result of “reemission events” from IR-active molecules having just prior absorbed photons from our hypothetical upward-moving surface-to-tropopause radiative flux. They are rather emitted simply as a result of the air temperature at each level, that is, the photon cloud that coincides with the air in question equilibrates with – and thus acquires – the temperature of the air, maintained by constant (kinetic/”thermal”) vibrational transitions in the IR-active molecules inside the air. This is explained quite well e.g. here:
http://tinyurl.com/k6jfexl
“The total radiation emitted by a cooling body is not correctly described merely as the sum of all the individual emission processes, as the particles can also absorb radiation. In the end, the statistics of a large number of emission AND absorp tion events determine the resultant radiation.
To start with, consider that the amount of radiation emitted by a hot body must depend on the number of particles in the hot body – the more particles the hot body contains, the more photons that can be emitted in each second. But having a large number of particles also increases the likelihood that some of the emitted photons will be absorbed by other particles in the body. Therefore, as more and more photons are created, there starts to be an exchange of energy from the photons back to the particles. This is the key issue – that the photons and particles have numerous interactions involving exchanges of energy. If the condition of numerous interactions is not met, then the resulting radiation will be quite different. We can think of the large number of photons, which are created in the body, as a second body of particles, so that there are two bodies present: the radiating matter (i.e., the atoms, molecules, or electrons) and a cloud of photons, both of which occupy the same volume. The particles in each body interact with those in the other, exchanging energy back and forth. The cloud of photons, though, is created by the matter particles and if more photons are created, then more energy is contained within the photon cloud. Now recall the fundamental laws of thermodynamics. The body of matter particles wants to cool by giving energy to the photon cloud (which will, in turn, carry the energy away into space). But, a hot body cannot heat another body to a temperature higher that itself. Therefore, the hottest the photon cloud can get is when it has the same temperature as the radiating body. In other words, if there are enough particles in the radiating body to produce a very large number of photons and photon-matter interactions, then the radiating body and the cloud of photons will achieve thermal equilibrium. The resultant radiation emitted from the body, then, is a cloud of photons at the same temperature as the body itself.
(…) with blackbody radiation, the photons have achieved a thermal distribution of energies. The gas molecules of the air in your room, for example, have an assortment of energies; because of collisions, their energies are randomized. Over a large number of collisions, the fraction of particles with energy falling in each small energy range can be described by a statistical function. For gas molecules, one uses the Maxwell-Boltzmann function. Likewise, for thermalized photons, the Bose-Einstein function describes the number of photons in each small energy range. The main point here is that the numerous interactions that the photons experience with the particles in the opaque medium accomplishes this. The photons and the radiating particles achieve thermal equilibrium, meaning that they both have thermal energy distributions, which we can write as N(E) (representing the number of particles as a function of their energy), that are described by the same temperature.”
So the photons from the surface are simply incorporated into the atmospheric photon cloud. It’s not like they appear distinct from it; only the ones that pass right through it.
The reason, then, why an apparent radiative flux (what is really just a radiative expression of temperature) has a higher intensity closer to the surface than to the tropopause, is simply because the air is warmer down low than up high. The air ISN’T, however, warmer down low than up high as a result of the constant supply of energy via photons to each incremental level from a continuously upward-moving radiative flux from surface to tropopause.
The energy (heat, really) from the surface to the atmosphere is – once it’s absorbed by the atmosphere – transported up through the tropospheric column by way of … mass transfer, movement of the air itself (convection, buoyancy, wind). The energy is held collisionally “trapped” inside the air (98-99% N2 and O2), ‘leaked’ upwards (and/or to the sides), moved to where it can be released, via radiation to space.