What If There Was No Greenhouse Effect?
by Roy W. Spencer, Ph. D.
The climate of the Earth is profoundly affected by two competing processes: the greenhouse effect, which acts to warm the lower atmosphere and cool the upper atmosphere, and atmospheric convection (thermals, clouds, precipitation) which does just the opposite: cools the lower atmosphere and warms the upper atmosphere.
To better understand why this happens, it is an instructive thought experiment to ask the question: What if there was no greenhouse effect? In other words, what if there were no infrared absorbers such as water vapor and carbon dioxide in the atmosphere?
While we usually only discuss the greenhouse effect in the context of global warming (that is, the theory that adding more carbon dioxide to the atmosphere will lead to higher temperatures in the lower atmosphere), it turns out that the greenhouse effect has a more fundamental role: there would be no weather on Earth without the greenhouse effect.
First, the big picture: The Earth surface is warmed by sunlight, and the surface and atmosphere together cool by infrared radiation back to outer space. And just as a pot of water warming on the stove will stop warming when the rate of energy gained by the pot from the stove equals the rate of energy loss by the pot to its surroundings, an initially cold Earth would stop warming when the rate at which solar energy is absorbed equals the rate at which infrared energy is lost by the whole Earth-atmosphere system to space.
So, let’s imagine an extremely cold Earth and atmosphere, without any water vapor, carbon dioxide, methane or any other greenhouse gases – and with no surface water to evaporate and create atmospheric water vapor, either. Next, imagine the sun starts to warm the surface of the Earth. As the surface temperature rises, it begins to give off more infrared energy to outer space in response.
That’s the Earth’s surface. But what would happen to the atmosphere at the same time? The cold air in contact with the warming ground would also begin to warm by thermal conduction. Convective air currents would transport this heat upward, gradually warming the atmosphere from the bottom up. Importantly, this ‘dry convection’ will result in a vertical temperature profile that falls off by 9.8 deg. C for every kilometer rise in altitude, which is the so-called ‘adiabatic lapse rate’. This is because rising warm air parcels cool as they expand at the lower air pressures aloft, and the air that sinks in response to all of that rising air must warm at the same rate by compression.
Eventually, the surface and lower atmosphere would warm until the rate at which infrared energy is lost by the Earth’s surface to space would equal the rate at which sunlight is absorbed by the surface, and the whole system would settle into a fairly repeatable day-night cycle of the surface heating (and lower atmosphere convecting) during the day, and the surface cooling (and a shallow layer of air in contact with it) during the night.
The global-average temperature at which this occurs would depend a lot on how reflective the Earth’s surface is to sunlight in our thought experiment. ..it could be anywhere from well below 0 deg F for a partially reflective Earth to about 45 deg. F for a totally black Earth.
So, how is this different from what happens in the real world? Well, notice that what we are left with in this thought experiment is an atmosphere that is heated from below by the ground absorbing sunlight, but the atmosphere has no way of cooling…except in a very shallow layer right next to the ground where it can cool by conduction at night.
Why is this lack of an atmospheric cooling mechanism important? Because in our thought experiment we now have an atmosphere whose upper layers are colder than the surface and lower atmosphere. And what happens when there is a temperature difference in a material? Heat flows by thermal conduction, which would then gradually warm the upper atmosphere to reduce that temperature difference. The process would be slow, because the thermal conductivity of air is quite low. But eventually, the entire atmosphere would reach a constant temperature with height.
Only the surface and a shallow layer of air next to the surface would go through a day-night cycle of heating and cooling. The rest of the atmosphere would be at approximately the same temperature as the average surface temperature. And without a falloff of temperature with height in the atmosphere of at least 10 deg. C per kilometer, all atmospheric convection would stop.
Since it is the convective overturning of the atmosphere that causes most of what we recognize as ‘weather’, most weather activity on Earth would stop, too. Atmospheric convective overturning is what causes clouds and rainfall. In the tropics, it occurs in relatively small and strongly overturning thunderstorm-type weather systems.
At higher latitudes, that convection occurs in much larger but more weakly overturning cloud and precipitation systems associated with low pressure areas.
There would probably still be some horizontal wind flows associated with the fact that the poles would still be cooler than the tropics, and the day-night heating cycle that moves around the Earth each day. But for the most part, most of what we call ‘weather’ would not occur. The same is true even if there was surface water and water vapor…but if we were able to somehow ‘turn off’ the greenhouse effect of water vapor. Eventually, the atmosphere would still become ‘isothermal’, with a roughly constant temperature with height.
Why would this occur? Infrared absorbers like water vapor and carbon dioxide provide an additional heating mechanism for the atmosphere. But at least as important is the fact that, since infrared absorbers are also infrared emitters, the presence of greenhouse gases allow the atmosphere — not just the surface — to cool to outer space.
When you pile all of the layers of greenhouse gases in the atmosphere on top of one another, they form a sort of radiative blanket, heating the lower layers and cooling the upper layers. (For those of you who have heard claims that the greenhouse effect is physically impossible, see my article here. There is a common misconception that the rate at which a layer absorbs IR energy must equal the rate at which it loses IR energy, which in general is not true.)
Without the convective air currents to transport excess heat from the lower atmosphere to the upper atmosphere, the greenhouse effect by itself would make the surface of the Earth unbearably hot, and the upper atmosphere (at altitudes where where jets fly) very much colder than it really is.
Thus, it is the greenhouse effect that continuously de-stabilizes the atmosphere, ‘trying’ to create a temperature profile that the atmosphere cannot sustain, which then causes all different kinds of weather as the atmosphere convectively overturns. Thus, the greenhouse effect is actually required to explain why weather occurs.
This is what makes water such an amazing substance. It cools the Earth’s surface when it evaporates, it warms the upper atmosphere when it re-condenses to form precipitation, it warms the lower atmosphere through the greenhouse effect, and it cools the upper atmosphere by emitting infrared radiation to outer space (also part of the greenhouse effect process). These heating and cooling processes are continuously interacting, with each limiting the influence of the other.
As Dick Lindzen alluded to back in 1990, while everyone seems to understand that the greenhouse effect warms the Earth’s surface, few people are aware of the fact that weather processes greatly limit that warming. And one very real possibility is that the 1 deg. C direct warming effect of doubling our atmospheric CO2 concentration by late in this century will be mitigated by the cooling effects of weather to a value closer to 0.5 deg. C or so (about 1 deg. F.) This is much less than is being predicted by the UN’s Intergovernmental Panel on Climate Change or by NASA’s James Hansen, who believe that weather changes will amplify, rather than reduce, that warming.
RE: anna v (22:59:02)
I know that energy is quantised thankyou anna. You will see I wrote at the start that if you push the anology too far it falls down as you have done. Regardless of weather the electrons in a molecule are still orbiting in the ground state or not they will still inevitably achieve that ground state if they are excited above it and left in isolation. Some molecules do it faster than others but N2 will still achieve its ground state inevitably if left alone in a vaccum. Even though the electrons continue to orbit.
Re: anna v (00:06:39):
Clarification: All except excitational radiation occurs always and constantly in all matter through interation/collision with other matter.
sorry there nick but I was unable to see anything that even vaguely appeared to be associated with thermodynamics.
cba (14:54:46) :
Well, let me try again. A convection cell is a heat engine. Imagine an insulated room with two plates in the floor on opposite sides. One is held at 50C, one at 0C. warm air rises from the hot plate, crosses the ceiling, descends and is cooled by the cool plate, then goes on to be warmed again. A temp diff is converted to kinetic energy (and dissipated by viscosity). Classic heat engine. The Earth’s Hadley cell is just one such an arrangement on a large scale.
Then in an atmosphere with less than the dry adiabatic lapse rate, you have the reverse. A heat pump can exist with these Carnot-like steps, visualized with a rising/falling balloon:
1. From an initially isothermal state, you raise it rapidly by 1 km. The air expands adiabatically and cools (by 9.8 K). Because it is denser than the surrounding air, work is done to raise it.
2. The balloon is then held still until it warms to the ambient temperature, absorbing heat from the high altitude. It expands further, doing wasted work displacing gas.
3. The balloon is then quickly lowered 1 km. It is compressed, becoming hotter than ambient (by 9.8K), so work is needed to pull it down.
4. Again, the balloon is allowed to cool to ambient, delivering heat to the lower altitude. The cycle can repeat.
Like an aircon on a room without heat sources, the work required to maintain the lapse rate depends on the leakage – heat that flows back against the temp gradient, which for a room you try to block with insulation. In the air, that leakage comes from turbulent heat diffusion, maybe augmented with latent heat. But that isn’t much, and the KE generated by convective flows is enough to drive the pump effectively.
“”
Nick Stokes (16:14:04) :
cba (14:54:46) :
Well, let me try again. A convection cell is a heat engine. Imagine an insulated room with two plates in the floor on opposite sides. One is held at 50C, one at 0C. warm air rises from the hot plate, crosses the ceiling, descends and is cooled by the cool plate, then goes on to be warmed again. A temp diff is converted to kinetic energy (and dissipated by viscosity). Classic heat engine. The Earth’s Hadley cell is just one such an arrangement on a large scale.
“”
Well, the hot air over the hot plate will rise. The cool plate has a serious problem.
“”
Then in an atmosphere with less than the dry adiabatic lapse rate, you have the reverse. A heat pump can exist with these Carnot-like steps, visualized with a rising/falling balloon:
1. From an initially isothermal state, you raise it rapidly by 1 km. The air expands adiabatically and cools (by 9.8 K). Because it is denser than the surrounding air, work is done to raise it.
“”
I’ve never seen a cold air balloon rising and floating around the sky.
When one has a warm parcel of air or balloon, it will rise. Work is done against gravity, increasing the potential energy of this parcel for this to happen. As it rises, it will expand due to lower ambient pressure and the T will drop. This is the physical meteorology 101 explanation of the lapse rate. Otherwise, there is nothing there to do the work of raising higher density cold air balloons.
“”
2. The balloon is then held still until it warms to the ambient temperature, absorbing heat from the high altitude. It expands further, doing wasted work displacing gas.
“”
Not hardly. LOL! It’s cooler up there, perpetual motion machines don’t work. They violate the 2nd law. The expansion of the balloon has reduced the temperature until (if it’s a parcel) it reaches the surrounding air temperature, air pressure, and hence air density. This defines how high up it is going.
“”
3. The balloon is then quickly lowered 1 km. It is compressed, becoming hotter than ambient (by 9.8K), so work is needed to pull it down.
“”
hmm, more deux ex machina again. However, LOL, the temperature has reduced by 9.8k accoring to your # 2 and is the same as at the 1km alititude. When it is forced down, it heats up by that 9.8k bringing it up to the same T as the surface started.
What you don’t have is a carnot cycle going on or a transfer of energy going on. Rather you’ve got a giant ferris wheel. You lift a bucket of air from the ground which was at ground T P and density and lift it up to the top of the wheel where the decrease in pressure dropped the T according to the ideal gas law as the pressure equalizes which puts the T at the dry lapse rate. It then proceeds down, repressuring and increasing its T to that of the surface.
“”
4. Again, the balloon is allowed to cool to ambient, delivering heat to the lower altitude. The cycle can repeat.
“”
OOPs, one doesn’t have any temperature differential to permit a transfer of heat.
“”
Like an aircon on a room without heat sources, the work required to maintain the lapse rate depends on the leakage – heat that flows back against the temp gradient, which for a room you try to block with insulation. In the air, that leakage comes from turbulent heat diffusion, maybe augmented with latent heat. But that isn’t much, and the KE generated by convective flows is enough to drive the pump effectively
“”
For your case, the heat doesn’t flow against the temperature gradient or with the temperature gradient. It doesn’t flow at all. LOL!
If you want to comprehend a heat engine, you’ve got to deal with proper conceptual physics.
1. heat some air, T goes up, density goes down (pv=nrt)
2. lower density air is forced up due to the lower density
3. It continues to rise, pressure drops, temperature drops, density rises until it reaches an altitude where it’s the same as the ambient
4. note that some air from above is forced down. as it goes down because it’s higher density than the rising hot air.
5. the dropping air pressurizes and increases in T as the higher altitude parcel goes down.
6. when it reaches the surface, the pressure and T have risen to local ambient.
7. golly gee where’s the energy transfer? There must be something else needed.
let’s try it again.
This time lets toss in some h2o vapor (something not included in Dr. Roy’s model simplification).
1. we get a parcel of moist air at surface ambient.
2. average molecular weight is 28.8 while h2o is 18. It weighs less – lower density even if T is at surface ambient.
3. lower density parcel rises, pressure decreases, temperature drops
4. Oh Wait! something’s different here
5. relative humidity shoots up because it is temperature sensitive
6. parcel becomes saturated or supersaturated, water drops out, rains out, turns into water particles, liquid or solid. there is less h2o vapor present
7. cool dry air is denser, falls down, dry air compresses and heats up. It also rehumidifies to some extent if possible.
ooh, what’s happening here.? Now we have liquid / solid water at the surface. Some evaporates to maintain some relative humidity for the area. Perhaps 15% for an extremely dry desert or 90% for summer on the gulf coast LA swamp area. That evaporation sucks out thermal energy into an internal phase change referred to as heat of evaporation and is greater for water than the specific heat energy required to raise liquid h2o from freezing to boiling temperatures. Of course as that moist parcel flies high where local temperatures are somewhat less, perhaps 1km altitude, the absolute humidity saturation amount drops as a function of temperature. For the h2o vapor to become liquid or solid requires that it give up this heat of fusion / heat of evaportation high up in the atmosphere, and btw, above most of the h2o vapor. That is energy being transferred from surface to high altitude.
Of course clouds tend to rain, most of which makes it in liquid form back to the surface. Some does not, evaporating higher up instead of at the surface but never the less, absorbing energy for the phase change.
Care for a redo?
cba (18:04:12) :
Flew sailplanes years ago, and your example is dead on. And if you fly a sailplane you will get to experience this process first hand. Sometimes violently! Just one time I almost got sucked into a cloud, mile wide cumulus, bad experience. At 4500 ft the rate of rise (by a variometer) was pegged at 1200 ft/min up. It took full flaps, side-slipping, and speeding up to red-line to drop that rate to zero. Whew! By the way, at cloud base the venalation vents were spewing HOT moist air though should have been about 70 degF at that altitude. And as you leave the cloud, just reverse all of the above states, in about 5-10 seconds! 1200+ ft/min down.
I’ve got a photo in a book of a b51 that flew through a thunderstorm. It never flew again. The leading wing edge had softball size holes and dents in it.
My 1st physics mentor got his diamond (???) rating 40 years ago. Last time I saw him (last year I think), he was still soaring.
cba (19:49:02) :
Diamond, wow! Never came close to anything like that. At about 60 hours logged a tornado destoyed all planes, school and toe-plane went to California, that was the end of my delightful experience in the 80’s.
Phil. wrote :
.
So by your definition of LTE it doesn’t apply to the troposphere!
Bear in mind that LTE is a convenient approximation not a mathematical definition and so can’t be used in the manner you are attempting to.
.
No scientific arguments beside vague handweaving ? Or is it that you really don’t know the definition of LTE ? I said exactly the contrary of your statement – the troposphere IS in LTE . If it was not , one could not define a local temperature .
OK , here it goes in an even more simplified manner .
1) The number of molecules in a quantum states E1and E0 is a constant in LTE . This is the result from the Maxwell-Boltzman distribution of the quantum states in LTE .
No objection ?
2) Transitions from E0 to E1 and from E1 to E0 for every molecule are done by 2 processes IR absorption/emission and collisional excitation/decay . Of course in reality there are many more energy levels than only 2 but it doesn’t change the principles .
No objection ?
3) Collisional excitation/decay is an equilibrium . I repeat – if it was not , there would be a net energy transfer from one molecule species to another .
That leads to different temperatures in the same local volume . This would violate the LTE condition . This has nothing circular , it is a trivial result easily shown . Either you have LTE or you have collisional energy transfers out of equilibrium . You can’t have both .
Yes the LTE is an approximation but one that has an accuracy of statistical thermodynamics which is really not discussed by anybody who has learned physics .
No objection ?
.
Well now if you can’t find objections to the statements 1) to 3) above and they are all pretty basic QM since some 80 years , the necessary conclusion is :
In LTE the rate of absorption of photons of frequency f is equal to the rate of emission of photons of frequency f
You can be sure that if the M-B distribution of quantum states in LTE was wrong , physicists would have found out already long ago .
But if you have some personal field theory contradicting QM , you can share it with us just for fun .
Tom Vonk,
A clarification please. When you talk of the emission = absorption for photons of frequency f, you are only talking about photons emitted and absorbed by the gas and you are not talking about photons from an external source, such as a surface at some other temperature. Is that correct?
anna v (21:58:17) :
“It makes no sense to say that if there are no GH gases the atmosphere has no way of cooling other than through ground conduction and convection close to the ground. The atmosphere as well as the ground have the T^4 way of radiative cooling regardless of the gas composition.”
Whilst I completely concur, it also makes no sense to prohibit EM radiation from one type of EM energy transport and not another. Especially when EM radiative cooling caries the least w/m^2 of all the energy transports to the mid tropo (troposphere), where the energy can finally ‘move on’ to be effectively radiated to ‘outer space’. For example, if we look at the radiation budget proposed in Kiehl, J. T. and Trenberth, K. E., 1997;
http://www.cgd.ucar.edu/cas/abstracts/files/kevin1997_1.html
(AKA “the cartoon”) we see that the diagram is slightly confusing for surface to mid tropo and on to TOA (top of atmosphere) for OLR (outgoing long-wave radiation).
If we look at OLR on the R/H/S of the diagram we see a surface OLR value of 390w/m^2, of which 40w/m^2 finds a ‘window’ through all of the atmosphere to ‘outer space’. This leaves 350w/m^2 at about the mid tropo region of altitude, but there’s only 235w/m^2 of OLR actually leaving the TOA inferring that all the OLR doesn’t actually leave Earth’s climate systems.
However, take a look at what is a little closer to the extreme R/H/S of the diagram and we notice an entry for “Back Radiation” to the value of 324w/m^2 that is totally “Absorbed by Surface”!
So it becomes apparent that 324w/m^2 that make the journey to between the mid tropo and TOA are actually ‘reabsorbed’ by the surface to start the journey to ‘outer space’ all over again!
In conclusion, there are only 26w/m^2 of ‘real’ OLR in the original figure of 350w/m^2 ‘phantom’ OLR to the mid tropo region. Something’s missing!
It would be ‘good practise’ to look again at the modes of energy transport to TOA and re-evaluate their ‘real’ share in achieving the transport of energy from the planet.
Though, before doing that, it would also be good practise to include solar insolation to the mid tropo.
Net energy to mid tropo that achieves ‘outer space’ includes:
67w/m^2 absorbed from solar insolation. 24w/m^2 from thermals. 78w/m^2 from evapotranspiration (latent transport). 350w/m^2 – 324w/m^2 (+26w/m^2) from surface radiation. This is equivalent to 195w/m^2 of the mid tropo energy that leaves the planet.
However, OLR from the mid tropo to ‘outer space’ is shown in the diagram as; 165w/m^2 “emitted by atmosphere”; 30w/m^2 emitted by cloud; 40w/m^2 emitted by the “atmospheric window”, which sums to 235w/m^2 and is 40w/m^2 more than is available at the mid tropo altitude.
Therefore, the assumption that back-radiation is generated within the altitudes above the mid tropo region of Earth’s atmosphere must be incorrect with respect to the ‘K&T’ model. The data suggests that all altitudes are responsible for this “back radiation” as 40w/m^2 must come from within the tropo. Again, there’s something missing!
The only rationale I’ve seen that can possibly address this is “The Steel Greenhouse”! Though, it’s impossible for that scenario to explain all the convolutions that make up the “Earth scenario”!
Perhaps the two should be amalgamated together for the inclusion of mass shielding of radiation, or perhaps, “radiative insulation” (the missing “u” factor)?
Finally. If we take the mediators of OLR to the mid tropo to be 67:24:78:26 to be one emission mole of OLR, this shows the total OLR as 195 to be 100% of a mole of OLR to the mid tropo. Thus, 26/195 is the ‘weighting’ of radiative forcing within this region.
However, from mid tropo to TOA emission the molar equivalent is 165:30:40 and constitutes a molar equivalence of 235 as a 100% total radiation to space.
PS. Spector asked for ETR (Earth thermal radiation), so I included this, but I’d imbibed a few glasses of brandy when I wrote it so feel free to find fault. Also I think the linked balance has been updated.
Best regards, suricat.
Before anyone does make this criticism, I realise that the 40w/m^2 comes from surface to TOA just after I posted. (-: embarrassed 🙂
Best regards, suricat.
Nick Stokes (04:35:01) :
Just whizzed through your site link. Sorry, but from an engineering POV I can’t accept the Wikipedia definition for the origin of the Hadley Cells. These are clearly centrifuge generations that undergo seasonal forcings from solar insolation as to their equatorial point of origin. Thus, their strong connection with the coriolis effect that is part of the centrifuge phenomenon.
If the Hadley Cells were primarily generated by solar insolation they would continue to the poles of each hemisphere, much like the Brewer Dobson circulation.
Best regards, suricat.
Suricat,
I am glad someone else has recognised that Kiehl & Trenberth’s global energy balance is an hypothesis aligned to the AGW/CO2 hypothesis and is not based on measurements or theory. I understand that Trenberth is named in the leaked correspondence from the East Anglia University CRU.
There are a number of problems for example
1/ One can not add linearly the radiation from the surface with a clear sky (no clouds) at day and night nor the radiation from and to the surface at different latitudes.
2/ The window for atmospheric radiation from the surface should be higher (50% or more on a clear day)
3/ Clouds cover is uneven and affects the incoming radiation from the sun, the absorbed radiation and the re-radiation both lost to space and back to the surface.
4/ Convection (forced and natural) which distributes heat around the globe and to the atmosphere is uneven depending on the nature of the surface (eg ocean, deserts, forests, mountains)
5/ There is storage and release of heat in the ocean over cycles lasting years eg ENSO
No global balance short term (over one hour or one day), medium term over say one year or one sun cycle (say 11 years) or long term over centuries makes any sense because it says nothing about the mechanisms occuring, the local climate or weather at a particular time or the medium term climate outlook.
Cement a friend (18:08:54) :
I concur. It’s chaotic!
No, I haven’t had any brandy (yet). 🙂
Best regards, suricat.
TomVonk (02:09:00) :
Phil. wrote :
“So by your definition of LTE it doesn’t apply to the troposphere!
Bear in mind that LTE is a convenient approximation not a mathematical definition and so can’t be used in the manner you are attempting to.”
No scientific arguments beside vague handweaving ? Or is it that you really don’t know the definition of LTE ? I said exactly the contrary of your statement – the troposphere IS in LTE .
And thereby lies the internal contradiction of your argument, your definition requires that absorption at a frequency f must equal emission at frequency f, since this is not true of the lower troposphere it does not meet your definition of LTE.
You can be sure that if the M-B distribution of quantum states in LTE was wrong , physicists would have found out already long ago .
But if you have some personal field theory contradicting QM , you can share it with us just for fun .
Indeed, it is your illogical introduction of the concept that there must be an exact balance between emission and absorption that I object to.
suricat (15:55:20) :
anna v (21:58:17) :
“It makes no sense to say that if there are no GH gases the atmosphere has no way of cooling other than through ground conduction and convection close to the ground. The atmosphere as well as the ground have the T^4 way of radiative cooling regardless of the gas composition.”
Whilst I completely concur,
It makes perfect sense to anyone conversant with Physical Chemistry, contrary to your statements above homonuclear diatomics such as N2 and O2 aren’t capable of radiatively cooling in the manner you describe.
AlexB (21:27:35) :
There was some value in the article by Spencer got two things wrong.
Non-greenhouses gases will radiate at the infrared (not much but will). So the atmoshphere can cool directly. Now assuming that isn’t true there would still be air circulation by convection and heat transfer between the equator and the poles, between areas of different heat absorption, etc. Thus we would have wind, dust devils, trade winds, etc. Which sounds like weather to me. With no water dust would itself have effects. Dust particles can act as radiative bodies.
Plus he even went on to ask us to imagine that water isn’t a GHG. In that case we would have rain, snow, etc. Sun hitting bodies of water would heat and one would get evaporation. Water vapor makes air less dense and it would rise. As it rose it would cool and then one would get rain.
So the blanket statement that there would be no weather without GHG is absolutely false.
The other stuff was interesting. Yes GHG make the air closer to the surface warmer and the higher altitudes colder. This would tend to make for the ability to have tighter convection cells where the heat is being pumped from the surface to be radiated away by the atmosphere at high elevations (instead of only being a medium to transfer heat from surface to surface).
This stuff should be obvious to someone who understands high school physics at the A+ level. It’s disappointing that someone in the field should misunderstand this.
Phil. (21:09:58) :
Whilst they are in their diatomic form this is basically true. However, with the soft X-ray and UV components of solar insolation unchanged, O2 and N2 produces ozone and NOx etc. The atmospheric chemistry still continues with all the components that are there, but I don’t know how a, probably, elevated temperature at higher altitudes would affect the chemistry. Accelerate it perhaps? 🙂
Best regards, suricat.
i thought I had a feeling of deja vu:
Starting here is a similar discussion i started on RC somewhile back.
http://www.realclimate.org/index.php/archives/2007/04/learning-from-a-simple-model/comment-page-5/#comment-31361
Alex
Re my own above;
I have not the time to read all the comments that I got back then (2007) but some of the learned brethren at RC had a real hard time accepting that noble gases and others like N2 had no significant IR spectrum, and that the lack GHGs could result in a “dead atmosphere”.
Alex
Roy W. Spencer, Ph. D.
This is your ‘baby’ Roy, so why don’t you clarify a few things here by participating!
“The climate of the Earth is profoundly affected by two competing processes: the greenhouse effect, which acts to warm the lower atmosphere and cool the upper atmosphere, and atmospheric convection (thermals, clouds, precipitation) which does just the opposite: cools the lower atmosphere and warms the upper atmosphere.”
What you describe here are parts of the same thing, “The Greenhouse Effect”!
If you remove the ‘radiative’ attractor the rest of the system ‘takes up the slack’ in order to maintain a balance at, most likely, another level of equilibrium. However, because you’ve chosen to negate ‘radiative energy transmission’ without ‘mass energy shielding’, ‘surface pressure transition’ and ‘thermal inertia/capacity’ the scenario doesn’t become devoid of “Greenhouse Effect”. You still permit some “Greenhouse” effects!
If you want any intelligible feedback from your post, I think you need to participate in the discussion.
Shame on Anthony for allowing your post in the first place, or did he just report this as ‘reportage’, borne of frustration from dearth of ‘news links’ (if this is so, I’ll not expect a reply).
Best regards, suricat.
Alex Harvey (17:22:20) :
Noble gasses! I think I empathise with your thoughts on this, though I’ve not read the posts either. A noble gas that forms an ‘amalgam’ displays totally different properties when compared to the original gas. Thus, O2 displays a variant property when compared to ozone (and ozone enjoys two states of existence, O and O3).
These forms of oxygen seem prohibited in this thread (as they’re ‘radiative’ gasses), but realistically, they are still there, and produced (mediated) by UV and soft X-ray solar insolation.
Best regards, suricat.
Alex,
It wouldn’t result in a dead atmosphere. Convection in the atmosphere would still occur but would merely move heat from warmer surface locations to cooler ones. This would lead to wind patterns.
Even if water were not a GHG the evaporation and condensation of water would occur in a non-GHG atmosphere. This would significantly enhance the ability to transfer heat to the upper atmosphere with convection (because water vapor laden air is lighter, and due to heat of evaporation/condensation).
The only thing I see GHG doing above this is to cool the upper atmosphere and warm the lower, while allowing convection to move heat to the upper atmosphere and then radiate it from the upper atmosphere to space. This would be intensified by the water based heat pumping described in the prior paragraph, and vice versa.
Alex,
Also I believe that a helium atmosphere can radiate away energy because gas is a collection of colliding atoms/molecules. The temperature determines the average velocity but there are atoms traveling much faster and slower. Collisions will rarely happen that accelerate particles at a high enough speed to radiate at a frequency that helium is compatible with. So there will be slight radiation at these higher frequencies.
Yes, it would radiate much less than a black body. Hell, we know this for solids. For example a thermos bottle is mirrored so that it will not radiate away as much heat.
This is also seen with glass. Black glass will glow bright cherry red at the same temperature at which clear glass only glows faintly.
Helium should be a very poor radiator of heat at room temperature.