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.
wayne (10:08:59) :
If you take one molecule and proceed as you do, yes, if the momentum of the system photon-molecule is 1(vector) it will be 1all the way. If it interacts in any way with another molecule at rest, it will still be 1 ( vector) as a system.
The problem comes when you try to extrapolate from the individual quantum mechanical picture to the thermodynamic one.
This goes through quantum statistical mechanics, i.e. the average behavior of ten to the twentieth something particles, all having random directions, and unlimited number of photons all having random directions 360 degrees. It is only then that you can talk of volume and pressure, i.e. thermodynamic quantities.
In order for quantum effects, i.e. the simple picture you are advocating, to become macroscopic you have to have coherence, i.e., the photons involved to be in a lock step, in phase, as with lazers. This is not the case in the atmosphere.
anna v (22:03:07) :
wayne (10:08:59) :
Come to think of it, even with a billiard ball like gas, where again you could apply your simple model, one molecule with vector momentum 1 hits the other whichis at rest, and sends it in the vertical direction , the total momentum will still be vector 1. To go to the macroscopic case you have to go through classical statistical mechanics which comes out with the average behavior that is pressure and volume.
RE: kadaka (14:10:43)
“Spencer concludes the Earth would be essentially isothermal, as Venus is.”
I am sorry, but the atmosphere of Venus is not isothermal. In fact, the tropopause is at an altitude of about 90 Km or 300,000 ft. and as we go down from this level, the absolute temperature rises from about 150 to 750 degrees K. The surface pressure is on the order of 90 atmospheres. Venus does not appear to be a candidate for Dr. Spencer’s thought experiment — I think conditions during the Ice-Ball Earth period might be a far better fit.
Just check this link:
http://www.daviddarling.info/encyclopedia/V/Venusatmos.html
I see 2 problems with this article .
.
First Roy says :
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.
.
In LTE (local thermodynamical equilibrium) the rate of emission of any frquency (f.ex the IR 15µ of CO2 vibrational spectrum) is necessarily equal to the rate of absorption of the same frequency .
This is due to the fact that the population of each quantum level is given by the Maxwell Boltzmann distribution . This distribution depends on the energy (frequency) of the considered quantum level and on the temperature .
That’s why for a layer in LTE , we have a constant temperature from which follows that the rates of absorption must necessarily match the rates of emission .
If they didn’t , it would mean that the populations of any quantum level vary with time what contradicts the hypothesis that the layer is in LTE .
So on the contrary in the general case these rates must match because the relevant part of the atmosphere is in LTE .
.
Second point is that the average temperature is irrelevant . A GHGless planet , (f.ex let’s imagine a pure helium atmosphere) could have a brutal weather .
To simplify , let’s imagine that the planet doesn’t rotate .
As the surface would be violently out of radiative equilibrium at every point , the surface temperatures would cover n vast range going from over 100°C on the day side to below 100°C on the night side .
These huge temperature differentials would create extremely violent atmospheric horizontal flows between the day and night halves .
So this planet would establish heat dissipation patterns which would involve heat transfers from the day half to the night half whic would look like mega storms .
.
If we allow the planet to rotate , the pattern would change as the Coriolis force and the variation of irradiation with time would probably transform these storms in more complex rotating hurricane like structures .
So definitely depending on the speed fo rotation and the thermal properties of the atmosphere (heat capacity , thermal conductivity , density) the planet would exhibit a large range of probably very violent weather features .
Re: TomVonk (02:37:24) :
“That’s why for a layer in LTE , we have a constant temperature from which follows that the rates of absorption must necessarily match the rates of emission .
If they didn’t , it would mean that the populations of any quantum level vary with time what contradicts the hypothesis that the layer is in LTE .
So on the contrary in the general case these rates must match because the relevant part of the atmosphere is in LTE .”
This is just not true. Constant temperature requires rate of energy in, equals the rate out. Heat a gas by another means and it can have a net radiative output and a constant temperature. This is the case for the atmosphere the radiative deficit being made up from sources like latent and sensible heat.
Alex
anna v (22:03:07) :
anna v (22:16:24) :
Yes, yes, Anna.
Read my reply to Ron House (05:31:04) first.
If you can, keep thermodynamics and QM in mind but by my careful definition, drop them for a minute. Go back to the basic laws they are built on.
And my only point of all of that was to press the problem I have with radiation and the way it’s currently viewed in science many places and papers, irregardless of whether you speak of classic, thermodynamically, or QM. I’m staying away from angles so sine and cosine factors don’t get dragged in to the conversation. The ‘other’ molecules can have angular velocities but their velocities are irrelevant in my case. I’m not tracking their velocities and therefore momentum. Radiation emitting from the sun will, irregardless of how many interaction and collisions occur, press down on the gases. And, radiation emitting from the surface of the earth will press upwards on the gases, even if a gas (like CO2) has absorption bands in proper frequencies and absorption is occurring. (Of coarse, allowing for the angles created).
I read statements about upward dwelling IR being absorbed by CO2, heating it, and it re-radiating (50% minus dip) back down to the surface and that traps the heat. That to me that totally violates conservation of momentum without accounting for the upward pressure which, since there is no ‘top’ on the atmosphere, will expand it, if pressure preserved in the long run. You have basically have created heat from nothing. Photon leaves surface, absorbed, molecule has v of one upward. Molecule emits photon down and absorbed by ground, molecule has v of two upward. The affect on the ground is null. The molecule has velocity up and therefore heat but from what? Nothing!
We can speak of energy, and of coarse you must in certain cases, and energy must always also preserve, but you lose the vector components which is vital to my point, but science lets me to take that view if I define it that way and in this specially defined view.
Now, do you now see a little deeper in my example. Dr. Spencer’s example brought all of this to mind again and I thought this a place to clarify if someone knew enough to grasp, it seems you do.
anna v (22:16:24) :
Oh, forgot to mention… this of coarse only occurs if the photons interact in some way when passing thru! No interaction, no effect.
Anna:
Now think this. A experiment on CO2 in a lab. The gas is in a enclosure of some sort, lets say flask. Irradiate it. It heats. It can’t expand. Pressure goes up and temp goes up.
Now do same experiment in a topless flask, which we probably can’t do in the lab. The gas can now expand as it heats. I am not that versed in TD enough to answer that question but the results will differ. Do you know in what way? Temp will go up once but CO2 can’t keep absorbing if it’s already in an excited state. A one time increase, right?
wayne (04:06:07) :
wayne (03:40:01) :
Have a look at that nice oven by Peden,
http://www.vermonttiger.com/content/2008/07/nasa-free-energ.html
It says the same thing, double counting due to mixing up radiative/qmechanical world view and thermodynamcs.
wayne (04:06:07) :
If the flask is open the pressure will be the ambient pressure ( 1 atmosphere I suppose) thus the volume will grow, from pv=RT.
“”Alex Harvey (03:17:28) :
Re: TomVonk (02:37:24) :
“That’s why for a layer in LTE , we have a constant temperature from which follows that the rates of absorption must necessarily match the rates of emission .
If they didn’t , it would mean that the populations of any quantum level vary with time what contradicts the hypothesis that the layer is in LTE .
So on the contrary in the general case these rates must match because the relevant part of the atmosphere is in LTE .”
This is just not true. Constant temperature requires rate of energy in, equals the rate out. Heat a gas by another means and it can have a net radiative output and a constant temperature. This is the case for the atmosphere the radiative deficit being made up from sources like latent and sensible heat.
Alex
“”
I think Tom Vonk and I are in agreement here, but perhaps neither of us have explained things successfully.
There is conservation of energy present so if the power in doesn’t balance the power out, there will be a change in internal energy – like a change in temperature or phase change. That includes latent & ssensible heat or conduction and convection as well as radiative. This is not the issue being covered.
What is being covered is that for a parcel of air with ghgs (a thin shell), the emission curve is actually going to be equal to the absorption curve multiplied by the maxwell boltzman black body emission curve such that where there is absorption likelihood of 1 (total absorption) for the parcel then there is an outward emission equal to that of a blackbody at that wavelength and where there is an absorption likelihood of 0, there is no emission. Tom describes it in qm terms that the maxwell boltzman distribution is the distribution of energy states for the gas at its temperature.
LTE, local thermodynamic equilibrium is referring to the fact that in a tiny area, all molecules will be at the same temperature due to energy sharing by thermal collisions. It this were not the case, the N2 molecules might be at 300k while O2 molecules might be at 320k and the co2 molecules in that tiny area might be at 390k or 220k. That is, there would not really be a unique temperature for any tiny local region.
A consequence of this emission absorption relationship is that if the parcel were at the same temperature as the surface (assuming only one parcel for a moment) then there would be no absorption spectra seen and if the parcel were at a hotter temperature, then there would be emission lines present. Finally, if the parcel of air were cooler, there would be absorption lines present but rather than the maximum absorption being one or the output power at a maximum absorption wavelength being zero, the outgoing spectrum would show the power output at these maximum absorption wavelengths as being at the rate of emission of a black body curve for the temperature of the parcel.
A final factor is that the parcel’s outward emission would be the same as its downward emission such that the absorption of radiant energy would be E and the outward emission E and the downward emission of power would be E, assuming the temperature was the same as the surface – that gives 1 E in and 2 E out – an imbalance. That means the temperature of the the parcel would have to drop to the level such that energy is conserved. If it’s in an area where there is convection bringing in more energy, then that temperature can be higher. However, one has a lapse rate defined here without convection.
If you have the same T for space above as for Earth below, then you have balance where the parcel reaching T as there is 2 E coming in and being absorbed and 2 E going out by emission and that means and no convection going on since there is no delta T. Note it is a thin and tiny parcel or the geometry will make things rather confusing and complex.
>> ginckgo (21:08:23) :
So what was earth’s climate like 200,000 years ago, Dr Spencer? Oh, that’s right, God hadn’t created it yet…
<<
If you actually read the link you provided you will note than Dr. Spencer never stated or implied that the Earth was less than 200,000 years old; his statement supports the big bang creation theory. So much for your pathetic ad hom attempt. Why is it that Big Climate seems to put forth ad hom attacks as their only 'science'?
Re. suricat (19:44:33) :
“I reiterate that; any mass above absolute zero temperature radiates its temperature signature until its mass temperature returns to absolute zero (though this is unobtainable).”
But for many simple gases like N2, that signature is “effectively” no emission.
Incredible as it may seem such gases have virtually no radiative emissions when at earth-like (e.g. room) temperatures.
Yes, it is true that N2 does have IR emission/absorption spectra but the peaks are few (very few compared to CO2) and they are tiny (about 10 orders of magnitude smaller). The are also well off to the high wavenumber end for earthlike (~290K) temperatures.
It is effectively IR transparent, so much so that it is used to backfill to obtain standard pressure when measuring the spectra of other gases. To all intents and purposes it cannot lose heat by radiating it away, when at earthlike temperatures. An atmosphere consiting of N2 would fit the bill of being free of the GH effect. Unless one wishes to be difficult.
Alex
Re. cba (05:40:39) :
I do not have a problem with your explanation and near the end you point out that the absorption does not match emission when the radiative field from above is deficient as is the case here. That is correct, but the statement I objected to states something that neither of us seems to agree with.
Alex
Thanks to Dr Spencer for providing us with the opportunity to learn something. As the scientists would say “This discussion raises the question: Could a planet with a transparent atmosphere have more violent weather than one with abundant water and plenty of CO2?” Haven’t we noticed a decline in hurricanes and tornados in recent years? If heat can exit the atmosphere at low latitudes, doesn’t that mean there is less heat to be rejected at the poles?
anna v (04:58:10) :
Oh, I’m rolling! That’s a great one!! Exactly. It’s scientifically impossible. CO2 cannot increase heat period from re-radiation.
Another thing I never hear in the conversions is the lifetime of the CO2 molecules and their heat, molecular level. It begins is life inside engine cylinders and furnaces mainly. Totally excited and HOT!! Do you think the radiation from the sun can further heat this CO2. I hardly think so!!
All but a small fraction of this excess heat (above ~60ºF global average) will radiate to space in the same way my hot patio concrete will. On the average these CO2 molecules will also end up in a mixed excited state radiating this difference also into space.
Along with the understanding above of re-irradiation effect, being impossible, I seem to end up with absolutely no abnormal heating from CO2 at all in the long run. Only a one time heat gain equal to the temperature of all engines, furnaces, homes, and offices in this world. Sounds large but really is minuscule. Might be wrong but can’t locate any more heat.
Thanks Anna. Its much clearer now.
Re: TomVonk (02:37:24) :
I think that you need to show more details regarding temperature differences between light and dark sides, and in the case of a rotating earth of temperature gradients in general.
Without the GH effect it is neither clear how, or why, the temperature of the atmosphere would change much even if the surface temperature rocketed up and down. There is a lot of radiative coupling between the surface and the atmosphere that would be missing in a world free of the GH effect.
During night conditions the atmosphere cools itself and and provides heat to the surface but the GH effect is significant in this process. With the surface cooler than the atmosphere convection is not going to provide much heat transfer and that leaves diffusion which is relatively feeble.
During day conditions, convection would be significant but it may just tend to raise the average temperature of the atmosphere above that of the surface, leading to a bit of a standoff.
It is not at all clear to me how large temperature gradients are going to be created and maintained. So I think you need to show more mechanism in this area.
Alex
Hi my name is Emily, Wayne is my grandpa, my best grandpa.
I heard about the global warming stuff and I think that it is all a hoax. My Grandpa said all that they want is money from other people. Oh, and by the way… I loved the energy-free oven. The part I loved most about it was the ”Chicken not included”. Don’t tell my Grandpa i wrote.
alex,
I’m not sure what Tom Vonck was referring to in his post. (I’m fairly familiar with Tom and english is his second language but I know better than to capriciously tangle with his command of the physics fundamentals). I suspect he may be referring to the einstein coefficients being equal under LTE. Whatever he meant with his statement, it’s not going to violate conservation of energy.
Well however, or by whatever mechanism, the atmosphere warms; and I’ll buy Dr Spencer’s GHG free atmosphere model, that warm atmosphere WILL cool by thermal radiation (at all levels in the atmosphere). That atmospheric emitted LWIR, should by all accounts be isotropic (at emission), so only a part of it is returned to the surface; the rest escapes to space (in the GHG free atmosphere). In fact the amount escaping to space should be about 50% since we have built in no LWIR absorption mechanism into the atmosphere; so both the upwards, and downwards thermal radiation experience no secondary atmospheric absorption.
So the planet should cool by direct thermal radiation from the ground, as well as thermalr adiation from a conduction heated atmosphere. Note that convection would also come into play in transporting the conductive heated air to higher altitudes, until it too cools by radiation.
I couldn’t agree more with Dr Roy, that a GHG free atmopsphere would give a quite different planet. Well if the angle of the H2O molecule was 180 degrees, instead of 104.xx it would be quite different too, but we wouldn’t have to worry about it, because there wouldn’t be any life on this planet, if that were so.
The emission of gases in the atmosphere, is spontaneous emission (all directions) or induced emission (in the same direction as the inductor photon)? I think it is mostly induced.
So what would be the source(cause) of induced emission ? I can understand that an excited GHG moleculec ould subsequently re-emit the IR photon; so long as the density is low enough so the mean free path is long enough; but otherwise I would expect that absorbed energy would be shared with the main atmosphere gases in collisions due to temperature. I’ve read that the normal thermal emission, is due to acceleration of charge in atoms/molecules moving due to thermal collisions.
Alex Harvery above: “”” Alex Harvey (06:41:56) :
Re. suricat (19:44:33) :
“I reiterate that; any mass above absolute zero temperature radiates its temperature signature until its mass temperature returns to absolute zero (though this is unobtainable).”
But for many simple gases like N2, that signature is “effectively” no emission.
Incredible as it may seem such gases have virtually no radiative emissions when at earth-like (e.g. room) temperatures. “””
….asserts that N2 doesn’t emit much in the way of thermal radiation. Now I realize that the Black Body Radiation sets an upper bound to the emissions from matter due solely to its temperature; but I am intrigued by Alex’s assertion that the emission is negligible in the case of N2; he says 10 orders of magnitude less than CO2.
How is that level Alex compared to the BB theory for that temperature.
I’m intrigued by Alex’s information; is that due to some extreme symmetry of electric charge distribution in N2 Alex, or what is the Physics behind its low emission.
Obviously gases do radiate as evidenced by the sun; but I have a hard time believing that the main radiation from the atmosphere (earth) is due to emission from GHGs rather than from the bulk of the atmopshere.
Others have suggested that during molecular collisions, the conditions might be such as to admit radiative transitions that might normally be forbidden for isolated molecules (of ordinary atmospheric gases).
If Alex can steer us toward any lterature, it would be helpful.
”
Alberto (12:20:30) :
The emission of gases in the atmosphere, is spontaneous emission (all directions) or induced emission (in the same direction as the inductor photon)? I think it is mostly induced
”
you’ve just practically said the sky is a laser. Both collisions and spontaneous emission are going on extremely rapidly with good likelihoods that any absorption can be converted to thermal energy.
There is a problem with the assertion that a molecule or atom can radiate as long as it is above absolute 0. This isn’t the case. They can only radiate at their spectral lines – and if the energy of the atom or molecule is lower than the lowest spectral line it can’t radiate. The BB curve will show the energy distribution for the energy states of the atoms or molecules at that temperature. Solids, liquids, and gases at sufficiently high temperatures can achieve the BB curve because the excited states include all those myriads of high transition numbers.
The Bohr theory is very instructive in this. Ground state associated transitions form the lyman series and that is in the uV. Visible hydrogen emissions are the balmer series. Each series is an infinite series. In order to emit in the visible, the atom must be excited by uV or enough heat to raise it beyond the excited state necessary to achieve uV emissions. Failure to raise it to that level results in no emission (ignoring the 21cm line which is related to spin).
I think cba is close to the facts.
There seems to be an opinion that CO2 will absorb all the emitted IR from the surface. That is not correct if one looks at the spectra of each of the gases. Water vapour has a much wider spectra than CO2. On the NASA website I found a statement that water vapour will absorb eight times the IR wavelengths of CO2. By sight of the spectra that appears correct.
Assuming that the atmosphere is 100% CO2 like Mars would mean that in excess of 70% of the surface emitted IR would be radiated directly to space. However, there will be heat transfer from the surface to the atmosphere by convection (natural and forced). This will distribute heat around the globe and where the surface temperature is lower than the gas temperature (around the dark side) the surface will be heated and radiate. Taking into account convection means that any atmosphere will cause the average temperature of the surface (around the globe) to be higher than it would be without an atmosphere (eg the moon approx 400K to 40K). Finally, the surface will be heated slightly by conduction from the nuclear reaction in the earth’s centre. This is not necessarily an even distribution and will have an effect of atmospheric movements.
It should also be noted that water (liquid) is almost a black body (average emissivity 0.95). At present the surface of the earth is about 70% covered by water. If there is no water then the planet will be a grey body which will reflect radiation particularly in the UV and visible range.
On earth the driver of climate is water and water vapor. CO2 makes little or no contribution.
Happy New Year and stay strong
Thanks for a wonderfully articulate article. Water seems to be the elixir that makes everything possible. Maybe the global warming oh no climate change is happening scientists, ought to go back and think about some of the most basic principles of science and have a bloody good look at how water behaves.
CO2 = $ = centralised government + corporate dominance = more $’s for the rich.
As a bemused bystander, I am astonished that N2 IR emissivity is a contentious topic amongst people with degrees in Physics. I certainly don’t have one, and I seldom stay at a Holiday Inn, so I would welcome a more intimate exposé of the low energy photon emerging from a dilute gas molecule. Since this is out of the realm of electron promotion, it’s unclear to me where the energy resides before it’s emitted. Is there something about inter-molecular bonds in dense matter that accounts for the difference? Would a lone N2 that has escaped into space keep going until a collision, without slowing down? If it emitted, would it slow down? Let’s assume that it cleverly avoided incoming photons.
If somebody has the patience to explain the mechanics of cold gas emission in layman’s terms, I’ll be grateful!