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.
anna v (13:21:20) :
“If there were no GH gasses the atmosphere would cool even better because it would be transparent to the infrared coming from the ground, and it would radiate with T^4. What happens every night in the dry deserts.”
I don’t do quantum much, but surely you mean that the ‘surface would cool even better’? As atmospheric IR radiative energy transfer is prohibited in this model, the atmosphere must find it more difficult to achieve the LTE that Spencer proposes. Though the prohibition of radiative energy transfer isn’t quite so disruptive as the prohibition of all water, with its latent energy transfer, that he also proposes.
The only methods of energy transfer open to his model are convection, advection (winds) and conduction, however, the atmosphere isn’t considered a thermal conductor as it insulates heat energy when it can’t employ radiation (molecular diffusion doesn’t really count for energy transfer either).
My guess is that Roy suggests that ‘radiation’ is limited to colisional energy transfer in his model, but without the evolution of photons?
Without a better ‘explication’ I’m finding it hard to ‘get my head around’ this model, because TOA (top of atmosphere) becomes a closed boundary to energy transfer without EM (electromagnetic) radiation and we still have the ‘GHE properties’ of thermal inertia against insulation by atmospheric mass to cope with in his model!
Due to the nocturnal ‘temperature inversion’, the atmosphere can only cool to greatest altitude by warming the point of highest surface altitude. This means that eventually, the planet exhibits an inverse lapse rate because the altitude of atmospheric cooling is at the greater altitudes of the planet surface (thus a near surface ‘sink’ for atmospheric energy).
I guess that we still will encounter atmospheric dust particles that aid atmospheric warming (global dimming material) from solar insolation as well as IR.
This can only add to atmospheric energy to the point where it becomes near to 40% of Sol’s radiating temperature source (total speculation on my part).
Either my reading is illogical, or Roy’s model is wrong.
I’d prefer to give Roy the benefit of the doubt, so can you tell me where I missed something?
PS. “What happens every night in the dry deserts”: In ancient Egypt, the manufacture of ice was achieved by covering an area of desert during the daytime and uncovering it at night (or so I’m told). Without the daytime solar insolation on the sand the night-time cooling is/was able to freeze water.
Just thought I’d add that for social interest.
Best regards, suricat.
cba (14:32:20) :
Here’s a quick calculation on the situation of no ghgs (and no h2o vapor)
Incoming average power at TOA is 341.
Earth albedo is 0.31 = 0.22 (clouds and atm) + 0.08 (average surface)
No H2O vapor = no clouds!
Tom_R (06:08:52)
Spencer says: “The possibility then presented itself that, despite all I had previously thought, Genesis, the first book of the Bible, might actually be true!”
Of all the books in the Bible, Genesis is arguably the least accurate from a scientific stand point.
And nowhere does he say the Genesis account is a metaphor or whatever. No, the Bible is “the most accurate and best-substantiated ancient book known to man”. Add to that his unimaginative denial of evolution.
Brian (16:58:38)
Its P Wilson, not P Nelson.
The point about the tarmac confirms the argument: Very little radiation leaves the earth to be absorbed by co2 or any other ghg and heat up the atmosphere , regardless of what any constant says about it. Those convectional waves/currents are not at a wavelength that c02 has the sufficiency to interfere with, so what little radiation does leave the earth, which is ideologically imputed to be 235w/m2 by the said constant at – which incidentally is hotter than your body temperature as determined by the basal metabolic rate – NOT), is actually a tenth of what it is calculated to be – air is a poor conductor in any case and ghg’s too sparse to give a greater density of air that would give an increase in temperature.
Anna – the delay between the transfer of energy from a c02 molecule and its subsequent thermalisation takes place in about a trillionth of a second. Its safe to assume that if heat retains in the atmosphere for any length of time, there are natural forces doing this such as air pressure, gravity, and convection reduction such as clouds. Its warmer during cloud cover as convection is severely reduced.
suricat (17:09:04) :
anna v (13:21:20) :
“If there were no GH gasses the atmosphere would cool even better because it would be transparent to the infrared coming from the ground, and it would radiate with T^4. What happens every night in the dry deserts.”
Heat loss from deserts comes mainly from the fact that they have to thermalise much more with cooler air above – the differential is much greater than elsewhere and this is where Dr Spencer is right – as the ground temperature decreases, it cools the air above it, the air contracts with cooling and floats downwards
“”
Phil. (18:19:55) :
cba (14:32:20) :
Here’s a quick calculation on the situation of no ghgs (and no h2o vapor)
Incoming average power at TOA is 341.
Earth albedo is 0.31 = 0.22 (clouds and atm) + 0.08 (average surface)
No H2O vapor = no clouds!
“”
That’s why my original posts has
“”
Energy arriving at surface = 341 – reflected = 341 (1-0.08) = 314 w/m^2
for balance, outgoing must be equal and since there’s no clouds or ghgs to block outgoing, the average outgoing power then is 314 w/m^2
doing a reverse calculation from stefan’s law, T = 273K, roughly freezing as compared to today’s temperature of 288.2K which is 15 K lower than present.
“”
Note that the albedo is broken down between surface and atm (primarily clouds) and that the clouds, like h2o vapor, are not in Dr. Roy’s model. Without ghgs, including h2o vapor, and without clouds, that leads to a simplified average whose surface comes out as 273K which is higher than the typical -33 deg C estimate because the cloudless albedo is going to be closer to 0.08 than to 0.31. I would expect that Dr. Roy’s simple model also ignores scattering and dust effects which would be pretty much the rest of the 0.22 portion of the albedo.
Radioactive Man (Norway) (07:14:37) : (http://theevolutioncrisis.org.uk_testimony2.php) where one can read Dr Spencer’s less than enlightened views on evolution and the historicity of the Biblical Gospels, among other things. I must admit I was quite shocked by what I read. I can’t avoid being sceptical of anything he writes on climate science from now on, even if it isn’t related to his religious/anti-evolutionist views.
So, I take it we can toss out that Einstein relativity and E=MC^2 stuff too… can’t have anyone with a religious idea doing science, after all, that might lead nuclear reactors and unlimited energy and the modern world.
I take it from your comments that Jews and Muslims ought not to be allowed into science courses since nothing they might do would be of value… After all, they too believe in Genesis /sarcoff>
Please, take just a moment to think about intense bigotry in the statement you made and were it leads.
Also, there is a rather fascinating book that simply takes into account relativity and finds that, adjusting for time dilation in calibrating the clock, Genesis matches rather well with “science as we know it” in chronology.
http://www.amazon.com/Genesis-Big-Bang-Discovery-Harmony/dp/0553354132
This topic is being discussed, but politely at:
http://chiefio.wordpress.com/2010/01/04/darwin-expelled-and-religious-science/
which is probably a better place for it since Anthony discourages discussion of religion here.
RE: cba (06:28:58)
‘If there is not enough thermal energy to raise the molecule to the lowest excited state capable of emission, then you don’t have the ability to have emission even though you have above zero temperature.’
Vibrational and rotational energy states are internal energy states of a molecule and will cause a molecule to emit discrete packets of thermal radiation down to its ground state. Radiation of the wavelengths which are termed thermal radiation are so called because they are the spectra of wavelengths that molecules emit down to thier ground state.
Oliver Ramsay (08:04:48)
‘I don’t see how changes in molecular velocity occur without interaction with other particles.’
I’m going to attempt an analogy here. As with all analogies if you push it too far it falls down but it is simply to make a point.
Imagine a molecule as a small Newtons cradle in air. As the cradle swings back and forth it inevitably loses momentum through various processes such as sound. The point I’m making here is that the energy loss is inevitable. It can’t just keep going and going.
Now the thing which is hard for us to imagine with radiation is that the energy loss requires no medium. Depsite this however if a molecule is on its own in a vacume and excited (i.e. temp above 0K) then energy loss by radiation is inevitable. Lets just consider vibration. The atoms in the molecule vibrate back and forth and this vibration will diminish over time due to thermal radiation the mechanism of which is the change in velocity of poles in the molecule.
Now as for rotational losses I’m afraid that I have trouble picturing this one too. Rotational losses are to do with angular momentum of components of the molecule such as (but not limited to) electrons. I think mainly of the electrons as I think they are the easiest to visualise. The way I like to think of it is that an electron spinning around in a molecule which has a fairly uniform charge distribution will have a more constant angular momentum than an electron spinning around in a molecule without a uniform charge distribution. Sorry I can’t be more concrete than that.
P Wilson (19:22:20) :
suricat (17:09:04) :
anna v (13:21:20) :
“If there were no GH gasses the atmosphere would cool even better because it would be transparent to the infrared coming from the ground, and it would radiate with T^4. What happens every night in the dry deserts.”
I don’t do quantum much, but surely you mean that the ’surface would cool even better’? As atmospheric IR radiative energy transfer is prohibited in this model, the atmosphere must find it more difficult to achieve the LTE that Spencer proposes.
The quantum bla bla was in order to establish that all matter cools by electromagnetic radiation according to the law Flux=constant*T^4 . 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.
How about heat loss on the dark side of the moon? Or is it not loosing heat because there are no gases?
Heat loss happens in deserts because the ground radiates according to T^4 . Deserts do not get to moon temperatures because of the complicated buffer provided by the atmospheric gases. GH gasses are superior in efficiency of buffering is all. By absorbing and thermalizing they increase the heat capacity of the atmosphere. Each quantum process may take place instantaneously, but the average kinetic energy is increased statistically and thus temperature, which will be lost slowly according to constant * T^4 of the atmosphere, instead of directly at the speed of light with which the ground infrared photon leaves ( which is what happens on the moon).
Brian (16:58:38) :
OH and Anna V., I still want my
Qm based toothbrush!
You already have a toothbrush I suppose? I can guarantee that it is working quantum mechanically at the hbar size level. You are just seeing the quantum statistics of the large number of molecules of which your toothbrush is composed. Every little pressure is at the final end a soft photon emitted by the toothbrush interacting with the residue molecules on your teeth.
Anna v, with respect, measurements and experiments have been carried out by many researchers on combustion gases containing CO2 and H2O (in closed systems) particularly by the late Prof Hoyt Hottel. You will find data and equations in text books on heat transfer (conduction, convection, radiation and phase change). Perry’s Chemical Engineering handbook gives a good summary and includes an equation for determining the absorptivity and emissivity of the total gas (which mainly comes from water vapour and CO2). The table in Perry is for temperatures in heat exchangers and will need extrapolation to lower temperature. Another book I have gives Hottel’s data in graphical form and this goes down to 100degreeF. The equation requires input of temperatures of emitter (surface) and receiver (gas) (or vice versa), the concentration of CO2 and water vapour (expressed as partial pressures) and the beam length (height of various layers of the atmosphere). I have made some reasonable assumptions in the equation and, as I hinted, I found that the absorptivity/emissivity of the CO2 component in the atmosphere insignificant in comparison to water vapour. Hottel (who wrote the section on heat transfer in Perry) has also considered and researched the effect of clouds. It should be noted that water (liquid) is close to a black body (emissivity >0.95)
I agree with the posts mentioning the naming of greenhouse gases. The earth is not a closed system. One just has to consider leaving a car closed up in the sun. It is hot inside and maybe at first the steering wheel is too hot to touch but open all the doors the the temperatures quickly go down. The heat transfer in the closed car comes from the surfaces absorbing radiation from the sun. Natural convection then heats up the air which rises up but can not go out. The air temperature can get to in excess of 60C (There are now criminal laws about leaving children and dogs in closed cars). If there is a wind blowing when the doors are opened the car will cool much quicker. I have made measurements of heat loss with surface temperatures around 50C and find that with winds around 15km/hr that forced convection exceeds radiation. I have not made the calculations about the earths heat balance but believe that Tremberth et al have very much underestimated heat transfer by convection and evaporation and very much overestimated the absorption/emission exchange between the surface and the atmosphere.
Everything points to CO2 in the atmosphere making an insignificant contribution to heat exchange and to climate.
AlexB (21:23:36) :
Oliver Ramsay (08:04:48)
‘I don’t see how changes in molecular velocity occur without interaction with other particles.’
I’m going to attempt an analogy here. As with all analogies if you push it too far it falls down but it is simply to make a point.
Imagine a molecule as a small Newtons cradle in air. As the cradle swings back and forth it inevitably loses momentum through various processes such as sound. The point I’m making here is that the energy loss is inevitable. It can’t just keep going and going.
The difference between the macroscopic world and the microscopic world is in that the energy momentum and angular momentum losses happen in a quantized way. It is not a continuum.
Do not confuse kinetic energy of an atom with the potential energy contained in its electrons. They do not mix. An atom in its ground state keeps going and going independently of its kinetic energy.
Same with molecules, except that the vibrational and rotational levels are low enough in energy that they can be activated by the soft quanta exchanged in collisions, ( I gave a more explicit picture in a post above) thus changing their kinetic energy.
Cement a friend (22:49:53) :
I do not disagree with what your are saying. Of course there are many mechanisms and important ones and the gas composition is important.
What started me is the proposition that the only way the atmosphere can cool is by conduction and convection in the absence of GH gasses. This is not true. The gas in the atmosphere is matter and all matter radiates according to the constant*T^4 law. The constant in this case may be small but not nonexistent as some here have been saying and as the quote I gave above assumes.
Anna v, I respect your views please do not get me wrong. I am sure that you know far more about quantum mechanics than I could ever hope. Thermodynamics is a chemical engineering subject but which always deals with the macro state, so my knowledge is inferior to yours.
One thing I have found in my past working life is, there seems to be very little communications across the various technical and scientific disciplines (I have also found lack of communications in different industries but in the same disciplines. I think it comes from too much specialisation). The so-called “climate scientists” think they know everything about what occurs in the atmosphere and ignore the vast amount of knowledge and research done outside their sphere of limited knowledge. For example the measurements made on atmospheric CO2 concentrations in botanical research (especially if it has been written in German) has been ignored by the climate pseudo-scientists. It seems to me that the latter also have little understanding of heat and mass transfer or fluid mechanics. Their “black box” models for average global conditions are meaningless. The conditions at day and night, at equator and at the poles can not be linearly averaged.
Anyway, I wish you a happy new year.
Spector (03:06:07) :
I believe the basic point being made here is that convection cannot continue unless the convected heat can be radiated out from the upper atmosphere.
Well, it isn’t true. A convection cell is a cycle, and the heat just has to be transferred from one place to another. It needn’t be removed at the top. The classic atmospheric circulation is the Hadley cell. Hot tropical air rises, it transported poleward, descends, and warms the cool mid-latitude surface. The source of heat is the excess of sunlight over outgoing IR in the tropics, and the sink is the corresponding deficit in mid-latitudes. Incidentally, this cell in no way requires GHG, and would work without them.
To others, I note a lot of pointless theoretical discussions about whether O2 or N2 can emit IR in the thermal range. They can’t, but this is also a simple matter of observation, well known to Tyndall in 1862,and much more exactly confirmed since.
Phil. wrote
.
No, the highlighted part is not correct, it is only necessary in LTE that the transition is made, not that emission occurs, in fact in the troposphere that is effected mostly by collisions not emission. It is the emissivity that equals absorptivity not “absorption=emission” (Kirchoff’s law).
.
This is again an example of deep misunderstanding of what LTE means .
In order to respect the Maxwell Boltzmann distribution in LTE , once a photon is absorbed and the molecules goes from E0 to E1 it is necessary that another molecule goes simultaneously from E1 to E0 .
It is true that it is not prescribed by what PROCESS this downward transition should take place .
And it is also true that the gas has 2 processes at its disposal – collisional decay and photon emission .
Of course I am well aware of all this and my original statement stays correct .
The proof is trivial .
.
Obviously the Maxwell Boltzmann distribution in LTE is achieved by taling in account ALL PROCESSES that modify the distribution of the quantum states .
And what I said about the couple absorption/emission also applies to the couple collisionnal excitation/collisionnal decay .
In other words for every molecule that collisionnaly decays (e.g goes from E1 to E0 by collision) there is one molecule that collisionnaly excites (e.g goes from E0 to E1 by collision) .
It is easy to see why .
If this was not the case , there would be a net energy transfer of one species of molecules to another by collision (f.ex from CO2 to N2) .
The result would be what cba already mentionned (but what I believe was misunderstood too) – the temperatures of 2 (or more) species in the same volume would be different .
And that is precisely a CONTRARY of LTE !
Actually it is the existence of collisionnal equilibrium that is the necessary and sufficient condition to have an LTE .
.
So what stays is that BECAUSE of the collisionnal equilibrium (e.g LTE) the rate of absorption of a frequency f is necessarily equal to the rate of emission of the same frequency f .
Anything else is a non LTE condition where the standard thermodynamics is no more valid and one must use a quantum mechanical treatment .
.
AnnaV
Yes . Strictly speaking there can be no “GHEless” atmosphere .
Even an atmosphere made out of N2 and/or O2 only would absorb and radiate in IR .
The mechanism is known – collisionaly induced absorption/emission .
It is due to the existence of metastable dimers and multipole moments that exist due to collisions .
The effect is indeed small compared to the “big” GHGs but observable even in our atmosphere for very dry conditions .
This effect would still exist in a “GHGless” atmosphere but could no more be neglected because it would be the dominant mode of the radiative transfer .
Obviously , due to the huge temperature differentials between the day and night halves that I already mentionned , the massive atmospheric flows would contribute more to energy transfers than radiation .
But as this system would be as chaotic as the one our real Earth has , we all should know better than to think that a small effect has always small consequences .
In a chaotic system it is not the case .
Spector (03:06:07) :
Kevin Kilty (21:01:47)
I’ve now put up a post at my blog explaining why the atmospheric heat engine drives motion independently of the GHE, and why this would maintain the dry adiabatic lapse rate (more uniformly, in fact), and why the main climate circulations would persist.
“”
“”Nick Stokes (04:35:01) :
Spector (03:06:07) :
Kevin Kilty (21:01:47)
I’ve now put up a post at my blog explaining why the atmospheric heat engine drives motion independently of the GHE, and why this would maintain the dry adiabatic lapse rate (more uniformly, in fact), and why the main climate circulations would persist
“”
And what drives your perpetual motion machine there Nick?
I did notice one correct statement there. That was adiabatic lapse rate not relying or not being associated with radiative emissions – something that would violate the concept of being adiabatic. It’s also a failing or limitation of the ideal gas law.
Usually in this world, parcels or balloons rise due to lower density. That is caused by moisture content and by warmer conditions. In Dr. Spencer’s discussion, the moisture content is not there, leaving only warmer conditions to permit your balloon to rise. As it rises, it expands out doing work and hence cooling off. As it rose it, the area below was forced to be filled by other air that started off cooler but when it went lower in the atmosphere, the pressure increased, doing work that warmed the replacement gas. Without the radiation, all that is available to lift the balloon or parcel is the lower density due to the heat. As the altitude pressure drop expands, that heat goes into the expansion leaving the density to reach that of the surrounding air – where the parcel no longer rises in altitude. It stops where the densities are equal and that is where the temperatures are equal (dry adiabatic conditions). There is no cooling or warming going on from outside as that violates the concept of being adiabatic. Note that the energy work activities going on include both against pressure and against the graviational effect.
Might I suggest rereading the wiki article you reference. I think it is accurate enough to provide details.
If you want energy transfer, you’ll have to consider the more complex case of h2o involvement.
RE: Nick Stokes (02:00:20) :
Responding to my comment “I believe the basic point being made here is that convection cannot continue unless the convected heat can be radiated out from the upper atmosphere.”
Saying “Well, it isn’t true. A convection cell is a cycle, and the heat just has to be transferred from one place to another. It needn’t be removed at the top.”
Yes you are right. Convection due to lateral temperature differences should be possible. Without water vapor condensation to accelerate this process and without upper atmosphere cooling, I would guess that such convection would primarily be manifested as laminar surface winds typical of conditions during a widespread temperature inversion.
In the real world, I believe an important question is, “What fraction of the Earth’s surface heat energy is convected away to the upper atmosphere as opposed to that fraction eliminated by direct thermal radiation?” It should be possible to measure the overall ETR (earth thermal radiation) brightness of the cloud-tops as compared to the ETR from the surface.
ginckgo (2010-01-02 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…
http://theevolutioncrisis.org.uk/testimony2.php”
Well, at least the “science” of origins of life is in fact nowhere to be found. As yet. Given a first replicator incorporating a universal constructor as well, darwinian evolution may be possible. However, even in this case the issue of ability to increase complexity or the lack of it thereof is far from resolved.
Anyway, both universal constructors (Turing) and replicators (von Neumann) have a lower bound for complexity (somewhere between 50-100 kBytes). It’s an understatement that the spontaneous accumulation of that much (meaningful!) info is unlikely. Remember. Existence of replicators is a precondition to natural selection, not its consequence.
Based on his testimony, I can’t see Dr Spencer is young earth creationist. If he were, I would consider it a serious issue. As it is, being Christian is a better starting pont to science than anything else.
For Natural Philosopy is deeply rooted in Christianity.
To do sciense one has no choice but have some faith in that there are at least some Laws of Nature out there to be found.
If you do not even believe in the existence of socks, it’s pretty unreasonable to look for them under the bed or anywere else.
The proposition “There are laws” is not a scientific one. It can’t possibly be falsified. It’s a belief.
For a Christian, a reasonable belief. For anyone else it just comes from the blue.
P. Wilson (19:11:47)
Define what you mean by:very little, radiation, heat, ideologically imputed, and said constant. Let’s start there. On the atmosphere I only have this:inert nitrogen and oxygen are insensible retainers of heat. CO2 and all the other
trace gases are not even worth considering when it comes to thermal heat
retention. Compare this to water vapour and summed up so economically
with these two conclusions by Tyndall himself. “He concluded that water
vapour is the strongest absorber of radiant heat in the atmosphere and is
the principal gas controlling air temperature. Absorption by the bulk of
the other gases is negligible.” Nuff said?
TomVonk (02:29:28) :
Phil. wrote
.
No, the highlighted part is not correct, it is only necessary in LTE that the transition is made, not that emission occurs, in fact in the troposphere that is effected mostly by collisions not emission. It is the emissivity that equals absorptivity not “absorption=emission” (Kirchoff’s law).
.
This is again an example of deep misunderstanding of what LTE means
Yes you do misunderstand the LTE.
In order to respect the Maxwell Boltzmann distribution in LTE , once a photon is absorbed and the molecules goes from E0 to E1 it is necessary that another molecule goes simultaneously from E1 to E0 .
It is true that it is not prescribed by what PROCESS this downward transition should take place .
And it is also true that the gas has 2 processes at its disposal – collisional decay and photon emission .
Of course I am well aware of all this and my original statement stays correct.
Actually it does not.
The proof is trivial .
A circular argument is not a proof.
.
Obviously the Maxwell Boltzmann distribution in LTE is achieved by taling in account ALL PROCESSES that modify the distribution of the quantum states .
And what I said about the couple absorption/emission also applies to the couple collisionnal excitation/collisionnal decay …………..
Actually it is the existence of collisionnal equilibrium that is the necessary and sufficient condition to have an LTE .
Correct
So what stays is that BECAUSE of the collisionnal equilibrium (e.g LTE) the rate of absorption of a frequency f is necessarily equal to the rate of emission of the same frequency f .
Anything else is a non LTE condition where the standard thermodynamics is no more valid and one must use a quantum mechanical treatment .
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.
cba (06:02:55) :
And what drives your perpetual motion machine there Nick?
The same as keeps the atmosphere in constant motion at present. Solar radiation, creating temperature differences, primarily latitudinal. The heat engine is driven by heat flow from the hot spots to the cold. The sources are maintained by a local excess of solar input over IR outflow; the sinks are maintained by a deficit.
Rising air parcels, where the lapse rate is less than 9.8 K/km, are not rising through buoyancy. That works against the rise. The rise/fall is forced by the fluid mechanic consequences of the heat engine – the KE of eddies that are present through the atmosphere, and are created primarily by lateral heat advection.
The concept of “adiabatic” here is relative. It refers to a stage where isentropic processes (eg compressive heating) are dominant. In the longer term, diffusion will always win out, so nothing in the atmosphere is truly adiabatic.
anna v (00:06:39): (And all posts above.)
Anna, could I have one more post from you. You have clarified so much for me! Have read many books but with no higher courses with professors to re-word many aspects, I could never get it all crystal clear.
Is this basically correct in all aspects? Don’t go any deeper into finer aspects but note back if something is blatantly incorrect.
There are two fundamentally different types of radiation from matter. One is excitational radiation. The other is energy related radiation which includes linear-kinetic, rotational, and vibrational. The rotational and vibrational only occur in molecules, not singular atoms.
Excitational radiation occurs when a photon of matching energy, maybe even matching or higher energy with residuals(?), as photon is absorbed and electrons are promoted to higher shells. Excited matter can re-radiate as electrons drop back to lower shells at some time in the future. The excitation or absorption also imparts a linear, rotational, or vibrational momentum to the particle upon absorption per conservation laws.
Linear energy radiation can only occur if there is interaction with other atoms or molecules. Rotational energy radiation in molecules also only occurs upon interactions with other particles. The interactions can also be with virtual particles if quanta levels and quanta interactions permit.
Vibrational energy radiation will occur until all of this type is radiated or dispersed away to other particles (may be with the same molecule). This energy is an oscillation between kinetic and potential.
All except excitational radiation occurs always and constantly in all matter. There are factors, such as emissivity, which affect how efficiently a certain type of matter absorbs and emits kinetic radiation. Other factors affect rates.
While digesting all aspects discussed in WUWT, this clarity will help!
Some talk of one of these aspects of energy (temperature) transfer but forget one or more of the others. Maybe it will help them also.