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Discussion > GHG Theory step by step

Aug 13, 2017 at 1:49 PM | Unregistered Commenter Entropic Man
When your theoretical models for Planet A prove accurate, then you can have a go at Planet B.

Using theoretical modelling of Planet B to develop models of Planet A, when real data from Planet A does not match the models for Planet A, is not reliable science.

Aug 13, 2017 at 2:04 PM | Unregistered Commentergolf charlie

Supertroll

I am not surprised that you are getting confused.

We are discussing the effect of atmospheric surface pressure and density on surface and lower atmosphere temperature. For clarity the effect of GHGs should be removed. Hence we are back with non-radiative atmospheres.

The main disagreement? The others think that a high pressure, high density atmosphere is automatically a high temperature atmosphere; something for which there is no basis in physics.
If surface pressure alone is enough to explain high surface temperatures, then they can deny the greenhouse effect on the grounds that pressure warming is sufficient to explain planetary temperatures.

I think that surface pressure is, in itself, irrelevant to surface temperature. Surface temperature is set by radiation balance in the absence of GHGs and radiation balance modified by GHGs.if they are present.

You may have noticed that unhappiness with the greenhouse effect is common among commenters at BH. They range from lukewarmness who think that the effect of increasing GHGs is overestimated, through to outright deniers who think that there is no greenhouse effect at all.

Aug 13, 2017 at 2:23 PM | Unregistered CommenterEntropic man

Let me clear, RR you are saying that GHGs have negligible effect in keeping the temperature of the lowermost atmosphere above where it would have been without said gasses? You appear to be implying that there is no greenhouse effect.

EM concerning your statement -"Convection cannot dissipate heat, only move it around within the atmosphere", might you allow insertion of the word "alone" after "heat"? I ask this because moving heat to locations where it might be more efficiently radiated away (like cloudless desert regions) is probably an important mechanism. Most people use the word dissipate to include removal of irregularities - you clearly are not using it in this fashion.

Aug 13, 2017 at 2:57 PM | Unregistered CommenterSupertroll

EM. Concerning your understanding of temperatures and pressure. The gas giants Jupiter and Saturn have extremely cold surfaces but with increasing depth both pressures and temperatures increase. Why might that be?

Aug 13, 2017 at 3:02 PM | Unregistered CommenterSupertroll

Ah, yes, Entropic man (Aug 13, 2017 at 1:20 PM). You are correct: I should have used the word “dispersed” – to distribute more evenly throughout the medium. As I have mentioned rather too many times that others may be getting quite bored with it, I have experienced the dissipation of surface heat by overnight radiation such that freezing occurred on the surface, while the air above remained comfortably warm. This indicates that the air, which is comprised of about 99% non-“greenhouse” gases, is quite capable of being heated, and retaining that heat during the night, and what greenhouse gases may be contained therein do little to limit radiated energy.

As we cannot compare two planets, your argument is utterly futile. At least I have tried to get the closest that is possible to be achieved with the scenario: two identical surfaces, both effectively the same distance from the Sun, both with the same angle of incidence with the incoming radiation, both with exactly the same atmospheric composition. With the only difference being surface pressure, then, with all else being equal, the resultant difference in temperature has to be caused by the difference in pressure. Not sure why you cannot understand that.

Aug 13, 2017 at 3:54 PM | Registered CommenterRadical Rodent

Minty: I am sceptical of the claimed effect. That is, of course, tantamount to being in total denial about it, so I must be one of the deniers Entropic man alludes to. Meh… I can live with that.

(BTW, stand by to be picked up with referring to the upper levels of the gas giants’ atmospheres as “surfaces”…)

Aug 13, 2017 at 4:08 PM | Registered CommenterRadical Rodent

Supertroll

"dissipation"

I used the term because RR did. It did not occur to me that we had different meanings. RR tends to be fuzzy about energy flows. She might regard convection as a way of dissipating heat without realising that on a planetary scale the energy would have to end up as OLR.

I regard a car radiator as dissipating heat from the engine into the atmosphere or OLR as dissipating heat from a planet into space.

I found this definition at Wikipedia. Perhaps a bit pedantic, but quite close to my usage.

Dissipation. ... A dissipative process is a process in which energy (internal, bulk flow kinetic, or system potential) is transformed from some initial form to some final form; the capacity of the final form to do mechanical work is less than that of the initial form.

It would apply to both convection and OLR.


Why should a gas giant not have a lapse rate?

Jupiter's atmosphere is mostly hydrogen. It also has GHGs, methane and water vapour. If it has GHGs it will have a radiating altitude and a radiating temperature. Below that altitude you would expect temperature to increase with depth, at least to the cloud tops where visible light is absorbed. With gravity of 2.4g the lapse rate would be quite impressive.

This effect will be amplified by an oddity in Jupiter's energy budget.( Search "Global energy budgets and `Trenberth diagrams' for the climatesof terrestrial and gas giant planets " and you'll find an interesting pdf.)

The planet generates enough internal heat to be a net producer of energy. With heat produced from deep inside the planet and radiating from whatever is Jupiter's equivalent to a tropopause, the temperature gradient should continue all the way down.

Aug 13, 2017 at 4:37 PM | Unregistered CommenterEntropic man

dissipate

Also found in: Thesaurus, Legal, Acronyms, Encyclopedia, Wikipedia.

dis·si·pate

(dĭs′ə-pāt′)

v. dis·si·pat·ed, dis·si·pat·ing, dis·si·pates
v.tr.
1.
a.To break apart or attenuate to the point of disappearing: The wind finally dissipated the smoke. See Synonyms at scatter.
b.To drive away; cause to vanish: a discovery that dissipated his doubts.
2.
a.To spend or expend intemperately or wastefully; squander: dissipated his fortune in casinos.
b.To use up, especially recklessly; exhaust: dissipated their energy. See Synonyms at waste.
3.To cause to lose (energy, such as heat) irreversibly.
v.intr.
1.To be attenuated and vanish: The dark clouds finally dissipated.
2.To become dispelled; vanish: His anger dissipated in time.
________________________________________
[Middle English dissipaten, from Latin dissipāre, dissipāt-.]
________________________________________
dis′si·pat′er, dis′si·pa′tor n.
dis′si·pa′tive adj.

Yes, I confessed that I used the wrong word – I should have used the word “disperse” (and/or its derivatives). Do keep up, please.

Entropic man: I am fuzzy about energy flows as there is nothing to be crystal-clear about them – to date, there really is not enough data to be anything but. As I have said before, a few of the things we do NOT know for certain:
the volume of the oceans;
the heat content of the oceans;
the heat content of the atmosphere.

With not knowing any of these, then it not possible to be anything but fuzzy.

Aug 13, 2017 at 5:42 PM | Registered CommenterRadical Rodent

Radical rodent

Dissipated worked fine. Supertroll is just being picky. :-)

I think the data is good enough to work with. You do not. We'll have to agree to disagree on that.

However, regardless of precise values, the pattern of energy flow is determined by a lot of routine physics. If you want t to reject that, you'll need to go a lot further into outer darkness than just doubting AGW.

Aug 13, 2017 at 6:07 PM | Unregistered CommenterEntropic man

EM. Jupiter is composed mostly of hydrogen and helium. Other gases, mostly ammonia are confined to the uppermost layers, giving the planet its colours. Thus most of the depth has a lapse rate without sensible amounts of GHGs, which was my point. Jupiter's heat is due to gravitational compression. It exports more energy than it receives from the distant Sun.

Aug 13, 2017 at 6:18 PM | Unregistered CommenterSupertroll

EM can't explain the 'average' temperature of the moon, all numbers known, no atmosphere to speak of. It isn't what S-B says it should be. S-B's equation works (in this context) only in the ideal case. For all other cases its result needs to be handled with caution.

Aug 13, 2017 at 7:26 PM | Unregistered Commenterrhoda

EM - You keep telling us that without GHG the surface would radiate its heat directly to space, therefore, without GHG present, there can be no warm lower atmosphere. Without wishing to involve a circular argument, you are saying that you cannot have the "greenhouse effect" without greenhouse gases.

Let us remain with a GHG free atmosphere for a moment. Our warmed surface can radiate heat directly to space as you say. Our solar warmed surface also heats the atmosphere in contact with it by conduction. These are not GHG and cannot radiate heat anywhere. They can transfer kinetic energy by collision and they can lead to expansion and convection, but they cannot radiate their energy to space.

The lapse rate, as we discussed, is a consequence of atmospheric mass and gravity. The consequence is that the highest molecular density is located at the bottom of the atmosphere. where our warmed gases with their high kinetic energy exist as just discussed.

The gravity effect is the lapse rate effect which is the badly named greenhouse effect. In other words, the GHG theory was dreamt up to explain the warm surface when in fact it wasn't needed at all. The greenhouse gases are in fact cooling aids. More carbon dioxide assists water vapour in radiating energy to space.

Aug 13, 2017 at 7:53 PM | Unregistered CommenterSchrodinger's Cat

Supertroll

Jupiter is indeed generating heat by gravitational compression. There is even a name for it, the Kelvin-Holmhertz mechanism.

It works for gas giants. They have the mass, the size and the gravity to maintain a shrinkage rate of a couple of centimetres per year for billions of years. Jupiter is producing 5.7W/m^2,

It was suggested in the 19th century as a mechanism for generating the Sun's energy output. This was after the 2nd law of thermodynamics forbade the creation of energy, but before nuclear reactions were discovered. Unfortunately the amount of energy generated by this effect would have been far too small to account for the observed energy output.

Try to explain the energy budget of a rocky planet like Earth in this way and you run into a number of problems as I discussed in three posts on page 11.

In brief;

There is no mechanism for compressing the atmosphere beyond the existing pressure gradient.

There is nowhere near enough gravitational potential energy in the atmosphere to generate even the current rate of warming.

Any energy liberated by compression would quickly radiate to space. You could produce a slight temporary warming ONCE.

Aug 13, 2017 at 9:34 PM | Unregistered CommenterEntropic man

Rhoda

Two presents for a lady

Here

and here.

Aug 13, 2017 at 10:18 PM | Unregistered CommenterEntropic man

EM - You still don't get it.

Let us address the fact that the earth has a warm lower troposphere. More specifically, the part inhabited by us, which, for the sake of argument is at 15 degrees Celsius. You would say that without GHG the surface would radiate its solar acquired energy to space, therefore it is GHG that gives us the warmth by trapping heat.

The gravity theory, if I understand it correctly, concentrates the molecules of the atmosphere in this lower troposphere region. When the heated surface transfers heat by conduction to the atmosphere, it is concentrated as kinetic energy, in this region. This region therefore has a higher temperature.

It seems to me that the lapse rate is a similar mechanism, brought about by atmospheric pressure resulting from atmospheric mass and gravity.

Now, take note, none of this involves atmospheric pressure doing work to create heat. I said, many pages back, forget the bicycle pump.analogy. This is about the creation of kinetic energy in gases by conduction and the concentration of these gases close to the surface as a result of atmospheric pressure.

The pressure affects the concentration of gases near the surface, therefore the amount of kinetic energy and therefore the temperature of the gases near the surface. The energy came from solar radiation, not the gas law. The gravity effect produces the temperature gradient, aka the lapse rate.

The greenhouse gases play a minor role.

Aug 13, 2017 at 10:23 PM | Unregistered CommenterSchrodinger's Cat

EM- I agree that gas law pressure induced heating is a one off, so put that out of your mind.

Think of the lapse rate or atmospheric pressure as the reason that the atmosphere closest to the ground has the most gas molecules.

This layer is heated by conduction by the earth which received solar energy. A portion is emitted directly to space by the earth. We shall ignore GHG for simplicity.

This gas layer has a high kinetic energy because it just received heat by conduction and it has the most molecules. Kinetic energy equals temperature. This atmospheric layer is warmer than the SB temperature that is due to radiation by the various greenhouse gases at various higher altitudes.

No pressure induced heat is necessary.

Aug 13, 2017 at 10:38 PM | Unregistered CommenterSchrodinger's Cat

There is nowhere near enough gravitational potential energy in the atmosphere to generate even the current rate of warming.

Aug 13, 2017 at 9:34 PM | Entropic man

There is nowhere near enough energy to generate Global Warming to match Mann's Hockey Stick, yet you deny Climate Science has got anything wrong. Why should Climate Science be trusted to dictate right from wrong now?

Perhaps you have great confidence about lapse rate and gravity theory not being right, because you know what is so wrong with Mann's Hockey Stick and why Climate Science can't afford to relinquish it.

Aug 13, 2017 at 10:46 PM | Unregistered Commentergolf charlie

Schrodinger's cat

Not a tautology. More like cause and effect.

I've been wondering if we got the non GHG lapse rate wrong. Take a look at this temperature profile of Jupiter's atmosphere.

Note that for the full depth of the stratosphere the temperature is constant.. There is no lapse rate. I suggest that this is because the stratosphere has too low a GHG concentration to radiate, so convection rapidly brings the whole depth of the stratosphere to the same temperature. At that point, with no lapse rate, convection stops.

On a non-radiative Earth you would see a similar effect.

Without GHGs the stratosphere would start at Earth's surface. The temperature profile of Earth's atmosphere would be flat, with a constant temperature from surface to mesosphere.

What would that temperature be? Since the only place the atmosphere can gain or lose heat is at the surface the whole depth of the atmosphere would end up at the same temperature as the surface.

"The lapse rate, as we discussed, is a consequence of atmospheric mass and gravity. The consequence is that the highest molecular density is located at the bottom of the atmosphere. where our warmed gases with their high kinetic energy exist
as just discussed."

Remember what you are trying to do. You are trying to use the atmosphere to deliver the extra energy required for the surface to be warmer than expected, an effect I would ascribe to GHGs.

To achieve that you must concentrate energy at the bottom of the atmosphere. This does not happen.

Remember PV=nrT. The bottom of the atmosphere has maxP and maxT (hence your high kinetic energy molecules). It also has minV.

As you rise through the atmosphere P and T decrease while V increases. The energy content does not change. Each kilogram of air carries the same energy at all altitudes, so adiabatic changes cannot be used as an energy pump.

Have you made RRs mistake? She misconstrued that the high temperature of the mesosphere was also indicating a high energy content. You are misconstruing that higher kinetic energy of molecules at the surface means more energy per kg of air, regardless of the modifying effect of maxP and minV.

Aug 13, 2017 at 11:16 PM | Unregistered CommenterEntropic man

Schrodinger's cat

We crossed, but I think I covered your last point.

In an atmosphere with a lapse rate and PV=nrT maxT is not the same as maximum energy.

Perhaps an alternative and slightly simpler formulation might show this more clearly.

PV/T=k

For adiabatic changes k is constant. The unit of P is the kg m^-2. The unit of V is m^3. The unit of temperature is C.

Put them together and k is in units of kilogram metre/C. That is an energy unit, so for adiabatic changes energy is constant.

Aug 13, 2017 at 11:48 PM | Unregistered CommenterEntropic man

Problem is EM, that the outer layers of Jupiter, those we see do not lack GHGs. Wikki gives the following -
" the remaining one percent of the mass [of Jupiter's outer atmophere] consisting of other elements. The atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur."

We all know that trace amounts of GHGs can perform climatic wonders, but, as a fully fledged climate scientist, always let a good contrary fact go to waste.

Aug 14, 2017 at 6:10 AM | Unregistered CommenterSupertroll

EM. Thought I'd check up on you, finally realizing that a planet generating internal heat and losing it to space would have to have a lapse rate. Suggest you check
https://www.windows2universe.org/jupiter/atmosphere/J_troposphere_2.html

For others - learnt the interesting factoid that, at the centre of Jupiter, temperatures are estimated to be six times those of the surface of the Sun.

RR (belatedly) by convention the "surface" of Jupiter is usually taken where pressure = 1bar. Notice that this "fact" became, it did not always exist.

Aug 14, 2017 at 6:36 AM | Unregistered CommenterSupertroll

EM, sincere thanks for those links. Dr Roy Spencer is obviously on the same page as me. He must be so proud.

Nikolov turns up in the comments saying rotation makes no difference but he is evidently wrong.

I don't think Spencer addressed the question of comparing an adjusted S-B number against a thermometer-based geographical average of high/low daily averages. How ever he is in a prime position to know whether that is important or just a quibble, and it doesn't seem to bother him. It only bothers me because it is an invalid approach, not because the answer can be very wrong.

Aug 14, 2017 at 8:10 AM | Unregistered Commenterrhoda

EM - Thanks for your comments which I shall study. Just a few general comments to explain where I am coming from.

I'm prepared to accept the GHG theory in the absence of anything else but I believe the climate sensitivity is very low. I'm interested in the scientific truth, not any political or environmentalist rubbish. I judge from your comments that you are a strong warmist believer, but based on interpretation of the science, so that is good.

I have a low opinion of the leading climate scientists, based mainly on their own actions and words. (ClimateGate and various other events.) I would love to see an alternative to the GHG effect, for several reasons. It would be good for the planet and our descendents, it would stop the crazy rush to unsuitable energy solutions and associated taxation of the poor. I dislike the often stated "the science is settled" by establishment figures, celebrity scientists and just about everyone else when they haven't got a clue about what they are talking about. The science is not settled and I think that you would agree about the uncertainty of the direction over the next 20 years. (That says something about climate sensitivity too.)

The N&Z idea is a refreshing alternative that deserves examination. I would like it to succeed for the above reasons but at this stage I have an open mind. I note that Roy Spencer thinks it is flawed as do many at WUWT. I respect these views but I would still like to give the debate a good thrashing because it is interesting to do that. Hearing the views of others is often a learning opportunity and trying to articulate one's own argument can be a self learning opportunity.

I do believe that the GHG theory (my label) is flawed in some way. For example, convection readily conveys IR emitting gases to higher in the atmosphere, therefore from being heat trapping agents to becoming cooling agents.This type of thing can mean that warming and cooling effects cancel out to some degree which explains the low climate sensitivity that observation suggests.

Anyway, thanks for the contribution of you and others and let the debate continue.

Aug 14, 2017 at 6:42 PM | Unregistered CommenterSchrodinger's Cat

Aug 14, 2017 at 6:42 PM | Schrodinger's Cat

1."I do believe that the GHG theory (my label) is flawed in some way"
I did trust Climate Science and Mann's Hockey Stick. My misgivings were prompted by Mann erasing the MWP and LIA

2. "I have a low opinion of the leading climate scientists, based mainly on their own actions and words. (ClimateGate and various other events.)" If Climate Scientists cannot be honest about the Hockey Stick, why should anyone trust them to be honest about anything?

3. "I'm prepared to accept the GHG theory in the absence of anything else but I believe the climate sensitivity is very low. I'm interested in the scientific truth, not any political or environmentalist rubbish." As a non Physicist, Climate Science seems dependent on multiplying by "X" Factors, of uncertain/dubious provenance.

4. "This type of thing can mean that warming and cooling effects cancel out to some degree which explains the low climate sensitivity that observation suggests." Climate Science never did very much science before determining Manmade CO2 was the root of all evil. They cannot confirm how this conclusion was reached.

My personal observation, as a country bumpkin is that it is no "warmer" at all. It might not be as cold in winter as it was in the 1970s, when we had a Global Ice Age Alarm, but no one is complaining.

There does seem to be an increase in alarm and panic amongst Climate Scientists and their highly alarmed disciples, as they have given up on evidence based Science, and tried to focus publicity on false attributions and consequences.

I welcome any attempt to explain past and present warming and cooling of the climate. Climate Scientists do not. Do they fulfil a purpose that justifies such colossal Taxpayer expense?

Aug 15, 2017 at 12:02 AM | Unregistered Commentergolf charlie

Aug 14, 2017 at 6:42 PM | Schrodinger's Cat

Climate Sensitivity stirs up Climate Scientist Sensitivity

https://judithcurry.com/2014/09/24/lewis-and-curry-climate-sensitivity-uncertainty/

https://andthentheresphysics.wordpress.com/2014/09/25/lewis-and-curry/

I may not understand all the Physics, but I do understand that the 97% Consensus has a fair amount of uncertainty, that has yet to be resolved.

Aug 15, 2017 at 6:23 PM | Unregistered Commentergolf charlie