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Discussion > An experimental demo of GHE.

rhoda, if you haven't already, ScienceOfDoom has a lot of articles about this.

Jan 10, 2013 at 7:15 PM | Unregistered CommenterTheBigYinJames

TBYJ

At present global temp is said to be relatively static, if we add CO2 to the atmosphere and the temp does not rise then water vapour will not increase so water vapour only matters if CO2 (and other GH gases) warm the atmosphere first so how much warming is one tenth of one percent of the atmosphere (CO2) going to add to surface temp? Experiment?

Jan 10, 2013 at 7:39 PM | Registered CommenterDung

Go to it, Dung! :) I don't know how to, though.

Jan 10, 2013 at 7:52 PM | Unregistered CommenterTheBigYinJames

TBYJ

Humph :)

Jan 10, 2013 at 8:28 PM | Registered CommenterDung

OK a very small group of people cough, me and TBYJ are saying that long wave radiation from the surface does not warm the atmosphere, the CO2 (and other GH gases) reradiate long wave IR back to the surface and this warms the surface. Conduction and convection then warm the atmosphere more than if GH gases had not been present.
So why does long wave IR from the planet not warm the CO2 molecules in the atmosphere but long wave IR reradiated downwards DOES warm the surface?

Jan 10, 2013 at 9:22 PM | Registered CommenterDung

Because CO2 has a tiny heat capacity, I showed you the graph earlier. It emits rather than vibrate.

Jan 10, 2013 at 9:38 PM | Unregistered CommenterTheBigYinJames

Case 1: CO2 doesn't backscatter IR:
100 photons enter the balloon from the left, 100 from the right.
Nothing interferes with the IR.
Result: 100 photons exit from the right, 100 photons exist from the left
Case 2: CO2 backscatters the radiation
100 photons enter the balloon from the left, 100 from the right.
50 from the left are scattered and go back out the left, 50 keep going
50 from the right are scattered and go back out the right, 50 keep going
Result: 100 photons exit from the right, 100 photons exist from the left

I proposed a simple experiment at the start of the thread that gets round this.
Hang two metal spheres in the center of two balloons, one with 'air' and one with an increase concentration of CO2, electrically heat them to the same temperature then switch the heater off.

Compare the cooling of the two spheres over time.

Then re-run the experiment with the gasses swapped to take any equipment anomalies out of the equation.

If the one in the CO2 filled balloon cools slower then this shows the CO2 is having _some_ green house/ blanketing effect.

If they cool at the same rate then....

Jan 11, 2013 at 12:47 PM | Unregistered CommenterNial

"that gets round this."

Should read "that doesn't rely on external heating"

Jan 11, 2013 at 12:49 PM | Unregistered CommenterNial

I would expect they'd need to be pretty big balloons to get a measurable effect, but I think the principle is sound. I'm not even sure you'd need to heat them. By definition, the one in more CO2 would settle to a higher temperature, but the cooling trends might be easier to compare than static figures.

It might be a good idea to repeat with H2O as the GHG for a more measurable effect.

Jan 11, 2013 at 1:44 PM | Unregistered CommenterTheBigYinJames

Nial

Sound like a goer ^.^ but you would have to describe the environment outside the balloon as well.

I already figured out what is wrong with the Bethold Klein experiment though.

Since the experiment took place outside in sunlight (assume sun directly overhead) then back radiation would depend on the whole column of CO2 above the balloon, not just the balloon. I have not tried to calculate it but I doubt that even having 100% Co2 in the balloon would make much difference to the total CO2 in that column.

Jan 11, 2013 at 2:23 PM | Registered CommenterDung

Good thinking Dung. I suspect the experiment was done that way because of the popular but mistaken belief that CO2 'warms' things. So it makes sense to bag it up and measure the temperature. When they didn't find any, this said nothing about the GHE, however.

When you realise it's the backscattered IR heating the ground, not the CO2 itself, you can see why it won't work. The ground under it is already being heated by kilometers of GHGs above it, the little dense pocket of CO2 near to it won't make much of a difference. It might have worked on the moon, with no air, and a large balloon.

Jan 11, 2013 at 2:37 PM | Unregistered CommenterTheBigYinJames

Over on the Chocolate Teapot thread modern science is being advanced at an alarming rate! Already it is known that chocolate Teapots are not practical and by 2016 it is expected that they will be declared edible ^.^ Other popular myths so far debunked include the need for a snooze button on a smoke alarm, all jolly stuff hehe.

TBYJ

Over on that thread you have said things like 'Slayers should be ignored because the science says they are wrong'. You also said (in respect of that same science) that you thought I was wavering and there I assume you mean in my disbelief in the GHE.
First I do not believe anyone on the planet can stand up and with any justification state that they know exactly what happens and that anyone else who disagrees is wrong, or that all our science is right, or even that more than half of it is right.
Take light as an example, we do not really know what light is or how it works. At certain wavelengths we find that mathematically it behaves more like photons but at other wavelengths it is better to consider it as waves but we do not really understand it.
In terms of me wavering I think you misunderstand me, I am trying to figure things out for myself so that I can have an opinion and know why I hold it. You helped me a great deal to get close to that but no matter what the eloquence of the science, the discussion returns to the need for experimental proof.
My own ability to move further at the moment is stuck on the effect of back radiation on surface temperature and surface IR emissions. There is no evidence to back up any assumptions about what happens there.
Within Bishop Hill both Martin A and RKS (not a slayer) believe that back radiation does not warm the earth's surface, Big Yin, you and others believe that it does and that in doing so it causes conduction and convection which is the cause of the warming atmosphere. Since there is no proof either way I find it unbelieveable that people spend all day swapping theories with each other instead of applying their brilliant minds to creating an experiment?
Somebody can correct me here but this is my memory of what Lindzen was saying 3 - 4 years ago.
There is only so much IR radiation from the earth within the wavelength band that CO2 molecules absorb. Once there is enough CO2 in the atmosphere to absorb all that wavelength, adding more CO2 makes no further difference. This explanation fits with all the facts.

Jan 11, 2013 at 11:41 PM | Registered CommenterDung

Dung, thanks for the thoughtful post.

Over on that thread you have said things like 'Slayers should be ignored because the science says they are wrong'.

I don't think I actually said those words, but I'm too lazy to go and check :) My thinking is more along the lines of 'slayers ARE being ignored because the science says they are wrong' - whether they should be or not is another thing. I'm a fan of science, always have been (I have three science degrees!) so although I think there has been a lot of skullduggery and ranks-closing within the scientific profession I don't let that interfere with my belief in Science. So while I'm on the side of those who want to see certain bad apples put out to pasture, I am dead against anything which seeks to attack, misuse or corrupt Science itself. This means I feel defensive now and again.

First I do not believe anyone on the planet can stand up and with any justification state that they know exactly what happens and that anyone else who disagrees is wrong,

Me neither, part of core skepticism is there are whole parts of this system we don't understand, so it is stupid of anyone to say the temperature in 2100 will be x. We don't know enough, that's why we're all here.

But even though we don't know enough about the whole system, we do know quite a lot about single mechanisms within this system. We know how the constituent parts of the hydrological cycle work. We know how pressure fronts and winds form. We understand convection. We understand the ozone layer. And we know about the radiative GHE.

We may not understand how much each of these mechanisms contribute an an overall climate temperature, in fact I would say our knowledge is woefully inadequate. But that doesn't mean the mechanisms isn't understood, just how they act in combination.

All through these questions and answer sessions, I have been explaining and defending the GHE. At no point have I claimed that it is the sole mechanism by which the average temperature of the planet is reached, because i don't believe it is the sole mechanism - it's one of many mechanisms which can have an affect on the temperature.

There seems to be a common misconception that if you 'believe' in the GHE then by definition, you have to 'believe' in the whole alarmist story, and that the only way to 'disprove' AGW is to somehow 'disprove' the GHE. They have become synonymous in people's minds. The GHE is the demon.

I'd like to separate them again in people's minds

The GHE is just that.. an effect. It's a well understood physical process, all of the constituent parts are well understood and are not in dispute by science.

The GHE as a contributor to a rising temperature trend. Unproven, in my opinion. It's a hypothesis, it has a physical basis which is feasible, but it's far from being proven.

I understand your need for an experiment to prove definitively that the GHE is a real effect, I'd love to see one as well. The large balloon on the moon would be a great one, but expensive. But to say we're swapping theories is giving the alternative theories more scientific credibility than they've earned. It's more a case of 'refute this or it's true' which is an adversarial legalistic tactic I don't really like.

When papers such as N&Z come along, they never say "here's another effect that might contribute part of the observed warming" No they always have to be a replacement mechanism, GHE has to be rejected COMPLETELY. This is what always gets my "bad smell" sensors out. As soon as the GHE is required to be completely abandoned by a theory, then I start to wonder why it's so important to them that it be rejected. Can't a new mechanism explain part of it? Why does it need to be all?

I really like your final paragraph about the effect of adding more CO2 won't have any more effect since it's all already being intercepted and scattered. I'm not going to try to counter it, because it has nothing to do with the defence of the GHE itself. It's actually an argument which takes the reality of the GHE as its base. Given the GHE, what does adding more CO2 do? There is a stream of skepticism which revolves completely around this 'optical depth' argument, and it's very interesting.

On a more general note, people seem to have enjoyed this thread. I think it's because, as the ancient Greeks found out, a dialogue of questions and answers is a fantastic learning tool. The protagonist gets to make a case, and an antagonist gets to ask a lot of awkward questions. At the end, a reader can judge the 'performance' of the theory and get a feel in their minds if it holds together. Thank you very much Dung (and others, lapogus etc) for being my antagonists :)

This is going to be my final word on the GHE. I think everyone knows by now I put it right in the middle of the 'confirmed' set of theories along with gravity, kinetics et al. Others may still be in doubt about how 'real' it is, which is fine, and if someone could come up with an experiment which could confirm the GHE, as an educational tool in itself would be a massive boon for everyone. Obviously I believe it would confirm the GHE :) AGW is a completely different kettle of fish....

From now on, I'll restrict my comments here to discussing and commenting on actual proposed experiments, feasibility and theoretical basis.

Thanks for a great thread!

Jan 12, 2013 at 11:37 AM | Unregistered CommenterTheBigYinJames

TBYJ

No antagonist could wish for a fuller or better response and one in which I can not find a single word to disagree with :)
What a great shame you have no desire to talk further since I was still learning but thank you for helping me along my journey ^.^
For any that still read or join the thread:
The Lindzen ideas are linked to the logarithmic proposition and they make wonderful things possible ^.^
One would be able to say that the GHE is real but at the same time say that there is no GHE.
There is no GHE because it has already played out and more CO2 has no effect. However the GHE is real because it did happen at lower atmospheric levels of CO2, it just does not happen at current temperatures and levels of atmospheric CO2.
Maybe without re entering the GHE discussion TBYJ can still help me because if certain things can be measured it must be possible to prove this.
Is it possible to measure, at the surface, the total w/sqm of radiation and also the w/sqm of radiation in the wavelengths that CO2 can absorb?
Is it possible to measure the amount of that wattage absorbed by a cubic metre of atmospheric CO2 at various altitudes?

Jan 12, 2013 at 1:41 PM | Registered CommenterDung

Following on from the above post; one of the biggest influences on my thinking has been the ice core record and specifically the existence of periods of up to 2000 years where atmospheric levels of CO2 are rising but temperature is not rising or is even falling.
In previous interglacials, levels of CO2 never got above 280 ppm (even though other "natural" effects made them warmer than today's climate) and so if the logarithmic proposition is correct then it points to a "maxed out" CO2 effect at between 200 and 240 ppm.
This would conveniently explain why chucking gigatons of CO2 into the atmosphere at the moment is having no effect.

Jan 12, 2013 at 1:54 PM | Registered CommenterDung

I'm quite happy to chip in on discussions about whether an experiment would or wouldn't test an aspect of the GHE, I could have saved the guy with the balloons a lot of time :)

At the moment, the best suggestion is the heated sphere in a mylar balloon of GHG and one in normal air, or an N2/O2 mix. It would be interesting to see if we could work out what volume of CO2 would produce say 1 degree of heat difference purely from gas absorption equations etc. I have a hunch it would need to be a pretty massive balloon.

I know it's not a linear relationship, but for a laugh....10km of GHG produces 33K warming, so to get 1/2 degree we'd need a balloon.... 300m wide.... that's a big balloon :)

Jan 12, 2013 at 3:50 PM | Unregistered CommenterTheBigYinJames

TBYJ

Any chance you could give me a pointer as to where I could get answers to the questions two posts up? (Jan 12, 2013 at 1:41 PM | Registered CommenterDung )

I was thinking of a long tube (horizontal) with a cross section of 1 sq metre of a length sufficient to give a measurable result and filled with pure CO2. Internal surface of tube totally reflective to all relevant wavelengths of IR. Source of IR at one end (only emitting wavelengths that CO2 can absorb), IR sensor at the other end. How much IR is picked up at the sensor end that is the same as input wavelength and how much is the wavelength emitted by CO2?
I would then run this with an atmosphere containing only 100/200/300 ppm of CO2.

Jan 12, 2013 at 5:00 PM | Registered CommenterDung

Is it possible to measure, at the surface, the total w/sqm of radiation and also the w/sqm of radiation in the wavelengths that CO2 can absorb?

Yes, you'd need a spectrum analyser.

Is it possible to measure the amount of that wattage absorbed by a cubic metre of atmospheric CO2 at various altitudes?

Well apart from the problem of getting the kit to the actual altitude, yes. Might be easier to reproduce the pressure, composition and temperature in the lab. Remember it's absorbed and re-emitted, it doesn't just disappear. Here's a paper you may want to read (skip the GW crap at the start)

Your tube experiment would only measure absorption of IR by CO2, something already proven in the lab. It wouldn't show any GHE.

Jan 12, 2013 at 5:30 PM | Unregistered CommenterTheBigYinJames

TBYJ

Thats what I wanted to measure; what proportion of the IR was taken up by the CO2.

Jan 12, 2013 at 6:58 PM | Registered CommenterDung

Popular science video demonstrating IR absorption - yes they could have faked it, but easy to check, looks like less than £500's worth of equipment.

Jan 12, 2013 at 8:18 PM | Unregistered CommenterTheBigYinJames

TBYJ

That was a clip from the abysmal Climate Wars featuring Dr Iain Stewart. He holds the candle outside the tube thus minimising the IR actually entering the tube. How much CO2 is piped in under how much pressure? How much of the IR from the candle is within the wavelength band that CO2 absorbs? What was the setting on the spectral analysis machine, was it picking up ALL wavelengths or only certain wavelengths?
Slippery guy Dr Stewart and that is being naively generous to him.

Jan 13, 2013 at 11:41 PM | Registered CommenterDung

Yeah I know, I wasn't commenting on him as such, I find popularist science presenters like him and Cocksy annoying, but as a repeatable experiment it looks kind of cheap to do.

The reason I don't think that is faked is when you look at the candle, you can see it's mylar/clingfilm covering the end of the tube - something he didn't mention but is relevant to the experiment. Also, not all the image disappeared, the lighter outer area of the candle (cooler) remained on the screen, which was a wavelentgh effect he also didn't mention, but which added believability to it for me.

Remember, mindless advocates can be complete ****s but the science still be right!

Jan 14, 2013 at 8:12 AM | Unregistered CommenterTheBigYinJames

Well I have an experiment that should prove the following:

There is a GHE yes/no
The effect is logarithmic yes/no

The experiment should give results which would enable one to calculate the level of atmospheric CO2 at which it effectively ceases to have an effect:

As per my last attempt a ten metre long, 1 sq metre cross section tube insulated and shielded from external IR and lined internally with material which is reflective to all IR.

At on end of this tube would be a low wattage IR source emitting at all wavelengths between 13μm - 17μm (NOTE 1), plus an IR sensor A capable of recording power and wavelength of all IR radiation received.

At the other end of the tube would be an IR sensor B capable of recording power and wavelength of all IR radiation received.

The two ends of the tube would be linked by further tubing shielded and insulated as above but including a thermostatically controlled heat exchange unit ensuring that gas in the tube entered the straight section at a constant temp. Also the loop section would contain a fan to circulate gas around the system at a constant speed.

Gas in the system would initially be Oxygen and Nitrogen in the same proportion (to each other) as they are in our atmosphere.

System would be run at a steady state and sensor results noted. At this point IR sensor B should simply show IR from the source and sensor A should show little or nothing.

CO2 should then be added to the gas mix at 100 ppm, the system run until a steady state is reached and the results of the 2 sensors noted (graphed). At this point both sensors should show a new profile of radiation different to the source (interesting to see if they are indeed equal to each other).
Sensor B should now show two wavelength peaks, one due to the source and one due to CO2 re radiation at a new wavelength. If this happens then the GHE is proven to be real and could be measured.

The experiment should be continued by increasing the CO2 level in 100 ppm steps. For each increase of CO2 the sensors A and B should show an increasing amount of radiation in the new wavelength (from the CO2). Interesting to see if the increase is linear or logarithmic. If the logarithmic aspect is proven then CO2 should continue to be increased until the CO2 wavelength is no longer increasing (or is close to zero increase)


Please tear this apart but it looks like it should work to me ^.^

NOTE 1 I looked at 5/6 websites and they all gave different figures for the peak absorbtion rate for CO2 so please correct this if it is wrong.

Jan 14, 2013 at 2:28 PM | Registered CommenterDung

I have apparently killed this wonderful thread by attempting to answer the question that started it? Is there nobody who is prepared to review my ideas?

Jan 16, 2013 at 5:03 PM | Registered CommenterDung

Can't we witness, every day, an experiment that shows the greenhouse effect and the contribution of CO2. I speak of the night time temperatures in the desert compared to the night time temperatures in the tropics and sub-tropics.

The desert tempertures, where there is no water vapour drip by 30C or so when the sun goes down, while the tropics, with plenty of water vapour barely drop at all.

Or am I talking complete bollocks, as usual?

Jan 16, 2013 at 7:48 PM | Unregistered Commentergeronimo