Do you know of a simple tabletop experiment demonstrating the GHG effect of CO2 ?
The results of the experiment using containers with/out co2 and lit by heat lamps is unrelated to GHG radiative absorption, see http://answers.yahoo.com/question/index;_ylt=Ak0_RsekAwrgM10AT9ONSmTsy6IX;_ylv=3?qid=20100606023517AAp9HP4
So is there something better on the market ? Please give explanations and refer to detailed texts in your answer , not to YouTube kind of hocus-pocus.
Please see the link to the past question above and references therein.
@Trevor, I don't see what your experiment demonstrates apart that the CO2 bottle warms more quickly than the air bottle, which has no relation with radiative GHG effect. You would certainly get the same result with some other gases without IR absorption bands. We don't even know what the steady state is in your experiment, since you haven't run it long enough, or haven't recorded the results long enough.
@pegminer I know that CO2 has IR absorption bands. That is not the question. The question is a honest experimental tabletop demonstration of the GHG radiative effect.
In fact, I don't think there exists one. The effect given by a model calculation is a small fraction of a degree, so experiments displaying large differences are most likely wrong. In the experiment quoted in the reference, argon, which has no IR absorption bands, was used as a counter test and it gave the same temperature curve as CO2.
@Trevor I just checked the reference to your explanation. The question is not the QM of molecular degrees of freedom, but how this can displace the point of radiative equilibrium of a system towards higher temperatures by greenhouse effect. And I don't see an experiment demonstrating this.
@Jeff tabletop can be very accurate. I only meant something doable in the lab, with adequate equipment. Even if this exists, it remains to be seen that it has a connection with the full size thing. But what Trevor describes shows nothing.
Ideally, there should be some heated backdrop which could not radiate away the heat it receives when it is behind a enriched CO2 atmosphere as well as it can radiate it behind a normal atmosphere. Consequently, it should reach a slightly higher steady state temperature than the backdrop behind the normal atmosphere, under identical heating conditions. That's why the bottle experiment shows absolutely nothing relevant to the question.
@Trevor, pegminer, d/dx
Again, I know that CO2 and CH4 have strong IR absorption bands. I don't want and experiment in spectroscopy. And I know the explanations about GHG so I need no site and I know and use and occasionally teach quantum mechanics. Thanks !
Please see my answer @Jeff to understand what kind of experiment I have in mind.
When I say 'tabletop' I do not mean 'kitchen'. This should be real demonstration of the GHG effect which is not addressed by Trevor's expt. This could be used, depending on the stuff needed, in classes. But it has to REALLY demonstrate the radiative GHG effect. Not some warming of the gas itself.
@Trevor when you say " the bottles are receiving the same amount of heat then they warm at the same rate, the increase in temperature can only be caused by greater heat retention" that's really not physics. For a given amount of heat received, the body which has the least heat capacity should warm quicker before steady state is reached.
So if your bottles are filled at the same pressure, at the same initial temperature and if they are lit in the same conditions (the co2 bottle should first be filled with air to make a test run of the set-up) and if the temperature probes are properly calibrated and shielded from direct light, then the CO2 bottle should warm more slowly. (check the constant volume specific heats ) So there is an unexplained effect in your expt. which is probably to be found at the plastic-gas interface. You cannot conclude at a 'retention effect' (which ought to be properly qualified) as long as you haven't reached a steady state, which is not the case with your data as I have already noted earlier. That would probably not be conclusive because your setup lacks any backdrop which should radiate heat away. (see my explanation for Jeff)
@Pegminer I don't think one makes a good cause by performing misinterpreted or badly controlled experiments and trying to sell the results for what they are not.
That's the reason why I asked this question. In the long run, people will know the results are wrong or misinterpreted and their disbelief will engulf whatever you might be telling them. Better NO experiment than wrong or wrongly interpreted ones.
@d/dx etc.. you should be better at differentiating, if not in math at least between the people you are talking to. I'm paid by a state agency to do basic research in fundamental physics. Not by exxon or any other of those who want/don't want to hire your abilities.
@TREVOR et al. One possible explanation of your bottle effect is that CO2 thermal conductivity is much lower than O2 or N2 thermal conductivity (just had the idea to check that, but not much time to work a model now) So since you do not wait for steady state, your CO2 bottle gets warmer because it transmits heat to be radiated away from the side opposite to the lamp more slowly. Again, no connection whatever with GHG radiative effect.
End of the game. It is a pity that nobody seems to care about this question. It may well have no answer, but that should be recognized. Not every effect taking place in a large scale system can be miniaturized. But replacing it by demonstrations which are not connected to it to try to persuade people is both dishonest and counter productive. @Trevor I don't mean that you are dishonest, you certainly believed your experiment had to do with GHG effect. However the true explanation is to be sought in the much lower CO2 thermal conductivity with maybe additional gaz-container effects. Note that even without these explanations, it could not tell you anything about GHG properties of CO2. Browse up the GHG mechanism and you will understand why a simple differential warming of the two gas bottles (what is more, before any steady state regime is established) cannot be related to it in any way.
So BA goes to the shortest and I think, most pertinent criticism of the only experiment presented.
I shall put this question again in the physics section. Maybe people will e more interested there.