Jul 31 2007
A Simple Experiment to Prove the Existence of the Greenhouse Effect
Equipment:
Infrared Spectral Radiometer
Space Shuttle
Procedure:
1.) Measure downwelling infrared radiation at ground level.
2.) Measure downwelling infrared radiation in space, making sure to be directly above the spot measured in part 1, at the exact same time, with the instruments aligned in the exact same direction (at the sun).
2a.) Alternatively, use measurements taken from existing satellites.
3.) Compare. If greenhouse theory is correct, the integrated measurement in step 1 needs to be greater than the integrated measurement in step 2.
Hypothesis: The integrated infrared radiation measured on the ground will be greater than that measured in space, showing that the ground is heated by both the sun and the atmosphere.
[I don't have the necessary money to buy a trip on the Space Shuttle nor to buy an infrared spectral radiometer. Donations accepted.]
(2 votes, average: 5 out of 5)
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15 Responses to “A Simple Experiment to Prove the Existence of the Greenhouse Effect”
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Step 1 sounds like the initial instruction in that famous recipe for Elephant Stew. “First, catch your elephant. …”
A system that shifts the absorptivity/emissivity value between day and night would also result in the integrated infrared radiation measured on the ground being greater than that measured in space, over a day/night cycle. And yes this shows that the ground is heated by both the sun and the atmosphere, but without the so-called greenhouse effect.
Are you interested in discussing this or are you a true believer in the greenhouse effect?
If you allow for any absorption in the infrared, you allow for the greenhouse effect.
The effect of infrared absorption gases is proportional to their concentration and their absorptivity/emissivity properties across the infrared spectrum. If that’s not the case then there’s no need to be concerned about their concentrations nor their absorptivity/emissivity properties. That would indeed be the end of the discussion.
Shifting emissivity over the day/night cycle can likely explain the observed temperature of the Earth without need of the greenhouse effect. If there is a greenhouse effect it may work with or against the shifting emissivity mechanism.
How do you propose to shift the emissivity from day to night?
From our prior discusinon on the “Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics” thread (now closed to comments)…
For the sake of argument, assume an atmosphere made up only of infrared transparent gases such as oxygen and nitrogen. It’s clear then that whatever heat is transferred to this atmosphere by a warm surface through conduction and convection would be preserved until the surface cooled to a temperature below that of the atmosphere. The system of surface and infrared transparent gases has a shifting emissivity such that the emissivity is lower at night than the absorptivity of the system is by day. The result is a higher average temperature than can be explained by simple black body calculations.
Now assume an atmosphere made up only of infrared opaque gases with an emissivity equal to that of the surface. There would be no shift in emissivity between night and day and simple black body calculations show it’s temperature would be much lower than the observed value of Earth.
If an atmosphere of infrared opaque gases results in a colder system temperature than an atmosphere of infrared transparent gases, it’s only logical to assume that adding infrared opaque gases to an atmosphere of infrared transparent gases would cause it to cool rather than warm.
The shifting emissivity of Earth’s mostly infrared transparent atmosphere likely explains the observed average temperature while being in harmony with all known laws of physics.
“Now assume an atmosphere made up only of infrared opaque gases… and simple black body calculations show it’s temperature would be much lower than the observed value of Earth.”
See Simple Model of Greenhouse Gases.
See Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics
[Response: I've read it. It's wrong. That's why it isn't published in a peer-reviewed journal. As all the anti-global warming "stuff".]
[Comment deleted. This conversation isn't going anywhere.]
I agree we’re not making progress here. What’s needed is a doable experiment to test the validity of the second law of thermodynamics in a system that approximates the theoretical greenhouse effect. I have been thinking about this and there may actually be a way to approach this. A preliminary version might even be doable by the home experimenter. Those results might then lead people with budgets to perform a far better controlled version. I need to draw something up. Developing…
An experiment would be a great idea. However, it’s going to be difficult to create an experiment that studies the (radiation) greenhouse effect without the effect of real greenhouses, suppressed convection. I look forward to reading your idea, and its results.
In attempting to create a valid experiment it seems reasonable to first test my understanding of what I’m trying to simulate. Below are a few key concepts. Don’t be offended by the “it’s said” phraseology. This is a science experiment to test a theory. If that theory were already proven fact neither you nor I would be designing experiments to test it.
The greenhouse effect is said to arise due to atmospheric gases like CO2 absorbing infrared radiation emitted by the Earth’s surface (dirt, rock, pavement, water, whatever). In turn these gases heat up and emit infrared radiation of their own. Some of that re-emitted infrared escapes into space, but some strikes the surface, where it’s said to be absorbed by the surface and this raises the temperature of the surface above what it would be without this re-emitted radiation. Is this consistent with your understanding?
[Response: That is usually how it's framed. However, I think an equally valid interpretation would be that the greenhouse gases, through their absorption and isotropic emission, slow the cooling rate of the surface. The net heat flow is still from the surface to the atmosphere.]
It’s been stated that in the lower atmosphere any gas would both absorb heat and lose heat by conduction and convection processes, and thus, gases like CO2 don’t act any different than gases like Nitrogen. Thus, the infrared absorption properties of gases like CO2 are only important in a region of the atmosphere that is significantly isolated from the conduction and convection processes. Is this consistent with your understanding?
[Response: Conduction is important in the lowest few inches of the atmosphere. Convection is dominant in the troposphere. Radiation is dominant above that. Some simple models, but much more complex than I've outlined on this site which are just very simple radiative models, assume a convective troposphere with the stratosphere and above being in radiative equilibrium.]
While most mathematical models I have seen assume daytime, the same greenhouse effect would also operate at night. Is this consistent with your understanding?
]
[Response: Yes. The only difference is the lack of an external forcing (the sun). And if we remove the sun, things get boring pretty quickly.
I agree there are many factors no doable “laboratory” experiment is going to be able to simulate. However, it may be useful to test what can be tested.
It appears you agree that only high altitude greenhouse gases are of concern and only because of heat transfer through radiation. And that the greenhouse effect is active at night as well as by day.
A solid material that has the properties of being transparent to visible light, yet absorbs infrared while having no reflectivity doesn’t exist that I know of.
To simulate night, however, we can drop the property of being transparent to visible light. We only need a solid material that absorbs and emits infrared without reflecting it. This would be a black body like material.
It’s true that the mix of greenhouse gases have a complex infrared absorption spectrum, but the effect being measured would be enhanced by using a black body like material. If the effect can’t be found using a black body like material in place of the greenhouse gases then the effect is less than the sensitivity of the experiment. If the effect can be measured using a black body like material, then the effect of the greenhouse gases can likely be calculated from their absorption spectrum and their emissivity (same as absorptivity for a given wavelength). Similarly, using a black body like material for the Earth’s surface would enhance any effect. Developing…
With a bit of calculating I find that not only would my experiment need to be done in a vacuum, but in space. Maybe it could be done on Earth with a sufficient budget, but that’s beyond my resources.
Apart from that, I believe an important idea may have been uncovered. That is the plausibility that the daytime absorptivity of the Earth is higher than it’s nighttime emissivity. This would occur anytime heat is retained at night in the atmosphere due to it’s low infrared emissivity as compared to that of the surface. As with the greenhouse effect, the shifting emissivity effect would be the devil to actually measure. It’s existence, however, may explain discrepancies between the greenhouse model’s predicted temperatures at various altitudes in the atmosphere and measured values. Maybe I’ll do some of the calculations around this idea.
[Response: I’ve read it. It’s wrong. That’s why it isn’t published in a peer-reviewed journal. As all the anti-global warming “stuff”.]
I can agree that Gerlich’s article is not peer reviewed, so it may be efficacious to provide a peer reviewed point A to point B exposition to validate IPCC’s hypothesis arriving at a ~2.5C increase in temperature by a doubling of atmospheric CO2. This exposition would include first principles of physics, chemistry, fluid dynamics, thermodynamics etc. for example.
Thanks.