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Published comment, and reply, on Gerlich and Tscheuschner 2009
Topic Started: May 8 2010, 03:45 AM (4,809 Views)
SkyHunter

You seem to have totally ignored the substance of the discussion and honed in on what you believe is a fallacy, making it the focus of your argument.

It leads one to wonder about your motive in this discussion.

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Terry Oldberg

Let's skip over the philosophical aspects and get into the substance. The paper of Halpern et al abuses the language of thermodynamics. This abuse creates the appearance of a violation of the second law of thermodynamics. In the language of thermodynamics, the idea that is referenced by the word "heat" does not flow up a temperature gradient unless it is pumped. Thus, the "heat flow" which, according to the Halpern et al article flows up a temperature gradient violates the second law.

The appearance of a second law violation may be avoided by referencing the concepts which Halpern et al reference as "heat flows" by words or phrases that are commonly used in technical English and that do not employ the word "heat" inappropriately. In surfing the Web, I've discovered that the phrases "vector irradiance" and "vector radiosity" are commonly used and precisely defined. Thus, they meet all requirements on a replacement for the phrase "heat flow" in circumstance in which this usage is inappropriate.

The vector irradiance is the vector sum of Poynting vectors that are incident on a surface. The vector radiosity is the vector sum of Poynting vectors that are reflected from the surface or are emitted or transmitted through this surface. By definition, the vector radiosity that is associated with a space point points away from this space point. The vector irradiance points toward the associated space point. At a space point, the radiative heat flux is the vector difference of the vector radiosity and vector irradiance.

Now, in regard to whether or not a given description of the atmospheric greenhouse effect is or is not falsified, it is pertinent that the entity that is subject to being falsified is a proposition. The proposition that there is an effect that results from a flow of heat up a temperature gradient is falsified by its second law violation, if the phrase "heat flow" references the associated concept of thermodynamics; this same proposition is not falsified if the phrase "heat flow" references a vector irradiance or vector radiosity. The effect is falsified and is not falsified. In this way, the law of non-contradiction is violated by the argument of Halpern et al.

In logical form, the argument that is made by Halpern et al is a paradox. That it is a paradox results from the ambiguity with which the phrase "heat flow" references the associated concepts of radiative physics.

In the literature of climatology authors often use the phrase "heat flow" or "heat flux" in this paradoxical way. Often authors make this usage in reference to the vectors that are represented in the Kiehl-Trenberth diagram. A Web page at the site of the University Corporation for Atmospheric Research makes this usage. To use the phrase "heat flow" or "heat flux" in a paradoxical way in the context of a problem in heat transfer to ask for trouble! Thus, it seems to me that it is high time for climatologists to adopt a use of language which, in this sense, is not abusive.

By the way, the Halpern et al article errs in implying that the vector irradiance and vector radiosity are collinear. Climatologists often imply they are collinear (e.g. by describing their directions as "up" and "down" ) but to do so is to confuse a characteristic of a kind of model with the real world. The two vectors are not collinear, for example, when the vector irradiance consists of a single Poynting vector that is incident on a reflective surface and not normal to this surface.

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apsmith

Terry, sorry I didn't notice your comments here until now, the forum had been quiet and I hadn't been checking in much.

I would like to understand what your complaint is with our comment. I do understand you have an issue with the term "heat" - we've discussed this before, and after some reflection I think using it with regards to the "back radiation" may actually be justified in comparison to its use in other thermodynamic systems (the Q term in heat engines, for instance). But you've apparently found other terms you're happier with, so I won't pursue that right now.

Here's my actual question: after replacing the terms used to your liking, is there actually a point in our "comment" paper that you find to be in error? If you could quote or cite specifically, together with what you think is actually wrong with it, that may be worth discussing here. Thanks.
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Terry Oldberg

Arthur Smith:

Thanks for taking the time to reply.

Regarding the Halpern et al paper, it appears to be written in a different language in reference to thermodynamic concepts than the paper of G&T which is the target of the Halpern et al paper's critique. In particular, the word "heat" references different concepts in the two papers; the "heat" of the Halpern et all paper seems not to be meant as the "heat" of thermodynamics. while the "heat" of the G&T paper seems to be meant as the "heat" of thermodynamics. The amgiuity of reference by the word "heat" muddles communication among the two sides to the debate between Halpern et al and G&T and among the members of the audience for this debate. This muddling could have been avoided through use by both sides of a disambiguated terminology.

A disambiguated terminology that works in practice reserves the word "heat" for use in reference to the associated concept of thermodynamics. In the disambiguated terminology, the concepts that are referenced as heat fluxes in the Halpern et al paper are referenced by the terms "vector radiosity" and "vector irradiance." The phrase "energy flux" is not used. At an (x, y, z) space point, the radiative heat flux is the vector difference of the vector radiosity and the vector irradiance.

Now, to employ this terminology in disambiguating the message of the the Halpern et al paper, at a space point in the atmosphere, the heat flux equals the non-radiative heat flux + the vector radiosity - the vector irradiance, where "+" designates vector addition and "-" designates vector subtraction. Halpern et al seem to claim that it is this heat flux and not the vector irradiance that is bound by the second law prohibition on a heat flux that up a temperature gradient and without a heat pump. This claim is correct.

For the future, I believe it would be very beneficial if authors of climatological papers and professors of climatology were join in disambiguation of the language of climatology in reference to thermodynamic concepts. A policy statement by one or more of the learned societies would help to get the ball rolling.

Cordially, Terry Oldberg

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