sci.energy

On Sun, 12 Aug 2007 13:27:50 -0400, daestrom wrote:

>
> "Bill Ward" wrote in message
> news: @ ...
>> On Tue, 07 Aug 2007 21:48:00 -0400, daestrom wrote:
>
>>
>> But I'm not convinced CO2 is affecting temperature at all. You might
>> want to take a look at this:
>>
>> /images/uploads/
>>
>> I've glanced through it, and haven't seen any glaring errors. I'd sure
>> like to know what you think of it.
>>
>>
> As I read throught this, I noticed it didn't really address several
> questions.
>
> First it does explain rather well that the term 'greenhouse effect' is
> probably very misapplied. The typical greenhouse warms, not due to the
> selective opacity of glass to different wavelengths so much as due to the
> trapping of warm air and stopping convective cooling of the surfaces
> within the greenhouse.
>
> The discussion of the 'High School experiment' states that, " One can
> touch the car's windows and notice that the panes, which absorb the
> infrared light, are rather cool and do not heat the inside of the car in
> any way." This suggests to me that the authors have never washed their own
> car. Anyone that attempts to wash the windows of a car sitting in the sun
> knows full well that the glass is very hot and quickly will evaporate the
> window cleaner applied to them. Those facing the sun are hotter than
> those facing away from the sun. So while I agree with many of the
> statements in this section (much of the heating is not really 'heating'
> but a lack of cooling by convection), the statement about glass
> temperature suggests they haven't actually *performed* the experiment they
> discuss.

I agree that fingers are not really the digital thermometer of choice,
since he apparently had an electronic version. The cold glass comment was
a distraction from his main points.

> The authors then use this 'observation' in to discredit
> Schonweise's statement.

Agreed. he should have used one of his other "many reasons".

>
> The discussion of Wood's experiment seems to have one glaring question.
> At first, Wood's experiments showed the test box with the rock-salt
> window warming faster. I agree with his assertion that this is probably
> owing to the rock-salt window allowing even the IR portion of the sun's
> radiation to pass into the box. To compensate for this Wood then
> decides to "...eliminate this action the sunlight was first passed
> through a glass plate." There is no explanation of how putting a glass
> plate over the rock-salt window to filter out the IR portion of the
> incoming solar radiation would not also filter out the IR portion of
> re-radiation. Even if the glass plate is held some distance above the
> rock-salt plate and convection currents are allowed between, the IR
> radiation result would still be affected by the glass plate since it is
> radiating IR into the rock-salt window at something higher than the
> average 'sky temperature'. No discussion of this is provided. The fact
> that the internal temperature very nearly matches the glass window box
> when there is a plate of glass suspended above the rock-salt window does
> not support Wood's conclusion. All he has done is substitute the smaller
> amount of IR radiated from the plate into the box for the larger amount
> of IR radiated towards the box from the sun. Without a 'one way' IR
> opaque coating, the experiment is flawed.

The basic observation that the salt plate chamber actually heated more
than the glass plate chamber seems to prove the point that it's not
"trapped IR" that's heating the chambers, but lack of convection
preventing them from cooling.

The attempt to remove the difference by correcting for the loss of
incoming IR on the glass side is interesting, and likely flawed as you
say, but does not change the initial conclusion.

> The 'disproof' in calls into question statements about thermal
> conductivity that weren't made.

Moller does claim the atmosphere takes the part of the glass in a
greenhouse, after saying there is "heat conduction...which requires a
certain temperature gradient". That's the essence of thermal conductivity.
He implies the radiatively active gases will be affecting that transfer,
so I wouldn't be so hard on them. Neither Mollers explanation or the
rebuttal are shining examples of clarity.

> This is a classic strawman argument,
> claim your opponent has made some statement that the haven't actually
> made, then attack that position as perposterous.
>
> Again in the authors claim (without support) that Stichel had
> proposed a violation of thermodynamics (A Perpetuum Mobile of the
> Seocond Kind). All that Stichel stated was that some IR emitted from
> the surface is absorbed by trace gasses and re-emitted. And that this
> 'leads to a warming' of the lower atmosphere. Stichel did not state or
> suggest that all IR re-emitted would raise the surface temperature and
> thus raise the IR emitted by that surface. It is apparent that the
> concept of equilibrium radiation from the surface escapes the authors.
> CO2 and trace gasses certainly would absorb some of the IR emitted from
> the surface and raising the temperature of those trace gasses (by IR
> absorbtion) certainly would affect the equilibrium temperature of the
> surface. But the authors don't apparently understand this and instead
> thought that Stichel was proposing a violation of thermodynamics. They
> make this *assumption* and then toss his statements out-of-hand. Later
> in they make the false assertion that "A modern climate is
> supposed to be such a variant of a perpetuum mobile of the second kind."
>
> For all their discussion about radiant heat transfer they do not seem to
> grasp that a cold body next to a warm one will still radiate some IR and
> that some of that IR will be absorbed by the warmer body. Thermodynamics
> states that the amount of energy absorbed by the warm body will be
> *less* than the amount the warm body radiates towards the cold one. But
> thermodynamics does not require that *no* IR from the cold body be
> absorbed by the warmer one. Climatoligists such as Stichel that claim
> some of the IR emitted from 'cool' CO2 will be absorbed by the warmer
> planet surface. The authors assertion that this is a violation of
> thermodynamics is false and shows a lack of understanding. They try to
> talk their way around this, but don't do a very good job of it. The key
> difference is individual quanta of IR radiation versus the total net
> flux of radiation.

This is an area I seem to have trouble with. I can see two apparently
equivalent ways to describe the radiation between two bodies:

1) The way it's actually observed, by measuring the radiation transmitted
between a hot body and a cold body and their respective absolute
temperatures. The transferred energy is always found to be from hot to
cold, proportional to the difference of the 4th power of the temperatures.

2) The mathematical simplification that assumes each is radiating
isotropically proportional to the 4th power of their absolute
temperatures, and that radiation is bidirectional between them, with the
cold object heating the hot object less than the hot object heats the cold
object. That will give the same result as #1, of course, but assumes that
the cold object is able to transfer heat to the hot object as long as the
quantity is less than the energy it receives.

It sounds like a distinction without a difference, until you consider the
following thought experiment:

Imagine two focal points Fc and Fh, d distance apart.
Construct two ellipsoidal perfect reflectors around those focii, one
skinny(C), of minor diameter about d/4, the other fatter(H), of minor
diameter about d/2 . Now construct a spherical perfect reflector (S) of
diameter d centered on Fh.

Remove the part of ellipsoid H around Fc outside the intersection with
sphere S, and similarly the part of ellipsoid C around Fh. Remove
S except for the annular section between C and H.

What you should have, if I didn't screw up the description too badly, is a
optical system consisting of a small ellipsoid reflector around Fc, a
larger ellipsoid reflector around Fh, and an annular spherical reflector
region centered on Fh connecting the two.

All radiated energy from Fc must reflect to the Fh, since they are both
foci of the H and C ellipsoids, and Fc can't "see" the sphere S.

But not all of the energy from Fh is reflected to Fc. Fc gets
only the energy from Fh reflected from the ellipsoids. as the portion
reflecting from sphere S returns directly to Fh.

Now, according to #2 above, if we start with Fc and Fh at the same
temperature, they will both radiate equally. Fh will receive all the
radiation from Fc, plus the energy from itself reflected by the sphere S.
Fc will receive less energy from Fh then Fc is sending to Fh, so it must
cool, while Fh gets hotter.

With a temperature difference, we can drive a heat engine and obtain
mechanical energy for free. That doesn't seem likely to me, so what's the
problem? I think it's the assumption in #2 above that hot bodies can be
heated by cold radiation.

If we go back to #1 above, and assume the 2nd law really means that
heat simply cannot be transferred from a cold body to a hot one, then the
temperature difference can't arise, and the Universe is saved.

Or, more probably, there's some boneheaded assumption that I missed in the
above explanation . I'd be much obliged if you could point it out.

I want to reiterate that I don't think the mathematical shortcut is wrong,
just misleading. The numbers obviously come out the same.

> In the authors are correct to point out that many discussions of
> the 'greenhouse effect' make the mistake made here. An increase in IR
> opaque gasses *do* interfere with the incoming solar radiation that
> reaches the surface. But they then make some irrelevant observation
> about an empty pot on the stove versus one filled with water. The claim
> here that even though water is an excellent absorber of IR a water
> filled pot is much cooler on the bottom then an empty one. This is a
> very poorly reasoned argument. Since heat is applied to the opposite
> face of the pot, water is in direct contact with the pot's inner
> surface, and the heating of said water is *not* in equilibrium, why they
> even try to use this as a 'disproof' is mind-boggling. That they reuse
> the (very poor) analogy in is no disproof of at all.

I agree, that's weak. They try too hard to use everyday analogies and it
distracts from the good points they do make.

>
> They later bring up this topic again in . By positing a
> glass-ceramic pot that is transparent to the IR of the stovetop's
> heating element they correctly point out that the water within the pot
> will be warmed by IR absorption. But then they go on to say that the
> warm water in the pot will not 'backwarm' the bottom of the pot and in
> fact, "the ground becomes cooler.". Claiming the pot bottom as the
> 'ground' and putting it between the IR source and the absorber is a
> completely different arrangement and proves nothing. Claiming that hot
> water inside the pot will not warm the pot bottom is equily ridiculous.

Same comment as above.
>
> (and by reference ) discuss the changes in thermal conductivity
> of air when CO2 is added. And that such changes are very small. Yet
> their own discussions show that most of the cooling of the earth's
> surface by air is not by conduction but by convection. So CO2 in the
> atmosphere doesn't affect convection cooling very much (since convection
> includes conduction from the surface to the circulating medium). But
> that is irrelevent to the discussion of atmospheric warming.

Some of that may be in response to the bogus "heat trapping" properties
of CO2 that have been claimed by misleading "demonstrations" that depend
on the TC and sp. gr. of concentrated CO2, rather than any radiative
properties.

> I'll take a moment here to point out that the authors seem to obsess
> that the earth's surface is warmed by radiation from the sun and cooled
> by convection with the atmosphere. Yet they do *not* address the
> obvious follow-on question, "How is the energy removed from the
> atmosphere after it has cooled the surface?"

I think that question is still up for grabs. There's no doubt it all
must be radiated, but from exactly which levels and by what seems obscure.
>
> The authors are quite right to point out (ad nauseum) that the term
> 'greenhouse effect' is a misnomer. But they do not address the issue of
> radiant cooling very well. In they discuss emission and reflection
> rather well. But they dismiss the emission of gasses at room
> temperatures because it "...normally does not work effectively at room
> temperatures." This seems to indicate they haven't considered that
> interplanetary space is not 'at rooom temperatures." Yes, in normal,
> earthbound cavity radiation the EM radiation from the gasses within the
> cavity are overwhelmed by the radiation emitted from the interior
> surface. Not until the cavity is heated significantly does the EM
> emitted by the gasses become more significant. But the emission from the
> atmosphere to interplanetary space is far from the 'normal' cavity
> experiments. They make no allowance for this difference.

What would be the effect? It seems to me space should just look like a
3K black body. What am I missing?
>
> One unanswered question is they do not address the planet wide energy
> balance as a whole. The planet has incoming radiant energy from the sun
> and internal heat rising to the surface via convection and conduction.
> The surface has two mechanisms for cooling, convection with the
> atmosphere and radiation to the sky. The atmosphere rejects the energy
> it absorbs from the surface in a number of ways but only one of them
> rejects energy in such a way as it does not re-enter the atmosphere and
> that is radiant transfer to outer space ( . wind and other 'work'
> done by the atmosphere eventually results in the energy being conducted
> back into the atmosphere). Putting an IR absorbing gas into the
> atmosphere means the atmosphere will absorb more of the incoming solar
> radiation before reaching the ground. So the question is how does a
> warmer atmosphere affect the overall system. They do not address this
> area at all.

If they could do that, they would be way ahead of the $50B effort by the
IPCC to answer those same questions.

> They point out that the macroscopic measurements of heat transfer known
> as 'conduction' are really 'conduction' and 'radiation'. But this is
> not new. 'Conduction' is the direct transfer of KE between molecules
> while radiation is transfer of molecular energy via EM. No, they cannot
> truly be measured separately. The fact that the large majority of texts
> on heat transfer do not consider the radiant heat transfer in most
> earth-bound applications is true but does not change the results. The
> radiant energy transferred is 'at normal room temperatures' several
> orders of magnitude less than conduction. So the error is trivial. And
> advanced texts *do* discuss that radiant energy transfer does have to be
> considered when unusual temperatures warrant.
>
> Overall, I find their arguments unconvincing. They are correct about
> the term 'greenhouse effect' being a misnomer. But there's a far cry
> between correcting a public misconception and falsification of the
> theories about CO2 impact on the planet.

The climate models start with the assumption that CO2 will have an effect
on climate, and that increased CO2 will have an increased effect. The
problem is that water vapor is assumed constant. If there are negative
feedbacks involving water, they will reduce the effect of CO2, whatever it
is.

Their mention of Wood's rock salt chamber and his results raise questions
of whether 400ppm of CO2 can have any direct detectable effect on the
climate. If it can't, the models are based on initial false assumptions.

I think it's going to cause a lot of consternation, and perhaps more
understanding of the basics, in spite of its quirkiness.

I really appreciate your taking the time to read and comment on the paper.
It almost keeps me honest.