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Energy flux versus temperature change

by kmarinas86
Tags: energy, flux, temperature, versus
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DaleSpam
#19
Apr9-12, 11:12 AM
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Quote Quote by kmarinas86 View Post
The wavelength changes in the above picture "scenario".
Sure, but the "above picture 'scenario'" is not relevant to your scenario. The "above picture 'scenario'" is fluorecense. That is energy which is absorbed by some object, A, at one wavelength and emitted by that same object, A, at a different wavelength.

In your scenario you are interested in energy which is emitted by A and then absorbed by some other object, B. The wavelength of energy emitted by A is always the same as the wavelength of energy absorbed by B, absent any Doppler or relativistic effects. Do you disagree with that?
kmarinas86
#20
Apr9-12, 11:57 AM
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Quote Quote by DaleSpam View Post
Sure, but the "above picture 'scenario'" is not relevant to your scenario. The "above picture 'scenario'" is fluorecense. That is energy which is absorbed by some object, A, at one wavelength and emitted by that same object, A, at a different wavelength.

In your scenario you are interested in energy which is emitted by A and then absorbed by some other object, B. The wavelength of energy emitted by A is always the same as the wavelength of energy absorbed by B, absent any Doppler or relativistic effects. Do you disagree with that?
Do you even know what the scenario is?

It is not "my" scenario. The topic is the system to be described, including all absorption, re-emission etc. not mentioned in the opening post. The OP is what, apparently, you think establishes the full context of the scenario. It does not.

The broader context:
A and B emit.
A and B absorb.
A and B re-emit.
A and B absorb.
etc.
DaleSpam
#21
Apr9-12, 12:06 PM
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Quote Quote by kmarinas86 View Post
The broader context:
A and B emit.
A and B absorb.
A and B re-emit.
A and B absorb.
etc.
I see you avoided answering the question. In the broader context, do you agree or disagree that the wavelength of any radiation emitted by A and absorbed by B is the same when it is emitted by A as when it is absorbed by B?
kmarinas86
#22
Apr9-12, 12:21 PM
P: 1,011
Quote Quote by DaleSpam View Post
In the broader context, do you agree or disagree that the wavelength of any radiation emitted by A and absorbed by B is the same when it is emitted by A as when it is absorbed by B?
No.

A emits radiation to B.
The wavelength is the same - AT FIRST - (obviously ignoring Doppler effects here).
BUT THEN, the energy sent to B is then absorbed and emitted WITHIN B.
Now the wavelength is NOT the same (even if you ignore Doppler effects).
Then B can ABSORB that energy AGAIN (more photons, but at lower frequency)!
So the wavelength is -NOT- the same!
Then that energy may be trapped for an extended period of time, because absorption and emission both take time to happen.
It means that energy will accumulate.
Yes, it does max out, but that accumulation does not fall back if you continue to have sufficient emissions from the other object.
Furthermore, the photons with the lower frequency may take more time being emitted or absorbed (hand-in-hand with the lower-frequency (longer time interval) of undulations which emit them), so the emissivity they experience can be less, which depends on the presence of appropriate carriers of energy at such levels. Thus the hot object may then emit less of such radiation than its temperature alone would imply, depending on the composition of the object.
The ability to be absorbed and reabsorbed at one level (the atomic level) can have a detrimental effect as to its ability to be emitted at a higher level (such as the level of the object itself). So you could even say that emissivity depends on the scale of matter, so it's NOT LIMITED to just wavelength, frequency, temperature, and incidence angle.
kmarinas86
#23
Apr9-12, 01:17 PM
P: 1,011
Quote Quote by kmarinas86 View Post
The ability to be absorbed and reabsorbed at one level (the atomic level) can have a detrimental effect as to its ability to be emitted at a higher level (such as the level of the object itself). So you could even say that emissivity depends on the scale of matter, so it's NOT LIMITED to just wavelength, frequency, temperature, and incidence angle.
Here's a simple example of this.

Let's have colors red, green, and blue.

Blue travels through the Earth's atmosphere without as much problem as red and green do.The light that does gets absorbed and re-emitted gets downgraded to lower frequencies. Red and green soon convert to thermal. The upper and lower atmosphere have no problem absorbing and reabsorbing thermal energy, when you compare it to the blue light.

A greater amount of blue light "gets in and gets out" of the Earth's atmosphere without much problem. So, to a distant observer, the Earth appears to have a high ability to absorb and emit blue light (i.e. the emissivity of the Earth at blue wavelengths appears rather high). This was due in fact to the reality that the atmosphere was less able to absorb the blue light, and less able to downgrade the blue light to lower frequencies. In other words, the fact that:
* The blue light was subjected to lower emissivity as far as the atmosphere was concerned.
Results in the following:
* The blue light experiences a high level of emissivity (easy to get in and easy to get out) as far as the Earth is concerned.

As far as the red and green are concerned, they get in and out of the atoms in the atmosphere more readily, and even more so when they convert to thermal, but this occurs at the expense of being as able to get out of the planet itself.
DaleSpam
#24
Apr9-12, 02:37 PM
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Quote Quote by kmarinas86 View Post
A emits radiation to B.
The wavelength is the same - AT FIRST - (obviously ignoring Doppler effects here).
OK, so this transfer is governed by the principles I outlined above. It always goes from hot to cold.

Quote Quote by kmarinas86 View Post
BUT THEN, the energy sent to B is then absorbed and emitted WITHIN B.
Now the wavelength is NOT the same (even if you ignore Doppler effects).
Then B can ABSORB that energy AGAIN (more photons, but at lower frequency)!
So the wavelength is -NOT- the same!
That is fine, this is all within B so there is no energy transfered.

Quote Quote by kmarinas86 View Post
Thus the hot object may then emit less of such radiation than its temperature alone would imply, depending on the composition of the object.
True. And if it does emit less of such radiation than its temperature would indicate, then it will also absorb less of such radiation, as I outlined above. Leading to transfer only from hot to cold.

Quote Quote by kmarinas86 View Post
So you could even say that emissivity depends on the scale of matter, so it's NOT LIMITED to just wavelength, frequency, temperature, and incidence angle.
You seem to be proposing new physics here. Do you have any mainstream scientific references that can corroborate? If not, then it is speculative and doesn't belong on PF.
kmarinas86
#25
Apr9-12, 08:02 PM
P: 1,011
The example that I just posted referred to the Earth's atmosphere. No new laws of physics were invoked.
DaleSpam
#26
Apr9-12, 08:14 PM
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P: 16,947
The example you posted also didn't show that the earth could heat the sun nor any other object warmer than the earth, nor did it show that emissivity depends on "the scale of matter". All it showed is that the earth is not a blackbody, to which I completely agree.
kmarinas86
#27
Apr9-12, 09:18 PM
P: 1,011
Quote Quote by DaleSpam View Post
True. And if it does emit less of such radiation than its temperature would indicate, then it will also absorb less of such radiation, as I outlined above. Leading to transfer only from hot to cold.
To test:
We should analyze the following scenario:

Quote unparsed:
Quote Quote by kmarinas86 (the big question) View Post
What if the colder sphere has a high emissivity at low-frequencies, the same frequency range where it peaks (thus helping it to emit heat), and a low emissivity at high-frequencies of which is scant inside the colder sphere (so negligible effect on limiting emission), the same high-frequencies which are at the same time being emitted by the hotter sphere (thus the heat of the hotter sphere is reflected away by the colder sphere), while the hotter sphere has a low emissivity in high-frequency range in which it would otherwise peak (thus reducing the emission of its own heat, providing yet another limitation on the transfer of heat from the hotter sphere to the colder sphere), while it has high emissivity at low-frequencies of which are scant inside the hotter sphere (so negligible effect on increasing emissions by the hotter sphere), permitting heat flux of low-frequencies from the colder sphere? Let's say that there exist super-low-frequencies which the colder sphere has a high emissivity for, while the hotter sphere has a low emissivity for them. So energy received by the hotter sphere from the colder sphere as low-frequencies get downgraded as super-low frequencies that get trapped by the hotter sphere. The result of all that is a net energy flux from the colder sphere to the hotter sphere. What does the energy affect when it is transferred like that?
Parsing this
The colder sphere:
- (A) Would peak at low frequencies (if it were an ideal black body)
- (B) High emissivity at low and super-low frequencies
- (C) Low emissivity at high frequencies
The hotter sphere:
- (X) Would peak at high frequencies (if it were an ideal black body)
- (Y) High emissivity at low frequencies
- (Z) Low emissivity at high and super-low frequencies
High frequencies:
- (P) May be downgraded to low frequency after absorbed
- The colder sphere emits little of it. Reasons are (A) and (C).
- The colder sphere absorbs little of it, and thus may re-emit little of it. Reason is (C).
- The hotter sphere emits little of it. Reason is (Z).
- The hotter sphere absorbs little of it, and thus may re-emit little of it. Reason is (Z).
Low frequencies:
- (Q) May be downgraded to super-low frequency after absorbed
- The colder sphere emits largely this amount, closer to the ideal black-body. Reasons are (A) and (B).
- The colder sphere may not have much to absorb at this frequency. Reason is (X). Or:
- The colder sphere may have much to absorb at this frequency. Reason is (Y).
- (R) The colder sphere does not keep much of it, whether or not the light was downgraded. Reason is (B).
- The hotter sphere emits some, but it's not a big fraction of its total output. Reason is (X).
- The hotter sphere may have much to absorb. Reasons are (A), (B), (Y), and (R).
- The hotter sphere may retain the energy of them. Reasons are (Q) and (Z).
Super-low frequencies:
- (T) The colder sphere emits some fraction of its output as super low frequencies, but less than it does in low frequencies. Reason is (A).
- The colder sphere cannot retain them. Reason is (B).
- The hotter sphere can generate much of it. Reasons are (A), (Y), and (Q).
- The hotter sphere can retain them after generating them. Reason is (Z).
- (L) The hotter sphere can retain most of the system's super-low frequency energy. Reasons are (T), (A), (Y), (Q), and (Z).
- (N) The hotter sphere cannot absorb much from the outside. Reason is (Z). This is insignificant. Reason is (L).
- Both emit little, though the colder sphere emits a relatively larger fraction of its output at these frequencies than does the hotter sphere. Reasons are (A) and (X).

Extension:
- Corollary of the above - If the colder sphere has high emissivity for "super-super low" frequencies, etc., while the hotter sphere has various emissivities, varying from high to low, for different frequencies of such, then the "super-super low" frequencies, etc. may persist longer in the hotter sphere than colder sphere and thus still maintain a higher concentration of them.
- At some point, the frequencies could be downgraded so many times, that they would cause only very slight movements similar to quakes.
DaleSpam
#28
Apr10-12, 09:40 PM
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P: 16,947
I didn't see anything in there to indicate net energy transfer from cold to hot at any frequency. As such, I didn't see anything major to disagree with.


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