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A potential source of asymmetry - methods of heat dissipation


A potential source of asymmetry - methods of heat dissipation16-09-2016 05:21
jwoodward48
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(1537)
For the sake of argument, let us assume that some component of the atmosphere absorbs radiation. In exchange, I (for this thread, at least) will give up the "CO2 absorbs infrared, therefore it absorbs earth-black-body-radiation better than sunlight" argument. I believe that this will improve the discussion. Note that it is not necessarily the case that an absorbent atmosphere will cause global warming; the discussion is about whether or not the absorbance affects temperature.

====

I have been posting about how I think that the random direction of the radiation emitted by CO2 excited by radiation from Earth's surface, but this is a flawed argument. First, without a significant difference in wavelength between sunlight and Earthly radiation, the CO2 will do nothing but slow down temperature changes, not create any itself. Second, it fails to consider the other means of temperature dissipation.

I believe that focusing on the three main means of heat dissipation (radiation, conduction, and convection) will be productive. For now, since I have pondered radiation to little effect, and I do not yet fully understand the convective cooling of the Earth, I will discuss the asymmetry of heat flow induced by conduction. Radiation and convection are all acceptable topics for this thread, though.

====

Let us consider sunlight coming toward the Earth. Upon reaching the outer atmosphere, there are two potential paths each photon may take. Some photons continue through the atmosphere unobstructed, hitting the ground and giving it thermal energy. A small number of photons will be absorbed by molecules in the atmosphere. Those photons and the energy they carry are the topic of interest for this post.

After the molecule absorbs a photon, it has excess thermal energy compared to its surroundings. It will usually dissipate that energy by conduction, though radiation may have some effect. This dissipation spreads the energy over the whole atmosphere, and eventually to the surface of the Earth. This leads to any solar energy hitting the earth being either reflected (ice caps, etc.) or absorbed, whether or not the point of absorption is on the Earth's surface.

Up to this point, I believe that I am mostly correct.

Now let us consider radiative energy leaving the Earth and coming through the same atmosphere which may absorb energy from above. Since the atmosphere does not have a sense of up or down, it will absorb all energy passing through it evenly (in that the direction a photon comes from does not matter for absorption; it does matter for whether a particular molecule does absorb it, but those directions are not aligned with the Earth's up-and-down. Additionally, energy may be absorbed more or less depending on the wavelength of the photon that carries it; I am not contradicting those possible effects on absorption. I am only stating that direction of radiation does not matter, not that nothing matters.).

But this energy will be radiated or conducted away just in the same way as solar energy would. Since solar energy tends not to be sent back to space after absorption by an atmospheric molecule, neither will this earthly radiation. Instead, it will most likely be spread throughout the atmosphere and eventually reach the surface again.

Would this not mean that energy tends to be "reflected" (layman) down at the Earth when it comes from Earth, but that it may "pass through" (ditto) the atmosphere without "reflection" (ditto) when it originates from the Sun?

No, that's too laymanish. Here's a more scientific paragraph:

Would this not mean that energy passing through the atmosphere tends to be redirected to remain in the Earth system, regardless of where it originated? If so, then the dissipation of heat from Earth would be slowed, while the intake would not.

If so, we have established that the inflow exceeds the outflow. If that is so, then the energy in the Earth system will increase. Eventually, the temperature will be high enough that the outflow (which is proportional to temperature, but not only temperature) will equal inflow again.

The first LoD is satisfied, and in fact invoked, by this. The energy that goes toward heating the Earth is taken away from that which would have otherwise radiated away from Earth.

The second LoD? I'm not quite sure how it would apply.

The Laws of Emission only concerns emission from the Earth's surface, which I believe makes up most of the radiation, rather than emission from the upper atmosphere after going up via conduction and convection. Even if the latter composes a large proportion of the Earth system's emissions, as long as some emission is from the former, a still-existent but lesser form of my hypothesized phenomenon will occur.
16-09-2016 07:22
Into the Night
★★★★★
(8592)
Thermal energy in the atmosphere will not return to the surface. This is where the 2nd law the thermodynamics applies. The surface is warmer. The atmosphere is cooler (in most cases). Heat only flows from warmer to cooler. The greater the difference, the greater the flow.

ALL of the atmosphere radiates infrared energy. Oxygen, nitrogen, carbon dioxide, argon, water vapor, anything. The reason is doesn't heat the surface more is because the surface is already excited from absorbing photons. It is emitting more of them and at higher energy than anything in the air.

Scattering and re-absorption will happen in all directions, but the tendency is for energy to move away from the surface.

High energy always tends to flow towards low energy. The greater the difference the faster the overall flow.
This is the law of entropy (the 2nd law of thermodynamics) applied to total energy flow.

Like a guy holding a six shooter against a squad of 100 armed men with machine guns, you might get one or two, but...you lose.

The colder atmosphere is just outgunned by the warmer surface.
16-09-2016 07:27
jwoodward48
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(1537)
Hmm, that's a good point. The thing about your "outgunned" analogy, though, is that increasing the outgunned atmosphere's energy "firing fate" will have the effect of decreasing the net outflow, right?

Of course, that seems like it would have a trivial effect on the temperature. Not as much as a few degrees.
16-09-2016 20:40
Into the Night
★★★★★
(8592)
jwoodward48 wrote:
Hmm, that's a good point. The thing about your "outgunned" analogy, though, is that increasing the outgunned atmosphere's energy "firing fate" will have the effect of decreasing the net outflow, right?

Of course, that seems like it would have a trivial effect on the temperature. Not as much as a few degrees.


No, it's more like reloading your six shooter (if you get the chance!
)


The Parrot Killer
16-09-2016 21:09
jwoodward48
★★★★☆
(1537)
*knows nothing about guns*

*does not get it*

Huh?
18-09-2016 04:13
IBdaMann
★★★★★
(4208)
jwoodward48 wrote:
*knows nothing about guns*

*does not get it*

Huh?

At least you're not claiming you understand the 2nd LoT.


.


Global Warming: The preferred religion of the scientifically illiterate.

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
18-09-2016 04:52
jwoodward48
★★★★☆
(1537)
You don't understand the 2nd LoT. It describes overall heat flow. If energy leaves at a lesser rate, the Earth will warm. This does not violate any laws.
18-09-2016 08:59
Into the Night
★★★★★
(8592)
jwoodward48 wrote:
*knows nothing about guns*

*does not get it*

Huh?


Too bad for you. Go learn to shoot one before you justify taking them away from people. You might learn something.

Yes, I carry. Yes it's concealed. Yes I will shoot anyone that tries to take it from me. Yes if they happen to succeed it will be the LAST thing they take from anyone.


The Parrot Killer
18-09-2016 09:00
Into the Night
★★★★★
(8592)
jwoodward48 wrote:
You don't understand the 2nd LoT. It describes overall heat flow. If energy leaves at a lesser rate, the Earth will warm. This does not violate any laws.


You do not understand the 2nd LoT. That's not how it works. I am through teaching this stuff to you over and over. Go look it up.


The Parrot Killer
18-09-2016 09:48
jwoodward48
★★★★☆
(1537)
The cold air is returning some energy to the Earth. With no atmosphere, no energy is returned. Some is more than none.
18-09-2016 10:54
Into the Night
★★★★★
(8592)
jwoodward48 wrote:
The cold air is returning some energy to the Earth. With no atmosphere, no energy is returned. Some is more than none.


Evasion. Go look up the 2nd LoT. Read the 1st LoT while you're at it. Then realize the carbon dioxide is not an energy source.

You still haven't answered my question concerning oxygen and carbon dioxide.


The Parrot Killer
18-09-2016 11:34
jwoodward48
★★★★☆
(1537)
I have answered the question. I'll do it again: they will be at the same temperature. Why, how does that matter?

I have looked up the 2nd LoT. Several times. Here's the definition. "The total entropy of an isolated system always increases over time." You need to show how that means that energy returning to Earth does not increase the Earth's temperature.

It's like a bathtub with the drain open and the faucet on. Energy comes in, energy comes out. Partially plugging the drain will lead to an increase in water height.




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