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Why the greenhouse effect does not violate the first law of thermodynamics



Page 7 of 9<<<56789>
09-08-2016 20:40
Into the NightProfile picture★★★★★
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Leafsdude wrote:
Pop quiz: what is heat?


Heat is the transfer of thermal energy.


The Parrot Killer
09-08-2016 22:21
Leafsdude
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(141)
And what is light?
09-08-2016 23:02
Into the NightProfile picture★★★★★
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Leafsdude wrote:
And what is light?


The movement of energy in electromagnetic form, which is to say as a combination of magnetic and electrical fields self supporting each other.

Light has a frequency and an amplitude (and a phase, when compared with other light).


The Parrot Killer
Edited on 09-08-2016 23:07
09-08-2016 23:12
Leafsdude
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And what are the possible results when light hits matter?
10-08-2016 00:27
Sheesh
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Ok, lets see so if energy is absorbed and re-emitted that means there is more energy leaving the atmosphere? again I may be completely wrong but when IR is absorbed it creates an increase in temperature if it is them reemitted at a lower energy level IR the remaining energy must go somewhere even if it is also re-emitted at a lower energy frequency?

And I did not specifically say that C02 changed the spead of light relative to other gases I said it increases the time it takes to leave the atmosphere, given that the statement immediately prior was about absorbtion and re-emmission I thought it implied that this would be relative to the path travelled through the atmosphere.

As for mylar I again did not say that it did not stop convection I said it was irrelevant in most cases, unless you are naked or wearing stupid clothes the most common use of a mylar blanket is to wrap around yourself in emergenies (I assumed you werent moronic enough to get into an emergency situation not wearing waterproof clothing which prevents the vast majority of convection anyway).
But again avoiding the point, convection cannot emit energy from the atmosphere only redistribute it, if a mylar blanket decreases the rate at which IR escapes a person wrapped in it would in theory warm the person by back radiation, your argument that the atmosphere is not an insulator falls down if this is true, it isnt providing significant insulation by transmission and yet the heat inside increases.
Let us take a simpler example, we have a cubic room with walls that are 100% transparent a light bulb in the centre, all energy is lost to outside, if you change the walls so that 50% of the light is absorbed then re-emitted, for simplicity 50% of the time it is emitted outwards 50% inwards. Now the number of photons inside the box at any time has increased, therefore the chance of a photon being in collision with a molecule of gas has increased and there is a small but observable increase in temperature. The only change is the boundary conditions which change the amount of time photons spend in the atmosphere.
While I am not suggesting it is this simple I think this demonstrates my point.
10-08-2016 00:35
Into the NightProfile picture★★★★★
(10243)
Leafsdude wrote:
And what are the possible results when light hits matter?


1) Nothing (most of the time)
2) Harmonic absorption (rare). The molecule reaches an excited state. If a chemical reaction does not take place as a result of this state, the molecule drops to its base state, emitting a photon. No thermal energy changes. This is the type of light from LED's, animals like fireflies and some fish emit. It so-called 'cold' light. It is like twanging a violin string.
3) Thermal absorption (unusual, but less rare than harmonic absorption). The molecule increases it's lateral energy. The resulting lateral movement is the definition of temperature. The photon ceases to exist and the molecule becomes warmer. All vibrating molecules contain moving charges that emit light on a new frequency completely unrelated to what gave it the thermal energy in the first place. This light has less amplitude and is on a different frequency. This is so-called 'hot' light. It is the light of an incandescent bulb, a fire, molten steel, or any other object warmer than absolute zero. The frequency of light emitted is determined by Planck's law, independent of what the substance is.
4) Reflection. The light bounces back generally toward its source without affecting the molecule.
5) Refraction. The light slows down as it passes through the substance, speeding up again as it leaves. No thermal change occurs. The frequency, amplitude, and phase stays the same.


The Parrot Killer
10-08-2016 00:40
Into the NightProfile picture★★★★★
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Sheesh wrote:
Ok, lets see so if energy is absorbed and re-emitted that means there is more energy leaving the atmosphere? again I may be completely wrong but when IR is absorbed it creates an increase in temperature if it is them reemitted at a lower energy level IR the remaining energy must go somewhere even if it is also re-emitted at a lower energy frequency?
[quote]Sheesh wrote:
And I did not specifically say that C02 changed the spead of light relative to other gases I said it increases the time it takes to leave the atmosphere, given that the statement immediately prior was about absorbtion and re-emmission I thought it implied that this would be relative to the path travelled through the atmosphere.
[quote]Sheesh wrote:
As for mylar I again did not say that it did not stop convection I said it was irrelevant in most cases, unless you are naked or wearing stupid clothes the most common use of a mylar blanket is to wrap around yourself in emergenies (I assumed you werent moronic enough to get into an emergency situation not wearing waterproof clothing which prevents the vast majority of convection anyway).
But again avoiding the point, convection cannot emit energy from the atmosphere only redistribute it, if a mylar blanket decreases the rate at which IR escapes a person wrapped in it would in theory warm the person by back radiation, your argument that the atmosphere is not an insulator falls down if this is true, it isnt providing significant insulation by transmission and yet the heat inside increases.
Let us take a simpler example, we have a cubic room with walls that are 100% transparent a light bulb in the centre, all energy is lost to outside, if you change the walls so that 50% of the light is absorbed then re-emitted, for simplicity 50% of the time it is emitted outwards 50% inwards. Now the number of photons inside the box at any time has increased, therefore the chance of a photon being in collision with a molecule of gas has increased and there is a small but observable increase in temperature. The only change is the boundary conditions which change the amount of time photons spend in the atmosphere.
While I am not suggesting it is this simple I think this demonstrates my point.


The only point it demonstrates is that by changing what a photon hits from something transparent (meaning most of the time it is refracted through and nothing else), for a completely different substance where thermal absorption is more likely, you can warm the room with a light bulb.


The Parrot Killer
10-08-2016 00:52
Sheesh
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ok now if we assume that the material remains the same apart from the increase of one component that absorbs a specific range of frequencies emitted by the bulb, (yes the bulb will create more heat than the energy absorbed by the gas in real life) but fundamental science says that there will be an increase to the atmosphere caused by the time photons spend travelling through the box.
10-08-2016 01:10
Into the NightProfile picture★★★★★
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Sheesh wrote:
ok now if we assume that the material remains the same apart from the increase of one component that absorbs a specific range of frequencies emitted by the bulb, (yes the bulb will create more heat than the energy absorbed by the gas in real life) but fundamental science says that there will be an increase to the atmosphere caused by the time photons spend travelling through the box.


That is still changing the material of the box.


The Parrot Killer
10-08-2016 01:28
Sheesh
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ok so if we change the material composition of the earths atmosphere there is a fairly good reasoning that says it "may" change the thermal energy in the atmosphere by increasing the time long wave radiation spends travelling through it.
10-08-2016 01:45
Into the NightProfile picture★★★★★
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Sheesh wrote:
ok so if we change the material composition of the earths atmosphere there is a fairly good reasoning that says it "may" change the thermal energy in the atmosphere by increasing the time long wave radiation spends travelling through it.


No.

The refraction (which is mostly a matter of density, not substance) does not cause any thermal change at all.


The Parrot Killer
Edited on 10-08-2016 01:46
10-08-2016 02:10
Sheesh
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Ok if refraction is the only thing occuring then does C02 have a higher density than the average composition of the atmosphere? "Yes" therefore increasing C02 increases the total density of the atmosphere increasing the chance of infrared becoming heat

are you disputing the fact that a gas can absorb electromagnetic energy by saying it is purely refraction?
10-08-2016 04:43
Into the NightProfile picture★★★★★
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Sheesh wrote:
Ok if refraction is the only thing occuring then does C02 have a higher density than the average composition of the atmosphere? "Yes" therefore increasing C02 increases the total density of the atmosphere increasing the chance of infrared becoming heat

are you disputing the fact that a gas can absorb electromagnetic energy by saying it is purely refraction?


The current density of carbon dioxide is somewhat below 0.04%.

Both types of absorption can occur with the refraction.


The Parrot Killer
10-08-2016 05:48
Leafsdude
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1) Nothing (most of the time)
2) Harmonic absorption (rare). The molecule reaches an excited state. If a chemical reaction does not take place as a result of this state, the molecule drops to its base state, emitting a photon. No thermal energy changes. This is the type of light from LED's, animals like fireflies and some fish emit. It so-called 'cold' light. It is like twanging a violin string.
3) Thermal absorption (unusual, but less rare than harmonic absorption). The molecule increases it's lateral energy. The resulting lateral movement is the definition of temperature. The photon ceases to exist and the molecule becomes warmer. All vibrating molecules contain moving charges that emit light on a new frequency completely unrelated to what gave it the thermal energy in the first place. This light has less amplitude and is on a different frequency. This is so-called 'hot' light. It is the light of an incandescent bulb, a fire, molten steel, or any other object warmer than absolute zero. The frequency of light emitted is determined by Planck's law, independent of what the substance is.
4) Reflection. The light bounces back generally toward its source without affecting the molecule.
5) Refraction. The light slows down as it passes through the substance, speeding up again as it leaves. No thermal change occurs. The frequency, amplitude, and phase stays the same.


Pretty good, though thermal absorption is not really rare, but that's beside the point.

Next question:

What happens if a beam of light flows into a open system, is refracted by one source and then thermally absorbed by another within that system?
Edited on 10-08-2016 05:55
10-08-2016 21:58
Into the NightProfile picture★★★★★
(10243)
Leafsdude wrote:
1) Nothing (most of the time)
2) Harmonic absorption (rare). The molecule reaches an excited state. If a chemical reaction does not take place as a result of this state, the molecule drops to its base state, emitting a photon. No thermal energy changes. This is the type of light from LED's, animals like fireflies and some fish emit. It so-called 'cold' light. It is like twanging a violin string.
3) Thermal absorption (unusual, but less rare than harmonic absorption). The molecule increases it's lateral energy. The resulting lateral movement is the definition of temperature. The photon ceases to exist and the molecule becomes warmer. All vibrating molecules contain moving charges that emit light on a new frequency completely unrelated to what gave it the thermal energy in the first place. This light has less amplitude and is on a different frequency. This is so-called 'hot' light. It is the light of an incandescent bulb, a fire, molten steel, or any other object warmer than absolute zero. The frequency of light emitted is determined by Planck's law, independent of what the substance is.
4) Reflection. The light bounces back generally toward its source without affecting the molecule.
5) Refraction. The light slows down as it passes through the substance, speeding up again as it leaves. No thermal change occurs. The frequency, amplitude, and phase stays the same.


Pretty good, though thermal absorption is not really rare, but that's beside the point.

Next question:

What happens if a beam of light flows into a open system, is refracted by one source and then thermally absorbed by another within that system?


Case 5, followed by Case 3.


The Parrot Killer
12-08-2016 14:45
Leafsdude
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Case 5, followed by Case 3.


Sorry, should have been more specific: what happens to the state of the system when what I described happens?
12-08-2016 20:15
IBdaMannProfile picture★★★★★
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"Greenhouse Effect" only violates the 1st Law of Thermodynamics when it isn't violating Planck's Law or when it isn't violating the 2nd Law of Thermodynamics.

Let's settle this right now:


Given:
a body B* in the vacuum of space with a constant energy source E* such that B* is at equilibrium temperature T[B]* and thermal radiation of R[B]*

We then apply "greenhouse gas" to B* and allow for equilibrium to be reestablished.

1. What happens to T[B]*?
a. Increases
b. Decreases
c. Remains the same

2. What happens to R[B]*?
a. Increases
b. Decreases
c. Remains the same
13-08-2016 01:22
Surface Detail
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(1673)
IBdaMann wrote:
"Greenhouse Effect" only violates the 1st Law of Thermodynamics when it isn't violating Planck's Law or when it isn't violating the 2nd Law of Thermodynamics.

Let's settle this right now:


Given:
a body B* in the vacuum of space with a constant energy source E* such that B* is at equilibrium temperature T[B]* and thermal radiation of R[B]*

We then apply "greenhouse gas" to B* and allow for equilibrium to be reestablished.

1. What happens to T[B]*?
a. Increases
b. Decreases
c. Remains the same

2. What happens to R[B]*?
a. Increases
b. Decreases
c. Remains the same


We've already done this to death. 1:a 2:c

Adding greenhouse gas to a body that is being illuminated by sunlight will cause its temperature to rise until it reaches a new equilibrium temperature. Once equilibrium is reached, the radiation emitted is, of course, the same as it was before the greenhouse gas were added. This is because the greenhouse gas reduces the effective emissivity of the body, which means that the body must become hotter in order to radiate the same amount of energy as previously.

For a more detailed explanation, see this link from the American Chemical Society:

Climate Sensitivity
Edited on 13-08-2016 01:25
13-08-2016 11:07
Into the NightProfile picture★★★★★
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Surface Detail wrote:
IBdaMann wrote:
"Greenhouse Effect" only violates the 1st Law of Thermodynamics when it isn't violating Planck's Law or when it isn't violating the 2nd Law of Thermodynamics.

Let's settle this right now:


Given:
a body B* in the vacuum of space with a constant energy source E* such that B* is at equilibrium temperature T[B]* and thermal radiation of R[B]*

We then apply "greenhouse gas" to B* and allow for equilibrium to be reestablished.

1. What happens to T[B]*?
a. Increases
b. Decreases
c. Remains the same

2. What happens to R[B]*?
a. Increases
b. Decreases
c. Remains the same


We've already done this to death. 1:a 2:c

Adding greenhouse gas to a body that is being illuminated by sunlight will cause its temperature to rise until it reaches a new equilibrium temperature. Once equilibrium is reached, the radiation emitted is, of course, the same as it was before the greenhouse gas were added. This is because the greenhouse gas reduces the effective emissivity of the body, which means that the body must become hotter in order to radiate the same amount of energy as previously.

For a more detailed explanation, see this link from the American Chemical Society:

Climate Sensitivity


A circular argument. You are assuming 1a and 2c are the only possible answers without describing any predicate for them.

T[B] and R[B] remain unchanged. The only way to increase T[B] is to add energy to the body. The only way to reduce R[B] with an increasing T[B] is to decrease entropy, which requires energy to do so.

The laws of thermodynamics do not allow for any other result.

If the body is rotating (such as our Earth does), the added mass will help narrow the range of temperature on a spot rotating from day to night and back again, but T[B] remains the same.


The Parrot Killer
Edited on 13-08-2016 11:10
15-08-2016 03:18
IBdaMannProfile picture★★★★★
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Surface Detail wrote:We've already done this to death. 1:a 2:c

Well, this violates Planck's law.

If a body increases in temperature, its emission must increase. Temperature drives emission.

You, however are saying that as temperature increases, emission remains the same, yes?

I wonder who's right, you or Planck's law. Hmmmm.


.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

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
15-08-2016 05:41
Leafsdude
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(141)
T[B] and R[B] remain unchanged. The only way to increase T[B] is to add energy to the body.


How does one add energy to [B]?

If a black body increases in temperature, its emission must increase. Temperature drives emission.


FIFY.

If what you said was true, it would violate the Stefan-Boltzmann law of grey bodies (of which Earth is one).
Edited on 15-08-2016 05:48
15-08-2016 16:09
IBdaMannProfile picture★★★★★
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Leafsdude wrote:If what you said was true, it would violate the Stefan-Boltzmann law of grey bodies (of which Earth is one).

Planck's Law incorporates Stefan-Boltzmann, ergo Planck's Law does not violate Stefan-Boltzmann.


.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

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
15-08-2016 16:17
Leafsdude
★☆☆☆☆
(141)
Planck's Law incorporates Stefan-Boltzmann, ergo Planck's Law does not violate Stefan-Boltzmann.


It incorporated the Stefan-Boltzmann constant. It does not incorporate the Stefan-Boltmann Law. In point of fact, it's actually the other way around: the Stefan-Boltzmann Law uses Planck's Law as part of its formula while adding in other factors. By doing so, the Stefan-Boltzmann Law is able to be used in a more wide range of real-world situations than Planck's Law, including changes in Earth's temperature unrelated to increases in energy input.
Edited on 15-08-2016 16:43
15-08-2016 20:02
IBdaMannProfile picture★★★★★
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Leafsdude wrote:It incorporated the Stefan-Boltzmann constant. It does not incorporate the Stefan-Boltmann Law.

When I say that Planck's Law incorporates the Stefan-Boltzmann Law, I mean that you can derive Stefan-Boltzmann from Planck's. It's in there, and Planck's Law certainly does not violate Stefan-Boltzmann (or vice-versa).


Leafsdude wrote: By doing so, the Stefan-Boltzmann Law is able to be used in a more wide range of real-world situations than Planck's Law, including changes in Earth's temperature unrelated to increases in energy input.

This statement is false. Aside from compressing the volume, the only way temperature can increase is by adding more energy.

I know, I know, this flies in the face of your dogma, and I feel for you, but this brings "climate change" to a full stop.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

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
16-08-2016 23:20
Surface Detail
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(1673)
IBdaMann wrote:
Surface Detail wrote:We've already done this to death. 1:a 2:c

Well, this violates Planck's law.

If a body increases in temperature, its emission must increase. Temperature drives emission.

You, however are saying that as temperature increases, emission remains the same, yes?

I wonder who's right, you or Planck's law. Hmmmm.


.

Oh dear, IBdaMann, once again you (deliberately?) forget that Planck's Law applies specifically to so-called blackbodies, that is, theoretical bodies with an emissivity of 1. Real bodies, such as the Earth, have an emissivity of less than 1, and hence emit less radiation than Planck's Law would suggest. Consequently, if you reduce the emissivity of a body by, for example, adding greenhouse gases to its atmosphere, you also reduce the rate of emission of radiation for a given temperature. In order to continue emitting the same amount of radiation as previously, the temperature of the body must therefore increase.
17-08-2016 03:24
Into the NightProfile picture★★★★★
(10243)
Surface Detail wrote:
IBdaMann wrote:
Surface Detail wrote:We've already done this to death. 1:a 2:c

Well, this violates Planck's law.

If a body increases in temperature, its emission must increase. Temperature drives emission.

You, however are saying that as temperature increases, emission remains the same, yes?

I wonder who's right, you or Planck's law. Hmmmm.


.

Oh dear, IBdaMann, once again you (deliberately?) forget that Planck's Law applies specifically to so-called blackbodies, that is, theoretical bodies with an emissivity of 1. Real bodies, such as the Earth, have an emissivity of less than 1, and hence emit less radiation than Planck's Law would suggest. Consequently, if you reduce the emissivity of a body by, for example, adding greenhouse gases to its atmosphere, you also reduce the rate of emission of radiation for a given temperature. In order to continue emitting the same amount of radiation as previously, the temperature of the body must therefore increase.

Planck's Law applies to ALL bodies. It even describes what would happen if you were actually to take something to absolute zero.

No light.


The Parrot Killer
17-08-2016 03:50
Surface Detail
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(1673)
Into the Night wrote:
Surface Detail wrote:
IBdaMann wrote:
Surface Detail wrote:We've already done this to death. 1:a 2:c

Well, this violates Planck's law.

If a body increases in temperature, its emission must increase. Temperature drives emission.

You, however are saying that as temperature increases, emission remains the same, yes?

I wonder who's right, you or Planck's law. Hmmmm.


.

Oh dear, IBdaMann, once again you (deliberately?) forget that Planck's Law applies specifically to so-called blackbodies, that is, theoretical bodies with an emissivity of 1. Real bodies, such as the Earth, have an emissivity of less than 1, and hence emit less radiation than Planck's Law would suggest. Consequently, if you reduce the emissivity of a body by, for example, adding greenhouse gases to its atmosphere, you also reduce the rate of emission of radiation for a given temperature. In order to continue emitting the same amount of radiation as previously, the temperature of the body must therefore increase.

Planck's Law applies to ALL bodies. It even describes what would happen if you were actually to take something to absolute zero.

No light.

Nope. Planck's Law refers to blackbodies. Google it. Look at any science textbook. Educate yourself. The emissivity of real body represents the fraction of the radiation that that body emits compared to a blackbody. An object with an emissivity of 0.5, for example, emits radiation at half the rate of a blackbody.

See what the UK's National Physical Laboratory has to say here, for example:

What is emissivity and why is it important? (FAQ - Thermal)

All objects at temperatures above absolute zero emit thermal radiation. However, for any particular wavelength and temperature the amount of thermal radiation emitted depends on the emissivity of the object's surface. Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a blackbody (a perfect emitter) at the same temperature and wavelength and under the same viewing conditions. It is a dimensionless number between 0 (for a perfect reflector) and 1 (for a perfect emitter).
17-08-2016 08:40
Into the NightProfile picture★★★★★
(10243)
Surface Detail wrote:
Into the Night wrote:
Surface Detail wrote:
IBdaMann wrote:
Surface Detail wrote:We've already done this to death. 1:a 2:c

Well, this violates Planck's law.

If a body increases in temperature, its emission must increase. Temperature drives emission.

You, however are saying that as temperature increases, emission remains the same, yes?

I wonder who's right, you or Planck's law. Hmmmm.


.

Oh dear, IBdaMann, once again you (deliberately?) forget that Planck's Law applies specifically to so-called blackbodies, that is, theoretical bodies with an emissivity of 1. Real bodies, such as the Earth, have an emissivity of less than 1, and hence emit less radiation than Planck's Law would suggest. Consequently, if you reduce the emissivity of a body by, for example, adding greenhouse gases to its atmosphere, you also reduce the rate of emission of radiation for a given temperature. In order to continue emitting the same amount of radiation as previously, the temperature of the body must therefore increase.

Planck's Law applies to ALL bodies. It even describes what would happen if you were actually to take something to absolute zero.

No light.

Nope. Planck's Law refers to blackbodies. Google it. Look at any science textbook. Educate yourself. The emissivity of real body represents the fraction of the radiation that that body emits compared to a blackbody. An object with an emissivity of 0.5, for example, emits radiation at half the rate of a blackbody.

See what the UK's National Physical Laboratory has to say here, for example:

What is emissivity and why is it important? (FAQ - Thermal)

All objects at temperatures above absolute zero emit thermal radiation. However, for any particular wavelength and temperature the amount of thermal radiation emitted depends on the emissivity of the object's surface. Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a blackbody (a perfect emitter) at the same temperature and wavelength and under the same viewing conditions. It is a dimensionless number between 0 (for a perfect reflector) and 1 (for a perfect emitter).


All bodies above absolute zero emit blackbody radiation, dope.


The Parrot Killer
17-08-2016 18:25
Surface Detail
★★★★☆
(1673)
Into the Night wrote:
Surface Detail wrote:
Into the Night wrote:
Surface Detail wrote:
IBdaMann wrote:
Surface Detail wrote:We've already done this to death. 1:a 2:c

Well, this violates Planck's law.

If a body increases in temperature, its emission must increase. Temperature drives emission.

You, however are saying that as temperature increases, emission remains the same, yes?

I wonder who's right, you or Planck's law. Hmmmm.


.

Oh dear, IBdaMann, once again you (deliberately?) forget that Planck's Law applies specifically to so-called blackbodies, that is, theoretical bodies with an emissivity of 1. Real bodies, such as the Earth, have an emissivity of less than 1, and hence emit less radiation than Planck's Law would suggest. Consequently, if you reduce the emissivity of a body by, for example, adding greenhouse gases to its atmosphere, you also reduce the rate of emission of radiation for a given temperature. In order to continue emitting the same amount of radiation as previously, the temperature of the body must therefore increase.

Planck's Law applies to ALL bodies. It even describes what would happen if you were actually to take something to absolute zero.

No light.

Nope. Planck's Law refers to blackbodies. Google it. Look at any science textbook. Educate yourself. The emissivity of real body represents the fraction of the radiation that that body emits compared to a blackbody. An object with an emissivity of 0.5, for example, emits radiation at half the rate of a blackbody.

See what the UK's National Physical Laboratory has to say here, for example:

What is emissivity and why is it important? (FAQ - Thermal)

All objects at temperatures above absolute zero emit thermal radiation. However, for any particular wavelength and temperature the amount of thermal radiation emitted depends on the emissivity of the object's surface. Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a blackbody (a perfect emitter) at the same temperature and wavelength and under the same viewing conditions. It is a dimensionless number between 0 (for a perfect reflector) and 1 (for a perfect emitter).


All bodies above absolute zero emit blackbody radiation, dope.

I think we can all see who the dope is. Carefully read the first sentence of the NPL reference that I quoted, and you may be able to see where you are going wrong. Hint: thermal != blackbody.
17-08-2016 22:25
Into the NightProfile picture★★★★★
(10243)
Surface Detail wrote:
Into the Night wrote:
Surface Detail wrote:
Into the Night wrote:
Surface Detail wrote:
IBdaMann wrote:
Surface Detail wrote:We've already done this to death. 1:a 2:c

Well, this violates Planck's law.

If a body increases in temperature, its emission must increase. Temperature drives emission.

You, however are saying that as temperature increases, emission remains the same, yes?

I wonder who's right, you or Planck's law. Hmmmm.


.

Oh dear, IBdaMann, once again you (deliberately?) forget that Planck's Law applies specifically to so-called blackbodies, that is, theoretical bodies with an emissivity of 1. Real bodies, such as the Earth, have an emissivity of less than 1, and hence emit less radiation than Planck's Law would suggest. Consequently, if you reduce the emissivity of a body by, for example, adding greenhouse gases to its atmosphere, you also reduce the rate of emission of radiation for a given temperature. In order to continue emitting the same amount of radiation as previously, the temperature of the body must therefore increase.

Planck's Law applies to ALL bodies. It even describes what would happen if you were actually to take something to absolute zero.

No light.

Nope. Planck's Law refers to blackbodies. Google it. Look at any science textbook. Educate yourself. The emissivity of real body represents the fraction of the radiation that that body emits compared to a blackbody. An object with an emissivity of 0.5, for example, emits radiation at half the rate of a blackbody.

See what the UK's National Physical Laboratory has to say here, for example:

What is emissivity and why is it important? (FAQ - Thermal)

All objects at temperatures above absolute zero emit thermal radiation. However, for any particular wavelength and temperature the amount of thermal radiation emitted depends on the emissivity of the object's surface. Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a blackbody (a perfect emitter) at the same temperature and wavelength and under the same viewing conditions. It is a dimensionless number between 0 (for a perfect reflector) and 1 (for a perfect emitter).


All bodies above absolute zero emit blackbody radiation, dope.

I think we can all see who the dope is. Carefully read the first sentence of the NPL reference that I quoted, and you may be able to see where you are going wrong. Hint: thermal != blackbody.


Thermal IS blackbody radiation. Thermal radiation doesn't change depending on the surface at all. It is not dependent on the substance radiating it in any way. The ONLY controlling factor is the temperature of the substance.

That's Planck's law. You do not get to redefine Planck's law.


The Parrot Killer
Edited on 17-08-2016 22:28
18-08-2016 02:11
Surface Detail
★★★★☆
(1673)
Into the Night wrote:
Surface Detail wrote:
Into the Night wrote:
Surface Detail wrote:
Into the Night wrote:
Surface Detail wrote:
IBdaMann wrote:
Surface Detail wrote:We've already done this to death. 1:a 2:c

Well, this violates Planck's law.

If a body increases in temperature, its emission must increase. Temperature drives emission.

You, however are saying that as temperature increases, emission remains the same, yes?

I wonder who's right, you or Planck's law. Hmmmm.


.

Oh dear, IBdaMann, once again you (deliberately?) forget that Planck's Law applies specifically to so-called blackbodies, that is, theoretical bodies with an emissivity of 1. Real bodies, such as the Earth, have an emissivity of less than 1, and hence emit less radiation than Planck's Law would suggest. Consequently, if you reduce the emissivity of a body by, for example, adding greenhouse gases to its atmosphere, you also reduce the rate of emission of radiation for a given temperature. In order to continue emitting the same amount of radiation as previously, the temperature of the body must therefore increase.

Planck's Law applies to ALL bodies. It even describes what would happen if you were actually to take something to absolute zero.

No light.

Nope. Planck's Law refers to blackbodies. Google it. Look at any science textbook. Educate yourself. The emissivity of real body represents the fraction of the radiation that that body emits compared to a blackbody. An object with an emissivity of 0.5, for example, emits radiation at half the rate of a blackbody.

See what the UK's National Physical Laboratory has to say here, for example:

What is emissivity and why is it important? (FAQ - Thermal)

All objects at temperatures above absolute zero emit thermal radiation. However, for any particular wavelength and temperature the amount of thermal radiation emitted depends on the emissivity of the object's surface. Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a blackbody (a perfect emitter) at the same temperature and wavelength and under the same viewing conditions. It is a dimensionless number between 0 (for a perfect reflector) and 1 (for a perfect emitter).


All bodies above absolute zero emit blackbody radiation, dope.

I think we can all see who the dope is. Carefully read the first sentence of the NPL reference that I quoted, and you may be able to see where you are going wrong. Hint: thermal != blackbody.


Thermal IS blackbody radiation. Thermal radiation doesn't change depending on the surface at all. It is not dependent on the substance radiating it in any way. The ONLY controlling factor is the temperature of the substance.

That's Planck's law. You do not get to redefine Planck's law.

You are talking utter nonsense. The NPL link I gave and any textbook on the subject will tell you that thermal radiation depends on both the temperature (in accordance with Planck's Law) and the emissivity of a surface. Why are you denying the existence of emissivity?
18-08-2016 03:18
Into the NightProfile picture★★★★★
(10243)
Surface Detail wrote:

You are talking utter nonsense. The NPL link I gave and any textbook on the subject will tell you that thermal radiation depends on both the temperature (in accordance with Planck's Law) and the emissivity of a surface. Why are you denying the existence of emissivity?


Because it effectively cancels out.

You can't emit more than you absorb.


The Parrot Killer
18-08-2016 03:30
Surface Detail
★★★★☆
(1673)
Into the Night wrote:
Surface Detail wrote:

You are talking utter nonsense. The NPL link I gave and any textbook on the subject will tell you that thermal radiation depends on both the temperature (in accordance with Planck's Law) and the emissivity of a surface. Why are you denying the existence of emissivity?


Because it effectively cancels out.

You can't emit more than you absorb.

Let's stick to the point, shall we? You have claimed that the radiation emitted by a body depends solely on its temperature. This is wrong. The radiation emitted by a body depends on its emissivity as well as its temperature. Do you, or do you not, now acknowledge this?
18-08-2016 07:28
Into the NightProfile picture★★★★★
(10243)
Surface Detail wrote:
Into the Night wrote:
Surface Detail wrote:

You are talking utter nonsense. The NPL link I gave and any textbook on the subject will tell you that thermal radiation depends on both the temperature (in accordance with Planck's Law) and the emissivity of a surface. Why are you denying the existence of emissivity?


Because it effectively cancels out.

You can't emit more than you absorb.

Let's stick to the point, shall we? You have claimed that the radiation emitted by a body depends solely on its temperature. This is wrong. The radiation emitted by a body depends on its emissivity as well as its temperature. Do you, or do you not, now acknowledge this?


That IS the point, stupid.


The Parrot Killer
18-08-2016 14:14
Surface Detail
★★★★☆
(1673)
Into the Night wrote:
Surface Detail wrote:
Into the Night wrote:
Surface Detail wrote:

You are talking utter nonsense. The NPL link I gave and any textbook on the subject will tell you that thermal radiation depends on both the temperature (in accordance with Planck's Law) and the emissivity of a surface. Why are you denying the existence of emissivity?


Because it effectively cancels out.

You can't emit more than you absorb.

Let's stick to the point, shall we? You have claimed that the radiation emitted by a body depends solely on its temperature. This is wrong. The radiation emitted by a body depends on its emissivity as well as its temperature. Do you, or do you not, now acknowledge this?


That IS the point, stupid.

You're not being very clear. You claimed earlier that the thermal radiation emitted by a body depends only on its temperature. The NPL says otherwise - that it depends on both temperature and emissivity. Are you saying the NPL is wrong?
22-08-2016 01:33
Leafsdude
★☆☆☆☆
(141)
When I say that Planck's Law incorporates the Stefan-Boltzmann Law, I mean that you can derive Stefan-Boltzmann from Planck's. It's in there, and Planck's Law certainly does not violate Stefan-Boltzmann (or vice-versa).


Actually, it's the exact opposite: Stefan-Boltzmann incorporates Planck's and expands upon it. Planck's only works on ideal black bodies, not on real-world bodies. By incorporating and expanding on it, Stefan-Boltzmann is able to work on grey bodies such as those in the real world, as well as on ideal black bodies.

It's like humans all being apes, but not all apes being human.

This statement is false. Aside from compressing the volume, the only way temperature can increase is by adding more energy.


Or, as I've said before, by decreasing the energy removed.

Planck's Law applies to ALL bodies. It even describes what would happen if you were actually to take something to absolute zero.


Either you deny that grey bodies exist, or you deny that Planck's law only applies to black bodies if you believe that. Either way, you're flying in the face of known facts.
Edited on 22-08-2016 01:33
22-08-2016 02:02
Surface Detail
★★★★☆
(1673)
Leafsdude wrote:
When I say that Planck's Law incorporates the Stefan-Boltzmann Law, I mean that you can derive Stefan-Boltzmann from Planck's. It's in there, and Planck's Law certainly does not violate Stefan-Boltzmann (or vice-versa).


Actually, it's the exact opposite: Stefan-Boltzmann incorporates Planck's and expands upon it. Planck's only works on ideal black bodies, not on real-world bodies. By incorporating and expanding on it, Stefan-Boltzmann is able to work on grey bodies such as those in the real world, as well as on ideal black bodies.

Sorry, but IBdaMann is quite correct here.

Planck's Law gives the intensity of emission of a blackbody in a particular direction as a function of both temperature and frequency, that is, it tells you how much radiation there is of each particular wavelength in a particular direction.

The Stefan-Boltzmann Law simply describes the total radiation in all directions as a function of temperature. It can indeed be derived from Planck's Law by integrating over all directions and wavelengths, though I believe it was discovered empirically before Planck's Law was formulated.

Both laws apply strictly to blackbodies; they must be modified by taking emissivity into account when used with real objects.
22-08-2016 03:23
Leafsdude
★☆☆☆☆
(141)
I thought emissivity was a part of Stefan-Boltzmann's Law. I supposed I'm incorrect in that assumption?
13-09-2016 18:47
jwoodward48
★★★★☆
(1537)
Okay, peoples. Hello.

1. No more ad hominems.

2. Here is my argument for global warming:

a. First, I establish that there is an equilibrium at play - there is energy coming into the Earth system from the Sun, and escaping via radiation. These two values are normally the same, but when -either- of them is changed, the equilibrium changes, and thus the temperature.

b. Next, let us assume that there is a magical material which lets radiation in like normal, but "reflects" (not necessarily reflection; it could be absorption and radiation) back at Earth 50% of the radiation trying to escape. This would result in the equilibrium changing, as the energy coming in would exceed the energy escaping. Far be it from the 1st LoT disproving my argument - it supports it! If the energy coming in exceeds the energy coming out, where does that excess energy go? It stays in the system, increasing the temperature.

c. Now, let us note that the temperature of the Earth has increased.

d. In addition, we have released large amounts of carbon dioxide into the atmosphere.

e. The energy coming from the Sun is largely visible and ultraviolet light, while the radiated light from Earth is largely infrared.

f. Carbon dioxide absorbs infrared radiation more than it does visible/UV light.

g. Thus, carbon dioxide is a greater barrier for escaping radiation than for incoming radiation.

h. This would produce the described "equilibrium lost" situation, increasing the temperature of the Earth system. The necessary energy came from the Sun, as per the 2nd LoT.

Conclusion: Our carbon dioxide pollution is increasing the energy, and thus the temperature, of the Earth.

Note: The melting of the ice-caps further decreases the energy being lost to space, exacerbating the problem.

Note: As the temperature increases, the radiation from Earth's surface also increases, leading to equilibrium being reached again. The incoming energy never changes. The outgoing energy has to go through a barrier, and so is the same whether you look at old-equilibrium or new-equilibrium, but the latter is like looking through a dark glass. When equilibrium is not reached, the outgoing energy is -not- constant, thus not violating the 1st LoT.

So where exactly do you think I go wrong, IBdaMan and Into the Night?
13-09-2016 20:41
Tim the plumber
★★★★☆
(1295)
^ Yes that is the hypothesis.

However, the IR that is supposed to be acted upon by CO2 is within, broadly, the same range as that which is acted upon by water vapour. There is a lot of that about and thus CO2 is likely to be significant only in a very few very dry places. But, the data is king in this not the hypothesis.

The way all this IR absorption stuff works is generally beyond me so I stick to the bits where I am more confident about the effects of a warmer earth.

Edited on 13-09-2016 20:41
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