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

Leafsdude wrote:
Pop quiz: what is heat?

Leafsdude wrote:
And what is light?

Leafsdude wrote:
And what are the possible results when light hits matter?

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.

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.

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.

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?

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.

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.

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

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

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

T[B] and R[B] remain unchanged. The only way to increase T[B] is to add energy to the body.

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

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.

Leafsdude wrote:It incorporated the Stefan-Boltzmann constant. It does not incorporate the Stefan-Boltmann Law.

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.

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.


.

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.

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.

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).

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.

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.

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.

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?

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.

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?

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.

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).

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

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

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.