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What would the world be like if every molecule in the atmosphere is a CO2?



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02-02-2016 22:18
Surface Detail
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IBdaMann wrote:
Surface Detail wrote:What you are proposing is absurd. How could Venus be emitting far more energy than it receives from the sun?

When did I propose that?

Just now. You wrote:

All the energy radiating from the surface of Venus drains off into space. Yes, it passes through the atmosphere but it does go into space.

Because of its high temperature, the surface of Venus radiates about 17,000 W/m2. This is far more than the planet receives from the sun (around 2,600 W/m2). So how can all 17,000 W/m2 be passing through the atmosphere and into space?
Edited on 02-02-2016 22:20
02-02-2016 23:32
One Punch Man
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Despite all this, Venus radiates back out into space EVERYTHING that it absorbs, just like Earth. The temperature on Venus is not climbing. It has been that way since it was formed.

Gosh really? Venus has been that way since it was formed? Oh sorry, I had no idea you had access to a two-way time-machine and knew what Venus was like billions of years of ago! I bow down to your infinite knowledge. However I am left confused wise-one. You have not addressed why Venus is radiating more energy than it gets from the Sun. Remember, oh wise-one, Venus has an average surface temperature of 740K corresponding to 17,000 W/m2 by the Stefan-Boltzmann law. However the planet is only getting a maximum of around 2600 W/m2. How is this disparity to be explained? It would appear that, given your interpretation of the laws of physics, Venus by all accounts should not even exist! But it does. Oh dear. Will you explain this, or should I simply expect more prevarication?
Edited on 02-02-2016 23:47
02-02-2016 23:38
One Punch Man
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This would be a good time to discuss the 1st LoT.
Are you claiming that Venus' CO2 atmosphere creates 14,400 W/m2? You need to account for this claimed disparity.

You've got the wrong idea about this. I don't have to account for anything. You were the one claiming that a planet cannot radiate more energy than it gets from solar radiation. But evidently it can otherwise Venus wouldn't exist.
02-02-2016 23:50
Tai Hai Chen
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Venus surface gives off 14000 W/m2?
That's new to me. Anyone know the number for Mars? Mars also has 96% CO2.
03-02-2016 01:08
One Punch Man
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Tai Hai Chen wrote:
Venus surface gives off 14000 W/m2?
That's new to me. Anyone know the number for Mars? Mars also has 96% CO2.

Mars has an effective temperature (i.e. the temperature of the planet if it were heated only by the Sun) of 210K (corresponding to 110 W/m2) and according to NASA's 'Mars Fact Sheet' and also NASA's 'Quick Facts on Mars' its average temperature is also 210K thereby implying essentially no warming from the CO2-greenhouse. However, other sources give estimates of 215K and 220K for its average surface temperature. Type average surface temperature of Mars into Wikipedia and it gives 218K (or 128 W/m2).
Edited on 03-02-2016 01:10
03-02-2016 05:06
Tai Hai Chen
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One Punch Man wrote:
Tai Hai Chen wrote:
Venus surface gives off 14000 W/m2?
That's new to me. Anyone know the number for Mars? Mars also has 96% CO2.

Mars has an effective temperature (i.e. the temperature of the planet if it were heated only by the Sun) of 210K (corresponding to 110 W/m2) and according to NASA's 'Mars Fact Sheet' and also NASA's 'Quick Facts on Mars' its average temperature is also 210K thereby implying essentially no warming from the CO2-greenhouse. However, other sources give estimates of 215K and 220K for its average surface temperature. Type average surface temperature of Mars into Wikipedia and it gives 218K (or 128 W/m2).


Interesting. This would suggest Venus' high temperature is not because of its CO2 atmosphere but because of chemical reactions in its atmosphere. It has sulfuric acid for rain.
03-02-2016 15:27
One Punch Man
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Tai Hai Chen wrote:
One Punch Man wrote:
Tai Hai Chen wrote:
Venus surface gives off 14000 W/m2?
That's new to me. Anyone know the number for Mars? Mars also has 96% CO2.

Mars has an effective temperature (i.e. the temperature of the planet if it were heated only by the Sun) of 210K (corresponding to 110 W/m2) and according to NASA's 'Mars Fact Sheet' and also NASA's 'Quick Facts on Mars' its average temperature is also 210K thereby implying essentially no warming from the CO2-greenhouse. However, other sources give estimates of 215K and 220K for its average surface temperature. Type average surface temperature of Mars into Wikipedia and it gives 218K (or 128 W/m2).


Interesting. This would suggest Venus' high temperature is not because of its CO2 atmosphere but because of chemical reactions in its atmosphere. It has sulfuric acid for rain.

It's not quite that simple. Even though Mars' atmosphere is essentially pure CO2, its atmosphere is much thinner. The total atmospheric mass of Venus is ~4.8 x 10^20 kg and the total mass of Mars' atmosphere is ~2.5 x 10^16 kg. With 96% CO2 on Venus the total mass of CO2 in the atmosphere would be around 4.6 x 10^20 kg and with 95% CO2 on Mars that works out at about 2.4 x 10^16 kg. Therefore Venus has about 20,000 times more CO2 than Mars in absolute terms. (It would be slightly less in concentration because the volumetric radius of Mars is smaller and the CO2 occupies a smaller space). The simplified calculation above also ignores the difference in the average atmospheric molecular mass of course but it is a good enough approximation nevertheless).

As for why Venus is so hot. The most likely explanation, in my view, is pressure. As pressure of gases increase so does the temperature, but this would require there to be continuous convective overturning of the atmosphere allowing for continuous re-compression, like a bicycle-pump. This pressure heat does not require there to be a corresponding input of outside-radiation and can operate under gravity alone and is the mechanism by which Suns are formed. It is why Uranus has a tropospheric base that is radiating at 600 W/m2 (around 320K) despite it receiving only 3.7 W/m2 from the Sun and why Jupiter (dubbed the 'Failed Star') has a core temperature of 24,000K (18,800,000,000 W/m2) even though solar isolation is 50 W/m2. This sort of gravitational pressure heat operates, to some degree, on all planets with atmospheres, including Earth, and can increase their temperature to a higher level than the input from solar radiation alone, and can easily be calculated with the Ideal Gas Law. Based on data from NASA's Venus Fact Sheet data the Ideal Gas Law predicts a temperature of T = PV/nR = 92000/(65000/43.45*0.083144621) = 739K and according to NASA's Fact Sheet the actual temperature is 737K.
Edited on 03-02-2016 15:55
03-02-2016 16:32
IBdaMannProfile picture★★★★★
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One Punch Man wrote: Gosh really? Venus has been that way since it was formed? Oh sorry, I had no idea you had access to a two-way time-machine and knew what Venus was like billions of years of ago!

A fundamental axiom of science is that the laws of physics don't change over time.

He does not need a time machine to assert how the laws of physics worked in the past, regardless of the length of time.

...or are you asserting that the laws of physics have changed?

One Punch Man wrote: However I am left confused wise-one. You have not addressed why Venus is radiating more energy than it gets from the Sun.

It doesn't. Venus radiates exactly as much energy as it absorbs.

One Punch Man wrote: Remember, oh wise-one, Venus has an average surface temperature of 740K corresponding to 17,000 W/m2 by the Stefan-Boltzmann law. However the planet is only getting a maximum of around 2600 W/m2. How is this disparity to be explained?

Your poor math would explain it.

Post your calculation so we can see where your error resides.

One Punch Man wrote: It would appear that, given your interpretation of the laws of physics, Venus by all accounts should not even exist!

He never said that. I take it you are yet another warmizombie whose only recourse is to invent absurd assertions, assign them to your political opponents and then attack your opponents for those absurd assertions they never made.

Perhaps you could try addressing something he did assert? Oh wait, that would require science...which is on his side. Awkward.


.


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
03-02-2016 16:43
Surface Detail
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One Punch Man, it's clear you've been doing your research, but I'm afraid you've gotten a bit mixed up here. Pressure, by itself, cannot generate energy, and there is no such thing as "gravitational pressure heat".

Perhaps you're thinking of the heat generated by compression, such as in the case of the bicycle pump. In this case, external work is being done on the gas, which leads to its rise in temperature. While you would get the same effect with a contracting star or planet (as gravitational potential energy is released), a stable body (or atmosphere) releases no net gravitational energy.

The ideal gas law just describes the relation between pressure, volume and temperature; it doesn't say anything about the flow of energy into or out of the system. While the ideal gas law allows you to calculate the temperature of Venus's atmosphere from its pressure and volume, it doesn't tell you why it has that particular combination of pressure, volume and temperature.

The high surface temperature of Venus is simply due to a massive greenhouse effect. The surface of Venus, with a temperature of 737K, radiates energy in accordance with the Stefan–Boltzmann law at a rate of about 17,000 W/m2. The vast majority of this is absorbed by Venus's dense CO2 atmosphere and is radiated back to the surface as back radiation. Only a small fraction passes though the atmosphere and into space, balancing the energy received from the sun. The overall effect is that Venus radiates the same amount of energy as it receives (aside, perhaps, from a little heat generated by internal radioactivity).
03-02-2016 17:02
One Punch Man
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Your poor math would explain it.

Post your calculation so we can see where your error resides.

What? Seriously? You're actually asking me this? There is a fixed relationship between radiation-intensity and temperature that is governed by the Stefan-Boltzmann law and according to that law if a body has a temperature of 737K then it should be radiating at just under 17,000 W/m2. This is simple calculation. Do really need me to show you? I can, but I'm amazed you're asking.
Edited on 03-02-2016 17:36
03-02-2016 17:24
One Punch Man
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There is no such thing as gravitational pressure heat

it's clear you've been doing your research, but I'm afraid you've gotten a bit mixed up here. Pressure, by itself, cannot generate energy

Of course it can. If you increase the pressure of a gas and volume stays constant there are more collisions per-second which increases temperature. For the last time, this is how stars are formed. Gases collapse due to gravitational forces and this compression causes heating and the temperature of the core eventually becomes hot enough for nuclear reactions to occur. All you need are gases and gravity does the rest. If Jupiter, for example, had around 70 times more mass than it currently does then it would be able to generate enough heat through gravitational compression for nuclear fusion.

While the ideal gas law allows you to calculate the temperature of Venus's atmosphere from its pressure and volume, it doesn't tell you why it has that particular combination of pressure, volume and temperature.

But we do not need to know why it has that "combination of pressure and volume" in order for us to infer that the temperature is due to that combination.

The surface of Venus, with a temperature of 737K, radiates energy in accordance with the Stefan–Boltzmann law at a rate of about 17,000 W/m2.

Yeah. Well done. You only know this because I told you a few pages back.

The vast majority of this is absorbed by Venus's dense CO2 atmosphere and is radiated back to the surface as back radiation.

Oh really? Is that so? Well go on, prove it. The Arrhenius law equation used for determining radiation increments from CO2 increments predicts a maximum temperature increase from all the CO2 on Venus of around 50K.
Edited on 03-02-2016 17:31
03-02-2016 17:34
Surface Detail
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One Punch Man wrote:
There is no such thing as gravitational pressure heat

it's clear you've been doing your research, but I'm afraid you've gotten a bit mixed up here. Pressure, by itself, cannot generate energy

Of course it can. If you increase the pressure of a gas and volume stays constant there are more collisions per-second which increases temperature. For the last time, this is how stars are formed. Gases collapse due to gravitational forces and this compression causes heating and the temperature of the core eventually becomes hot enough for nuclear reactions to occur. All you need is mass and gravity does the rest. If Jupiter, for example, had around 70 times more mass than it currently does then it would be able to generate enough heat through gravitational compression for nuclear fusion.

While the ideal gas law allows you to calculate the temperature of Venus's atmosphere from its pressure and volume, it doesn't tell you why it has that particular combination of pressure, volume and temperature.

But we do not need to know why it has that "combination of pressure and volume" in order for us to infer that the temperature is due to that combination.

The surface of Venus, with a temperature of 737K, radiates energy in accordance with the Stefan–Boltzmann law at a rate of about 17,000 W/m2.

Yeah. Well done. You only know this because I told you a few pages back.

The vast majority of this is absorbed by Venus's dense CO2 atmosphere and is radiated back to the surface as back radiation.

Oh really? Is that so? Well go on, prove it. The Arrhenius law equation used for determining radiation increments from CO2 increments predicts a maximum temperature increase from all the CO2 on Venus of around 50K.

Yes, I know how stars are formed. I have a degree in astrophysics.

The point is that when a star forms, the material is contracting, i.e. falling towards its centre of gravity. Gravitational energy is being released, which then heats the material. The material is being compressed.

Neither Venus nor its atmosphere are collapsing, so no gravitational energy is being transformed into heat. As I said it is compression, where work is being done on a material, not simply pressure that heats a material. Otherwise the bottom of the ocean would be boiling!
03-02-2016 17:40
Tai Hai Chen
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There is a well defined relationship between pressure and temperature. As seen below.

http://www.engineeringtoolbox.com/air-altitude-temperature-d_461.html

This relationship is universal. Jupiter is nearly 10,000 degrees C because of immense pressure. No greenhouse gases in Jupiter.

It does seem that Venus is hot because of its high pressure.
Edited on 03-02-2016 17:48
03-02-2016 17:50
One Punch Man
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I have a degree in astrophysics.

Don't be ridiculous.

Neither Venus nor its atmosphere are collapsing, so no gravitational energy is being transformed into heat.

All that is required are gases and a body with a sufficently large gravitational field. That's all. It should apply to Venus and Saturn just as it does for any star.

Otherwise the bottom of the ocean would be boiling!

What the ****? Liquid is not compressible like a gas for Christ sake. I'm done.
Edited on 03-02-2016 17:55
03-02-2016 17:55
Surface Detail
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One Punch Man wrote:
I have a degree in astrophysics.

Don't be ridiculous.

Neither Venus nor its atmosphere are collapsing, so no gravitational energy is being transformed into heat.

All that is required are gases and a body with a sufficently large gravitational field. That's all. It should apply to Venus and Saturn just as does for a star.

Otherwise the bottom of the ocean would be boiling!

What the ****? Liquid is not compressable like a gas for Christ sake. I'm done.

There's no need to get shirty. Just think about it for a moment. How is a gas that exists under a constant high pressure going to keep radiating energy without cooling down? Where's the energy going to come from? That would indeed violate the first law of thermodynamics.
03-02-2016 18:05
Surface Detail
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Tai Hai Chen wrote:
There is a well defined relationship between pressure and temperature. As seen below.

http://www.engineeringtoolbox.com/air-altitude-temperature-d_461.html

This relationship is universal. Jupiter is nearly 10,000 degrees C because of immense pressure. No greenhouse gases in Jupiter.

It does seem that Venus is hot because of its high pressure.

There are three possible factors contributing to the high temperature of Jupiter's interior:
1) Radioactive decay processes similar to those that provide the Earth's internal heat.
2) Shrinkage. It could be that Jupiter is still contracting after its initial formation, thus converting gravitational potential energy into heat.
3) Residual heat from its initial formation. It could be that Jupiter is still cooling down from when it first formed.
Edited on 03-02-2016 18:07
03-02-2016 18:38
IBdaMannProfile picture★★★★★
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Surface Detail wrote: Pressure, by itself, cannot generate energy, and there is no such thing as "gravitational pressure heat".

Perhaps you're thinking of the heat generated by compression, such as in the case of the bicycle pump. In this case, external work is being done on the gas, which leads to its rise in temperature. While you would get the same effect with a contracting star or planet (as gravitational potential energy is released), a stable body (or atmosphere) releases no net gravitational energy.

The ideal gas law just describes the relation between pressure, volume and temperature; it doesn't say anything about the flow of energy into or out of the system. While the ideal gas law allows you to calculate the temperature of Venus's atmosphere from its pressure and volume, it doesn't tell you why it has that particular combination of pressure, volume and temperature.

Kudos. You're fantastic up to this point.

Surface Detail wrote: The high surface temperature of Venus is simply due to a massive greenhouse effect.

Translation: "Venus holds a sacred place in Global Warming religion and operates according to a massive violation of physics! ...er, ...um, ...operates according to a massive 'climate' MIRACLE!"

Would you mind humoring me by walking me through Venus' "massive greenhouse effect" and how temperature is increased there?

Surface Detail wrote: The surface of Venus, with a temperature of 737K, radiates energy in accordance with the Stefan–Boltzmann law at a rate of about 17,000 W/m2. The vast majority of this is absorbed by Venus's dense CO2 atmosphere and is radiated back to the surface as back radiation.

If the energy were somehow not absorbed by a "dense CO2 atmosphere," would it not be equally absorbed by the surface? ...just as you are saying happens after it is first absorbed by the "dense CO2 atmosphere"?

Anyway, I'm interested in learning how the temperature increases without additional energy being provided and without the temperature increasing while the radiance decreases.

Surface Detail wrote: Only a small fraction passes though the atmosphere and into space,

Hold on! Is this where you are claiming the radiance somehow decreases while the temperature increases?

Surface Detail wrote: The overall effect is that Venus radiates the same amount of energy as it receives (aside, perhaps, from a little heat generated by internal radioactivity).

Please explain this. You are creating two energy sources, the sun and the planet (the atmosphere). It's easy to generate energy when you invent a fictitious energy source.


.


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
03-02-2016 18:48
IBdaMannProfile picture★★★★★
(5192)
One Punch Man wrote:
I have a degree in astrophysics.

Don't be ridiculous.

Neither Venus nor its atmosphere are collapsing, so no gravitational energy is being transformed into heat.

All that is required are gases and a body with a sufficently large gravitational field. That's all. It should apply to Venus and Saturn just as it does for any star.

Otherwise the bottom of the ocean would be boiling!

What the ****? Liquid is not compressible like a gas for Christ sake. I'm done.

You're being silly. Everything Surface Detail wrote in his post was factual. If you want to add information then please feel right at home but you otherwise need to explain how something he said is somehow incorrect.


.


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
Edited on 03-02-2016 18:49
03-02-2016 19:00
Surface Detail
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(1673)
IBdaMann wrote:
Surface Detail wrote: The surface of Venus, with a temperature of 737K, radiates energy in accordance with the Stefan–Boltzmann law at a rate of about 17,000 W/m2. The vast majority of this is absorbed by Venus's dense CO2 atmosphere and is radiated back to the surface as back radiation.

If the energy were somehow not absorbed by a "dense CO2 atmosphere," would it not be equally absorbed by the surface? ...just as you are saying happens after it is first absorbed by the "dense CO2 atmosphere"?

How do you think the majority of the energy radiated by the surface of Venus is absorbed by the surface? How does it manage to do a U-turn? Hint: CO2.
03-02-2016 20:06
One Punch Man
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You're being silly. Everything Surface Detail wrote in his post was factual. If you want to add information then please feel right at home but you otherwise need to explain how something he said is somehow incorrect.

Everything in his post was factual? Really? Including the bit when he says that if the temperature of Venus and Saturn were due to pressure then that means the bottom of the oceans would be boiling hot? Yes, that was very factual. *Clap Clap* I have already calculated the estimated surface temperature of Venus above, based on pressure, molecular mass and density, and got the temperature of 739K. Therefore the temperature is an expected consequence of pressure, density and molecular mass and there is no need for us to assume back-radiation or chemical reactions (that people on this forum like to talk about as being the cause but never explain) are responsible. Sorry that you don't like it. Since you are unable to calculate the radiance from the surface of Venus with the S-B law I guess I'll help you. Here: 737^4*0.000000056704 = 16,729 W/m2. This will be my last post. No point discussing this with someone who pontificates about the laws of physics and yet does not even understand how to calculate radiation-intensity at a given temperature with the S-B law.
Edited on 03-02-2016 20:48
03-02-2016 20:20
One Punch Man
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How is a gas that exists under a constant high pressure going to keep radiating energy without cooling down?

The gases do cool down. The gases that are hotter near the surface that are compressed by the weight of the atmosphere above are continously being replaced by cooler molecules above. You know, convective overturning.

Where's the energy coming from?

How can you still be asking this? It is gravity that is doing the work. How else do you think stars incrementally increase in temperature as they gain mass without an outside source of radiant-energy? The temperature is created when the gases are compressed due to gravity.
Edited on 03-02-2016 20:44
03-02-2016 20:56
Into the NightProfile picture★★★★★
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Surface Detail wrote:
IBdaMann wrote:
Surface Detail wrote: The surface of Venus, with a temperature of 737K, radiates energy in accordance with the Stefan–Boltzmann law at a rate of about 17,000 W/m2. The vast majority of this is absorbed by Venus's dense CO2 atmosphere and is radiated back to the surface as back radiation.

If the energy were somehow not absorbed by a "dense CO2 atmosphere," would it not be equally absorbed by the surface? ...just as you are saying happens after it is first absorbed by the "dense CO2 atmosphere"?

How do you think the majority of the energy radiated by the surface of Venus is absorbed by the surface? How does it manage to do a U-turn? Hint: CO2.

It doesn't do a U-turn. The atmosphere and surface simply absorbs energy from the sun and radiate it away.


The Parrot Killer
Edited on 03-02-2016 20:57
03-02-2016 21:08
Into the NightProfile picture★★★★★
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One Punch Man wrote:
How is a gas that exists under a constant high pressure going to keep radiating energy without cooling down?

The gases do cool down. The gases that are hotter near the surface that are compressed by the weight of the atmosphere above are continously being replaced by cooler molecules above. You know, convective overturning.

Where's the energy coming from?

How can you still be asking this? It is gravity that is doing the work. How else do you think stars incrementally increase in temperature as they gain mass without an outside source of radiant-energy? The temperature is created when the gases are compressed due to gravity.


Ok, dude. Explain why a bottle of compressed gas, such as carbon dioxide at 3000psi is at room temperature.


The Parrot Killer
04-02-2016 00:31
Tai Hai Chen
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Venus has 90 times the pressure as Earth does. Let us extrapolate. Even if Venus has the same atmospheric composition or even no CO2 in its atmosphere, it should be as hot as it is now because of its very high pressure.

http://www.engineeringtoolbox.com/air-altitude-temperature-d_461.html
04-02-2016 00:59
Into the NightProfile picture★★★★★
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Tai Hai Chen wrote:
Venus has 90 times the pressure as Earth does. Let us extrapolate. Even if Venus has the same atmospheric composition or even no CO2 in its atmosphere, it should be as hot as it is now because of its very high pressure.

http://www.engineeringtoolbox.com/air-altitude-temperature-d_461.html


It probably would be about as hot, but not because of it's pressure, because of it's mass. The only difference we be different absorption bands in the atmosphere on the way in, and assuming the same surface, a modified profile of lapse rate in the atmosphere. If the atmosphere were mostly oxygen/nitrogen, it would be a thicker one too, since those gases are lighter than CO2.

You wouldn't have the sulfuric acid clouds and the sulfur dioxide content either. So the reflectivity of visible would would be dramatically different. Venus would look quite different.

The equation you are using is not applicable here. It applies to changing pressure, temperature, or volume and how it affects the other two. If none of the three are changing, the equation doesn't apply. It's great at describing why diesel engines run, but not why a planet is hot. You too should examine why a bottle of compressed CO2 gas at 3000psi is not hot, but at room temperature.


The Parrot Killer
Edited on 04-02-2016 01:03
04-02-2016 01:45
Surface Detail
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If Venus had, say, a pure nitrogen atmosphere, so no clouds and no atmospheric absorption of incoming or outgoing radiation, then its average surface temperature would be something close to the temperature of a blackbody at the same distance from the sun: 54.5 °C.

See here for the calculation:

http://scholarsandrogues.com/2011/05/02/venus-climate-i-venus-surface-hot/
04-02-2016 01:56
Into the NightProfile picture★★★★★
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Surface Detail wrote:
If Venus had, say, a pure nitrogen atmosphere, so no clouds and no atmospheric absorption of incoming or outgoing radiation, then its average surface temperature would be something close to the temperature of a blackbody at the same distance from the sun: 54.5 °C.

See here for the calculation:

http://scholarsandrogues.com/2011/05/02/venus-climate-i-venus-surface-hot/


Nitrogen absorbs energy too, stupid.

Like CO2, it converts what it absorbed into thermal energy.


The Parrot Killer
04-02-2016 02:28
Surface Detail
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Into the Night wrote:
Surface Detail wrote:
If Venus had, say, a pure nitrogen atmosphere, so no clouds and no atmospheric absorption of incoming or outgoing radiation, then its average surface temperature would be something close to the temperature of a blackbody at the same distance from the sun: 54.5 °C.

See here for the calculation:

http://scholarsandrogues.com/2011/05/02/venus-climate-i-venus-surface-hot/


Nitrogen absorbs energy too, stupid.

Like CO2, it converts what it absorbed into thermal energy.

Nitrogen is almost completely transparent to visible and infrared radiation; it absorbs radiation only at wavelengths shorted than about 100 nm, that is, in the extreme ultraviolet. This means that it would absorb just a few percent of the incoming radiation and almost none of the outgoing radiation. Hence the surface of Venus with a pure nitrogen atmosphere would actually be a little cooler than the blackbody temperature of 54.5 °C.
04-02-2016 02:28
Tai Hai Chen
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Surface Detail wrote:
If Venus had, say, a pure nitrogen atmosphere, so no clouds and no atmospheric absorption of incoming or outgoing radiation, then its average surface temperature would be something close to the temperature of a blackbody at the same distance from the sun: 54.5 °C.

See here for the calculation:

http://scholarsandrogues.com/2011/05/02/venus-climate-i-venus-surface-hot/


That's just stupid. Venus would be a lot hotter than 54.5 C considering its proximity to the Sun.
04-02-2016 02:31
Surface Detail
★★★★☆
(1673)
Tai Hai Chen wrote:
Surface Detail wrote:
If Venus had, say, a pure nitrogen atmosphere, so no clouds and no atmospheric absorption of incoming or outgoing radiation, then its average surface temperature would be something close to the temperature of a blackbody at the same distance from the sun: 54.5 °C.

See here for the calculation:

http://scholarsandrogues.com/2011/05/02/venus-climate-i-venus-surface-hot/


That's just stupid. Venus would be a lot hotter than 54.5 C considering its proximity to the Sun.

Perhaps you could point out the error in the calculation?

Venus isn't that close to the sun. Closer than Earth, certainly, but not as close as Mercury (whose average temperature is actually lower than that of Venus).
04-02-2016 05:08
Into the NightProfile picture★★★★★
(10174)
Surface Detail wrote:
Tai Hai Chen wrote:
Surface Detail wrote:
If Venus had, say, a pure nitrogen atmosphere, so no clouds and no atmospheric absorption of incoming or outgoing radiation, then its average surface temperature would be something close to the temperature of a blackbody at the same distance from the sun: 54.5 °C.

See here for the calculation:

http://scholarsandrogues.com/2011/05/02/venus-climate-i-venus-surface-hot/


That's just stupid. Venus would be a lot hotter than 54.5 C considering its proximity to the Sun.

Perhaps you could point out the error in the calculation?

Venus isn't that close to the sun. Closer than Earth, certainly, but not as close as Mercury (whose average temperature is actually lower than that of Venus).


Sucks to not have an atmosphere at all, doesn't it?



The Parrot Killer
04-02-2016 06:10
Tai Hai Chen
★★★★☆
(1079)
How much atmosphere a planet has depends on the size of the planet. Mercury is very small so has a very small atmosphere. Venus is very big so has a big atmosphere. Earth is medium sized so has a medium sized atmosphere. Mars is small so has a small atmosphere. A larger atmosphere means more convection, that means more uniform temperature.
04-02-2016 12:36
One Punch Man
★☆☆☆☆
(117)
Ok, dude. Explain why a bottle of compressed gas, such as carbon dioxide at 3000psi is at room temperature.

Because the atmosphere is not a bottle of compressed static gas and there should be a constant cycle of convective overturning and re-compression of the atmosphere. I said that in my very first post above.

By the way, the blackbody temperature of Venus is not 54C or 327K. The effective temperature of Venus is 184K corresponding to 65 W/m2. See Venus Fact Sheet from NASA. The conventional method of calculating the effective temperature is simply a case of dividing the solar constant (for Venus of 2613 W/m2) by 4 and then multiplying that by albedo (i.e. 0.9 for Venus or 90%).

A temperature of 327K is the expected temperature of Venus without albedo factored in, although some people think 0.9 is too high. It used to be 0.75 until NASA changed it back in 2010. A lot of people still use 0.75.

I will quickly point out as my final comment that if back-radiation from the CO2-greenhouse were responsible for the high temperatures on Venus then the CO2 would have to back-radiate 16,700 W/m2 from the measly 65 W/m2 that the surface absorbs. Also the night side of Venus does not get any solar radiation for hundreds of days and yet has the same temperature as the side that is getting solar radiation which would not support the greenhouse hypothesis.

Furthermore CO2 is meant to catch heat according to Arrhenius formula: RF = Ln(C1/C0)X5.35. If Earth had around 160,000 times more CO2 in its atmosphere as Venus does then the temperature increase from all that CO2 would be around 50K. This leads me to think that the temperature on Venus is likely some other cause, and I think obviously the most logical explanation is presssure.

It is also interesting to note that at a height of around 50 Km in the atmosphere of Venus the pressure is the same at the surface of Earth and when factoring in the increased radiation the atmosphere would be absorbing due to the planet being closer to Sun the temperature is around the same as on Earth at 288K. Therefore if Earth (with a lapse-rate of 9.8C/Km) had an atmosphere 50 Km deeper then its surface temperature would be similar to that on Venus.

Harry Duff has a good blog-post on Venus with these calculations showing how pressure is the most likely candidate for the high surface temperature.
Edited on 04-02-2016 13:18
04-02-2016 14:11
spot
★★★★☆
(1207)
That's intresting but if the temputure of a world is due to the pressure of the atmosphere the enviroment on titan defies explaination.
Edited on 04-02-2016 14:17
04-02-2016 14:44
Surface Detail
★★★★☆
(1673)
One Punch Man wrote:
Ok, dude. Explain why a bottle of compressed gas, such as carbon dioxide at 3000psi is at room temperature.

Because the atmosphere is not a bottle of compressed static gas and there should be a constant cycle of convective overturning and re-compression of the atmosphere. I said that in my very first post above.

This is how an atmosphere transports heat upwards and into space from the surface of the planet by convection. There is no way the atmosphere can generate heat, purely as a function of its pressure. That would defy the first law of thermodynamics.

By the way, the blackbody temperature of Venus is not 54C or 327K. The effective temperature of Venus is 184K corresponding to 65 W/m2. See Venus Fact Sheet from NASA. The conventional method of calculating the effective temperature is simply a case of dividing the solar constant (for Venus of 2613 W/m2) by 4 and then multiplying that by albedo (i.e. 0.9 for Venus or 90%).

A temperature of 327K is the expected temperature of Venus without albedo factored in, although some people think 0.9 is too high. It used to be 0.75 until NASA changed it back in 2010. A lot of people still use 0.75.

A blackbody, by definition, has an albedo of 0, so the blackbody temperature of Venus is indeed 54C or 327K. This is the temperature that Venus would have if it had a perfectly transparent atmosphere and a perfectly black surface. Of course, as you rightly state, Venus has a layer of highly reflective clouds that give it its high albedo, so its surface temperature would indeed be a lot lower than 54C without the greenhouse effect.

I will quickly point out as my final comment that if back-radiation from the CO2-greenhouse were responsible for the high temperatures on Venus then the CO2 would have to back-radiate 16,700 W/m2 from the measly 65 W/m2 that the surface absorbs.

That doesn't make sense. How can the atmosphere radiate energy that has been absorbed by the surface?

Also the night side of Venus does not get any solar radiation for hundreds of days and yet has the same temperature as the side that is getting solar radiation which would not support the greenhouse hypothesis.

How so? As you've pointed out, the contribution that solar radiation makes to the energy arriving at the surface of the planet is minuscule. The vast majority is back radiation from the atmosphere. The IR-opaque CO2 atmosphere on Venus very effectively hinders heat loss during the night, not to mention the sheer thermal inertia of that much gas!

Furthermore CO2 is meant to catch heat according to Arrhenius formula: RF = Ln(C1/C0)X5.35. If Earth had around 160,000 times more CO2 in its atmosphere as Venus does then the temperature increase from all that CO2 would be around 50K.

Are you sure that you can apply Arrhenius formula directly to Venus like that? What dictates the value of the constant in the formula?

This leads me to think that the temperature on Venus is likely some other cause, and I think obviously the most logical explanation is presssure.

Which is, of course, nonsensical.

It is also interesting to note that at a height of around 50 Km in the atmosphere of Venus the pressure is the same at the surface of Earth and when factoring in the increased radiation the atmosphere would be absorbing due to the planet being closer to Sun the temperature is around the same as on Earth at 288K. Therefore if Earth (with a lapse-rate of 9.8C/Km) had an atmosphere 50 Km deeper then its surface temperature would be similar to that on Venus.

Which is also plainly nonsense. The surface temperature of a planet depends on its distance from the sun, the radiative properties of its atmosphere and the albedo of its surface, not the pressure of its atmosphere.

Harry Duff has a good blog-post on Venus with these calculations showing how pressure is the most likely candidate for the high surface temperature.

Harry Who?
04-02-2016 17:51
One Punch Man
★☆☆☆☆
(117)
This is how an atmosphere transports heat upwards and into space from the surface of the planet by convection. There is no way the atmosphere can generate heat, purely as a function of its pressure. That would defy the first law of thermodynamics.

On the contrary, it is your CO2 back-radiation theory that contravenes the 1st law of thermodynamics. Not mine. As already mentioned, pressure heat is real and is how stars are formed. The gravity of stars compact gases together and as these gases compact they increase in temperature. This process requires no outside source of radiation and all that is required are gases and gravity. The star must increase in temperature from -273K to 10 million K without any external source of radiant-energy and it does so principally through gravity. The gases inside the star are forced to the centre by gravity and as they compact thermal pressure works in the opposite direction forcing the gases outwards in proportion to the amount of compression exerted upon them. The gravity is doing the 'work' and the compacted super-heated molecules at the core are expanding and pushing outwards trying to escape the gravitational compression. The same process happens on other planets with gaseous atmospheres too, albeit to a lesser extent, most notably on Jupiter, Uranus and Venus. All of these planets achieve temperatures far in excess of solar isolation and the prime candidate for this cause is gravitationally-induced pressure heat. Once again, if Jupiter (dubbed 'The Failed Star') had 70 times more mass it would be able to generate enough heat through gravitational compression to become a star and this is commonly accepted. No radiant-energy is added whatsoever, only mass, and gravity does the rest.

On the other hand, your CO2 greenhouse back-radiation theory does violate the 1st law of thermodynamics because Venus is only getting a maximum of 2,613 W/m2 and the surface is radiating at almost 17,000 W/m2 and an inert body of course cannot radiate more energy than it absorbs. I am sorry you do not understand that. (Earth is different of course, since solar isolation is 1368 W/m2 and the planet is radiating at only 390 W/m2).

A blackbody, by definition, has an albedo of 0, so the blackbody temperature of Venus is indeed 54C or 327K.

The terms 'blackbody temperature' and 'effective temperature' of a planet are used interchangeably and simply mean the expected temperature of the planet if it were heated by solar radiation and both include the albedo of a planet. If you go and Google 'blackbody temperature of Earth' and 'effective temperature of Earth' you will get 255K in both instances (and that number includes albedo). However, I just re-read your comment and saw that you said 'no clouds' which I must have missed on my first read-through.

That doesn't make sense. How can the atmosphere radiate energy that has been absorbed by the surface?

You do understand that when a body absorbs radiation it also emits radiation, right? That fact is not lost on you, is it? Therefore if the surface of Venus absorbs short-wave solar radiation it will emit long-wave radiation and be absorbed by the CO2 molecules in the atmosphere which will then radiate some of that energy in all directions. That is the basic idea of the greenhouse effect. I am surprised you seem unaware of it considering the fact that you have been zealously championing it for the last several days. I should not be surprised though. This is a guy who thinks that if Venus were hot due to pressure then the bottom of the oceans must be boiling! Priceless.

How so? As you've pointed out, the contribution that solar radiation makes to the energy arriving at the surface of the planet is minuscule. The vast majority is back radiation from the atmosphere.

I should correct an error in my last post. The albedo of 0.9 for Venus should be 0.1 of course. So you are suggesting that CO2 back-radiates the energy it absorbs from the atmosphere? I should point out that the albedo factor of 0.1 that NASA uses (which may be wrong) allows us to calculate the radiation that is reflected by the entire planet (i.e. the surface and the atmosphere). Without albedo, incoming solar radiation for Venus averaged out over the planet would be about 650 W/m2. However with albedo factored in it comes out as 65 W/m2. Hence almost 600 W/m2 is reflected and not absorbed. Essentially all you have to work with is 65 W/m2, according to NASA. Now, I will only say this once as repeating it would be pointless. An inert body like a gas cannot emit more radiation than it absorbs. Therefore, CO2 cannot back-radiate 17,000 W/m2 when it is only absorbing 65 W/m2. Can it now? No, it can't.

Are you sure that you can apply Arrhenius formula directly to Venus like that?

Why not? Unless pressure broadening increases the ability of a CO2 molecule to absorb radiation by a factor of one-hundred (and unless a CO2 molecule can emit more radiation than it absorbs).

Which is, of course, nonsensical.

Nonsensical to you perhaps.

The surface temperature of a planet depends on its distance from the sun, the radiative properties of its atmosphere and the albedo of its surface, not the pressure of its atmosphere.

I'm afraid that narrative merely expresses the simplistic nature of your thinking. The real-world has a far more complicated story to tell. If that were true then non-greenhouse gas planets such as Jupiter would not be able to reach temperatures of 24,000K deep within its atmosphere and the tropospheric temperatures of Uranus would not be able to reach temperatures of 320K.

Harry who?

Harry Dale Huffman. This will be my last reply for sure. Too much.
Edited on 04-02-2016 18:35
04-02-2016 17:56
One Punch Man
★☆☆☆☆
(117)
spot wrote:
That's intresting but if the temputure of a world is due to the pressure of the atmosphere the enviroment on titan defies explaination.

Titan is relatively small mind you, and so one would expect its gravity to be significantly less than, say Jupiter or Uranus. (And I am not saying that pressure is everything, the energy from solar radiation also should be taken into account).
04-02-2016 18:54
Tai Hai Chen
★★★★☆
(1079)
Surface Detail wrote:
This is how an atmosphere transports heat upwards and into space from the surface of the planet by convection. There is no way the atmosphere can generate heat, purely as a function of its pressure. That would defy the first law of thermodynamics.


I beg to differ. If you ever visit a ski area you know the higher mountain is much colder than the village at the bottom. A plateau is also much colder, for instance, Tibet. The higher the ground, less pressure, less temperature. The lower the ground, higher pressure, higher temperature.
04-02-2016 19:24
Surface Detail
★★★★☆
(1673)
One Punch Man wrote:
This is how an atmosphere transports heat upwards and into space from the surface of the planet by convection. There is no way the atmosphere can generate heat, purely as a function of its pressure. That would defy the first law of thermodynamics.

On the contrary, it is your CO2 back-radiation theory that contravenes the 1st law of thermodynamics. Not mine. As already mentioned, pressure heat is real and is how stars are formed. The gravity of stars compact gases together and as these gases compact they increase in temperature. This process requires no outside source of radiation and all that is required are gases and gravity. The star must increase in temperature from -273K to 10 million K without any external source of radiant-energy and it does so principally through gravity. The gases inside the star are forced to the centre by gravity and as they compact thermal pressure works in the opposite direction forcing the gases outwards in proportion to the amount of compression exerted upon them. The gravity is doing the 'work' and the compacted super-heated molecules at the core are expanding and pushing outwards trying to escape the gravitational compression. The same process happens on other planets with gaseous atmospheres too, albeit to a lesser extent, most notably on Jupiter, Uranus and Venus. All of these planets achieve temperatures far in excess of solar isolation and the prime candidate for this cause is gravitationally-induced pressure heat. Once again, if Jupiter (dubbed 'The Failed Star') had 70 times more mass it would be able to generate enough heat through gravitational compression to become a star and this is commonly accepted. No radiant-energy is added whatsoever, only mass, and gravity does the rest.

We're not going to get anywhere here until you are able to comprehend that a gas at a constant pressure cannot generate heat! It is compression, not pressure that produces heat. When stars form from collapsing clouds of gas and dust, the heat comes initially from the conversion of gravitational potential energy. Eventually, the temperature reaches a point at which nuclear fusion reactions can begin, and the star stops contracting. All the power then comes from fusion reactions.

Neither Venus nor its atmosphere are collapsing. Any gravitational potential energy gained by rising packets of gas is balanced by that lost by descending packets of gas. Venus's atmosphere cannot generate energy from nowhere.

Venus's atmosphere, which is almost opaque to IR-radiation, simply acts as a very good insulator. If you don't let much energy out of a system, then you don't need much energy to enter the system in order to maintain it at a high temperature.

Edit: Here's what's going on:


Edited on 04-02-2016 19:54
04-02-2016 19:30
Surface Detail
★★★★☆
(1673)
Tai Hai Chen wrote:
Surface Detail wrote:
This is how an atmosphere transports heat upwards and into space from the surface of the planet by convection. There is no way the atmosphere can generate heat, purely as a function of its pressure. That would defy the first law of thermodynamics.


I beg to differ. If you ever visit a ski area you know the higher mountain is much colder than the village at the bottom. A plateau is also much colder, for instance, Tibet. The higher the ground, less pressure, less temperature. The lower the ground, higher pressure, higher temperature.

This is because the troposphere is heated from the bottom by the ground. The warm air that is heated by the ground rises, cooling as it expands. At least until you reach the stratosphere, at which point it starts to warm again with height (due to the absorption of incoming UV radiation by ozone).
Edited on 04-02-2016 19:32
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