Does a non-GHG Atmosphere warm a Planet?

[flacaltenn]

Once the the suns energy is gone it will cool very rapidly as it can not hold energy. What little energy is absorbed by the atmosphere will be emitted to space very quickly as there is nothing to stop it in the atmosphere. Its mass is incapable of holding energy for more than 1-2 seconds.

Then you go off the rails.

How does the atmosphere lose energy to space? N2 neither absorbs nor emits IR.

The N2 indefinitely holds on to its stored energy simply by staying in a gaseous phase, suspended in the gravity field. During daylight the surface inputs energy to the atmosphere, which is then returned at night.

N2 certainly emits the energy it absorbs via collisions with other molecules...it conducts till such time as it can't, then it radiates till it reaches its equilibrium temperature...ditto for O2 and argon...

You like to claim that every thing radiates till it becomes inconvenient then N2 doesn't radiate? How quaint.

Everything DOES radiate. Just not in the IR band.. To get coupled heating between objects from radiative transfers they have to be tuned to each other. And since the earth's surface is "kinda" like a black body radiator, it's major emission/absorptions bands are ALL mostly IR. So unless the gas has emission bands in that RANGE, no IR heating will result.

Liquid nitrogen and oxygen are "blue tinted". Go look at some pics. That's where the bulk of their emission bands are. But if you heat EITHER ONE to high enough temperature -- they will dissassociate the N2 bonds and reassociate them which causes emission in the IR range. That's NOT gonna happen very much in the atmosphere unless chemical action is taking place.

Heating of N2 in atmos is therefore mostly from convective (actual) heat transfer. But I'm not sure that Ian is right about the system "only losing heat to the ground" during convection, because EVERY component of the greenhouse has a LARGE net loss to the sky. The GHouse gases are only retarding that popsicle effect..

 

[Olde Europe]

I totally disagree that average surface temperature would similar with or without an atmosphere. Radiation has a relationship to the fourth power of temperature. Twice as hot means sixteen times the output.

I understand your point, but I think your deliberation is incorrect. After all, incoming and outgoing radiation must be of the same size, and equal, in both systems, with, and without, atmosphere. And if with, and without, atmosphere, outgoing radiation (entirely from the surface) is the same, the average temperatures also have to be the same. No?

Remember the old puzzle about having one hour to drive 30 miles? If you only go 15 miles per hour for the first half, how fast do you need to go for the second half?

Infinity. But that doesn't apply here.

Think about it. You have incoming radiation, the same in both cases. You have outgoing radiation. Also the same, in both cases, AND, in both systems this radiation originates from the surface, 100%.

With that, it's just Boltzmann to calculate the average surface temperature in both cases. I know, it's somewhat counter-intuitive, but still...

 

[CrusaderFrank]

But we agree that planet Earth without CO2 would vary from -298 degrees Fahrenheit (-183 degrees Celsius), at night, to 224 degrees Fahrenheit (106 degrees Celsius) during the day, right?

Ahhh... I see your comment has been edited.

No, I don't agree that the Earth would be minus 300C without CO2. I doubt I would agree with any figure unless it had a huge error range.

I had to change the range to conform with the "science" of manmade global climate warming change. It's only CO2 that counts

 

[flacaltenn]

N2 certainly emits the energy it absorbs via collisions with other molecules...it conducts till such time as it can't, then it radiates till it reaches its equilibrium temperature...ditto for O2 and argon...

You like to claim that every thing radiates till it becomes inconvenient then N2 doesn't radiate? How quaint

At what wavelengths is the N2 radiating away this energy? I don't think it has any emission lines in IR.

Oh it has plenty of emission lines -- depend on what you DO to it... Look at the temperature of the thermosphere, it's about 900DegF -- the space where satellites travel.. WHY? because the major atmos gases that are RARE up there bear full brunt of the UV and cosmic rays. N2 loves to absorb UV.. To the point where it BREAKS (dissassociates into atomic Nitrogen. Same for Oxygen.. That's 99% of the gas structure at the fringe of space.

Both of them emit in the UV and high range of frequencies because they ABSORB at those frequencies. So your N2 atmos is NOT transparent to the sun.. But it takes much more energy to be a UV emitter than an IR emitter.

In fact man -- YOU HAVE a near perfect N2 atmos right now..Just about 1% contaminated besides the oxygen. And it's boundary with space is quite hot, just doesn't glow red and doesn't hardly see any kinetic energy charging up there.


Just had a thread on the Sun's shift to UV with it going "blank".. It's THINNING the thermosphere because it's exhausting all the available N2 and O2 into atoms. We have NO fucking idea what the effect is on the climate system...

So I GUESS --- you're ahead of your time and on the cutting edge of climate science here..

Not to change the subject, but to highlight the importance of Atmos N2, that thermosphere REGULATES variations in solar irradiance. It's thick and puffy when the sun is ACTIVE and thins out when it's snoozy.. And up there there's no molecular gases. THey've all been reduced to atomic structure. And N2 and O2 are the FOOD for this thermoregulator.. Since this acts on DIRECT solar irradiation, TINY fractions of change here would swamp out the tiny fractions of back-radiation from CO2. AND YET -- we don't seem to be "there yet" in complete modeling and understanding. Maybe I've missed it. But I've looked for QUANTITATIVE estimates and didn't find them...

 

[IanC]

I totally disagree that average surface temperature would similar with or without an atmosphere. Radiation has a relationship to the fourth power of temperature. Twice as hot means sixteen times the output.

I understand your point, but I think your deliberation is incorrect. After all, incoming and outgoing radiation must be of the same size, and equal, in both systems, with, and without, atmosphere. And if with, and without, atmosphere, outgoing radiation (entirely from the surface) is the same, the average temperatures also have to be the same. No?

Remember the old puzzle about having one hour to drive 30 miles? If you only go 15 miles per hour for the first half, how fast do you need to go for the second half?

Infinity. But that doesn't apply here.

Think about it. You have incoming radiation, the same in both cases. You have outgoing radiation. Also the same, in both cases, AND, in both systems this radiation originates from the surface, 100%.

With that, it's just Boltzmann to calculate the average surface temperature in both cases. I know, it's somewhat counter-intuitive, but still...

Radiation goes up by temperature to the fourth power. Even a small increase in surface temperature uses up a lot of the daily allotment of solar energy.

 

[IanC]

But I'm not sure that Ian is right about the system "only losing heat to the ground" during convection, because EVERY component of the greenhouse has a LARGE net loss to the sky. The GHouse gases are only retarding that popsicle effect..

I think you must have accidentally used convection for conduction.

This thought experiment uses only N2 for the atmosphere. The whole point is to be able to ignore GHGs.

Energy is stored and released via the gaseous variant of conduction .

 

[IanC]

Both of them emit in the UV and high range of frequencies because they ABSORB at those frequencies. So your N2 atmos is NOT transparent to the sun.. But it takes much more energy to be a UV emitter than an IR emitter.

Sorry, I seemed to have missed this post.

I don't really want to veer into esoteric reactions in the thermosphere.

You did make a good point that N2 can absorb some shortwave frequencies no matter what temperature it is at, but can only emit those same frequencies when it is very hot.

 

[flacaltenn]

Both of them emit in the UV and high range of frequencies because they ABSORB at those frequencies. So your N2 atmos is NOT transparent to the sun.. But it takes much more energy to be a UV emitter than an IR emitter.

Sorry, I seemed to have missed this post.

I don't really want to veer into esoteric reactions in the thermosphere.

You did make a good point that N2 can absorb some shortwave frequencies no matter what temperature it is at, but can only emit those same frequencies when it is very hot.

There's some discussion about that. Because in chem books, Nitrogen has a rather rich IR emission spectra. Problem is --- it seems to be only activated in IR at extremely high temperatures. Interesting LAY read at ---

Nitrogen – Active In The IR, A GHG? Comments nail his misconceptions.

Bottom line is -- you're right. The thermosphere boundary would work essentially the same whether it's 80 N2 or 100% N2... But that ionic disassociation would probably cool the planet overall on the "incoming" side of the equation because of the broader spectral absorption lines.

 

[Olde Europe]

Also, I think, convection plays a role in that the equator / pole temperature difference should be somewhat lower with, compared to without, atmosphere.

Without the presence of GHGs, I am unsure that a big enough local temperature differential can build up to initiate convection, either vertically or horizontally.

That's an interesting question. You know, I am sure, that solar radiation heats up non-GHG / no atmosphere planets far more than earth (assuming similar surface albedo) during day, and these planets cool down far more on the night side. So, the lack of IR absorption by the atmosphere is (partly) compensated by far higher / lower surface temperatures. I'd say, a 120°C surface should generate quite a bit of upward convection even through "mere" conduction, and this upward convection must be distributed through horizontal convections near surface and higher up. Not sure about the magnitude, but...

 

[Olde Europe]

Infinity. But that doesn't apply here.

Think about it. You have incoming radiation, the same in both cases. You have outgoing radiation. Also the same, in both cases, AND, in both systems this radiation originates from the surface, 100%.

With that, it's just Boltzmann to calculate the average surface temperature in both cases. I know, it's somewhat counter-intuitive, but still...

Radiation goes up by temperature to the fourth power. Even a small increase in surface temperature uses up a lot of the daily allotment of solar energy.

I know that, Ian, but that doesn't change the planet's radiative balance. I fear, I am at the end of my wit trying to express myself better.

 

[IanC]

I know that, Ian, but that doesn't change the planet's radiative balance. I fear, I am at the end of my wit trying to express myself better.

Thank you for trying!

Logical insights often arise from trying to explain a simple idea that turns out not to be as simple as first thought.

The problem is that a short interval at a slightly higher temperature is paid for by a much longer interval at a lower temperature.

 

[Billy_Bob]

How does the atmosphere lose energy to space? N2 neither absorbs nor emits IR.

The N2 indefinitely holds on to its stored energy simply by staying in a gaseous phase, suspended in the gravity field. During daylight the surface inputs energy to the atmosphere, which is then returned at night.

An N₂ atmosphere can lose energy to space in case very hot molecules escape the planet's gravity. Otherwise, no. That's probably negligible.

I think you are right. Conduction warms the near-surface atmosphere during the day, and gives back during the night. Once equilibrium is established, the absorbed and returned energy need to be equal. That means, the planet's average temperature should be equal to a planet with no atmosphere, but the day / night extremes are somewhat moderated. Also, I think, convection plays a role in that the equator / pole temperature difference should be somewhat lower with, compared to without, atmosphere.

N2 has a very low energy residency time, even lower than that of O2 and CO2. ITs the mass of these and the very narrow regions that LWIR can affect which determine the energy it can store and how long it can store it.. In a N2 only environment it will cool without input in just a few seconds..

As per usual, your post makes zero sense.

Lets make this easy for you and Crick...

Bill whips out the crayons....

Item number 1: The bandwidth of black body LWIR is about 100um

Item number 2: The points within the band N2 can Affect is 0.5 of just ONE POINT (1um).

Item number 3: The mass of N2 in our atmosphere is just 3 parts per BILLION..


SO lets identify what part of upwelling, LWIR power, at 394w/m^2 is affected by N2. Just 0.029% of the the total 394w/m^2 is heating the atmosphere. Even in a 100% N2 atmosphere, it in creases to just 0.63%

In earths atmosphere it affects just 0.03% of upwelling energy. In a 100% N2 atmosphere it will affect just 0.6% of the upwelling energy. In both cases heating of the gas is not going to happen give the energy release rate to space.

Ian, You simply do not have the mass+energy to effect temperature increase of the atmosphere and N2 is transparent to 99.97% of upwelling energy in the LWIR bands. That atmosphere will lose energy at a 99.97/0.3 ratio. This is why it will cool in seconds.

 

[Billy_Bob]

Just had a thread on the Sun's shift to UV with it going "blank".. It's THINNING the thermosphere because it's exhausting all the available N2 and O2 into atoms. We have NO fucking idea what the effect is on the climate system...

Bingo...

The change results in cooling of our atmosphere, primarily the stratosphere as the suns output is forced into longer wavelength IR that is not easily seen by the surface of the earth, due to water vapor and clouds.

 

[Billy_Bob]

Heating of N2 in atmos is therefore mostly from convective (actual) heat transfer. But I'm not sure that Ian is right about the system "only losing heat to the ground" during convection, because EVERY component of the greenhouse has a LARGE net loss to the sky. The GHouse gases are only retarding that popsicle effect..

Heating is done by conduction and convection in an N2 atmosphere is a bit player. (Collisions with the black body are the primary source of heating) once heat is obtained it will radiate out quickly. Not sure about Ian's magical photons radiating only to the surface, violates every law of emission I know about.

 

[IanC]

How does the atmosphere lose energy to space? N2 neither absorbs nor emits IR.

The N2 indefinitely holds on to its stored energy simply by staying in a gaseous phase, suspended in the gravity field. During daylight the surface inputs energy to the atmosphere, which is then returned at night.

An N₂ atmosphere can lose energy to space in case very hot molecules escape the planet's gravity. Otherwise, no. That's probably negligible.

I think you are right. Conduction warms the near-surface atmosphere during the day, and gives back during the night. Once equilibrium is established, the absorbed and returned energy need to be equal. That means, the planet's average temperature should be equal to a planet with no atmosphere, but the day / night extremes are somewhat moderated. Also, I think, convection plays a role in that the equator / pole temperature difference should be somewhat lower with, compared to without, atmosphere.

N2 has a very low energy residency time, even lower than that of O2 and CO2. ITs the mass of these and the very narrow regions that LWIR can affect which determine the energy it can store and how long it can store it.. In a N2 only environment it will cool without input in just a few seconds..

As per usual, your post makes zero sense.

Lets make this easy for you and Crick...

Bill whips out the crayons....

Item number 1: The bandwidth of black body LWIR is about 100um

Item number 2: The points within the band N2 can Affect is 0.5 of just ONE POINT (1um).

Item number 3: The mass of N2 in our atmosphere is just 3 parts per BILLION..


SO lets identify what part of upwelling, LWIR power, at 394w/m^2 is affected by N2. Just 0.029% of the the total 394w/m^2 is heating the atmosphere. Even in a 100% N2 atmosphere, it in creases to just 0.63%

In earths atmosphere it affects just 0.03% of upwelling energy. In a 100% N2 atmosphere it will affect just 0.6% of the upwelling energy. In both cases heating of the gas is not going to happen give the energy release rate to space.

Ian, You simply do not have the mass+energy to effect temperature increase of the atmosphere and N2 is transparent to 99.97% of upwelling energy in the LWIR bands. That atmosphere will lose energy at a 99.97/0.3 ratio. This is why it will cool in seconds.

You are a total whackjob. There is nothing there that makes a modicum of sense.

 

[SSDD]

N2 certainly emits the energy it absorbs via collisions with other molecules...it conducts till such time as it can't, then it radiates till it reaches its equilibrium temperature...ditto for O2 and argon...

You like to claim that every thing radiates till it becomes inconvenient then N2 doesn't radiate? How quaint

At what wavelengths is the N2 radiating away this energy? I don't think it has any emission lines in IR.

Try reading...it isn't a closely guarded secret.

 

[Crick]

Diatomic nitrogen emits very weakly between 550 and 675 nm. That is above infrared. Do you know something different Same Shit? That certainly seems to be what you're implying. How about a link?

 

[IanC]

This question is for the posters here who don't think GHGs have an effect.

Do you think an atmosphere warms the surface even without enhancement from GHGs?

If yes, how does it warm the surface? Could you briefly describe the mechanism.

 

[ding]

Hi Flac. Hope you had a great Holidays and all the best for the New Year.

Where am I headed with this? I'm not sure. Hopefully there will be more like you that realize the radiation aspect has vanished but warming still occurs (by moderation of extremes).

The surface warms and cools primarily by solar radiation input and terreterrestrial infrared output.

The N2 atmosphere only heats and cools by conduction at the surface boundary. I'm not even sure if convection would be in action.

The important thing to take away is the unequal heating and cooling rates for the surface and atmosphere. Actually the atmosphere ONLY loses energy back to the surface.

I think there will always be some convection.

Water vapor is the most dominant GHG. So I’m not sure if your scenario excludes all GHG.