Greenhouse Effect

[icefisher]

Here is a simple diagram of the problem I have with the greenhouse effect as described by Steve.



Here the big balls are rotating planets and the small balls are theoretical blackbody molecules. It could be carbon black, water, or a gas.

Based upon the use of the Stefan Boltzmann equations its important to be a blackbody but Steve has an unstated factor to use the blackbody equations on greybodies like transparent liquids and gases.

Here we have not applied the conversion factor. It would not seem to matter because even if the absorption and emission rate is slower the molecule should warm to equilibrium with the body warming it.

Anyway the absorption model should continue to absorb energy until it is equalized to the nearby body that is warming it.

The diagram is at equilibrium.

So from this it becomes obvious that the reflection model would warm the surface as there is zero outgoing from the backside of the mirror.

As I see it the outgoing 396w from the molecule to the space suggests it needs to be absorbing 396w and losing it all via radiation. Clearly if 396w is going back to the surface we have a problem here. And since the 396w average is in fact the atmosphere 6' above the surface one cannot say it would radiate at less than 396 upwards. Steve has already confirmed the solid molecules on the surface also radiate downwards, like in the diagram but it a net no change for the molecule on the planet surface as it has to replenish the 396w leaving the molecule for space.

I can see a warming possibility from delaying the emission slightly but how in the world would one calculate the effect of that?

So Steve where are we going wrong here. Be very explicit, no arm waving, lets really get into the weeds here.

[sigurdur]

Icefisher:
I know I am not Steve......but bear with me.
1. There is no such thing as a "greybody".
Physics recognizes mass and density, it does not recognize form.

The theory of light spectra heating is a confirmation of what SW and LW radiation does to mass. One thing that a lot of folks miss in the theory of light spectra heating is the mass/balance equation. If our atmosphere has no mass, there would be no temperature stability at all.

Let's see...where am I going with this? The composition of the atmosphere changes with the mass of the atmosphere. Hydrogen/oxygen by themselves are very poor absorbers/emitters of LW radiatioin, but bonded into water vapor they are excellent absorbers and radiators. What happens tho, is h20 vapor is pressure sensative. Once the pressure gets low enough, the bond stregth decreases. This is one of the reasons that h20 is not a prevelant gas at the top of the stratosphere.
co2 has a very small LW spectra. The only place that co2 becomes important at all is high in the atmosphere because h2o vapor is present in such a small quantity and the LW can be emitted by co2 without being absorbed virtually instantaenously by h2o.

Remember tho, the photons do not recognize gravity up there and are emitted in all directions. By the nature of our atmosphere haveing a circle shape, more photons are emitted to outer space than are emitted down to be absorbed by h2o.

So what this proves is that co2 actually has a cooling effect, rather than a warming effect.

(This is one theory.....I am waiting to be lamblasted for this one)

[steve]

Well the most explicit I've been is my little program wot I wrote and posted here a while ago.



solarcycle24com.proboards.com/index.cgi?action=gotopost&board=globalwarming&thread=1429&post=58711

You could run my program or you could follow the instructions below and write it yourself.

In that program you see that each layer emits equally up and down proportional to its temperature to the power 4.

Each layer absorbs a *fixed* proportion of the radiation incident on it.

Temperature goes up or down in proportion to the amount of radiation emitted or absorbed.

The surface absorbs the radiation incident upon it and also absorbs all the solar radiation (I played around with some of the solar radiation being absorbed in the atmosphere as well - but the principle results stayed the same)

The values of heat capacity, absorptivity and emissivity of the surface and atmosphere are fixed.

As you iterate the program, the temperature of a layer goes up if it absorbs more than it emits and goes down if it absorbs less than it emits.

So for example, if the ground emits 400 Joules in one time step of the model, then maybe 40 (10%) of the Joules are absorbed by the first layer, 36 (10% of the remainder) by the next layer and so forth. The ground is also given, say, 300 Joules from the Sun.

In the same timestep, lets say the temperature of the first layer is such that it emits 80 Joules up and 80 Joules down. The surface absorbs all the 80 downward Joules, the second layer absorbs 10% of the 80 Joules (8 Joules) the third layer absorbs 10% of the remainder (7.2 Joules)

However the second layer has also emitted energy up and down - say 70 Joules (because it is cooler). The first layer absorbs 7 Joules and the surface absorbs the remaining 63 Joules. The third layer absorbs 7 Joules, the 4th layer absorbs 6.3 Joules etc. etc.

So, so far, the surface has emitted 400 J and absorbed 80 J from the first layer and 63 J from the second layer plus the 300 Joules from the Sun. This will warm it a bit such that in the next time step it will emit a bit more.

The first layer has emitted 160J and absorbed 40J from the surface and 7J from the second layer.

So probably in this case, the surface is going to be a couple of hundred J down and will cool a bit.

My program did this for any number of layers and for different emissivities.

When you start the program you give all the layers arbitrary temperatures. The only fixed parameters are the amount of solar radiation, the emissivity of the layers and surface and the amount each layer absorbs.

As you run the model the temperatures converge to the same answer regardless of the starting conditions. In the above examples with numbers off top of head it seems that the surface will initially warm rapidly whereas the atmosphere will cool - so I've inadvertently chosen an unstable temperature profile. But eventually the temperatures will stabilise.

The crux of the issue though is that the temperatures will stabilise at a higher value if you nudge up the emissivity and absorptivity of the model and keep everything else the same.

But for your purpose, my "molecules" (or my layers of molecules) are indeed each radiating equally up and down, so showing the "absorption model".

In essence what you are missing is the fact that the real atmosphere is not a single layer at uniform temperature.

[icefisher]

Temperature goes up or down in proportion to the amount of radiation emitted or absorbed.

So for example, if the ground emits 400 Joules in one time step of the model, then maybe 40 (10%) of the Joules are absorbed by the first layer, 36 (10% of the remainder) by the next layer and so forth. The ground is also given, say, 300 Joules from the Sun.

In the same timestep, lets say the temperature of the first layer is such that it emits 80 Joules up and 80 Joules down. The surface absorbs all the 80 downward Joules, the second layer absorbs 10% of the 80 Joules (8 Joules) the third layer absorbs 10% of the remainder (7.2 Joules)


Well why pray tell does not this layer continue to heat until its emitting up exactly what it absorbs from down?

Above you have it absorbing 40 joules from the surface and emitting 80 joules to space. I think not!

Back to the diagram for the absorption model. Even if it only absorbs a trace amount of the radiation from below it should continue to warm to equilibrium with below. Ultimately backradiation to the extent it exists only serves to ensure it heats up to equilibrium and outgoing to space balances to what it absorbs from the ground. The delay may cause some heat build up to go through this process but it doesn't seem to be a straightforward calculation as you propose it is.

I get there is a resistance. But transmitting through solid objects amounts to gazillions of absorptions and reemissions as opposed to our magical gas that is constantly seeking kinetic equilibrium through out its entire volume and may fail to heat as much as a solid object.

I realize that leaves us without an explanation for warming above the BB estimate, but maybe it is as G&T calculated it or maybe its due to poorly emitting trace gases in the thermosphere that occupy a far larger disk facing the sun than the solid surface of the earth exposes.

We see calculations for the atmosphere absorbing 78 watts on incoming. But that 78 watts is attenuated to the surface. Nearing the tangent point of the earth the greatest atmospheric absorption exists. Then right at the tangent point it doubles and is not attenuated to the surface. Its completely unaccounted for in the radiation budgets!

When the thermosphere is included the earth+atmosphere disk is about 20% larger than the solid earth disk.

I gave you the references that gasses in contact with the surface is having heat conducted into it can't easily shed. I can demonstrate the warming effect this has in a lab. Its a basic construction principle. The reflectivity of the surface of the ocean is a double whammy. It reflects a lot of the solar incoming that is subtracted from our expected equilibrium. But it is not figured back in as poor emission ability as well sequestering heat into the ocean in a real world greenhouse effect that can be lab demonstrated. And its not just reflectivity! Its transparency as well making it a poor emitter more so. Water spectra suggests its about 50% of the emitter of a blackbody. Spell that as heat build up that can be demonstrated in a lab and is fundamental to
building design.

Then of course there is the thermosphere. High, hot, and trace gases that can see almost 2/3rds of the earths surface from their lofty perches while being bathed in sunlight that average over a thousand degrees!

These trace gases are also going to radiate heat back to the surface. and if you compound that calculation via your trace gas compounding model they should have toasted us off the surface of the earth a long time ago!

and gee Steve they can do it without violating the 2nd law of thermodynamics! We might start by asking why its so damned hot up there in the first place. It would seem they must absorb heat from friction or maybe SW and be forced to heat to a level where it can emit the SW. It could be an important contributor to raising the temperature of the surface.

I don't know if there is anything from cold gas radiation that is capable of heating the earth via a strict radiative process. What goes in from below should increase the kinetic energy of the molecule until what goes out the top is equal to what comes in the bottom.

I just don't see the justifications of setting all other possibilities to zero to put the finger on CO2 when the one with the finger on it seems the least plausible.

[steve]

Well why pray tell does not this layer continue to heat until its emitting up exactly what it absorbs from down?

Any layer will continue to heat or cool until it is emitting exactly what it is absorbing. However, what it is absorbing will comprise radiation from both above *and* below.

Above you have it absorbing 40 joules from the surface and emitting 80 joules to space. I think not!

Well those were numbers off the top of my head, so if they are unrealistic then it suggests that the system is not in equilibrium. Perhaps the atmosphere layer will quickly cool such that emissions are lower.

Anyway, to reduce the level of handwaving, I added some diagnostics to my program. I changed it so that I can output the amount of emission and absorption of a chosen layer. Also it displays where all the absorbed radiation comes from. Below is data from a 20-level run once equilibrium is reached. At equilibrium the radiation emitted to space is the same as the radiation input at level 1.

So for example, it shows that level 7 is emitting 0.208 up and 0.208 down, and it is absorbing radiation emitted by all the other layers. In this example, it absorbs more from nearby layers than from further off layers because the emission from the further off layers is attenuated by absorption from the layers between.

The exception is absorption from layer 1 (the surface) which is higher because the surface emissivity is higher.

Level 7 absorbs 0.158757522141 from level 1
Level 7 absorbs 0.0198667278969 from level 2
Level 7 absorbs 0.0221493372205 from level 3
Level 7 absorbs 0.0246520900068 from level 4
Level 7 absorbs 0.0273867226072 from level 5
Level 7 absorbs 0.0303630469422 from level 6
Level 7 is emitting 0.208698371249 both upwards and downwards
Level 7 absorbs 0.027500428244 from level 8
Level 7 absorbs 0.0224551714035 from level 9
Level 7 absorbs 0.0182802504966 from level 10
Level 7 absorbs 0.0148313170395 from level 11
Level 7 absorbs 0.0119873192303 from level 12
Level 7 absorbs 0.00964681477749 from level 13
Level 7 absorbs 0.00772486226003 from level 14
Level 7 absorbs 0.00615039443199 from level 15
Level 7 absorbs 0.00486400454907 from level 16
Level 7 absorbs 0.00381607856225 from level 17
Level 7 absorbs 0.00296522235807 from level 18
Level 7 absorbs 0.00227693570075 from level 19
Level 7 absorbs 0.00172249667131 from level 20

If you check the numbers you will see that for Level 7 total absorption equals total emission (you have to double the emission number as it is the value for both upwards and downwards emission).

Here is the data for level 14:

Level 14 absorbs 0.0558553137783 from level 1
Level 14 absorbs 0.00698966767351 from level 2
Level 14 absorbs 0.00779275314809 from level 3
Level 14 absorbs 0.00867329121832 from level 4
Level 14 absorbs 0.00963541105938 from level 5
Level 14 absorbs 0.0106825647778 from level 6
Level 14 absorbs 0.0118172024032 from level 7
Level 14 absorbs 0.0130403602192 from level 8
Level 14 absorbs 0.0143511417235 from level 9
Level 14 absorbs 0.0157460696782 from level 10
Level 14 absorbs 0.0172182770822 from level 11
Level 14 absorbs 0.0187565082397 from level 12
Level 14 absorbs 0.0203438810823 from level 13
Level 14 is emitting 0.136425366749 both upwards and downwards
Level 14 absorbs 0.0174812621067 from level 15
Level 14 absorbs 0.0138249569764 from level 16
Level 14 absorbs 0.0108464376235 from level 17
Level 14 absorbs 0.00842804958593 from level 18
Level 14 absorbs 0.00647173286607 from level 19
Level 14 absorbs 0.00489585117214 from level 20

The temperature profile of this example is:

Level 1 Heat Content 372.984355905
Level 2 Heat Content 350.849495973
Level 3 Heat Content 347.324690576
Level 4 Heat Content 343.68862814
Level 5 Heat Content 339.932779615
Level 6 Heat Content 336.047540914
Level 7 Heat Content 332.022038464
Level 8 Heat Content 327.843891232
Level 9 Heat Content 323.498906825
Level 10 Heat Content 318.970706216
Level 11 Heat Content 314.240227342
Level 12 Heat Content 309.285099274
Level 13 Heat Content 304.078791163
Level 14 Heat Content 298.589496529
Level 15 Heat Content 292.77857754
Level 16 Heat Content 286.598401798
Level 17 Heat Content 279.989209738
Level 18 Heat Content 272.874484181
Level 19 Heat Content 265.1537916
Level 20 Heat Content 256.691273

If you nudge up emissivity/absorptivity you get a slightly different equilibrium state:

Level 14 absorbs 0.0549106496396 from level 1
Level 14 absorbs 0.00732975305029 from level 2
Level 14 absorbs 0.00823350689153 from level 3
Level 14 absorbs 0.00923246081254 from level 4
Level 14 absorbs 0.0103328224011 from level 5
Level 14 absorbs 0.0115401512211 from level 6
Level 14 absorbs 0.0128589582909 from level 7
Level 14 absorbs 0.014292186853 from level 8
Level 14 absorbs 0.0158405480062 from level 9
Level 14 absorbs 0.0175016740406 from level 10
Level 14 absorbs 0.0192690493862 from level 11
Level 14 absorbs 0.0211306658511 from level 12
Level 14 absorbs 0.023067340061 from level 13
Level 14 is emitting 0.147046534489 both upwards and downwards
Level 14 absorbs 0.0197411141339 from level 15
Level 14 absorbs 0.0154465508177 from level 16
Level 14 absorbs 0.0119839543704 from level 17
Level 14 absorbs 0.00920211398036 from level 18
Level 14 absorbs 0.00697621232266 from level 19
Level 14 absorbs 0.00520334498354 from level 20


Level 1 Heat Content 375.904117212
Level 2 Heat Content 354.245052629
Level 3 Heat Content 350.636817168
Level 4 Heat Content 346.912998049
Level 5 Heat Content 343.064599002
Level 6 Heat Content 339.081470615
Level 7 Heat Content 334.952102417
Level 8 Heat Content 330.663356304
Level 9 Heat Content 326.200140806
Level 10 Heat Content 321.544987533
Level 11 Heat Content 316.677513152
Level 12 Heat Content 311.573711237
Level 13 Heat Content 306.205012267
Level 14 Heat Content 300.537014307
Level 15 Heat Content 294.527726647
Level 16 Heat Content 288.125085102
Level 17 Heat Content 281.263341762
Level 18 Heat Content 273.857630623
Level 19 Heat Content 265.795485985
Level 20 Heat Content 256.922926738

The point of this exercise is to show that the layers can be emitting equally upwards and downwards while *also* giving you a temperature profile *and* resulting in warming if emissivity/absorptivity is increased slightly.

[steve]

This is what each layer emits to space:

Level 1 emits 0.125456928274 to space
Level 2 emits 0.0167483739802 to space
Level 3 emits 0.018813718851 to space
Level 4 emits 0.0210966691102 to space
Level 5 emits 0.0236114217812 to space
Level 6 emits 0.0263706948255 to space
Level 7 emits 0.0293848110228 to space
Level 8 emits 0.0326605125997 to space
Level 9 emits 0.0361994414372 to space
Level 10 emits 0.0399962053582 to space
Level 11 emits 0.0440359335106 to space
Level 12 emits 0.0482912029685 to space
Level 13 emits 0.0527181931004 to space
Level 14 emits 0.0572518940261 to space
Level 15 emits 0.061800158059 to space
Level 16 emits 0.0662363396352 to space
Level 17 emits 0.0703902145321 to space
Level 18 emits 0.0740368067169 to space
Level 19 emits 0.0768826730269 to space
Level 20 emits 0.07854910355 to space

[julianb]

Can some of you with more physics than I have explain why the speed of rotation of the Earth does not seem to be considered in the calculations of the GH Effect?

For instance Venus has a daytime that is something like 260 Earth days, this allows the temperature to rise far beyond what it would in an Earth day, but it distributes the heat to the unlit side via atmospheric circulation so 'night-time' temperatures are virtually the same as the day-time temps. so the average for the planet is greater than it would be if it rotated in just 24 hours.

On another point, the Moon has a 'GH' effect from radiation that is absorbed in the top half meter of the surface which results in a morning temperature some 40 degrees K above the assumed temp. before measurement was possible. Is the effect of the ground heat remaining overnight counted before the warming 'GH effect' of the atmosphere is calculated, i.e. are we giving the atmosphere too much weight in calculations? (and therefore over estimating the CO2 effect)

[steve]

julian,

Looking from space, both Venus and Earth have similar temperatures (as I think we've discussed) because the upper layers of the Venusian atmosphere are as cold as the upper layers of the Earth's atmosphere. In essence this is because both planets have to get rid of about the same amount of solar heat in order to maintain their steady temperatures.

However, Venus has about 100 times as much atmosphere as Earth, so for the same rate of cooling the average temperature change per unit time would need to be 1/100th that on Earth. ie if a place on Earth cools about 5-10C overnight a place on Venus might cool 5-10C in 50 days worth of night. Of course as you say atmospheric circulation happens, which in this nominal 50 day period will cancel out some or all of this cooling.

I'm talking off the top of my head here. It would be interesting to see the diurnal temperature changes on Venus at different levels in the atmosphere as well as some idea of how much atmospheric circulation is happening.

[trbixler]

I assume that there are only 20 layers for ease of calculation. Further for ease of calculation convection is disregarded. I assume that variations in atmospheric gas concentrations are also disregarded. Likewise the involvement of clouds. Additionally the variability of particulates. I suspect the declination of the rotating earth is not included for ease of calculation. Likewise the orbit of the earth around the sun. I wonder if any of these factors have any effect on the "greenhouse (without glass)"?

[steve]

trbixler, your sarcasm is entirely unnecessary. Have you asked if icefisher's blobs include all these effects? Every time I bring up this program you come up with minor and irrelevant criticisms, yet you never engage constructively. Are you trying to be a mini-Steve McIntyre?

Icefisher, and others, have a problem with the basic radiative consequences of things such as "back radiation". Some of the effects appear counter-intuitive to people. This opens an opportunity for fake arguments about lack of adherence to the 2nd Law of Thermodynamics, or confusion about why increasing the emissivity of the atmosphere doesn't cause the atmosphere to cool rather than warm.

This simple program aims to demonstrate that basic physics principles underlie the "greenhouse effect".

Better, more scientific, and more constructive questions to ask would be - *If* I increase the number of layers what happens to the result (as it happens any number of layers can be chosen. More layers slows the program down)? *If* I add in convection what happens to the results? *If* I vary emissivity from layer to layer what happens? etc. etc.

Once you spend a bit of time examining the program and the underlying scientific principles, you will conclude that the intuitive answer to all the above is that the temperature will still rise for an increase in emissivity/absorptivity. In other words, the result (increased emissivity/absorptivity causes warming) is insensitive to attempts to tweak the program.

[sigurdur]

Steve:
And at this point is where sensativity comes in.

[cybertiger]

To be fair to steve his little program does adequately explain the CO2 based global warming theory, which was your question.

I don't agree that it demonstrates the validity of the theory though

[icefisher]

Any layer will continue to heat or cool until it is emitting exactly what it is absorbing. However, what it is absorbing will comprise radiation from both above *and* below.

Steve for starters you are assuming a kinetic profile in the troposphere.

Since gases seek kinetic equilibrium via physical processes how was this particular diminishing kinetic profile of the atmosphere determined to exist? And how is it maintained? What force prevents the molecules from physically moving and breaking down the profile?

Without evidence to support that profile you are purely engaging in numerology here.

gas theory requires a seeking of kinetic equilibrium yet it does not apply to the upper layers of the atmosphere. why?

The lapse rate in the troposphere allegedly is at equalized kinetic value (no kinetic profile unlike in your calculation) and the drop in temperature is due to the air getting thinner and the same energy filling a far larger volume.

Yet that does not continue into the other layers and an inversion occurs. With weakening temperature from ever increasing volumes per mole of gas what causes it to get hotter?

Here your vertical calculations fall off the back of the truck in a big heap.

Fact is absorption by the atmosphere is at its smallest value directly under the sun. As the curve of the earth falls off sunlight has a longer path through the atmosphere.

When it hits the point of tangency the path suddenly doubles. The area of space where the atmosphere is absorbing energy is considerably bigger than the area of the disk that represents the surface of the earth exposed to the sun.

How much of the greenhouse effect comes from super heated molecules far out at the margins of the atmosphere radiating back to the surface in compliance with the laws of thermodynamics? Those temperature inversions would seem to have to be kinetic profiles getting hotter as it more than compensates for the increase in volume.

And we already know that our trusted academic professors rigged the game by subtracting cloud top reflection and keeping mitigating cloud bottom reflection.

They know this because they equivocate over the effect of more clouds whether the effect will be positive or negative feedback. But these people living off the public's largesse have chosen to lie to the public, hide the decline so to speak through hokey and they know it to be hokey accounting.

Can the outer atmosphere outside the disk of the planet surface gather another 55 watts?

How about we combine it with poorly emitting water that absorbs everything? Maybe water sitting on the surface has a greenhouse effect also, warming the water because water is only absorbs portions of LW and thus emits it inefficiently. Water surfaces release about 126 watts (85/.67) per square meter on top of all that radiation. Is this the source of the major greenhouse effect? CO2 lacking phase change may be just along for the ride doing nothing, radiatively netting out.

Then what about conduction? 51 watts is conducted from dry surfaces according to Trenberth (3 times the global average of 17 watts) into an atmosphere with poor emission characteristics. A nice study in construction insulation here.

And what about the dynamic nature of clouds moving from covering a shaded space to an exposed hotter space perhaps increasing its greenhouse effect. Is this what gives rise to suspicions that clouds could be positive feedback?

[richard]

Aug 4, 2011 20:22:34 GMT icefisher said:

And we already know that our trusted academic professors rigged the game by subtracting cloud top reflection and keeping mitigating cloud bottom reflection.

BRAVO! Nice rant. can you provide a shred of evidence on this point?

[icefisher]

Aug 4, 2011 22:17:43 GMT richard said:

Aug 4, 2011 20:22:34 GMT icefisher said:

And we already know that our trusted academic professors rigged the game by subtracting cloud top reflection and keeping mitigating cloud bottom reflection.

BRAVO! Nice rant. can you provide a shred of evidence on this point?

Trenberth's budget Richard. Or do you think there is a question about clouds reflecting IR?