Explaining misconceptions on "The Greenhouse Effect"

Jim D says:
July 27, 2010 at 8:18 pm
[snip for brevity–] How about atmospheric measurements of these things that are explainable in terms of the above listed? How about the fact that those measurements include what we call back radiation? [–snip rest–]
Do tell: How —by what mechanism— does CO2 produce a such an effect?
If you presume to say that CO2 causes ‘back radiation,’ then you must of necessity address the reflected radiation received from space.
After all, if CO2 produces as much ‘back radiation’ as you are wont to declare, then that gas must of necessity reflect the very largest part of that radiation received from space.
If CO2 were to have that quality, then the very largest amount of radiation received from space which reached the ground would be rather insignificant.
Additionally, explain how it is —by what mechanism— that CO2 ‘reflects’ energy?
Finally, the Earth isn’t a ‘greenhouse’ —as if you needed to be informed of such— so since that isn’t the case, then why do you continue employing the term?

Dear Anna V and All…
I agree with you on that many people think that by mixing thermodynamics with statistical quantum mechanics their downwelling radiation would be “explained”. Nevertheless, even statistical quantum mechanics go off the point with the idea of a downwelling radiation warming up the surface.
The last two weeks, I have been working on two issues related with quantum mechanics; one of them is on the EMRP, which is absolutely measurable with instruments on ground. The principles related to EMRP, although came from theoretical statistical quantum mechanics in the beginning but being corroborated until today by experimentation, absolutely respect the four laws of thermodynamics.
I can only state for now that the idea of a downwelling radiation warming up the surface is as thinking that we can inflate a balloon by means of taking out the air inside it, i.e. by pulling out the air from inside the balloon.
These “small” things cause much apprehension on AGW proponents, who use lots of verbosity for hiding this natural phenomenon (which happens at every point of the observable universe).

@899
Isolation (sunlight) power peaks in the visual wavelength band and tapers off to very low power in the long wave infrared bands.
CO2 is transparent to visual wavelengths and it passes right through. The ground and the oceans are warmed by visual wavelengths during the day. At night the warmth received from the sun radiates out of the ground in long wave infrared. C02 has some narrow absorption bands in LWIR and can absorb as much as 8% of it in the absence of water vapor and it absorbs all that’s available in the first 100 feet or so above the ground.
Water vapor has much wider LWIR absorption bands some of which overlap CO2 absorption bands. So basically if there’s much water vapor in the air CO2 plays very little role. Think of water vapor like a high quality sleeping bag that can keep you warm at night in frigid cold weather. CO2 is then like putting a light blanket over the top of the sleeping bag which will keep you a tiny bit warmer but not much because the sleeping bag is already keeping you warm. Now imagine you don’t have the sleeping bag. In that case the light blanket, while not keeping you near as warms as the sleeping bag, is still a lot better than being naked in the cold.
So the situation is that CO2 has some noticeable effect at keeping the surface a bit warmer at night in very dry climates. Little of the air over the oceans is dry enough for CO2 to play any noticeable role unless there’s ice covering it so for nearly 70% of the earth’s surface CO2 warming is so small it’s insignificant. A lot of land surfaces have a significant amount of water vapor in the air near the ground so CO2 has little role there either.
So, back to the sleeping bag/light blanket analogy, it’s like you always have a sleeping bag around you but one of your arms is hanging out of it. Having a light blanket to cover your arm will help to keep you warm.
Unlike the blanket analogy, and this is critical, CO2 is a light blanket at around 200ppm and that point it’s retaining all the heat it can possibly retain so adding more does nothing. Adding more simply decreases the distance in which all the available radiation is captured. 200ppm will capture it in the first 200 feet off the ground. 400ppm will capture it in the first 100 feet off the ground. Because of convective and conductive heat transport in the air it makes very little difference at ground level if the captured heat is distributed in the first 100 feet vs. 200 feet because convective and conductive heating is going to spread it out evenly anyhow.
All the crap about back radiation and so forth is no more than a technical description about how a blanket or sleeping bag keeps you warm night. You don’t really need to know that. The important thing to know is that a blanket does indeed help keep you warm at night. Exactly how the blanket works to do that talking about LWIR photons going up and coming back down pretty much of academic interest only. Even a caveman knows that a blanket (or mammoth hide as the case may be) helps keep you warm.

@899
continuing;
The CAGW cabal know exactly what I described above so they invented this fake positive feedback mechanism involving water vapor. The claim is that if the the surface is a little warmer from CO2 that makes water evaporate a little faster and since water vapor is powerful greenhouse gas it amplifies the small effect into much larger one.
What they don’t tell you is that 99% (or more) of the heat that turns water at temperature X into water vapor at temperature X is called latent heat of vaporization and doesn’t register on a thermometer! Adding insult to injury water vapor is lighter than air so it rises up in the atmosphere until it hits air cold enough to cause it to condense where it forms a cloud and gives up that heat much farther than 100 feet above the surface. That heat has two potential escape paths – downward toward the warmer surface or upward into colder air. The upward escape path is much easier to thats where the heat goes. Evaporation at the surface and condensation at altitude is essentially a heat pump that transports the surface heat straight through the ground layer of greenhouse gases like it wasn’t even there. Something like thunderstorm like a heat pump on steroids – water vapor goes up and sometimes, even on a very hot day, ice falls back down. Ice falling from the sky on a hot day is pretty graphic evidence of the water cycle in operation drawing heat off the surface and dumping it high in the air.
Adding even more insult to injury for the CAGW hypothesis is that the condensed water vapor forms a rather high albedo cloud which reflects an order of magnitude more energy in the visual wavelenghts directly back out into space. Albedo changes due to liquid water on the surface, snow on the surface, and clouds in the sky have far, far greater ability to change surface temperatures than CO2 can do at any concentration.
Complicating the picture even more is the average temperature of ocean being only 4c. Just a thin surface layer gets warm enough for brass monkeys. The oceans store 1000 times as much heat as the atmosphere! So any significant change in the rate of mixing between the warm surface layer and the frigid depths can have a rather dramatic impact on surface air temperatures, again easily enough impact to make CO2 look insignificant in comparison. No one has a model that predicts ocean surface temperature change events like ENSO, PDO, and AMDO from first principles. All they can do is statistical modeling based on past oscillations which are useful but can be very wrong, similar to predicting sunspot numbers – we know sunspot number follows a rough 11 year cycle so we can make some useful predictions but because we don’t have sunspot model based on first principles some of the predictions are way off the mark. Or like predicting earthquakes or volcano eruptions. We can make some useful guesses based on past behaviors but they are still largely unpredictable.
Climate science is in its infancy and any predictions coming out of it have even less precision and accuracy as earthquake and volcano predictions.

kwik says:
July 27, 2010 at 6:40 am
[–snip for brevity–] Because “person a)” works for the government. And 8 presidents did say the US govt must stop being dependant of foreign oil. Therefore CO2 must be declared a pollutant.
I find no other explanation.
You make a very good point, and just to get others to think about things, allow me to put forth just this piece of info:
There really is ‘no such thing’ as ‘foreign oil’ when you think about it.
Consider: There are —or were— just seven major oil companies in this world, and it matters not from where they get their oil. Really, it does not.
Think about this: They get their minerals from all over the world, and they sell them to the highest bidders.
They bought —or lease— certain lands, both here in the U.S. as elsewhere.
Once they pump that mineral crude, it belongs to them. There is no U.S. law which prohibits them from selling mineral crude which has been extracted from U.S. shores to someplace else.
The whole argument about ‘foreign crude’ is a crass deception.
Here’s the bottom line: The lie has been propagated by BIG OIL for the purposes of shafting the American public in the worst way.
If the only oil Americans used were mined from entirely American sources, that in itself would give BIG OIL a lock on the market, and the prices would be set accordingly, probably twice as high as now which would result in such a windfall of profits that it would reduce the lot of us to paupers.
Think about it: If the U.S. government made the demand that Americans use only American derived oil, then even if foreign mineral crude dropped precipitous in price, we’d be stuck with a connived situation designed to take terrible advantage of us.
The excuse would be used that mining crude here in America is more expensive than foreign oil, and they would jack their prices according to their remarks.
It would be a monopoly of the worst sort, not unlike that which existed at the beginning of the 20th Century with J.D. Rockefeller’s Standard Oil.
Perhaps the Gulf spill is just a peek into the future regarding what machinations we might expect?
THINK: Drilling off-shore is fraught with hazards, so the price of the oil of necessity be accordingly priced higher.
BP didn’t make any ‘mistakes,’ rather what they engaged in was a calculated gamble.
Sure, they ‘lost’ money, but not nearly as much as they stand to make.

John Finn says:
July 27, 2010 at 3:31 am
anna v says:
July 26, 2010 at 10:32 pm
Back radiation hand waving does not use the sun in the problem.
You haven’t understood the problem. Back radiation is about the reduced effectiveness of the earth to radiate the cnstant source of energy it gets from the sun. A bit like how the water in my kettle boils after a certain length of time because the constant source of energy is much greater than any heat losses.
There are so many things incorrect about that assessment, that I don’t quite know where to begin.
The bottom of kettle is flat, but the Earth is spherical.
The Earth rotates, but the pot doesn’t, unless of course you have an interesting pot!
The Solar energy arriving at the earth’s surface at any given point in time is relative to the atmospheric curvature, and the greater the angle which that energy intercepts the Earth’s atmosphere, the less effect it has.
So at any given time, the energy imparted to the surface is quite variable, kinda sorta like exposing only a portion of your pot’s lower surface to the heat.
And then there is that matter of proximity: How much energy does the Earth’s surface receive at any given moment, versus the angle at which the energy arrives?
The variables here are, well, astronomical!

Dave Springer says:
July 27, 2010 at 3:03 am
There is considerable evidence of the earth being completely covered by icecap in the past. The ocean basins then effectively become like a corked bottle. In the meantime underwater volcanoes at plate boundaries (the “ring of fire” that runs around the earth like the seams on a baseball) continually adds CO2 to the corked bottle. The first thing to come along, say a meteor, which breaks the cork would release the dissolved CO2 somewhat like uncorking a bottle of champagne.
The mechanism that melts a snowball earth is not known with any degree of confidence but clearly something comes along to end the runaway freeze. That’s as good a scenerio as anything else.
Yes but: Your hypothesis isn’t supported by geological record, regarding CO2 being an agent of any kind of warming, and in fact quite the opposite may be shown to be all the more the truth.
As I’ve put forth priorly, if CO2 is to be seen as any kind of agent for warming, then it must —of necessity— be seen consonantly as an agent of cooling as well.
Show me a gas which isn’t reciprocal in nature, and I’ll show you the perfect gas to be employed as a battery, i.e., it stores energy. Got any?
And, if CO2 is supposed to reflect energy back at the Earth, then it MUST reflect energy away from the Earth in exactly that way for Sunlight striking the Earth’s atmosphere.
There are no two ways about it: It’s either reciprocal, or it’s a battery.
And finally, the whole “CO2 is a greenhouse gas” is a charade.
Think about this: If CO2 is supposed to reflect energy, then a specific portion of the Sun’s energy isn’t reflected as it sneaks past those pesky molecules.
Consonantly, the very same proportion of energy which hits the Earth must not be reflected by the CO2 back at the Earth’s surface, as it sneaks past those same molecules!
And again: That energy which is re-reflected must also escape the very same pesky molecules.
I’m reminded of watching a ball bounce with it’s decaying frequency of rebound …

@jim d
Cold dense gases emit continuous blackbody spectra with a peak dependent soley on temperature. A chunk of iron and a bottle of CO2 both at the same temperature are vitually indistinguishable. Cold gases so thin that there are few collisions emit line spectra. Troposphere pressures are in the dense regime.
Curious as to how ratios of water vapor to CO2 emissions could be measured I spent some time reading about the primary instrument used in the Antarctic downwelling irradiance study. Its a recently designed super sensitive infrared interferometer called AERI (Atmospheric Emitted Radiance Interferometer).
Interferometers are exquisitely sensitive. This one continuously internally calibrated using one cold and one hot blackbody reference. A digital signal processor then performs FFTs on interference data. For the sake of argument I’ll concede that this instrument can dig spectral lines out of the continuous blackbody radiation emitted by cold dense gases.
So that takes us back to someone else’s response that if, in the driest place on the planet, water vapor still accounts for twice as much downwelling radiation as CO2 it only goes to show how small is CO2’s contribution to downwelling irradiance.
So just how dry is dry when it comes to Antartica?
For most purposes it is considered to be zero (0.03%). Comparatively the absolute humidity over temperate land masses ranges from 1% to 5%. Over the oceans it tends to the higher end of that range.
So can we now drop this nonsense about CO2 contributing any significant amount of so-called back radiation when water vapor almost everywhere else on the planet is 30 to 150 times greater than in Antarctica?
I learned a few things investigating the details of the Antarctic downwelling radiation study you mentioned and for that I can sincerely thank you for playing.

tallbloke says:
July 28, 2010 at 12:24 am

And you don’t want to widen it to iclude the fact that albedo modulated surface insolation varies in energy terms far more than the size of the alleged co2 signal, rendering all talk of being able to determine what co2 is up to from radiative balance observations moot.
1. I wouldn’t have wanted to widen the discussion at the time I was making the comments as it would simply have confused the issue.
2. I’m quite sure (in fact I know) there are many factors that are larger than the CO2 signal particularly over a relatively short periods of time (e.g. ENSO, volcanos etc) and I have no problem accepting that a change in albedo could swamp the CO2 effect but …..
3. If I was looking for an explanation for recent warming, say, I’d need to see the evidence that the albedo changees were consistent with the timing and the extent of the warming.
I was not commenting on the magnitude of the “CO2-induced” warming – just making the point that if a ~4 w/m2 reduction in outgoing radiation did occur because of a doubling of CO2 this would lead to some warming which would have an impact on the surface radiation budget. The fact that this warming may be offset (completely or partially) by a change in albedo doesn’t alter that fact.
To use (or paraphrase) a commonly used phrase “we would be warmer that we would otherwise be without it”.

Nasif Nahle says:
July 27, 2010 at 11:32 pm
Dear Anna V and All…
I agree with you on that many people think that by mixing thermodynamics with statistical quantum mechanics their downwelling radiation would be “explained”. Nevertheless, even statistical quantum mechanics go off the point with the idea of a downwelling radiation warming up the surface.
We have no disagreement. I am sure if one were to calculate with quantum statistical ensembles there would not be any downwelling etc radiation because thermodynamics and quantum statistical mechanics have been shown to lead one to the other given the proper conditions.
The thing is with quanta one has these cute pictures of photons hitting and bouncing off in all directions that it is easy to hand wave and count on fingers as if that is what photons and atoms do.
Rigorous calculations in the quantum statistical framework would show up the illusion.

Somebody check me, because I think that even in the naive picture of a single photon hitting a single CO2 ( or H2O) the assumption that 50% of redistributed energy goes outwards and 50% downwells violates conservation of momentum.
The photon gives up energy equal to h*nu and transmits momentum by h*nu/c. Conservation of momentum means that the total of the redistributed energy in thermal photons/ collisions will have also a component of that momentum , which is pointing up and out. Otherwise there would be radiation pressure pushing all those CO2 and H2O molecules up and away.
Since the number of molecules is limited but the number of long wave ground radiation photons unlimited we would end having all H2O and Co2 in the stratosphere :). A bit tongue in cheek but am waiting for corrections.

Dave Springer says:
July 28, 2010 at 5:19 am
@899
“Show me a gas which isn’t reciprocal in nature, and I’ll show you the perfect gas to be employed as a battery, i.e., it stores energy. Got any?”
The gas is reciprocal but the spectral bands of insolation vs. LWIR are quite different.
Little energy in absorptive bands of CO2 comes down from the sun during the day compared to the amount of energy in the same band that comes up from the ground at night.
This results in differential energy absorption between day and night.
What part of that don’t you understand?
We’re tuned to the same wavelength!
I agree with your statement.