ssat,

I may have to take some time disentangling your large second para.

As for the first one, the speed of light is not constant everywhere. Under certain temperature conditions in certain materials, it can be slower, and sometimes much slower than the usual value for c. Harvard scientists have had it travel as slow as 40mph.

Now for the second para

For the system in equilibrium, incoming and outgoing are in balance

Yes they are, up to a point. A system can be in equilibrium while parts of the system can be imbalanced. A good example is the moon. Because it turns so slowly, one side is almost always heating up, and one side is almost always cooling down. They are not in equilibrium with the universe, but the entire system is in equilibrium.

both fluxes are travelling at the speed of light

This is where I start to get bogged down. Fluxes don't travel. A flux is a measure of the quantity of energy passing through a surface of a known area. The flux itself doesn't move. Photons may be travelling through the area defined by the flux at (or close to) the speed of light, but the flux itself is simply a point of observation, it isn't an entity in itself. All a flux says is "at this point (or across this area) - this number of joules of energy pass in a second (or whatever time period you want)"

This distinction is important, because flux is a measure of energy density, not total energy.

If 100 photons move one way, and 100 photons move the other - the flux is zero. But that doesn't mean energy isn't moving, it doesn't mean there is no energy present in the system. I just means there is no NET flow of energy. The idea that a flux is a measure of NET flows is important later. Just because 333 Watts/m^2 is flowing into the ground on a diagram, this says nothing about the ACTUAL energies going in either direction. All it tells you is that "one subtract the other" = 333. There are still plenty of photons flowing in both directions.

The system itself has a thermal capacitance which reduces the difference between temperature max and min during diurnal and annual cycles

OK, so now we've jumped back to describing to the whole system, and I'm glad you now agree with me that the atmospheric system presents a capacitative delay. I'm assuming form the tone that you don't believe the radiative effects are what cause this capacitative effect, however. Let's see...

It is the slower speed of energy flows within the mass of the system that dictate thermal capacitance, conduction, convection etc being examples

Absolutely. Heat which arrived as high energy photons, have entropied into lower state heat and vibrational energies, such as convection, which are slower, so the heat cannot escape out as fast as it came in. We agree! The earth is warmer because high entropy heat (IR, kinetic) can't escape the atmosphere as fast as the low entropy high energy photons bring it.

Now add a small quantity of CO2 to the atmosphere (ignore the heat in the gas from combustion, assume it to be neutral)

Yes, I think we can ignore the heat of combustion, not all CO2 comes from combustion anyway.

Now measure temperatures and find that both the surface temperature and the atmospheric temperatures have increased.

Yes.. it's called the Greenhouse Effect, the title of this thread. Where are you going?

We know that the additional CO2 will have absorbed some surface emitted infra-red and some of that energy will have been passed by conduction into the atmosphere as a whole thereby raising its temperature

I don't like to use the term conduction, but I know what you mean. Energetic CO2 molecules will have collided with O2 and N2 molecules, and heated them up. Also, CO2 will itself have become heated up. All the air is heated.

but what of the increase in temperature at the surface? Is it from 'back radiation' from the CO2? No because that would be against the flux and we know that the flux is always from higher to lower temperature

And here we get to it. Again. I'll try to explain it. Again.

Your mistake is believing that energy (photons, whatever carrier) cannot move against a 'flux' from colder to hotter.
I'll say up front, cards on the table, this belief is incorrect. Its incorrect because of an old popularly dragged-out statement of a law of thermodynamics that says a colder object cannot heat a warmer object. This statement relies on a very specific meaning to the word 'heat' which relies on a macro view of the world.

Taken at face value it is wrong. A colder object can cause a warmer object to become warmer. By slowing down the rate at which it can emit photons! It does this by throwing some of them straight back at it! The rate, just like the flux, is a measure of the NET number of photons getting out of the system, not the total number of photons flowing back and forth. Some of them coming back means it's not losing temperature as fast - which means it's staying hotter than it would be otherwise.

It's also incorrect because that little CO2 molecule up in the air emitting a photon, neither the molecule nor the photon have any idea what temperature the ground is at. It doesn't have a little heat detection system that means it only fires photons in certain directions. Photons fly out in all directions, regardless of the temperature of the eventual destinations.

The temperature of a body determines how many photons it throws out.
The rate that it can throw the photons out determines how quickly it cools.
If something gets in the way, and throws some of the photons back at it, then it fails to cool as much as it would.
So it is hotter than it would be.

I really, truly hope this explains it for you. This delusion has to stop.

TBYJ

There are many points here that we do not differ on, however described but first let us agree on what we are discussing. You will see that I have no objection to the idea that our atmosphere causes the surface to have a lower temperature range than our near neighbour, the atmosphereless moon. Now we move to AGW theory - by our actions, we add CO2 to the atmosphere unnaturally and increase average temperatures. It is just this that I have done in my scenario and is useful to examine greenhouse effect.

Speed of light. this is important because of the rate of energy flows within the system as against those without (outside) it. Within the system the (average) flows are much slower as a function of all of the constituents of thermal capacitance.

Flux

Flux is a measure of the quantity of energy passing through a surface of a known area.

Quite. Please note that I have only discussed net flux. I do this because I accept that a body with a surface temperature above absolute zero will radiate energy. Your allegation that I do otherwise does not hold. The climate science diagram I cite shows fluxes as energy flows and I have no problem with that convention.

I don't like to use the term conduction...

Why not: there are radiation, conduction and convection as the three forms of energy (as heat) transfer and conduction within a gas is by collision.

Yes.. it's called the Greenhouse Effect, the title of this thread. Where are you going?

I have in fact been. I have shown the effect of additional CO2 in the atmosphere warms both atmosphere and surface without the need for inclusion of 'back radiation' in flow diagrams and by extension how all radiative gasses do likewise (excluding any evaporation/condensing effects, another subject). I believe Occam's razor applies.

But why is this important? To you it may not be but to me it is because if popular climate science can have this wrong, a cornerstone of alarm, then its practitioners are not infallible.

I have shown the effect of additional CO2 in the atmosphere warms both atmosphere and surface without the need for inclusion of 'back radiation' in flow diagrams and by extension how all radiative gasses do likewise

Interesting. So.... Sun warms ground, ground warms air by convection/conduction, ground cools.

I can see how having such a heat sink narrows the diurnal temperature ranges, compared with, say the airless moon. What It doesn't explain is why the average temperature is greater. I can see why it does't get as cold (with a supply of warm air to draw from) or as hot (with a supply of cool air to draw on) - but what I can't see is why the average temperature of earth is some 33K warmer than that of the moon. Wouldn't any 'heat sink' effect be symmetrical around the average temperature of a black body at the appropriate distance from the sun?

Are you saying IR photon exchange plays no part in the warming mechanism? Can you explain how a CO2 molecule sitting in warm air manages NOT to emit IR photons? There is no known mechanism in time or space that will stop that photon being emitted as far as I know. We know exactly how many IR photons any given CO2 molecule will emit per second at a given temperature, this is basic physics.

If IR photons must be emitted, what stops them hitting the ground and imparting energy?

If IR photon exchange plays no part, how does energy escape from the atmosphere at all? If it's all convective and conductive, how does the earth manage to lose enough energy to stay cool?

Your explanation defies physics, I'm afraid. Photons MUST play a part. If a CO2 is in the atmosphere at a set temperature, it MUST be emitting IR, and some of them WILL hit the ground. We can even measure it.

Back radiation just means "heat from the air" - it's not hoodoo.

TBYJ,

You keep accusing me of stating things that I have not and missing things that I have stated. I have explained how the average temperature of the Earth is warmer than that of the moon. It is getting late here and rather than go over things again I offer this analogy of a ropeworks to explain popular climate science;

The source machine produces rope. The sink (drum in this case) pulls that rope. In between is a grouped system of many pulleys between manufacturing and packaging. As the rope travels back and forth around the pulleys, friction causes the group to warm. The system attains equilibrium where the sink is hauling exactly the same as the source is producing. Every molecule in the rope plays follow-me-leader. No molecule travels against that flow. The distance across the group of pulleys is short but the time taken to traverse it is slower than it would be if it were not there. That heat is some function of speed across the system.

Now add a pulley within the group. Friction has increased and therefore heat increases. The source is producing as before and the drum is keeping pace.

The technician in the ropeworks that oiled the pulleys retires and management hires a guy that has just passed his geography degree and needs work. He arrives, notes that the pulleys are warm and declares to management that it is because some of the rope is travelling backwards and so the production of rope must be drastically reduced until a universal substitute can be found to prevent impending fire. He suggests chains of daisies.

Martin A

Referring to your neighbour's balls! You stated earlier

I am one of those who think that "heating via 'back radiation' " is nonsense. It's a red-herring that misleads lots of people.
An object, heated by some source of heat, that receives a proportion of its radiation reflected back will be hotter than one that can radiate without obstruction.
But it is the heat source that does the heating, not the 'back radiation'.

I completely agree but think your golf ball analogy is flawed (aren't they always). You have forgotten the demand for golf balls that causes them to be struck and your neighbour's generosity in wanting to give them away. Your garden just happens to lie in one of the multiple directions that he is hitting them. As clearly you don't play golf (you throw), you don't want the balls. You could throw (as could your neighbours) them in all directions until they are picked up by golfers. Some of the balls you throw return to the golfer's garden but the rate at which he drives balls out remains unchanged. Some of the balls you throw bounce of the fence but land outside your garden. The fence causes the average time for a ball to be in your garden to rise slightly but your increased level of annoyance, once kicked in, keeps their numbers constant.

ssat,

Your pulley analogy suffers from Occam-syndrome - it has too many moving parts. Why a pully? Why a group of pulleys? Why friction? Too many obscure parts, analogies are supposed to be simpler than the original problem! Your counter to Martin about the supply of golf balls, and the motivations of the participants also displays a lack of focus about what the analogy was saying.

I'm getting to the point of abandonment (again) because either you believe physics or you don't. I'm not ready to abandon every advance we've made in science since the Enlightenment.

Physics, and deductive science in general, got where it is by extensions of logic. If that is true, then this is true, and if that is true, perhaps that is not true... over many years we build up layers of theorems that appear to explain everything we see. Some of the newer stuff gets overturned quickly by observation, the older stuff generally doesn't. But we don't come to theories because we like them - or we dislike a competing one. That's what the AGWers do. Countering it with another preference theory is sinking to their level.

Very very occasionally, science has made an oversight in some of the older stuff - but we only get an Einstein every so often.

On the law of averages, I don't believe that the whole of EM Theory, Thermodynamics and quantum theory have it wrong in this case. Too much modern science and technology depend on the effects we are talking abut here. Refrigeration wouldn't work without the very combination of IR photons and radiation that we are talking about. Where is your 'convection fridge' if it is such a good mechanism?

By 'denying' the basic physics behind Greenhouse theory, you are throwing away some of the oldest layers of modern physics, including the greats - Rutherford, Faraday, Einstein. I can't do that without some very good evidence. Evidence you don't have, because counter evidence exists. If greenhouse gases did not emit IR back towards the ground, our eyeballs would freeze on clear nights. We would not be able to see a spectral analysis of IR coming from a clear sky contains emission bands for H2O, CO2, CH4 and other trace gases.

It's a free country, you are allowed to believe what you like. But actual rational scientific doubt about the correlation of CO2 and global average temperature is conflated with all these voluntary non-rational beliefs in the eyes of the other side. They've used the fact that minority beliefs exist over here to rubbish the legitimate rational scientific criticism. In many ways, you have been the unwitting architects of our failure.

When I get to work I'm going to have one more try to explain the issue, not so much for you, since I now consider you a 'lost cause' in terms of convincing you, but more for anyone else still reading.

TBYJ

If greenhouse gases did not emit IR back towards the ground, our eyeballs would freeze on clear nights.

Our eyeballs do not freeze on a clear night not because of back radiation from the cold atmosphere to the warmer eyeball but because of the temperature difference between those two objects being less than the temperature difference from eyeball to space (temperature around 2degK, if it were that that you were getting at). I have not and do not deny back radiation and which you have failed to notice in your various critiques of my posts.

As far as the golf analogy goes, I assumed Martin A was describing the golfer as a source, I merely added a sink.

As far as the rope analogy goes, choose any number of pulleys you want from one upwards.

ssat

I have not and do not deny back radiation and which you have failed to notice in your various critiques of my posts.

That's not quite true is it? You may not deny its existence, but you deny its role in warming.

Martin's analogy was about the fence, not the source or sink. The fence reduces the efficiency of the garden-owner's throwing arm, meaning he has to start throwing them faster to keep up. The crux of his argument was that the fence means he has to throw faster (be warmer) than he would if the fence wasn't there. Where the sources and sinks are is irrelevant - the source is always the sun, the sink is always the vacuum of space.

"If greenhouse gases did not emit IR back towards the ground, our eyeballs would freeze on clear nights."

That can't be right. Astronauts with nothing between their eyeballs and Cassiopeia except for two inches of air and the plastic of their space helmet visor have no problems with frozen eyeballs.

Presumably the small radiation loss from the eyeball to outer space is easily replaced by heat arriving by conduction from the eyesocket and eyelid, transported directly by bloodflow to the eyeball and by convection from contact with the atmosphere.

Splitpin, convection does warm the eye, so if you were looking through a tube at the open sky, convection would no longer be able to do it, so your eyeball would freeze.

This is the same technique the native Americans used to make ice in summer. Dig a hole in the ground, line it with mud to insulate it, put some water at the bottom. Since no air movement can warm the water, it loses all its energy to the open sky by radiation, dropping its temperature to below zero.

TBYJ

You may not deny its [back radiation] existence, but you deny its role in warming.

Correct. As clearly stated by me at the beginning. Now your example of eyeballs;

Newton's Law of Cooling states that the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature.

The difference between the temperature of your eyeball and space is around 308degK. Between your eye and atmosphere, around an order of magnitude less. The net radiation loss rate is a function x [Th^4 - Tc2^4] where T is temperature, h is hotter body and c is cooler body. Using that equation for both scenarios of eyeball will show the very big difference of the rate of heat loss. In both scenarios, Tc is 'back radiating' as both are above absolute zero. In neither scenario is it necessary to calculate or even consider back radiation. Yet both you and practitioners of popular climate science both do so.

Tc2^4 Tc^4

ssat,

It's actually amusing when you cite things like Newton's Law of Cooling, because that particular theory actually supports greenhouse back-radiation theory. It would have to, or else it would have been discarded years ago. It supports my view not yours (that a nearby cooler object can inhibit loss of heat), which is why it's amusing. Let me explain.

Body A at 1000 degrees sitting in a vacuum ( at 0 )
Body A cools at a known rate proportional to 1000-0. (newton's law of cooling)
After a long time, Body A approaches 0.

Reheat Body A to 1000 degrees.

Body A at 1000 degrees sitting in a vacuum
Body B at 200 degrees placed 20cm away

This is the point you get confused. The ambient temperature that Body A experiences is an average of
all the temperatures it 'sees' in all directions. Unfortunately for you, Body B, emitting heat, is part of the
'background ambience' that Body A sees. The temperature of Body B impacts what Body A thinks it is
trying to cool to.

Body A now has an 'ambient' temperature higher than 0, because body B is part of it's ambience.
Let's say Body B eclipses 10% of Body A's view of the world.
Body A now has an ambient temperature of 10% of 200 degrees, 20 degrees, not zero.

Body A cools at a rate proportional to 1000-20 = 980.

Body A has cooled more slowly this time because of the presence of Body B.
So at any point of time > 0, Body A is warmer than it would be if Body B wasn't present.

No doubt you'll just ignore this, and plough on about eyeballs and other stuff.

TBYJ

This is the point you get confused.

Not at all. I have read your post and agree with all of it except the first paragraph. It is you that is confused as it is you that believes Body B is warming Body A by back radiation when in fact it is reducing the rate of heat loss from Body A to the zero degree vacuum you have placed them in. Here is a simple, although expensive, experiment you can do: buy two pyrgeometers* and mount them back-to-back. Place them between any two of your three temperatures and take their readings. Their direct reading of each will be a function of the potential energy of the object they are viewing, the difference between their readings will be a function of the kinetic energy moving between them. Newton's Law of Cooling states that the direction of the kinetic energy is from the hotter to the cooler.

You can buy net pyrgeometers or net radiometers here.

Oh, and eyeballs - you introduced them!

ssat

It is you that is confused as it is you that believes Body B is warming Body A by back radiation when in fact it is reducing the rate of heat loss from Body A to the zero degree vacuum you have placed them in.

OK, I'm confused, if you say so...

So how does Body B 'reduce the rate of heat loss' in Body A?

What physical mechanism are you proposing for Body B to influence Body A if they are not touching and in a vacuum?

Go on.

What physical mechanism are you proposing for Body B to influence Body A if they are not touching and in a vacuum?

I am not proposing any. I am using radiative heat transfer.

ssat,

I am not proposing any. I am using radiative heat transfer.

There is a type of logic you can't argue with. This is an example of it.

So, you finally admit radiative heat transfer keeps a warmer body warm, but somehow that's not back-radiation.

Somebody slap me.

No wonder they think we're loons.

Rhoda

Would I be right in thinking that the back-radiation over a cold ocean would be different from over a warm land in open sky conditions?

To a certain extent Rhoda, but remember the atmosphere is pretty well mixed. Also air over the ocean (even a cold one) would be more likely to contain higher amounts of H2O, so the effect of reduced ULR might be masked completely. As usual, the actual DLR at any point is a combination of complex inter-linking factors - the amounts of GHGs, how much energy is in the air (how warm it is), what the ground is made of, etc.

Like temperature, a point measurement could be swayed by many factors.

WUWT has a post at the moment which shows no trend in the DLR over the years where increasing CO2 might be supposed to have been increasing the effect. If this is borne out, then some other effect is masking the theoretical rise in DLR, which is where scientific scepticism has always has its rational roots. Not in denying basic physics with wordplay, but in saying - yes the mechanism is theoretically sound, but climate is so complex that other factors may wipe it out.

If greenhouse gases did not emit IR back towards the ground, our eyeballs would freeze on clear nights.
Jan 14, 2014 at 8:11 AM TheBigYinJames

Splitpin, convection does warm the eye, so if you were looking through a tube at the open sky, convection would no longer be able to do it, so your eyeball would freeze.
Jan 14, 2014 at 11:37 AM TheBigYinJames

But you have just said that greehouse gas radiation keeps them warm, so lack of convection due to the tube would not matter, if that is correct.

If I have read correctly, you are giving two different reasons why our eyeballs don't freeze when we look at the night sky:

- Back radiation keeps them warm (8:11 am)
- convection keeps them warm (11:37 am) (but looking at the sky through a tube would prevent convection so you'd get eyefrostbite )

The latter sounds like one of those experiements where a result is assumed to be obvious but the person describing it has never actually tried it (like the religious teacher who argued that animals do not have free will and this could be proved by putting a hungry goat midway between two bales of hay. Since the animal does not have free will, it will be unable to choose which bale to eat and so will starve.)

In the interest of science, I am willing to risk the loss of an eyeball by looking at the night sky through a tube - let me know what diameter, length and material would give the most significant effect and I'll try it. Tonight if the sky is clear and I can find a suitable tube. I'll report back tomorrow. However, I think that the risk to my eye is minimal because, as I mentioned before, the eye is warmed by conduction from the eye socket and blood flow (as well as by convection and by any radiation it receives.)

No wonder they think we're loons.
Jan 14, 2014 at 2:50 PMc c TheBigYinJames

Don't worry about it. They think we are loons anyway. A discussion to get to the bottom of what really goes on in a physical situation would be unimaginable on some of the 'antiskeptic' sites and shows a spirit of enquiry that would never be found there.

splitpin,

But you have just said that greehouse gas radiation keeps them warm, so lack of convection due to the tube would not matter, if that is correct.

The tube would do two things - cut down on convection (as I said) but also cut down on the impingent IR back radiation (which is omnidirectional) - instead of IR from a complete hemisphere of warm air, all you would be getting is the IR that managed to be vertical to get down the tube - a tony fraction of the usual. The native Americans made ice in summer this way.

You can try the experiment if you like :) I'm sure it would become uncomfortable long before your eyes froze :) (hint: it's not exactly water in your eyes - it's aqueous humor, so probably has a freeze point way under zero) If you haven't guessed already, the frozen eyeball thing was always a throwaway comment, but they would get cold if you did the experiment. You could use water with a thermometer in it. Have some water outside the tube as a control.

TBYJ

I don't finally admit anything. I have disproved your every argument, including your eyeball. Back radiation can do no work. I am not going to go around the loop again. Besides, I am learning to read those captchas too easily.

Rhoda

They, and you do and can measure it. You need a net pyrgeometer or net radiometer which are shown in my link at 1:59PM. The reason to only use the net figure should be apparent. If not, consider Marks & Spencer: they have sales figures for the Christmas period. They have returns from that in January. The net sales for the Christmas period are the first figure minus the second. The first figure is meaningless until the returns are subtracted. Similarly, the figures per store are meaningless until all stores are aggregated.

Climate scientists can go around pointing instruments to the sky and writing down numbers as much as they want. They can then calculate the average and insert it into a diagram (they do) but without knowing anything about the net figure they are kidding themselves they have a sensible measure of anything.