Is Earth's Temperature Governed by Physics Alone?

[John Creighto]

Perhaps I missing something, but shouldn't these radiation power figures be referenced to some power spectrum? That is, the measurement can not cover DC to gamma rays. The Earth Radiation Budget for instance measures 0.2 - 50.0 µ m and 0.385 - 1.02 µ m.

They are average quantities. Given that most of the energy lies between the IR and Infra Red wavelengths it is not necessary to measure the entire spectrum.

However, it would also be interesting to break it down by frequency.

 

[Xnn]

http://asd-www.larc.nasa.gov/ceres/brochure/brochure.pdf

on page 12:

Each CERES instrument has three channels—-a shortwave channel to measure reflected sunlight, a longwave channel to measure Earth-emitted thermal radiation in the 8-12 μm “window” region, and a total channel to measure all wavelengths of radiation. Onboard calibration sources include a solar diffuser, a tungsten lamp system with a stability monitor, and a pair of blackbodies that can be controlled at different temperatures. Cold space looks and internal calibration are performed during normal Earth scans.

Spectral Channels: Solar Reflected Radiation (Shortwave): 0.3 - 5.0 μm
Window: 8 - 12 μm
Total: 0.3 to >100 μm

 

[mheslep]

They are average quantities. Given that most of the energy lies between the IR and Infra Red wavelengths it is not necessary to measure the entire spectrum.

However, it would also be interesting to break it down by frequency.

The radiation balance is being reported down to ~one part in 1366W/m^2. So just how tight is the most-of-the-energy-is-longwave assumption about the outbound radiation?

 

[John Creighto]

The radiation balance is being reported down to ~one part in 1366W/m^2. So just how tight is the most-of-the-energy-is-longwave assumption about the outbound radiation?

I ment to say between IR and UV. We can look at the black body distribution to see how much energy we are missing. I do question though if it is as accurate as reported particularly for modes of energy transfer which are hard to measure like convection and evaporation.

 

[Bored Wombat]

So this is Earth Science? The Earth is not a 'coloured body'.

Sure it is. It's a body. It's got a colour. So it radiates EMR as a function of its temperature. The power radiated is proportional to the fourth power of the temperature.

 

[Phrak]

Sure it is. It's a body. It's got a colour. So it radiates EMR as a function of its temperature. The power radiated is proportional to the fourth power of the temperature.

A mirror reflecting most energy from the sun has a radiation temperature of about 5000K. Clouds reflect light.

With plenty of variable cloud cover conditions, varying widely from year to year there is plenty of opportunity for data mining to support an adhoc theory.

Without something more solid than interesting opinions on the nature of human character, and poor science, without a single reference to some energy balance study, what are we doing here?

 

[WeatherRusty]

Maybe this will answer a few questions.

http://eesc.columbia.edu/courses/ees/climate/lectures/radiation/index.html"

 

[Skyhunter]

A mirror reflecting most energy from the sun has a radiation temperature of about 5000K.

No it does not. Reflection is not emission.

With plenty of variable cloud cover conditions, varying widely from year to year there is plenty of opportunity for data mining to support an adhoc theory.

Pure speculation. Where is your references?

Without something more solid than interesting opinions on the nature of human character, and poor science, without a single reference to some energy balance study, what are we doing here?

Read your posts then ask yourself that question.

 

[Skyhunter]

I really think we should be discussing the science and not the politics but anway:


http://www.uoguelph.ca/~rmckitri/research/ispm.html

This might also be worth taking a look at:
http://www.sepp.org/Archive/controv/ipcccont/ipccflap.htm

John Creighto,

Your links are political not scientific.

If you want to discuss the politics of AGW please take it to the PW&A. I'll be happy to join you there.

 

[sylas]

The Moon is at the same average distance from the Sun as Earth and so receives the same 1366W/m^2. It has an albedo of .12 as opposed to Earth's .30...but harbors no meaningful atmosphere.

Mean surface temperature (day) 107°C
Mean surface temperature (night) -153°C

Lunar Mean surface temperature: -23CEarth's radiative equilibrium temperature: -18C (15C-33C greenhouse effect)

Why might Earth without an atmosphere be 5C warmer than the Moon without an atmosphere even though the Moon is the darker (albedo) object? The oceans? The oceans are the great reservoir of accumulated heat which maintain a higher than equilibrium temperature near Earth's surface. Where does the additional accumulated heat come from? The greenhouse effect! The warmed atmosphere baths the oceans in thermal radiation warmer than an atmosphere containing no greenhouse gases. Night time temperatures drop very little over the liquid oceans because of the large heat carrying capacity of the water, maintaining a higher average diurnal temperature than over a solid surface.

I just saw this, and have recently addressed this very issue [post=2127367]in another thread[/post]. So I'll just add a late response here to have it on record also in this thread.

You ask:

Why might Earth without an atmosphere be 5C warmer than the Moon without an atmosphere even though the Moon is the darker (albedo) object? ​

You taking the -18C temperature expected for a blackbody sphere radiating the energy the Earth receives from Sun, and comparing this with the -23C average temperature observed for the Moon.

But these are actually different things. The -18C is for the Earth is a calculated value, obtained as (0.7*1366/4/σ)^0.25. The 0.7 is (1-albedo). The 1366 is the solar constant. The 4 is a factor for spherical geometry. The σ is the Stefan-Boltzmann constant.

The proper comparison for the Moon would be to repeat the same calculation using the Moon's albedo. You get (0.88*1366/4/σ)^0.25, which is about 269.8K, or -3.3 C. This is WARMER than the same effective radiating temperature of the Earth, which is -18C. The Moon is darker, and so absorbs more radiation, and has a higher effective radiating temperature.

A better question would be... why is the average measured temperature of the Moon (-23C) so much LESS than its effective radiating temperature?

This is a consequence of the variation of temperature over the Moon's surface. The -3.3C is the temperature you would get on the Moon if it was able to conduct heat freely over the surface so as to have a single uniform temperature. When you have non-uniform temperatures over the globe, but maintain the same total emitted radiation energy level, you raise the hot parts less than you have cooled the cold parts, because the energy is temperature raised to the fourth power. Put another way, the -3.3C effective radiating temperature is an upper bound on the average temperature. (This follows from inequality[/i][/url].)

Now the ocean plays a very important role for movement of heat around the Earth surface. The ocean does not act as a source of heat, but as a large heat sink, which helps to make temperatures more uniform. There's less difference between night and day on Earth, thanks in part to the effect of the ocean. It works by smoothing temperatures out by transferring energy around the surface, NOT adding more energy.

The problem is, smoothing temperatures out should only bring the average surface temperature up to a maximum of the effective radiating temperature. And we got -18C for the Earth's effective radiating temperature. Our surface is a lot warmer than this. So it cannot be explained just by smoothing temperature out.

The solution is that the Earth radiates into space mainly from high in the atmosphere. And up high in the atmosphere, in the regions that emit most of the radiation that escapes out into space, we do indeed have temperatures around about -18C... and it's comparatively uniform, because the atmosphere moves as a fluid and so is pretty good at moving heat around within itself.

The surface is warmer than the atmosphere, because the surface has to heat up the atmosphere to this effective radiating temperature, in contrast to the Moon, where the surface radiates directly to space.

 

[Skyhunter]

This is a consequence of the variation of temperature over the Moon's surface. The -3.3C is the temperature you would get on the Moon if it was able to conduct heat freely over the surface so as to have a single uniform temperature. When you have non-uniform temperatures over the globe, but maintain the same total emitted radiation energy level, you raise the hot parts less than you have cooled the cold parts, because the energy is temperature raised to the fourth power. Put another way, the -3.3C effective radiating temperature is an upper bound on the average temperature. (This follows from inequality[/i][/url].)

Nice post sylas.

Does not the fact that the Moon rotates once every ~28 days also a key factor in the large disparity of temperature?

[Edit] Never mind. I just read your posts in the falsification thread where you already answered my question.

 

[WeatherRusty]

sylas,

Your description of the atmospheric greenhouse effect is as detailed and well stated as I have come across anywhere. Thank you!

The ocean does not act as a source of heat, but as a large heat sink, which helps to make temperatures more uniform.

But the ocean is a source of heat. It radiates in the infrared because of it's temperature. The photosphere of the Sun is not a source of heat by your definition, it radiates only because of it's temperature. The source of energy in both cases comes from the Sun's core where it is generated.

The Earth's surface and hence it's atmosphere are warmer with large bodies of liquid water present than they would be without. Oceans absorb a whole lot more solar energy and dissipate that energy much more slowly than solid land. Is this not essentially the same effect as produced by the atmospheric greenhouse (albeit a different mechanism), slowing the release of accumulated thermal energy to space, in effect concentrating it near Earth's surface thus maintaining a warmer near surface temperature even as the source of energy (solar irradiance) remains approximately constant?

If the lower troposphere is warmed adiabatically by the raising of the 255K infrared emitting layer due to additional greenhouse gases, over time will this not increase oceanic heat content independent of direct insolation as the atmosphere and oceans exchange energy?

 

[sylas]

Your description of the atmospheric greenhouse effect is as detailed and well stated as I have come across anywhere. Thank you!

I'm honoured! Thanks.

But the ocean is a source of heat. It radiates in the infrared because of it's temperature. The photosphere of the Sun is not a source of heat by your definition, it radiates only because of it's temperature. The source of energy in both cases comes from the Sun's core where it is generated.

The ocean is not a source of heat. Neither is the photosphere. They are both are in approximate energy balance, giving up only what energy they take in.

Because of its massive heat capacity, the ocean takes longer than the land to respond to changing temperatures. As a result, days are cooler and nights are warmer and there's a large flux of heat into and out of the ocean with the day and night cycle. The actual source of the heat involved is the Sun. This is stored and released within the ocean, but the net shift, in total, is zero.

Actually, that's not quite true. The ocean is at present soaking up a little bit more more heat than it receives, so there's a net effect on the surface of the Earth removing heat energy. It's a flux of energy corresponding to about 1 W/m^2 continuously over the whole surface of the Earth, going from the surface into the ocean. Roughly. It's hard to measure, but recent research is gradually pinning this down.

This is a temporary situation that follows directly from the fact that the ocean is at present warming up. If, for any reason, there is a long term net shift in temperature for the whole planet, then the ocean responds to that more slowly than the land. Until an equilibrium is reached, there will be a net flux of energy from the surface into or out of the ocean, depending on whether the net shift is up or down. This corresponds to warming, or cooling, the ocean to a new equilibrium temperature.

The Earth's surface and hence it's atmosphere are warmer with large bodies of liquid water present than they would be without. Oceans absorb a whole lot more solar energy and dissipate that energy much more slowly than solid land. Is this not essentially the same effect as produced by the atmospheric greenhouse (albeit a different mechanism), slowing the release of accumulated thermal energy to space, in effect concentrating it near Earth's surface thus maintaining a warmer near surface temperature even as the source of energy (solar irradiance) remains approximately constant?

This gets a bit subtle. Yes, there is a small net warming effect for a planet with an ocean, but this not because there's any extra heat going in or out. All that happens is that with an ocean, temperatures become more mild. Without an ocean, the cold parts of a planet would be colder, and the warm parts of a planet would be warmer. But the total energy flow out from the surface remains about the same.

This is where it gets tricky. The energy radiated from a body by virtue of its temperature is proportional to the fourth power of temperature. Hence, if the energy in any out remains precisely the same, but temperatures get smoothed out a bit, then the warm bit reduce by less than the cold bits increase.

This is where the example of the Moon is useful. The average temperature is about -23C. But if we made all the surface the same temperature, the average would be -3C. The total energy radiated back out from the surface would be the same as before; but the dayside would have cooled by 110 degrees, from 107C to -3C and the nightside raised by 150 degrees, from -153C to -3C. The calculations, which have to apply over the whole surface, are in the other thread, which I've linked above.

If the lower troposphere is warmed adiabatically by the raising of the 255K infrared emitting layer due to additional greenhouse gases, over time will this not increase oceanic heat content independent of direct insolation as the atmosphere and oceans exchange energy?

Yes, the ocean will be warmer, and hence it will have a greater "internal energy". In physics, the phrase "internal energy" is preferred to the term "heat content". The term heat is usually reserved for the transfer of internal energy by virtue of temperature difference. This is explained also in the physicsforum glossary.

It may take some time for the ocean to heat up to its new equilibrium temperature, because of the enormous heat capacity. That seems to be what is occurring at present. If we somehow held the atmospheric composition constant, then we should expect surface temperatures to continue increasing until this warming up of the ocean was complete, which would remove the small flux of heat down into the ocean. That is, there's another W/m^2 or so of additional energy which we haven't noticed because it is vanishing into the ocean. It's sometimes called "warming still in the pipeline".

I don't think the word "adiabatically" is appropriate there. A process is "adiabatic" if there's no change in the internal energy content. But with greenhouse warming, the internal energy of a given volume is greater than otherwise, for the atmosphere and for the ocean. It's just a new equilibrium state.

Cheers -- Sylas

 

[WeatherRusty]

The Earth's effective temperature of 255K is reached at approximately 16,000' above the surface on average. By raising this level, we effectively increase the temperature at all lower levels at the environmental lapse rate, ie. 6.5 deg C/1000 meters (3.6 deg F/1000 feet). This involves no vertical air motion, no loss or gain of energy across a boundary. It is solely the result of changing air pressure with changing altitude and is on average what you would experience if you ascended in a hot air balloon through dry air (relative humidity less than 100%).

Not to nitpick, but the Earth's surface is the source of energy warming the atmosphere. The source of your body heat is the food you eat. That this can all be traced back to an origin at the core of the Sun is in fact true, but not really relevant as to why your body or the surface radiates infrared. In the context of global warming, a warmer sea surface is a prerequisite to a warmer atmosphere since it is the surface that for the most part warms the atmosphere. However if the sea surface is not first warmed by increased solar irradiance, the slightly greenhouse gas warmed lower atmosphere must be warming the water as it exchanges energy with it tending toward thermal equilibrium, everything else remaining equal.

 

[sylas]

The Earth's effective temperature of 255K is reached at approximately 16,000' above the surface on average. By raising this level, we effectively increase the temperature at all lower levels at the environmental lapse rate, ie. 6.5 deg C/1000 meters (3.6 deg F/1000 feet). This involves no vertical air motion, no loss or gain of energy across a boundary. It is solely the result of changing air pressure with changing altitude and is on average what you would experience if you ascended in a hot air balloon through dry air (relative humidity less than 100%).

Correct. More or less greenhouse effect is a shift in the equilibrium. No matter how how or how high or low the effective radiating level, no matter what the mean surface temperature, there is still a balance of energy at equilibrium.

Not to nitpick, but the Earth's surface is the source of energy warming the atmosphere.

Yes. That is what I have said also, consistently in all discussions of the greenhouse effect.

The present equilibrium is roughly as follows (rounding some figures a bit):

• 170 W/m^2 from space absorbed at the surface.
• 65 W/m^2 from space absorbed into the atmosphere.
• 40 W/m^2 from the surface direct out into space. (The infrared window.)
• 450 W/m^2 from the surface up into the atmosphere. (Special heat 100 and radiant heat 350.)
• 320 W/m^2 from the atmosphere back to the surface (backradiation).
• 195 W/m^2 from the atmosphere back out to space (atmospheric emissions).

If you add up those figures, you'll see there's energy balance at surface, atmosphere and space. The total flux in from space is 235, which is equal to the total flux out into space.

You can also check the net flow between any two of surface, atmosphere and space. It is:

• Net flow from space to surface = 130 (170-40)
• Net flow from surface to atmosphere = 130 (450-320)
• Net flow from atmosphere to space = 130 (195-65)

Roughly speaking, if you increase greenhouse absorption you increase surface temperature and surface radiation. Suppose the surface radiation increases by a factor of 10%. (That's a large increase as temperature, about 7 degrees.) Assuming atmospheric absorption of solar input is unchanged, and albedo is unchanged, there's no change to the flows out of space. The flow direct from surface to space becomes 44. This means the flow from the atmosphere to space will be less, at 194. The net flow from space to surface becomes 126. (Being hotter, the surface is radiating more effectively.)

The flow up from the surface will increase, but not by 10%, because some of that flow is special heat, which should stay roughly the same to a first order approximation. Suppose we have 100 as the special heat, then the 10% increase applied to the remaining 350. That is, the total flow from surface to atmosphere increases from 450 up to 485. Because the atmosphere is in balance, the backradiation increases to 485+65-191 = 359.

In the new equilibrium state, you still have energy balance. All the input ultimately comes from space, and it is balanced by the longwave emissions. The difference between the radiant energy in and the radiant energy out at the bottom of the atmosphere is 350-320 = 30 in the original equilibrium. In the new equilibrium it reduced to 385-359 = 26.

The source of your body heat is the food you eat. That this can all be traced back to an origin at the core of the Sun is in fact true, but not really relevant as to why your body or the surface radiates infrared. In the context of global warming, a warmer sea surface is a prerequisite to a warmer atmosphere since it is the surface that for the most part warms the atmosphere.

Exactly. A stronger greenhouse effect results in a warmer surface, which also results in a warmer atmosphere... at least, for altitudes below the effective radiating level!

However if the sea surface is not first warmed by increased solar irradiance, the slightly greenhouse gas warmed lower atmosphere must be warming the water as it exchanges energy with it tending toward thermal equilibrium, everything else remaining equal.

Yes again. As the greenhouse effect increases, there's no particular effect on the solar input (ignoring secondary effects like ice-albedo feedbacks). What does increase is the atmospheric backradiation.

If you have an instantaneous change in the absorption characteristics of the atmosphere, but hold the surface temperature steady, then what changes first is the difference between upwards surface radiation and downwards backradiation. Basically, the backradiation to the surface is coming from lower down in the warmer parts of the atmosphere, as the thermal optical depth decreases. So you get an increase in backradiation, but no change (yet) in surface temperature. The excess 4 W/m^2 in the above case will be being soaked up in the ocean. Once the ocean has warmed up to the new equilibrium, you'll be back at the case of balanced energy flows. Until this occurs, there is a net flow of energy from the surface down into the ocean depths. the extra energy has come from increased atmospheric backradiation, which came ultimately from the Sun. But the actual solar input at the surface is unchanged.

Are we confused yet?

Cheers -- Sylas

 

[vorcil]

42 is the awnser

 

[skypunter]

In fact, greenhouse gases inhibit radiation to such an extent, that convection of heat is the dominate mechanism for transporting energy from the surface to elevations where it can be effectively radiated to outer space.

Why then is convection not addressed further in this thread? Probably because the heat it transports cannot be accurately quantified for modeling purposes.

When the tropics heat up, what is the result? Nature's thermostat.

Due to convection, greenhouse gases appear more like a leaky sieve than a blanket.

 

[sylas]

Why then is convection not addressed further in this thread? Probably because the heat it transports cannot be accurately quantified for modeling purposes.

Due to convection, greenhouse gases appear more like a sieve than a blanket.

I don't know what you are quoting here, but the various transports can be quantified quite nicely. There are uncertainties, but there is more than enough to establish that actually, convection is the smallest part of heat transport into the atmosphere from the surface.

If we take global averages, over all latitudes, and seasons, and times of day, the net transports work out to about

• Convection: around 17 W/m². Accuracy not particularly good, but it's around this magnitude.
• Latent heat: around 80 W/m². Accuracy here is pretty strong; it follows directly from annual precipitation. This is the heat of evaporation which is released into the upper atmosphere as water condenses.
• Radiant heat: around 63 W/m². Accuracy here is fair; enough to be confident that its rather less than the latent heat, and a lot more than the convection.

These fluxes vary enormously from day to night, of course; the numbers are mean values for the net contribution to transfer of energy from the surface up into the atmosphere.

The radiant heat numbers are confounded somewhat by the fact that it is actually measuring the difference between two very large flows of energy. There's something like 396 W/m² being radiated up into the atmosphere from the surface, and then about 333 W/m² being radiated back down again. These values are probably all good to within a couple of W/m², or 3 at the outside. Convection thus has the largest proportional uncertainty, but in absolute value they are all reasonably well constrained by empirical observations.

The basic idea of the greenhouse effect has been known for well over 100 years. I've recently been reading the work of John Tyndall, in about 1860, where he first discovered the importance of how different gases respond very differently to heat radiation. He describes how this effect results in the Earth's surface being maintained at a much warmer temperature than otherwise. Science has gone a long way since then, to quantify and understand much better how light interacts with matter.

Basic recognition that certain gases -- especially H2O and CO2 -- trap heat by strong interaction with thermal radiation is about as solid as anything in science can get.

More recent discussions of these questions can be found as follows:

• More on Tyndall's experiments, with links at [post=2187943]msg #10[/post] of "Need Help: Can You Model CO2 as a Greenhouse Gas (Or is This Just Wishful Thinking?)"
• Diagram of the various heat fluxes, with references, at [thread=307685]msg #1 of Estimating the impact of CO2 on global mean temperature[/thread].

Cheers -- sylas

 

[skypunter]

It seems that there is a great deal of attention paid to radiational "balance" formulae within the climatological community, but very little toward the acknowledgment of the dynamic nature of the atmosphere. Surely there are many studies of the thermohaline circulation, but so little data which can be applied to a practical global model.
It makes one wonder if the general scientific community is so preoccupied with proving how much it does know, that it has lost sight of how much it does not.
Just a personal observation, perhaps inappropriate here.
Advance apologies if format is breached hereby.

 

[sylas]

It seems that there is a great deal of attention paid to radiational "balance" formulae within the climatological community, but very little toward the acknowledgment of the dynamic nature of the atmosphere. Surely there are many studies of the thermohaline circulation, but so little data which can be applied to a practical global model.
It makes one wonder if the general scientific community is so preoccupied with proving how much it does know, that it has lost sight of how much it does not.
Just a personal observation, perhaps inappropriate here.
Advance apologies if format is breached hereby.

No apologies necessary -- you're doing fine. (Except that you're wrong , but that is a detail.)

I don't think the science community spends much time at all proving how much they know. All the attention is being spent on what they don't. There's one heck of a lot of acknowledgment of the dynamic nature of the atmosphere. It's fundamental, and there's a massive associated literature. There's a heck of a lot of data and theory involved in making practical global models of atmospheric circulations, and experiments in measuring as much of the atmosphere as we can, with satellite sounding, radiosondes, thereoretical modeling and so on. Have you ever thought of what goes into a weather forecast? That's mostly all atmospheric dynamics right there, and the amount of data being collected to try and make those forecasts is so vast that the biggest problems are managing it all! We've come a heck of along way over recent decades; and scientists are mostly working on improving things, rather than just trying to persuade people how great they are right now.

I'd say scientists have an excellent notion of what they know and of how much they still have to learn. And they are working away at the boundaries of knowledge, all the time.

Cheers -- sylas

 

[vorcil]

I reckon the temperature will stay at equilibrium,
With the temperature TEMPOARILY RISING it will melt ice
YES
BUT with more water being melted, it's also making it colder simutaneously due to the absorbtion of heat by the water

 

[sylas]

I reckon the temperature will stay at equilibrium,
With the temperature TEMPOARILY RISING it will melt ice
YES
BUT with more water being melted, it's also making it colder simutaneously due to the absorbtion of heat by the water

Um... you do realize that the primary reason for increasing global temperatures over the last several decades is a change in the temperature required for equilibrium?

Temperatures are increasing mainly because with increased thermal absorption in the atmosphere, a higher temperature is required to stay at equilibrium. The relevant equilibrium here is a balance between energy in from the Sun, and being radiated out again from the Earth.

Cheers -- sylas

 

[bellfreeC]

We've come a heck of along way over recent decades;

I would like an expansion on that, if you don't mind terribly. ...if you especially could fit Tim Palmer in the discussion.

MrB.

 

[bellfreeC]

Quantum Physics (quant-ph): [I see that he has six papers in this area, but maybe only one that has relevance to this thread (and my previous question on what have we learned over the past few decades) ?? -MrB.]

Quantum Reality, Complex Numbers and the Meteorological Butterfly Effect
Author: T.N.Palmer
http://arxiv.org/abs/quant-ph/0404041
(Submitted on 7 Apr 2004 (v1), last revised 17 Jan 2005 (this version, v2))
Abstract: A not-too-technical version of the paper: "A Granular Permutation-based Representation of Complex Numbers and Quaternions: Elements of a Realistic Quantum Theory" - Proc. Roy. Soc.A (2004) 460, 1039-1055.

The phrase "meteorological butterfly effect" is introduced to illustrate, not the familiar loss of predictability in low-dimensional chaos, but the much less familiar and much more radical paradigm of the finite-time predictability horizon, associated with upscale transfer of uncertainty in certain multi-scale systems. This motivates a novel reinterpretation of unit complex numbers (and quaternions) in terms of a family of self-similar permutation operators.

A realistic deterministic kinematic reformulation of the foundations of quantum theory is given using this reinterpretation of complex numbers. Using a property of the cosine function not normally encountered in physics, that it is irrational for all dyadic rational angles between 0 and pi/2, this reformulation is shown to have the emergent property of counterfactual indefiniteness and is therefore not non-locally causal.

Comments: Revised version, accepted for publication in Bulletin of the American Meteorological Society

 

[sylas]

I would like an expansion on that, if you don't mind terribly. ...if you especially could fit Tim Palmer in the discussion.

MrB.

I don't think I can do that topic justice in a post. I said that we've made a heck of a lot of progress in recent decades. The progress covers almost every aspect of climate and weather studies. There's more data, better models, more detailed physics, new sources of information. It would take a book, not a post, to take up such a broad topic as the progress in climatology in recent decades. So I'll just leave it at that.

On Dr Tim Palmer. I've never heard of him, so I'm the wrong person to ask.

I did look, however, and he sounds very impressive. His work seems to be mainly related to the effects of chaos. It looks to me that he's contributing lots of useful ideas and work on the link from climate to weather. Climate is, in my opinion, substantially less complicated than weather, and Dr Palmer is working on the link between the two, which is potentially going to be enormously significant.

What I found on looking:

• http://royalsociety.org/page.asp?id=2650, a press release from the Royal Society on his election as a Fellow of the Society.
• http://www.ecmwf.int/research/predictability/[/URL], the group at the [i]European Centre for Medium-Range Weather Forecasts[/i] headed by Dr Palmer.
  [*][URL]http://www.nature.com/nature/journal/v439/n7076/full/7076xia.html[/URL], a paper in [i]Nature[/i] Vol 439, xi (2 February 2006) doi:10.1038/7076xia
  [/list]
  
  Cheers -- sylas

 

[skypunter]

I don't know what you are quoting here, but the various transports can be quantified quite nicely. There are uncertainties, but there is more than enough to establish that actually, convection is the smallest part of heat transport into the atmosphere from the surface.

If we take global averages, over all latitudes, and seasons, and times of day, the net transports work out to about

• Convection: around 17 W/m². Accuracy not particularly good, but it's around this magnitude.
• Latent heat: around 80 W/m². Accuracy here is pretty strong; it follows directly from annual precipitation. This is the heat of evaporation which is released into the upper atmosphere as water condenses.
• Radiant heat: around 63 W/m². Accuracy here is fair; enough to be confident that its rather less than the latent heat, and a lot more than the convection.

It seems to me that radiant heat is the only one of the three which might be accurately estimated. We have plenty of spectral data coming down from satellites on a daily basis.
When I say convection, I mean any transport of heat within a rising air column, including that contained in water vapor. So if you add the latent heat to convection (both being dynamic transport mechanisms which respond to temperature) then this transport mechanism does have a greater total effect than radiant heat. It rapidly by-passes the majority of the "thermal blanket".
How do you substantiate the claim that latent heat accuracy is pretty strong?

 

[sylas]

It seems to me that radiant heat is the only one of the three which might be accurately estimated. We have plenty of spectral data coming down from satellites on a daily basis.
When I say convection, I mean any transport of heat within a rising air column, including that contained in water vapor. So if you add the latent heat to convection (both being dynamic transport mechanisms which respond to temperature) then this transport mechanism does have a greater total effect than radiant heat. It rapidly by-passes the majority of the "thermal blanket".
How do you substantiate the claim that latent heat accuracy is pretty strong?

The latent heat transported up from the surface is given precisely by the mass of water that is evaporated, and that in turn is known from the annual rate of precipitation, for which there is good data available.

The latent heat plus convection is much less than the one-way radiant heat flux up from the surface; but if you consider the difference between radiant heat going up and the backradiation coming down, then the numbers are as I gave previously and as you have quoted, up to the measurement errors. Convection is easily the smallest contribution; but if you put convection and latent heat together as "special heat", then it is about half as much again as the net upwards radiant heat flux.

Radiant heat up from the surface is much harder to measure than you might think at first. The great majority of the radiant heat is absorbed by the atmosphere. Satellites can only see through the atmosphere at those wavelengths where the atmosphere is transparent. This is called the "infrared window". But satellites cannot see to the surface across the spectrum, and so the radiant heat transport into the atmosphere must be obtained more indirectly.

The methods used for estimating all the various fluxes are explained in Trenberth, K.E., Fasullo, J.T., and Kiehl, J. (2009) http://ams.allenpress.com/archive/1520-0477/90/3/pdf/i1520-0477-90-3-311.pdf , in Bulletin of the AMS, Vol 90, pp 311-323.

Cheers -- sylas

Postscript, added in edit: Here is a diagram of energy flows, from Trenberth et al (2009)

 

[bellfreeC]

It seems to me that radiant heat is the only one of the three which might be accurately estimated.

if you put convection and latent heat together as "special heat", then it is about half as much again as the net upwards radiant heat flux.

This is Chjoaygame:

"Inside the window, one is interested in separate radiative transfer of heat from the land-sea surface. The mean free path of "single photons", when the air is relatively dry and the CO2 relatively little, can be hundreds of kilometers. The very importantly and greatly variable IR radiative flux through the window, direct from the land-sea surface to space, is on the order of magnitude of 60 W m^-2. In a cloudless sky, the notion of "back-radiation" does not arise here.

Consequently, the overwhelming varying, and nearly the only, flow, of back radiation from atmosphere to land-sea surface is from the lower surfaces of clouds."1


"Clouds are king."2 That is how I put it.
MrB.
1. msg=34 of thread id:252066
2. msg=160 of thread id:204120

 

[bellfreeC]

The phrase "meteorological butterfly effect" is introduced to illustrate, not the familiar loss of predictability in low-dimensional chaos, but the much less familiar and much more radical paradigm of the finite-time predictability horizon, associated with upscale transfer of uncertainty in certain multi-scale systems.

"The fifties and sixties were years of unreal optimism about weather forecasting. Newspapers and magazines were filled with hope for weather science, not just for prediction but for modification and control. Two technologies were maturing together, the digital computer and the space satellite."1,2

Well, i would say things haven't changed... about being unreal.

"Precise long-term weather-forecasting is impossible, because the two-week time barrier cannot be surmounted; in order to do so, one would need unlimited precision both in the initial conditions and in the computer interations, and both requirements are absurd.

Long-term climatological prediction on the other hand is possible, because the existence of a strange attractor shows that only certain kinds of turbulent motion will occur. The tool of long-term prediction is the calculation of physical quantities averaged by integration over the entire attractor. Since everyone is allowed to dream, we can imagine a day when we shall know the strange attractor say of the département du Rhône, and its deterministic evolution in time; that would enable us to predict, for May next year, 5 cm of precipitation, 17 sunny days, and an average temperature of 15°C. this kind of prediction would prove extremely useful for all outdoor econonmic activities like farming, building, transport, and so on, which underlines the value of abstract research on strange attractors, since it could lead to the solution of very concrete problems."3

I would not consider one-year forecasts climate but I am not sure it has a name. Anyway, I get the impression that Tim Palmer would laugh less than I would and from Sylas: I think we can at least get a chuckle. Am I right? Of the three of us; Dr. Palmer{which opens this post} is clearly the expert.
http://www.fortunecity.com/emachines/e11/86/weather.html

"Tim Palmer is head of the predictability and diagnostics section of the European Centre for Medium-Range Weather Forecasts in Reading, Berkshire," and the ECMRWF is featured in Gleick's famous book_Chaos_.

Here is what he says on the physics used as part of a whole climate attractor:

The critical question that climatologists are trying to answer is whether the climate attractor will suffer a minor perturbation (for example, small shift of the whole attractor along one of the axes of phase space), or whether there will be a substantial change in the whole shape and position of the attractor, leading to some possibly devastating weather states not experienced in today's climate.

Yeah, good luck on that! Color me dubious on any efficacy for emergency managment teams.
MrB.

1. Gleick, James(1987) p18.
2. https://www.physicsforums.com/showpost.php?p=2194226&postcount=30
****[ http://www.wilsoncenter.org/index.cfm?fuseaction=wq.print&essay_id=231274&stoplayout=true of "The Climate Engineers"]
3. Ruhla, Charles(1989) as translated by Barton(1992) p142.

 

[sylas]

This is Chjoaygame:

"Inside the window, one is interested in separate radiative transfer of heat from the land-sea surface. The mean free path of "single photons", when the air is relatively dry and the CO2 relatively little, can be hundreds of kilometers. The very importantly and greatly variable IR radiative flux through the window, direct from the land-sea surface to space, is on the order of magnitude of 60 W m^-2. In a cloudless sky, the notion of "back-radiation" does not arise here.

I don't think you have any idea of what you are reading. You don't use old threads on physicsforum as primary sources. You must backup your claims with legitimate scientific references. Not old threads.

I have no idea who chjoaygame is... he's a user here apparently and otherwise an unknown.

The statement above seems fine, and you've failed to comprehend what it is about. It is about the thermal radiation in the infrared window, where the atmosphere is transparent. The flux direct to space from the surface though this window is indeed of the order of magnitude 60 W/m², and this does depend very much on cloud. In clear sky conditions it is about 100 W/m² and when there is heavy cloud it can be zero. In the flux diagram I have shown above, this component is given as 40 W/m². This is a similar order of magnitude, and the difference between 40 and 60 probably depends mostly on how the window is being defined.

In any case, there is OF COURSE almost no backradiation in this band, precisely because this is where the atmosphere is transparent.

The great majority of backradiation comes from the atmosphere, not from cloud, and OF COURSE it comes from the bands of the spectrum where there is strong interaction of greenhouse gases with thermal radiation. This flow of heat from the atmosphere down to the surface, night and day, clear and cloud, all the time. Clouds contribute in total much less than the atmosphere itself.

Direct measurements of backradiation were first made in about 1954. These were made in clear sky conditions, and repeated in the day and in the night, over a period of 6 months. Observations were made near to Frederick, Maryland. The night time backradiation measured was about 290 W/m² on average, ranging from about 270 to 310. The daytime values measured were about 360 W/m² on average, ranging from about 320 to 420 W/m².

Remember – these are all clear sky measurements, with no cloud involved.

Reference: Stern, S.C., and F. Schwartzmann, 1954: url=http://ams.allenpress.com/perlserv/?request=get-abstract&issn=1520-0469&volume=011&issue=02&page=0121[/URL]. J. Atmos. Sci., 11, 121–129.

 

[skypunter]

The latent heat transported up from the surface is given precisely by the mass of water that is evaporated, and that in turn is known from the annual rate of precipitation, for which there is good data available.

Perhaps the rate of past precipitation can be measured, but can it be accurately forecast over the long term?
Surely an estimation of heat transport based upon past precipitation cannot be treated as a constant in climate models.

 

[sylas]

Perhaps the rate of past precipitation can be measured, but can it be accurately forecast over the long term?
Surely an estimation of heat transport based upon past precipitation cannot be treated as a constant in climate models.

You were asking about the measurement of energy flows and how well they are known. The diagram I showed is energy flow in the present based on empirical data for the period March 2000 to May 2004.

Cheers -- sylas

 

[vanesch]

What has been concluded (TS.4.5 on page 64) is that the Earth's temperature is sensitive to changes of CO2 concentration. In particular, equilibrium change is likely to be in the range 2°C to 4.5°C per doubling of CO2, with a best estimate value of about 3°C.

Just a question, as we are talking about the *physics* of this effect. When you do the calculation with MODTRAN, you find rather 0.9 K per doubling of CO2 if you switch of water vapor feedback (keep same partial pressures for water vapor).

http://geosci.uchicago.edu/~archer/cgimodels/radiation.html

Do the standard calculation (CO2 = 375 ppm) and you find an upward flux of 287.844 W/m^2 (at ground temp 299.7 K).

Now, put CO2 to 750 ppm, and put the ground offset to 0.9 K, then you find an upward flux of 287.875 W/m^2.

So this would mean that in order to put the same heat flux out when we have a CO2 doubling, and we make the assumption of "all else equal", especially water vapor, so no feedback mechanisms or anything, that the *purely optical* effect gives rise to a needed heating of 0.9 K to have again the same outward heat flux.

Is this, according to climatologists, still a correct way of seeing the "primary drive" ? As a physicist, I would say so, in as much as MODTRAN is a correct optical radiation transport model.

(you can of course vary several things, different atmosphere models etc... but you always find values of a bit less than 1 K).

 

[sylas]

Just a question, as we are talking about the *physics* of this effect. When you do the calculation with MODTRAN, you find rather 0.9 K per doubling of CO2 if you switch of water vapor feedback (keep same partial pressures for water vapor).

http://geosci.uchicago.edu/~archer/cgimodels/radiation.html

Do the standard calculation (CO2 = 375 ppm) and you find an upward flux of 287.844 W/m^2 (at ground temp 299.7 K).

Now, put CO2 to 750 ppm, and put the ground offset to 0.9 K, then you find an upward flux of 287.875 W/m^2.

So this would mean that in order to put the same heat flux out when we have a CO2 doubling, and we make the assumption of "all else equal", especially water vapor, so no feedback mechanisms or anything, that the *purely optical* effect gives rise to a needed heating of 0.9 K to have again the same outward heat flux.

Is this, according to climatologists, still a correct way of seeing the "primary drive" ? As a physicist, I would say so, in as much as MODTRAN is a correct optical radiation transport model.

(you can of course vary several things, different atmosphere models etc... but you always find values of a bit less than 1 K).

Yes, that is correct. You are getting what is sometimes called the "Planck Response". This would be the temperature response of the Earth to a forcing if nothing else changed. Yes, this can be considered a kind of base response; and any feedback effects can be considered as amplification of this basic response.

There's one minor complication, because if you look at the literature you'll usually see slightly higher numbers for the Planck response; more like 1.1 or 1.2 K. You can get this with MODTRAN by locating your sensor at about the tropopause, rather than the 70km default. Try getting the radiation at an altitude of 18km with the tropical atmosphere. In this case, you should have something like this:

• 288.378 W/m² (375ppm CO₂, Ground Temp offset 0, tropical atmosphere, 18km sensor looking down)
• 283.856 W/m² (750ppm CO₂, Ground Temp offset 0, tropical atmosphere, 18km sensor looking down)
• 288.378 W/m² (750ppm CO₂, Ground Temp offset 1.225, tropical atmosphere, 18km sensor looking down)

I think I can explain what is going on here. It's a minor additional detail to do with how the stratosphere works.

When you hold surface temperature fixed, MODTRAN will hold the whole temperature profile of the atmosphere fixed.

Now consider the effect of extra CO₂ in the stratosphere. The stratosphere has a negative lapse rate, because it is heated primarily by direct absorption of solar radiation, with ozone in particular. Adding extra CO₂ up here actually has a cooling effect, because a greenhouse gas is better both at absorbing and emitting radiation. Whether this helps warm things up or cool things down depends on temperatures of background radiation.

Up in the stratosphere, all the hot surface radiation that CO₂ could normally absorb is already absorbed lower down. Mostly what the stratosphere sees in these bands is the tropopause... which is very cold indeed. Hence the stratosphere is warmer than the surrounding thermal radiation, and the effect of CO₂ is to let it emit thermal radiation more effectively... and cool down. Furthmore, this happens rapidly. It's not at all like the gradual heating up of the surface, with all the other stuff going on with evaporation and convection, and changes to ground cover etc. The stratosphere heats up and cools down very quickly, and by quite large amounts. The cooling trend of the stratosphere over recent decades is one of the strongest temperature trends on the planet... and this is in fact one of the "signatures" of an increasing greenhouse effect.

The cooling of the stratosphere is so immediate that it is not treated as a feedback process at all, but is taken up as part of the definition of a change in energy balance. Hence MODTRAN is not quite giving you what is normally defined as the Planck response. To get that, you would have to drop the stratosphere temperature, which would reduce the thermal emission you are measuring a little bit. By placing the MODTRAN sensor at the tropopause, you are avoiding worrying about the stratosphere at all, and getting a better indication of the no-feedback Planck response.

References: the standard definition of forcing notes that the stratospheric response is considered separately from response below the tropospuase. See IPCC 4AR WG-1 "The Physical Science Basis" (Chapter 2, section 2.2, page 133):

[Radiative forcing is] the change in net (down minus up) irradiance (solar plus longwave; in W m^-2) at the tropopause after allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values.​

The notion of Planck response is given throughout the literature. A good introductory reference is Bony, S. et. al. (2006) How Well Do We Understand and Evaluate Climate Change Feedback Processes, in J. of Climate, Vol 19, 1 Aug 2006, pp 3445-3482. Extract:

The Planck feedback parameter λ_P is negative (an increase in temperature enhances the LW emission to space and thus reduces R) and its typical value for the earth’s atmosphere, estimated from GCM calculations (Colman 2003; Soden and Held 2006), is about -3.2 W m^-2 K^-1 ..​

Since the forcing of doubled CO₂ is 3.7 W/m², the Planck response here is about 1.16 K per doubling of CO₂.

That's just a bit of background to help explain why you will usually see slightly different numbers for no-feedback response being used in the literature. You've got the principle idea, however; it is the temperature response to balance energy in the absence of any feedback processes.

Cheers -- sylas

PS. Just to underline the obvious. The Planck response is a highly simplified construct, and not all like the real climate response. The real climate response is as you quoted from Xnn: somewhere from 2 to 4.5 K/2xCO₂. It is the real response that you can try to measure empirically (though it is hard!). You can't measure Planck response empirically, because it is a theoretical convenience.

The full response in reality is just as much physics as the simplified Planck response; real physics deals with the real world in all its complexities, and the climate feedbacks are as much as part of physics as anything else.

 

[bellfreeC]

The diagram I showed is energy flow in the present based on empirical data for the period March 2000 to May 2004.

Yes, this has been provided many times. "Figure — Details of Earth's energy balance (source: Kiehl and Trenberth, 1997). Numbers are in watts per square meter of Earth's surface, and some may be uncertain by as much as 20%..." The black and white version that currently brings up the rear of thread id:123613 was by AEBanner, June19-06. Why shouldn't old threads be remembered?

The statement above seems fine, and you've failed to comprehend what it is about. It is about the thermal radiation in the infrared window,

Thread id:204120!

The earliest thread that I see "an infrared window" appearing in is thread id:243619.
I win that pissing match.

To quote you, Sylas, from that thread,
"For a gas, or any transparent medium, the emissivity and absorptivity depends on the path length through the gas. It's no longer a dimensionless ratio, but has units of inverse length. Alternatively, you can speak in terms of "optical depth".

Much of your discussion on emissivity is a bit muddled as a result." Yes, we agree that plenty of muddled thinking is going on. I'm figuring it is you. People seem to have crazy ideas on how greenhouses and their roofs work. But until I can find the thread that mentioned your ideas on the average greenhouse glass roof, never mind.

Unless, you care to refresh my memory...?
MrB.