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CO2 is not the only driver of climate

Posted on 25 October 2009 by John Cook

Climate scientists tend to go on a bit about CO2. However, as readers often point out, CO2 is not the only driver of climate. There are a myriad of other radiative forcings that affect the planet's energy imbalance. Volcanoes, solar variations, clouds, methane, aerosols - these all change the way energy enters and/or leaves our climate. So why the focus on CO2? Is it because scientists are all hysterical treehuggers determined to run peoples' lives with a one world government? Or is there a rational, scientific reason for this CO2 preoccupation? Let's find out which...

When I first started investigating global warming science, I attempted to discern the cause by a process of elimination. I studied all possible causes and ruled out any that couldn't be causing all the warming. As my understanding grew, I came to realise this was an inappropriate approach. Understanding what drives climate does not occur by a process of elimination. It's happens by a process of integration. There are many influences of climate and they all need to be considered together to gain the full picture.

For clarity, let me note a few definitions. Radiative forcing is loosely defined as the change in net energy flow at the top of the atmosphere. In this post, we're talking about the radiative forcing from 1750 to 2005. Values are taken from Chapter 2 of the IPCC AR4 which in turn took all their values from peer reviewed papers - apologies that I was too lazy to cite all the original sources. Positive radiative forcing has a warming effect (so obviously, negative radiative forcing has a cooling effect).

  • Surface Albedo has changed due to activity such as deforestation. This increases the Earth's albedo - the planet's surface is more reflective. Consequently, more sunlight is reflected directly back into space, giving a cooling effect of -0.2 Wm-2.
  • Ozone affects the climate in two ways. The depletion of stratospheric ozone is estimated to have had a cooling effect of -0.05 Wm-2. Increasing tropospheric ozone has had a warming effect of +0.35 Wm-2.
  • Solar variations affect climate in various ways. The change in incoming Total Solar Irradiance (TSI) has a direct radiative forcing. There is an indirect effect from UV light which modifies the stratosphere. The radiative forcing from solar variations since pre-industrial times is estimated at +0.12 Wm-2. Note that the radiative forcing from solar variations may be amplified by a possible link between galactic cosmic rays and clouds. However, considering the sun has shown a slight cooling trend over the last 30 years, an amplified forcing from solar variations would mean a greater cooling effect on global temperatures during the modern warming trend over the last 35 years.
  • Volcanoes send sulfate aerosols into the stratosphere. These reflect sunlight, cooling the earth. A strong volcanic eruption can have a radiative forcing effect of up to -3 Wm-2. However, the effect of volcanic activity is transitory - over several years, the aerosols wash out of the atmosphere and any long term forcing is removed.
  • Aerosols have two effects on climate. They have a direct cooling effect by reflecting sunlight - this is calculated from observations to be -0.5 Wm-2. They also have an indirect effect by affecting the formation of clouds which in turn affect the Earth's albedo. The trend in cloud cover is one of increasing albedo which means a cooling effect of -0.7 Wm-2.
  • Stratospheric Water Vapour has increased due to oxidation of methane and had a slight warming effect of +0.07 Wm-2.
  • Linear Contrails from aviation have a slight warming effect of +0.01 Wm-2.
  • Nitrous Oxide reached a concentration of 319ppb in 2005. As a greenhouse gas, this contributes warming of  +0.16 Wm-2.
  • Halocarbons (eg - CFC's) were used extensively in refrigeration and other industrial processes before they were found to cause stratospheric ozone depletion. As a greenhouse gas, they cause warming of +0.337 Wm-2.
  • Methane is actually a more potent greenhouse gas than CO2. Pre-industrial methane levels, determined from ice core measurements, were around 715 parts per billion (ppb). Currently methane rates are at 1774 ppb (eg - 1.774 parts per million). The radiative forcing from methane is +0.48 Wm-2.
  • CO2 levels have increased from around 280 parts per million (ppm) in pre-industrial times to 384 ppm in 2009. The radiative forcing from CO2 is +1.66 Wm-2. CO2 forcing is also increasing at a rate greater than any decade since 1750.

Here's a visual summary of the various radiative forcings:


Figure 1: Global mean radiative. Anthropogenic RFs and the natural direct solar RF are shown. (IPCC AR4 Figure 2.20a)

Putting it all together, Figure 2 compares the warming from human caused greenhouse gases to the total radiative forcing from all human sources.


Figure 2: Probability distribution functions (PDFs) from combining anthropogenic radiative forcings. Three cases are shown: the total of all anthropogenic radiative forcings (block filled red curve); Long-lived greenhouse gases and ozone radiative forcings (dashed red curve); and aerosol direct and cloud albedo radiative forcings (dashed blue curve). Surface albedo, contrails and stratospheric water vapour RFs are included in the total curve but not in the others. Natural radiative forcings (solar and volcanic) are not included in these three PDFs. (IPCC AR4 Figure 2.20b)

Greenhouse gases and ozone contribute warming of +2.9 Wm-2. The majority of this is from CO2 (+1.66 Wm-2). This warming is offset by anthropogenic aerosols, reducing the total human caused warming to 1.6 Wm-2. So surprisingly, the warming from CO2 actually exceeds the final total radiative forcing. If ever asked how much CO2 contributes to global warming, you could say "all of it... and some!" But a more appropriate response would be to list the various contributors of forcing, both negative and positive, although this may cause the questioner's eyes to glaze over (and wish they'd never asked). Framing science is never easy.

The other important point to glean from Figure 2 is that we have a relatively high understanding of greenhouse gas radiative forcing. The probability density function (PDF) shows a much higher probability than the aerosols PDF, meaning the uncertainty associated with greenhouse gas forcing is much lower. This degree of confidence is also confirmed by experimental observations from both satellites and surface measurements which confirm the degree of enhanced greenhouse effect from rising greenhouse gases.

So bringing it all together, there are two reasons for the focus on CO2:

  1. CO2 is the most dominant radiative forcing
  2. CO2 radiative forcing is increasing faster than any other forcing

UPDATE: just read an interview with climate scientist Ken Caldeira which focuses on the issue of geoengineering. But one particular quote summed up the issues discussed above:

Question: They also write that you are convinced that human activity is responsible for “some” global warming. What does that mean?

Caldeira: I don’t think we can say with certainty whether we’re responsible for 90 percent of it or we might be responsible for 110 percent of it. But the vast majority of global warming, I believe, is due to human release of greenhouse gases to the atmosphere.

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Comments 101 to 136 out of 136:

  1. Tom Dayton - re:Your Post #100 Yes, of course you will see your reflection. What's your point?
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  2. Gord, while I wait for your answer to my comment 100, here is the Rabett's version of the explanation that folks in this thread having been trying to get you to understand: http://rabett.blogspot.com/2009/03/second-law-and-its-criminal-misuse-as.html
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  3. Gord, 3. Please describe (and back-up by Physics) how a -20 deg C atmosphere can heat a -18 deg C Earth up by 33 deg C to a whopping +15 deg C. I don't have to describe how that might happen because it does not and can not happen the way you assume it must, in violation of the Laws of Thermodynamics. You are the one arguing outside the mainstream in defiance of well understood physics. A colder atmosphere does not radiate at higher energy than the warmer surface. The flow of energy from the solar warmed surface is on average out to space, the tendency is always, in the absence of sunshine and warm air advection, for the surface and atmosphere to cool. Atmospheric greenhouse gases increase the time required for the dissipation of energy to space by effectively decreasing the mean free path of individual photons. A surface that cools more slowly ends up being a warmer surface. It can't be described any more simply.
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  4. What would happen to the Sun if the gases overlying the stellar core were not opaque to electromagnetic radiation? The core would be layed bare to gamma radiation which would rush out instantly cooling the stellar interior in a flash. The whole star would collapse in on itself due to a lack of "radiation pressure" which holds up the body of the Sun against the force of gravity. Just as the Sun's interior is kept hot by overlying radiation absorbing matter, so is Earth's surface kept warmer by greenhouse gases absorbing IR radiation. The physics is the same, even if the exact mechanism leading to the absorption of radiation differs.
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  5. My point, Gord, is to then ask you to stand again in front of the bathroom mirror but aim a regular, visible-light, flashlight at the mirror. Aim it angled so the light reflects off of the mirror into your eyes, not straight back into the flashlight. Question 1: Is your answer the same as in #101? That is, do you agree with me that light from the flashlight traveled to the mirror, reflected off the mirror, traveled to your eyes, and was absorbed by your eyes? Now angle the flashlight so it is aimed directly at the mirror, so if you were inside the flashlight you would see the full image of the flashlight's lit lamp head-on. Question 2: Do you agree with me that the light from the flashlight's lamp travels to the mirror, reflects off the mirror, and illuminates the interior of the flashlight, including the lamp?
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  6. In order to have a serious scientific discussion, we have to agree on the description of phenomena. Gord shows no respect for that principle, on the contrary, he continues to make absurd claims like requesting us to explain "how a -20 deg C atmosphere can heat a -18 deg C Earth up by 33 deg C". Exactly, my greenhouse glassing heats the greenhouse! This is rather elementary radiation physics, well understood, and it is Gord's business to walk through the textbook examples, and point out where they are wrong - NOT where he thinks they are wrong, but where they produce demonstrably false predictions. It's very interesting whenever someone is able to show that a theory gives false predictions, but in order to do that, you have to get "inside" the theory. Not belief-wise, but technically, so you are sure that you are not mis-applying it. Gord does not seem to be in the position to apply the standard basic theory correctly. The inconsistencies he perceives come from his lack of understanding, not the basic theory itself.
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  7. Tom Dayton - re:your post#102 I answered your post#100 in my post#101 Now re: Droppings along the bunny trail Saturday, March 21, 2009 The Second Law and its Criminal Misuse "If the Clausius statement referred to any flow of heat when the two disks were placed opposite each other B would have to stop radiating towards A because if it did not, heat would be transferred between a body at lower temperature to a body at higher temperature. This is obviously absurd. The ability of either disk to radiate does not depend on the presence of another disk that absorbs the emitted radiation." "The ability of either disk to radiate does not depend on the presence of another disk that absorbs the emitted radiation." is correct. The rest is utter nonsense! Rabett obviously does not understand that the radiated Electromagnetic Fields are VECTOR fields and must be treated as such. Gerlich and Tscheuschner made that point very clear in their paper. Rabett's explaination is so dense it is astounding. The simple existance of the Interference Properties Of Waves proves that Rabett has absolutely zero knowlege of Electromagnetic Physics. Interference (wave propagation) "In physics, interference is the addition (superposition) of two or more waves that results in a NEW WAVE pattern." http://en.wikipedia.org/wiki/Interference_(wave_propagation) Electromagnetic Physics has been in constant use by Electrical Engineers and Physicists for over a hundred years. Every Antenna radiation pattern design, every TV-Radio transmission, every Satellite link, every Microwave link, every Optical/IR link etc. uses Electromagnetic Fields as VECTOR fields. Somebody should explain that to the "Rabett"! Maybe he could make the big leap in understanding to include the late 19th Century Physics. ---------- Rabett's Heat Transfer examples totally ignore Electromagnetic Field Vectors and can also be easily disproven using The Law of Conservation of Energy. Example: Look at Rabett's diagram where he has the Surface T = 300K and Atmosphere T = 260K. Surface T = 300K is due to the ONLY energy source...The Sun....that's ALL the energy it can receive PERIOD. The Surface and Atmosphere ARE NOT ENERGY SOURCES! If ANY energy flows from the Colder Atmosphere T = 260K to the warmer Surface T = 300K then Surface T would have to increase in temperature thus CREATING energy. This is as basic as it gets....YOU CAN'T GET MORE ENERGY OUT OF A SYSTEM THAN YOU PUT IN! --------------------- Rabett Run is perfectly named...."droppings along the bunny trail".
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  8. WeatherRusty - re:your post#103 RE: Please describe (and back-up by Physics) how a -20 deg C atmosphere can heat a -18 deg C Earth up by 33 deg C to a whopping +15 deg C. You said... "I don't have to describe how that might happen because it does not and can not happen the way you assume it must, in violation of the Laws of Thermodynamics. You are the one arguing outside the mainstream in defiance of well understood physics." If it is "well understood physics"...then don't "babble" about it....POST THE PHYSICS! ------ You said.... "Atmospheric greenhouse gases increase the time required for the dissipation of energy to space by effectively decreasing the mean free path of individual photons. A surface that cools more slowly ends up being a warmer surface. It can't be described any more simply." Photon energy is carried by Electromagnetic Fields that propagate at the speed of light. All surfaces that have a temperature will radiate energy according to their temperatures....at the speed of light...they don't speed up or slow down. "In physics, interference is the addition (superposition) of two or more waves that results in a NEW WAVE pattern." The NEW WAVE produced will have a magnitude of [Earth Radiation w/m^2 - Atmosphere w/m^2] and a direction toward the colder atmosphere. This is also confirmed by the 2nd Law. This NEW WAVE also travels at the speed of light. It can't be described any more simply.
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  9. Tom Dayton - re:your post#105 You asked... Question 1: Is your answer the same as in #101? "...do you agree with me that light from the flashlight traveled to the mirror, reflected off the mirror, traveled to your eyes, and was absorbed by your eyes? Answer: Yes to both. Your eyes are lenses that concentrate the reflected EM energy at a focal point. ------ You asked... "Now angle the flashlight so it is aimed directly at the mirror, so if you were inside the flashlight you would see the full image of the flashlight's lit lamp head-on. Question 2: Do you agree with me that the light from the flashlight's lamp travels to the mirror, reflects off the mirror, and illuminates the interior of the flashlight, including the lamp?" No, the hot lamp filament CANNOT absorb the reflected energy because it has a smaller flux density w/m^2 compared to w/m^2 leaving the filament. If the filament absorbed the reflected light it would have to increase the filament's energy and temperature. If the filament increased in temperature, it would produce more light. More light would be reflected back to the filament causing it's temperature to rise again, producing more light etc. The process would continue until the filament reached an infinite temperature producing infinite energy. This would be called a Perpetual Motion machine in a positive feed-back loop. Just like the FANTASY "Greenhouse Effect" produces.
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  10. SNRatio - re:your post#106 You said... "Gord shows no respect for that principle, on the contrary, he continues to make absurd claims like requesting us to explain "how a -20 deg C atmosphere can heat a -18 deg C Earth up by 33 deg C". Exactly, my greenhouse glassing heats the greenhouse!" "This is rather elementary radiation physics, well understood, and it is Gord's business to walk through the textbook examples, and point out where they are wrong - NOT where he thinks they are wrong, but where they produce demonstrably false predictions." Really? If it is "rather elementary radiation physics, well understood" then it should be a "snap" for you to explain it and back-up your answer with Physics...right? Intead of "babbling" about it why don't you just DO IT? You CAN'T because it requires a VIOLATION of the 2nd Law of Thermodynamics and a VIOLATION of The Law of Conservation of Energy. COME ON....PROVE ME WRONG! HAHAHA...Good Luck!
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  11. Gord, You Said: "Photon energy is carried by Electromagnetic Fields that propagate at the speed of light." Yes, until absorbed by a greenhouse gas molecule. The photon has at that moment ceased to exist, being converted to and added to the kinetic energy of the molecule. "All surfaces that have a temperature will radiate energy according to their temperatures....at the speed of light...they don't speed up or slow down." The propagation of energy is interrupted by greenhouse gas absorption. The propagation to space is not at the speed of light, the propagation between subsequent absorptions and emissions, reflecting the free path of the photon, is at the speed of light. The flow of energy exiting the system is slowed down. "The NEW WAVE produced will have a magnitude of [Earth Radiation w/m^2 - Atmosphere w/m^2] and a direction toward the colder atmosphere." With respect to the directionality of energy, electromagnetic radiation is not heat and heat is not radiation. By the above statement you clearly confuse the two. Radiation is emitted in all directions, no direction is preferred for any reason. Heat, or more specifically a temperature gradient within matter will tend toward equalization as determined by the second law, entropy.
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  12. Gord, given that we were not able to explain the physics, let's try a different approach and see some consequences of your model. Just to make it simple, assume that all the radiation coming from the earth surface is totally absorbed. - the atmosphere absorbs 390 W/m^2 from the earth and emits the same amount but both upward and downward, twice the amount it absorbs; - the atmosphere changes it's temperature but not the earth surface; alternatively, the atmosphere does not warm upon absorption but then it must be at 0 K. - the net flux between atmosphere and earth surface is zero but the earth does not warm while still receving the flux from the sun; - the temperature of a planet is determined only by the distance from the sun and its albedo. For example, the moon (albedo 0.12) must be warmer than earth and Mercury (albedo 0.12 and nearer to the sun) warmer than Venus (albedo 0.7). For the same reason, the temperature variations of the earth across millennia are explained only by solar forcing and albedo feedback, both in timing and magnitude; a pretty regular pattern, indeed. - the same reasoning must apply to incoming solar radiation as well; if it is totally absorbed by the atmosphere the only change at the earth surface can be that it is now diffused radiation as opposed to direct radiation but temperature is unchanged. These are the first five i can think about. Many other both related and non-related to planetary climate can be immagined. But if you find even just one of the above not matching reality, the model is incomplete (at the very minimum) or plainly wrong.
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  13. Okay, Gord, since you answered my question #2 by saying the lamp filament cannotabsorb the reflected energy, here is the crucial followup question: What happened to the photons that were innocently traveling from the mirror toward the filament, having started their journey from the mirror blissfully unaware that their destination was hotter than the mirror they came from? 1. Did they self-destruct before they got there? If so, where did their energy go? How far away from the filament did they self-destruct? Is the distance from the filament what triggers their destruction, or is there some other trigger? 2. Or did the photons maneuver to the side of the filament to avoid it? If so, how did they maneuver--did they do it themselves, or did some outside force move them? How close to the filament did they get before they swerved? 3. Or were there no photons emitted by the filament straight toward the mirror, because the filament emitted those photons at an angle in order to avoid a head-on reflection? 4. Or did the filament emit fewer photons, because it refrained from emitting any straight toward the mirror?
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  14. WeatherRusty - re:your post#111 You said... "Yes, until absorbed by a greenhouse gas molecule. The photon has at that moment ceased to exist, being converted to and added to the kinetic energy of the molecule." Wrong. Energy cannot be created or destroyed. Whatever energy the gas absorbed will be re-emitted. -------------- You said... "The propagation of energy is interrupted by greenhouse gas absorption. The propagation to space is not at the speed of light, the propagation between subsequent absorptions and emissions, reflecting the free path of the photon, is at the speed of light. The flow of energy exiting the system is slowed down." Wrong. ALL propagating EM waves travel at the speed of light....they are light...only the frequency varies! HAHAHA....Tell that "story" to the Cop that gives you your next 'radar' speeding ticket. Now, that would be funny. --------------- You said... "With respect to the directionality of energy, electromagnetic radiation is not heat and heat is not radiation. By the above statement you clearly confuse the two." You are hilarious! Ever hear of Field Vectors ? (HAHAHA..They have been used for over a hundred years) Vector addition of fields... http://hyperphysics.phy-astr.gsu.edu/hbase/electric/mulpoi.html#c3 ------ Heat Radiation Radiation is heat transfer by the emission of electromagnetic waves which carry energy away from the emitting object. For ordinary temperatures (less than red hot"), the radiation is in the infrared region of the electromagnetic spectrum. The relationship governing radiation from hot objects is called the Stefan-Boltzmann law: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2 ------- Heat flux "Heat flux or thermal flux, sometimes also referred to as heat flux density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI units, it is measured in [W·m-2]. It has both a direction and a magnitude so it is a vectorial quantity." http://en.wikipedia.org/wiki/Heat_flux ------------------------ Why don't you look up the Physics for yourself instead of just contantly "babbling"? ------------------------ You said... "Radiation is emitted in all directions, no direction is preferred for any reason. Heat, or more specifically a temperature gradient within matter will tend toward equalization as determined by the second law, entropy." -Pick a point. -Draw a line from the emitting body to the point. -That will give the direction. -The length of the line will determine the magnitude (inverse distance^2 loss). -Now you have a FIELD VECTOR. (By the way, the radiation from the emitting object will be at a 'right angle' to the emitting surface.)
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  15. Ricardo - re:your post#112 You said... "given that we were not able to explain the physics" What Physics?...and pertaining to What? ---------------- You said... "- the atmosphere absorbs 390 W/m^2 from the earth and emits the same amount but both upward and downward, twice the amount it absorbs" Wrong. If the atmosphere absorbs 390 w/m^2 it will radiate 390 w/m^2 in all directions. How did you get the atmosphere radiating twice the amount it absorbs? -------------------- The rest of your post is a jumble of errors and contradicting "babbling". Replying to all those errors and "babbling" would be very tedious and just a waste of my time.
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  16. Gord, oh well, as for the ONLY point i made you were able to answer, you confirm your wrong picture without even noticing the absurdity of energy appearing from nowhere. But it dooes not come as a surprise. You that ironically shout "PROVE I'M WRONG" are only able to copy and paste pices of physics you clearly do not understand and, as a consequence, can't use your own model to check if its predictions are indeed correct. No surprise that you can't, there are a lot of flaws in your knowledge of physics. - You don't know the difference betweeen heat and EM radiation. Plenty of time you interchanged this two concepts. - You don't know that a photon can annihilate (be absorbed) and disappear, hence you don't know how the interaction between matter and radiation works. Indeed you keep repeating that they must be re-emitted in any case, which contraddict everyone's everyday experience. In you view there is no way to warm a body by irradiation given that each and every photon absorbed must be re-emitted. - you don't understand what the vectorial nature of the electic field of the electromagnetic radiation imply. You make confusion between direction of propagation and direction of the electric field. You immagine the latter fixed becuase you don't know what polarization is. - you also use the concept of interference without knowing that emission from exicted gas molecules (and any warm body as well) is incoherent. - you don't understand what a flux is, let alone a balance between fluxes. Indeed, you subtract the fluxes from earth surface and from atmosphere downward whitout realizing that this reduces the net flux from earth surface. Then, I understand that you don't want reply and that it's a waste of time, you'd be forced to obsessively repeat the same story avoiding to look at it, to use it, to understand it. You are not able to question your ideas and confront them with your everyday experience, let alone apply them to more complex systems like climate. So yes, I agree with you that you're wasting your time. Writing and reading in this blog is like the quadrature of the circle. For you.
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  17. Gord, I challenged you to produce a clear example where the standard basic teory gives wrong predictions. When you maintain that a standard, well-proven theory is wrong, it's your business to show where it produces false predictions. Not the defenders' - this is basic scientific conduct. If you don't want to confirm to that, I think your behavior may be said to border on trolling. And you requext that we "explain" seems utterly misplaced to me - there are hundreds of treatments of these phenomena available. I'll be more than happy to see you refute established theory! But I'm still awaiting your crucial counter example.
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  18. Gord and Tom I dont know if anyone is deleting posts or the poor server software has simply maxed out for thread space. If this does get to you, I like Tom's question and would like to throw in my half pence. There seems to be an inconsistency in the mental model of a light source in comparing it as if it were some kind of hose spewing photons. In working with radio, you find that impedance is everything in terms of electromagnetic energy transfer efficiency. The source and sink have to be "matched" in terms of impedance for optimal energy transfer. As far as a mental model, how the heck does the source "know" that the load is matched before it "spews" out radiation? It cant. Something is gravely wrong with the conceptual model in keeping with the idea of a "before" and "after". And since light is also supposedly the same kind of thing, electromagnetic radiation, the same principal must apply, as well as the same conceptual inconsistency. We use a language to describe what is not happening, and thus a lot of confusion and arguing. Aside from the issue with modeling of basic physics, I do have a more prosaic and rather mundane thing to say. And that is that whether CO2 is causing global warming or not, as things warm up, there SHOULD be less energy consumed at least during the winter. This should contribute to less CO2, and therefore human behavior is likely one of the most important feedback mechanisms to consider. Behaviorism is considered science... maybe not so hard, etc.
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  19. RSVP, there will be less energy consumed during winter at high latitude and more energy consumed during summer at middle and low latitudes. Nevertheless, human behaviour is an important issue, no question about it. We definitely have to modify our attitudes to waste energy; we can't afford it anymore.
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  20. In any collection of matter composed of individual molecules and atoms, the random velocities of those constituent components will range from near zero to very high velocity. The higher the temperature the greater the average velocity of the component molecules and atoms, but there will always be some in a low energy state.. These lower energy state components are able to absorb energy from a source radiating a full spectrum of ER as all warm bodies do. Some ER emanating from a relatively cooler body will resonate with some relatively few components making up a body of warmer temperature. The warmer body will not experience a rise in temperature because while it is absorbing low energy ER it is simultaneously emitting ER of higher energy, therefore experiencing a net loss in energy. Make sense?
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  21. Gord says: "Warmer objects receive radiative energy from cooler objects.." That VIOLATES the 2nd Law of Thermodynamics." If this were true, i.e. warm objects can not receive radiative energy from cooler objects, we could not see any object colder than our retina. Let's further reflect (no pun intended): 2 objects of different temperatures emit radiative energy in all directions; according to this same statement, the energy coming from the cooler object that is emitted toward the warmer object has to, somehow, either disappear (which would violate the first law) or be rerouted in another direction. This could be detected, as the energy budget somewhere would reflect the "extra" energy that did not end up on the warmer object. I don't know of any experimental setting that shows this. Also this statement: "All objects that Absorb energy HAS to increase in temperature." Formulated this way, it would imply that, if you're floating in deep space, looking at stars, the light from these stars is going to make your body increase in temperature.
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  22. Question for Gord: if a photon is absorbed by a molecule, converted into kinetic energy (note that the energy does not disappear, it becomes kinetic), then re-emitted as an IR photon at that molecule wave length, then the process repeats a great number of times, will the time taken by the photon to go from surface to TOA be the same as the time taken by a photon going directly, without being absorbed and re-emitted?
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  23. Gord, I doubt that John Cook has been deleting your replies. The server has been acting strangely for the past couple of days. A few of my replies did not appear until the next day.
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    Response: Actually, I have been deleting Gord's replies. I'm getting tired of the tone of some of these comments. In the past, if someone was rude or disrespectful towards another commenter, I might let their comment remain if it had other interesting content. Nowadays, I'm older and grumpier - I just delete the entire content if the tone is not civil and respectful.

    For the record, I will now be deleting off-topic comments also.
  24. conjecture to 124 if you are seeing a cooler object, you are seeing light reflected from a warmer source if your vision was IR, it would be "black" and yes the stars would theoretically warm you with whatever part of the starlight you could absorb sort of like how much the Earth accelerates when you jump,
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  25. The stars would not warm you up, because you will always radiate vastly more than you're receiving from them, although you are receiving some radiation. Only if you get close enough to one so that the incoming radiation exceeds the outgoing will your temperature rise. Gord did not specify IR only, he said "radiative energy" and the rest of his comments imdicates he means EM radiation at large. It does not matter what the original source is, a photon is a photon is a photon. My question on the 2 objects of different temp still is relevant, albeit a paraphrase of Chris' question on the filament. I'm curious what the answer could be. The other question about the time to reach TOA is still relevant also. In fact it should even mention that some of these photons will go back to the surface and then be re-radiated from there again. Details.
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  26. Tom Dayton - re:your post #113 (Another attempt of actually getting my post to display without deletion) It's really astonishing how little people understand about Physics and especially Electromagnetic Physics! Do you understand that Photons do not propagate by themselves? Propagating Electromagnetic Fields "CARRY" Photon energy. If an Electromagnetic Field has zero magnitude it will not propagate, hence Photon energy cannot move. The Photon energy is CARRIED in the DIRECTION of the LARGER Electromagnetic Field!...and EM fields ARE VECTOR FIELDS! ----------------------------- Photon "In physics, a photon is an elementary particle, the quantum of the electromagnetic field and the basic "unit" of light and all other forms of electromagnetic radiation. It is also the force CARRIER for the electromagnetic force. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances" http://en.wikipedia.org/wiki/Photon --- Heat Radiation Radiation is heat transfer by the emission of electromagnetic waves which CARRY energy away from the emitting object. For ordinary temperatures (less than red hot"), the radiation is in the infrared region of the electromagnetic spectrum. The relationship governing radiation from hot objects is called the Stefan-Boltzmann law: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2 --- Properties of electromagnetic waves "An electromagnetic wave, although it CARRIES no mass, does CARRY energy." "A more common way to handle the energy is to look at how much energy is CARRIED by the wave from one place to another." http://physics.bu.edu/~duffy/PY106/EMWaves.html --- Heat flux "Heat flux or thermal flux, sometimes also referred to as heat flux density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI units, it is measured in [W·m-2]. It has both a direction and a magnitude so it is a vectorial quantity." http://en.wikipedia.org/wiki/Heat_flux ------------------------------- If people can't understand Electromagnetic Physics they should at least understand what FORCE is. I wonder if you are even remotely aware that there are four "fundamental forces" and one of these forces is the "Electromagnetic Force"? ------------------------------ Electromagnetic force "The electromagnetic force is one of the four fundamental forces. The other fundamental forces are: the strong nuclear force (which holds quarks together, along with its residual strong force effect that holds atomic nuclei together to form the nucleus), the weak nuclear force (which causes certain forms of radioactive decay), and the gravitational force. All other forces are ultimately derived from these fundamental forces." "In physics, the electromagnetic force is the force that the electromagnetic field exerts on electrically charged particles. It is the electromagnetic force that holds electrons and protons together in atoms, and which hold atoms together to make molecules. "The electromagnetic force operates via the exchange of messenger particles called photons and virtual photons." "The electromagnetic force is the one responsible for practically all the phenomena one encounters in daily life, with the exception of gravity." http://en.wikipedia.org/wiki/Electromagnetic_force --------------------------- Hot objects are not “spatially aware” any more than a block of wood “knows” that it is supposed to move in the direction of greatest force when two opposing forces are applied to the block of wood! - Heat Radiation is accomplished by propagating EM fields. - EM fields are Force fields, in fact the Electromagnetic Force is one of the four fundamental forces. - EM fields carry “Photon Energy”. - Photons have zero Mass. Is it so surprising that opposing EM fields and corresponding Forces will only move the zero mass Photon energy in the direction of the larger force? The “block of wood” analogy should be apparent except that, unlike a “block of wood”, a Photon has zero mass. Hot objects produce a larger EM field (and force) than Cold objects so heat energy can only flow from Hot to Cold!….The direction of the larger force! This is really what 2nd Law of Thermodynamics is fundamentally saying! “Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. Energy will not flow spontaneously from a low temperature object to a higher temperature object.” http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/seclaw.html#c3 When some say that Heat can flow from Cold to Hot it’s like saying the “block of wood” will move in the direction of the weaker force! ------------------------ Now go back and really read what you said in your post.
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  27. Ricardo - re: your Post #116 (Another attempt of actually getting my post to display without deletion) I'm really tired of your not checking out the Physics for yourself! ----------------- Heat "Heat may be defined as energy in transit from a high temperature object to a lower temperature object. An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy. The internal energy may be increased by transferring energy to the object from a higher temperature (hotter) object - this is properly called heating." http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/heat.html --------------- Heat Radiation Radiation is heat transfer by the emission of electromagnetic waves which carry energy away from the emitting object. For ordinary temperatures (less than red hot"), the radiation is in the infrared region of the electromagnetic spectrum. The relationship governing radiation from hot objects is called the Stefan-Boltzmann law: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2 --------------- Heat flux "Heat flux or thermal flux, sometimes also referred to as heat flux density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI units, it is measured in [W·m-2]. It has both a direction and a magnitude so it is a vectorial quantity." http://en.wikipedia.org/wiki/Heat_flux ---------------------- "Power Density and Radiated Power The Poynting Vector P is defined as: P(vector) = (1/2) E(vector) X H(vector) which is a power density with units of W/m2. Figure 4.1.3 The w/m2 Varies with Position on the Surface of a Sphere "n = unit normal directed outward from the surface." "We now continue to calculate the total radiated power from an antenna. It is the number of watts per square meter that happens to be at a given point and the direction of the vector is the direction of the power flow." http://www.engr.psu.edu/cde/courses/ee497c/M4L1.pdf
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  28. SNRatio - re:your post#117 (Another attempt of actually getting my post to display without deletion) What "well proven" theory are you talking about? ---- Terms Used in Describing the Nature of Science* Fact: In science, an observation that has been repeatedly confirmed and for all practical purposes is accepted as "true." Truth in science, however, is never final, and what is accepted as a fact today may be modified or even discarded tomorrow. Hypothesis: A tentative statement about the natural world leading to deductions that can be tested. If the deductions are verified, it becomes more probable that the hypothesis is correct. If the deductions are incorrect, the original hypothesis can be abandoned or modified. Hypotheses can be used to build more complex inferences and explanations. Law: A descriptive generalization about how some aspect of the natural world behaves under stated circumstances. Theory: In science, a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses. http://www.nap.edu/openbook.php?record_id=6024&page=2 -------------------- Well let's look at AGW and the Greenhouse Effect. Facts: a) The Sun is the primary source of Energy for the Earth. The gravitional forces and the Earth's molten core are other sources of Energy, but are totally ignored by those that support AGW. The Atmosphere is NOT an energy source and cannot "create" energy. Proof: If the Sun were removed the Earth and atmosphere would rapidly cool to near absolute zero. b) The average temperature of the atmosphere is about -20 deg C. c) The average temperature of the Earth's surface is about +15 deg C. d) The AGW and Greenhouse Effect rely on a colder atmosphere heating a warmer Earth. There are ZERO Laws of Science and ZERO measurements to support this. e) The AGW and Greenhouse Effect violate The Law of Conservation of Energy and the 2nd Law of Thermodynamics. Actual measurements confirm this. ---------- Laws: - The Law of Conservation of Energy says that "Energy cannot be created or destroyed". - “Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. Energy will not flow spontaneously from a low temperature object to a higher temperature object.” --------- As you can see, AGW and the Greenhouse Effect do not qualify as a Hypothesis or a Theory. In fact, AGW and the Greenhouse Effect, are dis-qualified as a Hypothesis or a Theory because they violate Laws of Science and are disproved by actual measurements. ------------ Yet, you continue to say that AGW is a solid theory supported by climatology research? Please provide ANY Laws of Science or ANY measurements that support AGW and the Greenhouse Effect. This should be no problem since over $200 Billion has been spent on this garbage already and there are thousands of papers on the subject. You can't produce ANY Laws of Science or ANY measurements that support AGW and the Greenhouse Effect because THEY DON'T EXIST. Stop posting your "opinions" and deal with the FACTS!
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  29. Philippe Chantreau, For the person who always is making irreverent remarks about why you could POSSIBLY be wasting your time with such meaningless discussion, it is now surprising you have posed a question about "seeing" stars out in deep space. First of all, is this person wearing a protective "insulated" space suit, clothes, or just stark naked? If he is seeing stars, are these in his head as he is approaching unconsciousness, or through the glass of his protective head gear? My point is, the problem statement as posed lacked a specific piece of data that was relevant to your real question. I assume that your real point is that if a body is already warm (and-or generating heat) and subject to a tenuious amount of radiation, it is able to absorb radiation, but it will not be warmed by that radiation. All this to show that the statement "All objects that Absorb energy HAS to increase in temperature." is questionable. I think the issue you are bringing up is definitely interesting, but unless the question is framed properly, and there is a little more patience and good will on all sides for clarifying semantics it will all be a waste of time. I think my initial answer actually agrees with your view that energy can be absorbed by a warmer object. That was my first thought, but I will not put my hand in the fire (no pun intended) as things here may depend on semantics and how exactly you want to look at things. The fact that the starlight is not OBSERVED as contributing to temperature rising may have more to do with the fact that we are talking about a TRANSITIONAL condition, as opposed to a STEADYSTATE condition. All this would need to be clarified. On the other hand, and in the same way, Gord's statement may also be lacking the necessary qualifications in terms of INSTANTANEOUS vs STEADYSTATE, etc. A simple analogy may be found in the way air affects a falling object's velociy as compared to what the equations predict for a falling body in a vacuum. Theory is theory, but you have to qualify the conditions.
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  30. Philippe Chantreau - Re:your post#121 The Laws of Science are called "Laws" because they have never been shown to be falsified....EVER! “Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. Energy will not flow spontaneously from a low temperature object to a higher temperature object.” http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/seclaw.html#c3 ANY flow of heat energy from cold to hot without work being done will result in a VIOLATION of the 2nd Law. When there is a violation of the 2nd Law, it will show up as a violation other Laws of Science.....usually as a violation of The Law of Conservation of Energy. (see my many posts that demonstrate this like post#109) ---------------- Yes, "All objects that Absorb energy HAS to increase in temperature." Even starlight when absorbed will produce a small increase in temperature. It may have to be concentrated by a lens or a parabolic dish (ex. radio astronomy with cooled detectors) but ABSORBTION will ALWAYS will produce an increase in temperature. This is absolutely verified by other Laws of Science called the Stefan-Boltzmann Law (that relates the absorbed EM field to temperature) and The Law of Conservation of Energy. It is also "common sense". ----------------------- Do you really think that you can somehow dis-prove these Laws of Science? Science Professionals accept Laws of Science as being "fundamental truths of Science" and they are used as "first principles" for evaluating the validity of any process. Perhaps your time could be better spent if you adopted a similar approach instead of trying to dis-prove established Laws of Science.
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  31. Philippe Chantreau - Re:your post#122 Electomagnetic Fields travel at the speed of light in a vacuum and ALL EM fields "carry" Photon energy. The only variable that can lower the "speed" is the "dielectric constant" of the medium that the wave propagates through. Wave propagation speed Calculating velocity of propagation V = 1/ K^0.5 where V = speed of light and K is the dielectric constant of the material. http://en.wikipedia.org/wiki/Velocity_of_propagation The dielectric constant of AIR is 1.00058986 +/- 0.00000050 !!! http://en.wikipedia.org/wiki/Dielectric_constant
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  32. This discussion is irrelevant in any case because it is not postulated that a colder atmosphere is warming the surface to higher temperature by direct radiation at higher energy such as is the case with direct solar warming. The greenhouse effect doesn't work that way. Heat is not being transfered from a colder atmosphere to a warmer surface. The warmth that is accumulated during the daytime is slowed in it's radiative release to space by the greenhouse effect. The confusion here derives from the notion that the atmosphere radiates photons in all directions, including down toward the surface. These are "colder" photons, but they still represent energy that otherwise would have escaped directly to space if the atmosphere where not opaque to particular wavelengths in the IR spectrum. The entire atmosphere is radiating thermal radiation, not just the greenhouse gas molecules at specific wavelengths. The entire troposphere (all the gases) and surface are warmed by the greenhouse effect and thus they radiate at higher energy than they otherwise would have in the absence of a greenhouse effect. This then leads us to the concept of radiative forcing of climate, an entirely different matter which is however entirely based on an enhancement to this greenhouse effect. Thus the desire by some to dispute the greenhouse effect's very existance.
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  33. WeatherRusty - re: your post #132 You said... "The greenhouse effect doesn't work that way. Heat is not being transfered from a colder atmosphere to a warmer surface." I wonder how many times I have to repeat this? Here are the links to the "Greenhouse Effect" that say EXACTLY THE OPPOSITE OF YOUR POST! Tutorial on the Greenhouse Effect- University of Arizona “In this case, the Earth still gains 240 Watts/meter2 from the sun. It still loses 240 Watts/meter2 to space. However, because the atmosphere is opaque to infrared light, the surface cannot radiate directly to space as it can on a planet without greenhouse gases. Instead, this radiation to space comes from the atmosphere. However, atmospheres radiate both up and down (just like a fire radiates heat in all directions). So although the atmosphere radiates 240 Watts/meter2 to space, it also radiates 240 Watts/meter2 toward the ground! Therefore, the surface receives more energy than it would without an atmosphere: it gets 240 Watts/meter2 from sunlight and it gets another 240 Watts/meter2 from the atmosphere — for a total of 480 Watts/meter2 in this simple model.” http://www.lpl.arizona.edu/~showman/greenhouse.html The Greenhouse Effect “Absorption of longwave radiation by the atmosphere causes additional heat energy to be added to the Earth’s atmospheric system. The now warmer atmospheric greenhouse gas molecules begin radiating longwave energy in all directions. Over 90% of this emission of longwave energy is directed back to the Earth’s surface where it once again is absorbed by the surface. The heating of the ground by the longwave radiation causes the ground surface to once again radiate, repeating the cycle described above, again and again, until no more longwave is available for absorption.” http://www.physicalgeography.net/fundamentals/7h.html Both examples violate the 2nd Law because there is heat energy flowing from a colder atmosphere to a warmer Earth. The above Greenhouse Effect links describe a Perpetual Motion Machine, actually a Perpetual Motion Machine in a Positive Feedback Loop. --------- Trenberth's Energy Budget Diagram clearly shows 324 w/m^2 of Back Radiation from the Colder atmosphere being ABSORBED by a warmer Earth surface ! http://www.windows.ucar.edu/tour/link=/earth/climate/greenhouse_effect_gases.html Again, EXACTLY THE OPPOSITE OF YOUR POST ! --------- John Cook's response to my very first Post #15 said: "Response: The atmosphere doesn't create energy. Greenhouse gases absorb outgoing infrared energy, preventing some of it from escaping out to space. The absorbed infrared energy is then reemitted in all directions, some of it heading back to Earth where it warms the surface. It's not an argument or a theory that CO2 causes global warming. It's an experimentally observed physical reality." Again, EXACTLY THE OPPOSITE OF YOUR POST ! Advice to WeatherRusty....READ before you comment! I really am getting tired of constantly repeating my posts. ------------------------------- You said... "The warmth that is accumulated during the daytime is slowed in it's radiative release to space by the greenhouse effect." Did you not read my Post #131? I really am getting tired of constantly repeating my posts. ------------------------------ You said... "The entire troposphere (all the gases) and surface are warmed by the greenhouse effect.." Gee, I thought you said... "The greenhouse effect doesn't work that way. Heat is not being transfered from a colder atmosphere to a warmer surface." ------------------------------ I could continue, on and on, with more of what you posted but...Enough said.
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  34. Gord, in answer to my question, you wrote "Hot objects produce a larger EM field (and force) than Cold objects so heat energy can only flow from Hot to Cold!….The direction of the larger force!" That statement is incorrect, and seems to be the crux of your confusion. The vector EM field propagating from a warmer object does not sum with (interfere with) the vector EM field propagating from a colder object, halfway between the objects. If they did, you are right that the result would be a net field aimed at the colder object. But in reality, the two fields pass each other and hit their respective targets. The field that hits the colder object imparts a lot of energy, because that field has a lot of energy, because that field arose from a warm object. So the colder object gets a lot warmer. The field that hits the warmer object imparts less energy, because that field has less energy, because that field arose from a colder object. So the warmer object gets only a little warmer. The net result of those two fields' impacts on their respective targets is that the colder object warms more than the warmer object warms. A frequent and easily misinterpreted way of rephrasing that last sentence is that heat flowed from the warmer object to the colder object.
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  35. Gord @ 131, you're not answering the question. The question is in fact a thought experiment, which is as follows: We are observing 2 IR photons emitted simultaneously from the surface of the Earth. One is going its merry way to the TOA unhindered. The other bumps into a gas molecule, becomes kinetic energy, the molecule re-radiates that kinetic energy quantum as a photon at the proper wave length, that photon heads out in a random direction, bumps again in a gas molecule, and so on and so forth until it reaches the TOA. Which photon arrives first at the TOA? In the case of the objects at different temperatures, there will be photons emitted by the cooler object toward the warmer object. Representing their sum as a vector is only that: a representation, which is convenient. However, that does not change the fact that, physically, there will be photons emitted by the cooler object toward the warmer object. What happens to them? We could consider vectors as forces, since you mentioned it, which was a good idea. An individual is applying a force to a solid in certain direction. It makes the solid move in that direction. Another individual is applying a lesser force to that same solid in the exact opposite direction. The solid, and its movement, are affected by the lesser force, are they not? The direction will not change, the velocity will, but the surface of the solid, if somewhat soft, will deform at the point of application of the lesser force, will it not? In the links and quotes above, seems to me you are playing on words. These quotes don't say whay you say they say. Their fault is to somewhat abuse language for the sake of simplification, but the expectation is that one knows the obvious fact that the direction of the net energy flow (to space) is conserved. Especially for John's quote; in his context, "warms" means "changes the balance of incoming and outgoing radiation." The result is raised equilibrium temperature. You're playing around with the fact that words are employed outside of their pure thermodynamic meaning. Yet you do the same thing, merrily interchanging radiative energy and net heat flow. Here is another thought experiment: Hot object A radiates energy in the form of IR EM radiation. Object B, next to A, radiates same type of energy at 2/3 the rate of A. According to your interpretation of the 2nd law as you expressed it earlier, no IR EM energy at all can travel from B to A. We add objects B2 through B12 (they all have the same characteristics) in the vicinity of A, all the B objects are evenly spaced around A. What is the net heat flow for object A? According to your interpretation of the 2nd law, none of the B objects can radiate any heat toward A, and A should still radiate and not absorb. Is that really what is going to happen?
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  36. Gord, thank you for your copy and paste some of the relevant physcal concepts. But you forgot a couple, heat trasnfer and absorption. After that you can expand the them.
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  37. Somewhere I read that light is a particle. I wont say who said this. Light propagates more slowly in anything but a vacuum. If for instance it is propagating through air and then hits a new medium like glass it somehow "decelerates" instantaeously, then when emerges out a slower medium will "accelerate" instantaneously. Supposedly photons are particles containing energy. Physics says that energy and mass are equivalent, so when the photon decelerates or accelerates instantaneiously, why doesnt this require or release an infinite amount of energy? Is a photon massless? If so, how then can it contain energy if mass and energy are equivalent? I suspect there is some off-the-shelf explanation for this question containing semantic gyrations that satisfies conventional wisdom.
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  38. RSVP, I would suggest that you consider when light passes through a discontinuity or medium of suddenly changing density, the light is diffracted or bent along it's path. The distance traveled to the receiver is thus increased and the time required to get there is increased. Light traveling though a gas is scattered by atoms and molecules repeatedly thus requiring greater time to reach a given point.
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  39. The light is also refracted or bent when encountering a discontinuity in density such as a glass surface or from air to water for instance.
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  40. RSVP: the photon is massless but has a relativistic momentum. Its energy is not dependent on its mass but momentum. If you call p the momentum, c the speed of light and E the energy of the photon, you have E=pc. That can be easily found by using the expanded special relativity equation, the one that can apply to all cases, not only massive particles. That formula does not say that mass and energy are equivalent, it says that the energy of a particle is a function of the speed of light, the mass and the momentum of the particle. All this is easy to find on physics web sites and such. Like all elementary particles, it has characteristics of both wave and particle, as in the double slit experiment.
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  41. Philippe Chantreau I understood momentum = mv. What does calling it p buy you except occulting m, or is relativistic momentum something different? You go on to say..."That formula does not say that mass and energy are equivalent, it says that the energy of a particle is a function of the speed of light, the mass and the momentum of the particle." I understood that mass and energy were equivalent manifestations of matter, and the equation you cited was used precisely to describe this relationship. Furthermore I understood that the speed of light was a constant, not a function. So, it doesnt help me to know that "All this is easy to find on physics web sites and such", when these are precisely the inconsistencies I will be finding. I prefer WeatherRusty's explanation which is more straightforward and intuitive... light slows down in glass because it is zigzaging around and taking longer to propagate. Either way, the point of the question is to illustrate that you cant always take verbage from one chapter of a physics book, apply it to problems in another, and necessarily expect things to make sense. And personally, if a thing is said to require a non-intuitive explanation, it is probably because the basic conceptual model is completely off track.
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  42. You asked a question, I gave you an answer. It was about the mass of the photon, not its speed in various media. I guess I could have kept it drier: yes, the photon is massless. The momentum of a photon is a function of its wavelength and the Planck's constant. If you don't like my answer, which I found very clear, feel free to seek another one but if the counterintuitive aspect bothers you, forget about any enquiry on Quantum or Special Relativity, there is nothing intuitive about it. Elementary particles behave both as waves and particles, that's the way it is. Mass and energy are manifestations of matter indeed. A photon is energy; it can "become" mass, but it does not "have" mass. If it "becomes" mass, it ceases to be a photon. If you think that the basic conceptual model of Quantum or SR is off track, go right ahead and challenge it, that's how progress is made. However, unlike some who challenge the consensus model of Earth climate, make sure you know what you're talking about before you cast the challenge. Both theories are actually very consistent. Mass and energy are "equivalent" only for massive particles at rest (zero momentum). C is not a function of anything, it's the energy of a particle that is a function of c. The square of the energy of a particle is the sum of momentum square x c square and mass square x c fourth power (mass is the invariant mass). With zero momentum and a non zero mass, it simplifies to mass x C square. Sorry John, I don't know how to import LaTEX formulas and such goodies.
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  43. Tom Dayton - re:your post#134 It is YOU that are confused and obviously can't seem to do any vector mathematics. I never said that "The vector EM field propagating from a warmer object does not sum with (interfere with) the vector EM field propagating from a colder object, halfway between the objects." !!! Where did you dig that little "gem of wisdom" up?? I have already posted this before: Vector addition of fields... Multiple Point Charges Example: E1 = kq1/r1^2, E1x = E1*cos a, E1y = E1*sin a E2 = kq2/r2^2, E2x = E2*cos b, E2y = E2*sin b The resultant Vector E components are computed as: Ey = E1y + E2y = E1*sin a + E2*sin b....because the vector components ADD Ex = E1x + E2x = E1*cos a - E2*cos b....because the vector components SUBTRACT The resultant Vector E will have a Magnitude E = (Ex^2 + Ey^2)^0.5 The resultant Vector E will have a Direction Tan(theta)= Ey/Ex http://hyperphysics.phy-astr.gsu.edu/hbase/electric/mulpoi.html#c3 --------- Heat flux "Heat flux or thermal flux, sometimes also referred to as heat flux density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI units, it is measured in [W·m-2]. It has both a direction and a magnitude so it is a vectorial quantity." http://en.wikipedia.org/wiki/Heat_flux --------- Heat Flux is a VECTORIAL QUANTITY and HAS to be computed AS VECTOR QUANTITIES !! This has been KNOWN and USED by ALL Electrical Engineers and Physicists for OVER A HUNDRED YEARS! What don't you get about this very simple FACT ??? --------------------------------------------- You said... "But in reality, the two fields pass each other and hit their respective targets." Wrong again. If the Fields are continuous the Interference is continuous and the NEW WAVE is continuous !!! Interference (wave propagation) "In physics, interference is the addition (superposition) of two or more waves that results in a NEW WAVE pattern." There is even an animation of continuous waves creating a continouous Interference pattern that produces a NEW WAVE that is CONTINUOUS! http://en.wikipedia.org/wiki/Interference_(wave_propagation) --------------------------------------------- You said... "The field that hits the colder object imparts a lot of energy, because that field has a lot of energy, because that field arose from a warm object. So the colder object gets a lot warmer. The field that hits the warmer object imparts less energy, because that field has less energy, because that field arose from a colder object. So the warmer object gets only a little warmer. The net result of those two fields' impacts on their respective targets is that the colder object warms more than the warmer object warms." Wrong again. Just like the Physics links above CLEARLY prove and are ABSOLUTELY vefified by the 2nd Law. -------------------------------------------- I am tired of constantly repeating the PHYSICS over and over again. Why don't you save us all a lot of time and BACK-UP your Posts with Physics Links BEFORE posting your un-informed and continually "WRONG OPINIONS" ??
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  44. Philippe Chantreau - Re:your post#135 Again, I am repeating the PHYSICS that I have ALREADY POSTED! The "VELOCITY" that an EM field propogates at through the atmosphere is determined by the DIELECTRIC CONSTANT OF THE ATMOSPHERE! The Velocity of all EM fields in a vacuum is 3 X 10^8 meters/sec. The change in velocity of an EM field propagating through the atmosphere is given by: Wave propagation speed Calculating velocity of propagation V = 1/ K^0.5 where V = fraction of speed of light and K is the dielectric constant of the material. http://en.wikipedia.org/wiki/Velocity_of_propagation The dielectric constant of AIR is 1.00058986 +/- 0.00000050 !!! http://en.wikipedia.org/wiki/Dielectric_constant If we use K = 1.00058986 then V = 0.99971 So the VELOCITY that an EM field will propagate through the atmosphere is 0.99971 X 3 X 10^8 = 2.999 X 10^8 meters/sec !!! This includes ALL the factors found in the atmosphere ! How long does it take for a Satellite Up-Link to transmit it's signal to a Satellite in Geostationary orbit 36,000 km above the Earth? It takes about (36 X 10^6 meters)/(3 X 10^8 meters/sec) = 0.12 SECOND ! How many DAYS did you think it took? ---------------------------- You said... "Yet you do the same thing, merrily interchanging radiative energy and net heat flow." Here is the "MERRY PHYSICS" that I have posted MANY times before. Heat "Heat may be defined as energy in transit from a high temperature object to a lower temperature object. An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy. The internal energy may be increased by transferring energy to the object from a higher temperature (hotter) object - this is properly called heating." http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/heat.html --------------- Heat Radiation Radiation is heat transfer by the emission of electromagnetic waves which carry energy away from the emitting object. For ordinary temperatures (less than red hot"), the radiation is in the infrared region of the electromagnetic spectrum. The relationship governing radiation from hot objects is called the Stefan-Boltzmann law: P = e*BC*A(T^4 – Tc^4) Where P = net radiated power (Watts), e = emissivity, BC = Stefan’s constant, A = area, T = temperature of radiator and Tc = temperature of the surroundings or another body. ..when rearranged gives P/A = e*BC*T^4 – e*BC*Tc^4 (Watts/m^2) This is an obvious subtraction of two Electromagnetic Fields. It also complies with the Vector subtraction of Electromagnetic Fields which are Vectors. The resultant Electromagnetic Field will have a magnitude of P/A and have a direction of propagation in the direction of the larger field. There is absolutely no energy flow from cold to hot, complying with the 2nd Law. http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2 --------------- Heat flux "Heat flux or thermal flux, sometimes also referred to as heat flux density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI units, it is measured in [W·m-2]. It has both a direction and a magnitude so it is a vectorial quantity." http://en.wikipedia.org/wiki/Heat_flux --------------- Looks like the "MERRY PHYSICISTS" including Stefan and Boltzmann also use "radiative energy" as "heat flow". ------------------------------------------------------ The rest of your post is just more un-informed and wrong "OPINIONS" ! I am tired of constantly repeating the PHYSICS over and over again. Why don't you save us all a lot of time and BACK-UP your Posts with Physics Links BEFORE posting you un-informed and continually "WRONG OPINIONS" ?? --------------------- PS: I did an actual Heat Transfer calculation using the actual "MERRY PHYSICS" developed in the Stefan-Boltzmann Law for Heat Transfer. The example is shown in my Post#34 Now let’s see YOUR calculations with energy flowing from the colder body to the hotter body. Do the calculations until thermal equilibrium is achieved. Remember that there is ONLY one energy source emitting 5.67 watts/m^2 and the Law of Conservation of Energy says “Energy cannot be created or destroyed”. GOOD LUCK!
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  45. "The relationship governing radiation from hot objects is called the Stefan-Boltzmann law: P = e*BC*A(T^4 – Tc^4)" All in all, the whole game reduces to this simple expression no one can desagree with (anyone questioning Boltzman?). This will tell us what is the power (energy per unit time) leaving an object at temperature T surrounded by an environment at temperature Tc. So, we should think (hard!) on who's the guy called T and who's the other guy called Tc. And that's it.
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  46. Gord, do you remember John Cook's comment about your inappropriate tone? I wasn't so much bothered by your tone before, but your most recent tone does bother me. Please calm down. Please stop using all uppercase letters, because it really does feel like yelling. We do seem to be making progress toward understanding, but your tone is hampering us. I understand that you are frustrated, but don't take it out on me. You wrote:
    "If the Fields are continuous the Interference is continuous and the NEW WAVE is continuous !!! Interference (wave propagation) "In physics, interference is the addition (superposition) of two or more waves that results in a NEW WAVE pattern." There is even an animation of continuous waves creating a continouous Interference pattern that produces a NEW WAVE that is CONTINUOUS! http://en.wikipedia.org/wiki/Interference_(wave_propagation)
    But objects that radiate have no obligation to do so continuously. Consider two very cold objects--both so close to absolute zero that they infrequently radiate. One is slightly warmer than the other. Most of the time, neither is radiating. Now the warmer object emits a single photon (i.e., emits a single wave set/pulse), which travels to the cooler object. During the transit time, the other object continues to not emit. Therefore the warmer object's wave arrives without encountering a wave in the opposite direction. Therefore the warmer object's wave proceeds unaltered until it hits the cooler object, and the cooler object absorbs the energy of the wave. The cooler object thereby is warmed by the warmer object. The same mechanism operates in the other direction. Neither object is emitting. Now the cooler object emits a single photon/wavepulse, which travels to the warmer object while the warmer object happens to not emit. So the wave from the cooler object makes it all the way to the warmer object without interference, until it hits the warmer object and the warmer object absorbs that energy. The warmer object thereby is warmed by the cooler object. The warmer object emits more often than the cooler object does, and with more energy in each photon/wavepulse. So the net effect of those exchanges, summed across time, is the cooler object getting more energy than the warmer object does. Which is what the second law of thermodynamics requires.
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  47. Your calculations are of no interest to my questions. You have not really answered any of them. If it bothers you so much, stop repeating the physics and explain how they apply to the situations I described. When RSVP asked a specific question about the mass of the photon, I answered it plainly. Why not do the same? My questions were clearly stated above. They're all tought experiments. I guess we could say you answered the first one, the unhindered photon being hypothetical. Obviously, the photon going through numerous absorbtions and re-emissions will take longer to reach the TOA. It means that the atmosphere imposes a longer residence time to IR photons in the periphery of the Earth. Now I'm wondering all the things that happen if the atmospheric composition is changed in a way that further increases that residence time. Vectors are not physical phenomena, they are ways to represent them. You can play around with formulas and plug numbers in them, that does not provide us with an understanding of the principles described by them. So enlighten us by showing how the formulas apply to the situations given in the thought experiments, why not? What happens to the photons emitted by a cooler object in the direction of a warmer object? Do they disappear? Do they turn around? Do they anihilate against photons coming from the warmer object? If yes, how exactly does that happen? How about the multiple object experiment? What is the net heat flow for object A? None of these thought experiments requires calculations to be answered, the exact values are of no interest, only the principles. According to the principles, what direction of heat flow must object A experience when surrounded by B through B12? I will pay attention to an answer that's well explained. My "opinions" are like scientific knowledge: open to revision.
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  48. Try this out for size. The atmosphere being cooler than the surface can not conduct or convect heat to the warmer surface. This is where the Second Law of Thermodynamics applies. The atmosphere will radiate energy toward the surface regardless of the temperature difference. Electromagnetic radiation is not heat and does not represent a thermal gradient to be dissipated by increasing entropy. ER can traverse the entire visible Universe without loosing it's integrity or energy except to the expansion induced redshift. The Second Law does not apply to the propogation of ER. Am I correct?
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  49. Gord, from all the capitalized shouting, it does not seem that patience is your strongest virtue. However, I'm asking that you exercise more of it, especially since my own weakness is to be wordy at times. I have more questions. Anyone else's answers will be welcome too, BTW. I can't help to think that, in order to subtract a field vector from another, the field vector has to exist. Which brings the question, what quantity is represented by the field vector? What is it made of, physically? Considering the Stefan-Bolzman equation that governs heat transfer as you expose it above: P=e*BC*A(T^4-Tc^4) P being the net heat flow. Since P is a heat flow and the result of a subtraction, a priori the terms of the subtraction also have to be heat flows, don't they? If not, what are they? The S-B above should be the same thing as P=(e*BC*A*T^4)-(e*BC*A*Tc^4). It looks like a heat flow, minus another heat flow, yielding a resultant heat flow. Perhaps I'm wrong but this is physics, so these terms do describe physical quantities, i.e. they each correspond to a physical phenomenon. What quantities, what physical realities are respectively described by e*BC*A*T^4 and e*BC*A*Tc^4? Next question: if T=Tc, then P=0. There is no net heat transfer. However, neither e*BC*A*T^4 nor e*BC*A*Tc^4=0. In this case, although the net heat transfer is zero, both terms do exist. Translated in plain language, it means that both bodies radiate and absorb at the same rate. I'd think they have to. Since they have a non zero T, they must radiate; since P=0, they must absorb too, both of them, both at the same rate, which is the same as their rate of emission. The vectors "cancel out" but the physical quantites represented by the vectors do exist don't they? Energy can not disappear. Is there anything in the S-B relation that prevents to describe all other situations as both bodies radiating and absorbing, but at different rates? Back to the block of wood analogy. A force is applied to the block of wood in a certain direction, while a lesser force is also applied to the block. The fact that a greater force is being applied does not make the application of the lesser force impossible, does it? What it makes impossible is a resultant motion that, if represented as a vector, would have a component equal or greater than zero in a direction opposite to the greater force. But the lesser force does exist and can be applied opposite to the greater one, or in any direction for that matter. Can it not?
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  50. Ricardo - re:your post #145 The equation P = e*BC*A(T^4 – Tc^4) is not representative of just one Law of Science (Stefan-Boltzmann Law) Here is the Stefan-Boltzmann Law: P/A = BC*T^4 http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/stefan.html ------------ Here is the 2nd Law of Thermodynamics: “Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. Energy will not flow spontaneously from a low temperature object to a higher temperature object.” http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/seclaw.html#c3 -------------- Here is some Electromagnetic Physics: Heat flux "Heat flux or thermal flux, sometimes also referred to as heat flux density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI units, it is measured in [W·m-2]. It has both a direction and a magnitude so it is a vectorial quantity." http://en.wikipedia.org/wiki/Heat_flux ----------------- Here is the Mathematics of Vectors applied to vector fields: Vector addition of fields... http://hyperphysics.phy-astr.gsu.edu/hbase/electric/mulpoi.html#c3 ------------------ Here is the Law of Conservation of Energy: Conservation of Energy "Energy can neither be created nor destroyed" http://hyperphysics.phy-astr.gsu.edu/hbase/conser.html -------------------- Here is the Result of Violating the 2nd Law and/or The Law of Conervation of Energy: Perpetual motion "The term perpetual motion, taken literally, refers to movement that goes on forever. However, the term more generally refers to any closed system that produces more energy than it consumes. Such a device or system would be in violation of the law of conservation of energy, which states that energy can never be created or destroyed." "Perpetual motion violates either the first law of thermodynamics, the second law of thermodynamics, or both" "A perpetual motion machine of the first kind produces energy from nothing, giving the user unlimited 'free' energy. It thus violates the law of conservation of energy." http://en.wikipedia.org/wiki/Perpetual_motion ----------------- Here are some actual measurements that confirm that the Colder Atmosphere cannot heat a warmer Earth. Look at my Post #18 where I provide a link to a paper and measurements done by the Physics Dept. of Brigham Young University proving that Back Radiation cannot reach the Earth. -------------------- As you can see: The equation P = e*BC*A(T^4 – Tc^4) describes much, much more than the Stefan-Boltzmann Law! It is a representation of numerous Laws of Science, Principles of Science and Actual Measurements.
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