Guest post by Bill DiPuccio, Science Teacher
Let’s face it, high school science videos can be boring and ineffective. I like my science with a twist of comic exaggeration. So I decided to produce a video with enough humor to keep the students awake, and enough depth to challenge them intellectually.
This 30 minute video on the Greenhouse Effect is the prototype for a possible new series: “Bill Scientific” (I gave it a personal imprint to infuse some warmth and presence). Unlike introductory videos which attempt to cover a broad field of knowledge in a short time, the goal of this prospective series is to drill down into specific, but pivotal, topics in the physical and earth sciences.
Rather than just spooning out information, each program would be designed around experiments (the simpler the better) that can be used to illuminate and verify crucial scientific principles. Students will see science in action and gain a better grasp of the empirical basis for scientific theories.
Of course, future programs will depend on the response from students, educators, and scientists, as well as securing funding. The “Greenhouse Effect” was shot and produced on amateur equipment and software. Despite these limitations, I believe the final product faithfully conveys the intent of series.
P.S. If you like the video, pass it on!
The idea of a video of this type is good, but the science presented is wrong, and would add to bad thinking. I only make a few comments, but much more is possible:
1) The atmosphere does redistribute the solar energy to prevent hot and cold from being as extreme as possible, but this alone is not a greenhouse effect, only storage and convection (also aided by ocean currents).
2) The Moon turns much slower than Earth to the Sun, so extreme surface heat and cold (in vacuum) are made worse by longer accumulation times.
3) The greenhous effect of actual greenhouses is caused mainly by the physical barrier of the surface trapping warm air, not just trapped long wave re radiation. The atmosphere has no physical barrier to free convection, so is different.
4) The Earth’s greenhouse effect is caused by longwave radiation partial insulation combined with the lapse rate of the atmosphere (due to air pressure drop with altitude). The longwave partial insulation moves the average location of radiation to space to higher altitude, locking the average temperature of the atmosphere at that average altitude.
Make certain when you do the ‘PET bottle’ experiment, which purports to show the GHE with CO2, that you don’t use the PET bottle in the first place.
This is because most of the warming is from the increase of pressure AND the `indirect thermalisation of the pseudo-scattered IR at the bottle walls.
So, use a Mylar balloon like Nahle has,except you need to use a different thermometer than he used [an IR pyrometer which is optical depth dependent].
I think you’ll find there is no detectable direct thermalisation so the GHG-AGW effect is bunkum!
Still waiting for an explanation, why 6,000 ppm CO2 on Mars does not exhibit any measurable effect on theoretical vs practical temperature. Those 6,000 ppm should have the same overall “GH effect” as 400 ppm CO2 + thousands ppm H2O (g) here.
Oh, and the “+33K” is plain wrong.
It stopped just when it was getting interesting! And it would have been carbon monoxide that made Bill pass out from inhalation of exhaust fumes, not CO2.
It looks like part 2 and 3 were too difficult for this website. (LOL)
Nice videos. I liked them.
I’ll apologize in advance – I swear I don’t mean this as an insult:
When I read ‘Bill Scientific’, the first thought to come to me was of Bill Nye.
Lively and Beakman-ish.
Two quibbles:
The intro seems a bit cluttered. Maybe start where Rebecca says “Are you sure you know what you’re doing?”
Maybe more emphasis on the experimental parts (the car as greenhouse) and the sensory parts (you can feel that with your feet).
I’m afraid you made a serious scientific error at the begining. The reason the Earth doesn’t have the diurnal range of the Moon is the thermal capacity of the Earth’s atmosphere and to some degree the thermal capacity of the Earth’s oceans. Although you can’t really separate the two.
Otherwise, not bad, although you introduce terminology without explaining the terms.
Not bad the end needs a bit more work
Maybe it’s me, but I prefer my science more like the style Brian Cox, his boyish enthusiasm and knowledge is moreish and how many other Professors can list 9 top 40 UK hits on his CV?
Nice project. There may be mixed reviews in a classroom setting as some kids like the cheesy jokes and some will be turned off by it. It does convey the information though, so maybe it will hold their attention enough for them to pick up some of the basics of the atmospheric energy resistance in the IR spectrum (ok, we call it the greenhouse effect.)
Liked it very much!
The ending was a bit abrupt. I think that could have been spread out a bit. Very impressive overall, though!
There is no lid on earth, that´s the difference.
2% of 5% = 0.1% of the greenhouse effect caused by humanity’s fossil fuel combustion
Nice to see some facts presented for a change instead of hype. Loved the line about the glass sphere around the world. A lot of people really think there is some kind of sphere of CO2 ‘up there’ for which we are responsible. With ignorance-as-fact promoted by ‘An Inconvenient Truth’ abounding I will take Bill Scientific hands down over Suzuki as a source of knowledge.
CBC, are you listening? (Can you improve their accents?)
I like it
Watched all 3 parts – not bad – author stays away from the politics (mostly).
I had to pick out the links for parts 2 and 3 from the list. here are the YouTube web links:
Part 1
Part 2
Part 3
Unfortunate that the author is named Bill – He chose the name Bill Scientific for these reasonable links. He could easily be confused with similarly named “Bill the (non)- Science Guy”, who has recently been more an advocate than a scientist.
Makes the standard error most naif folk do. See http://en.wikipedia.org/wiki/Greenhouse_effect#Real_greenhouses
Could someone please show me the calculations, based on Radiative Heat Transfer, Thermodynamics and Quantum Chemistry/Spectroscopy, that shows the CO2 molecule to have the radiative properties and capacities to behave as stated under the temperature and pressure our atmosphere can provide for it? Responsible for 5 to 26% of the atmospheric thermostatic regulation of temperature??? Prove it to me please…
The 3 videos had a lot of positive and fun ways to explain things to Highscool students though… 🙂
Very good presentation. Packs a lot into 30 minutes. Brian Cox would have taken at least nine hours to cover the same material. There would have been 30 minutes of Brian Cox gazing at one single cloud, and the BBC would have called that “Science”.
I think the Thermo-Slayer types rushed to judgement without watching the 30 minutes series, which is why they were first to comment.
@AnotherPhilC
LMAO, agreed
AnotherPhilC says:
April 27, 2012 at 6:48 am
“Brian Cox would have taken at least nine hours to cover the same material.”
That’s not true, he covers a lot in a fue minutes here. lol
From the video: “…and clouds can push that number even higher”
The subject of clouds as a positive forcing is controversial.
Really good Bill, that took a lot of time.
The part about clouds was very important because it is almost never discussed.
Here is the Modtran downwelling radiation in the Tropics when low cloud cover is present. A perfect blackbody – no CO2 lines, no methane lines, just a blackbody. Now how often is cloud cover is present. How does it change with differing heights and thickness of clouds.
http://img832.imageshack.us/img832/295/tropicalsurfupclouds2xc.gif
Roger Abel says:
April 27, 2012 at 6:43 am
Could someone please show me the calculations, based on Radiative Heat Transfer, Thermodynamics and Quantum Chemistry/Spectroscopy, that shows the CO2 molecule to have the radiative properties and capacities to behave as stated under the temperature and pressure our atmosphere can provide for it? Responsible for 5 to 26% of the atmospheric thermostatic regulation of temperature??? Prove it to me please…
No, Roger. No one will ever explain this or prove this. No matter how many time you ask.
Roger Abel says:
April 27, 2012 at 6:43 am
I think there is plenty of work done already that shows the math. Doing experiments in a lab that confirms the model seems to be a bit harder to come up with. Just sayin’…
🙂
Bill: downwelling radiation does not exist. it’s an artefact of a radiometer blocking the Prevost Exchange Energy from behind the detector. It measures Temperature x emissivity only. There can be no energy transfer [2nd Law].
This Meteorological mistake is the reason why climate science is mostly wrong. indeed, I can’t think of anything they have got right except temperature, And as for the IR from the Earth being S-B for a B-B in a vacuum, no professional engineer who actually measures such stuff, and I am one, agrees.
This is why the climate models exaggerate radiative heat transport by .10 times.
wmconnolley says:
April 27, 2012 at 6:41 am
Makes the standard error most naif folk do. See
From your link: “In the greenhouse effect, rather than retaining (sensible) heat by physically preventing movement of the air, greenhouse gases act to warm the Earth by re-radiating some of the energy back towards the surface.”
Mr. Connolley please write a radiative heat transfer equation showing how this takes place between the surface of the earth and a molecule(s) of CO2. Please use 1 atm and 288 K. I have asked you before but never heard back. So I ask again.
Babsy says:
April 27, 2012 at 7:31 am
Got a link?
If only CAGW was about science and NOT a religious/political campaign. GK
If nitrogen and oxygen “absorb almost no radiation,” how are they warmed then?
I think the comments here are an interesting study on how subjective science and especially science education is. Subjective in the sense that when you are simplifying, the degree of simplification and the choices of what to leave out is underdetermined, even for a reasonably well-defined audience, and different choices will make more or less sense to the subject presenting the science. There may be factual errors–I’m not too worried about them. In the end, teaching the greenhouse effect is a lot more like teaching the civil war than most scientists (and probably historians) usually appreciate, which points to a breakdown of enlightenment notions of a strict dichotomy between purely subjective and purely objective. Real teaching involves the messiness involved here, regardless of the subject.
RICH says:
April 27, 2012 at 7:53 am
I would say that it is direct contact with the surface that just absorbed that incoming energy. Think about this – if you have a hot cup of coffee, what makes it cool down as it sits on your desk (beside your keyboard)? Without any scientific experiment I will bet a steak dinner that contact with the surrounding air has a much greater effect (x10) than IR emissions. Now, relate that to the world outside your window.
RICH says:> If nitrogen and oxygen “absorb almost no radiation,” how are they warmed then?
Std thermal exchange via collision.
mkelly says:> Mr. Connolley please write a radiative heat transfer equation… Please use 1 atm and 288 K
Dunno quite what you want; your question doesn’t really make sense as you’ve posed it. The std stuff is all available in the obvious places, most obviously http://en.wikipedia.org/wiki/Idealised_greenhouse_model If you want more details, then http://scienceofdoom.com/roadmap/atmospheric-radiation-and-the-greenhouse-effect/ is a good place to start. If you want to pretend that the GHE doesn’t exist, find someone else to talk to.
Liked the videos, they have a human quality to them — a quality over produced broadcast videos lack. Consider using the initial video as a means to empower the students to add to the series. This would allow the topic and videos to evolve from their perspective. Students educating students — a one room school house approach that allows the videos to interrelate to other disciplines comes to mind.
This is a tall request. One of my pet peeves, aspects of the climate system are frequently discussed without a reference to the system as a whole. This over emphasizes the importance of the aspect and under emphasizes compensating factors and system relationships. The intro to each segment could illustrate the system and the aspect being discussed in the video segment.
Another intro video to the topic as a whole could discuss many of the terms that are being thrown around — roles you could have a lot of fun portraying. Terms like Affirmer (Warmer), Denier, Skeptic, Lukewarmer, Consensus, Settle Science come to mind.
See Lord May’s presentation for some glossary ideas.
The motto of the Royal Society is [s/b was]: Nullius in verba: on the word of no one
Science as Organized Skepticism by Lord May
http://downloads.royalsociety.org/audio/DM/DM2010_03/May.mp3
Bzzzzzt WRONG!
You may be able to peddle or push that nonsense over on the Bish site, but you’re being called on it here … ever heard of a field of science called IR Spectroscopy?
Do you understand how a bipolar molecule responds to EM energy?
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I’ve posted this before; apologies beforehand to those who have seen it before, but this is the perspective an RF guy (Radio Frequency and radio engineer who works with and designs, and models antennas including the MOM – Method of Moments (NEC) and FEM – Finite Element Method (Ansoft HFSS) techniques) sees this all this:
The 12 easy steps to understanding the physics of the minor, but important, GHG effect.
1. The ‘motion’ of Electrons and Protons can be affected by externally applied electric and magnetic fields. Computer CRTs are an example with the electron beam forced towards the phosphor-coated screen by a more or less ‘static’ electric field all the while under the back and forth influence of a dynamic magnetic field from the deflection coils (called ‘the yoke’ in the trade).
2. Conversely, when Electrons or Protons move, they create ‘fields’ and then perhaps (propagated) ‘waves’ as well. Electromagnets and antennas are examples.
3. Molecules, such as CO2 and H20 are comprised of atoms the components of which are Protons and Electrons (we ignore the Neutron). This is elementary; consult any HS text for a refresh.
4. Many molecules such as O2 (and even CO2 and H2O) have specific mechanical resonances, at specific frequencies (or wavelengths if one prefers).
5. These mechanical resonances are like miniature tuning forks. The vibrational modes get a little intricate and differ from molecule to molecule on account of the ‘atomic relationship’ of the member atoms.
6. During these vibrational modes, certain ‘member’ atoms can move more than others, and some ‘parts’ are electrically charged … referring to 2. above this will create a ‘field’.
7. Should a particular frequency EM field pass by a resonant molecule, the molecule, like a resonant dipole antenna will ‘pick up’ (the field will induce into the molecule) energy from the passing field .. refer to 1. above.
8. The actual resonant frequencies of resonant molecules is affected by pressure; this means more collisions between atoms, and sometimes vibrational energy can be absorbed in a collision while sometimes energy is given off. ‘Broadening of spectral lines’ is the basic effect.
9. Any vibrational modes amount to ‘stored energy’,
10. Said ‘stored’ energy is also continually being re-radiated (refer to 2. above) in basically all directions (any given molecule will have a given radiation pattern, but in the aggregate among all randomly oriented molecules this yields an ‘omni’ directional pattern).
11. An increased amplitude ‘Vibrational mode’ (no matter how arrived at) amounts to a ‘higher temperature’ locally.
12. From insolation (incoming sunlight), to heating of the earth’s surface, some convective heating of the air near the surface (consult a meteorology text; the MAJORITY of the heating of the air is in the boundary layer), to radiation of LWIR from the earth’s surface, some LWIR is captured’ (excites or is EM induced into) various GHG molecules e.g. CO2 and H2O … and that ‘captured’ EM energy is re-radiated in all directions, *including, and this is very important: BACK to earth … some term this ‘back radiation’, perhaps after the close radio term, ‘back-scatter’ (as used in RADAR to identify energy ‘reflected’ or scattered back from a target).
And so there you have it.
The 12 easy steps to understanding the minor but important (as to moderating the surface temperature of the earth) GHG effect.
Added: How does this ultimately affects the climate and what the ‘sensitivity’ of the climate is to changes in CO2 levels? I’m going to kick this can down the road for the time being, but I don’t think there are any ‘tipping’ points that will be reached.
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Well the camera does love Brian Cox or is it the other way around?
wmconnolley thinks people who believe in something in which he does not believe, and for which he has disdain, should “find someone else to talk to”. Hmmm. That he comments here at all demonstrates he (correctly) assumes the rest of us don’t ascribe to his arrogant attitude.
The problem is that the greenhouse effect, per a glass greenhouse, does not exist in our atmosphere as a greenhouse specifically prevents convection, which is the entire reason a greenhouse warms. Glass lets IR out, so the glass of the greenhouse is actually a negative in keeping the greenhouse warm.
The IR absorbed and re-emitted by molecules in the atmosphere and sent downward hits a surface which is warmer than the atmosphere and must either exchange evenly with emitted radiation or resonate and reflect back. [The equivalent energy levels in the surface are full and the IR cannot be absorbed as new energy unless another IR is emitted leaving an empty energy level.] The downward IR CANNOT warm the surface, per the 2nd Law of Thermodynamics. The greenhouse effect, thus, does not exist as the atmosphere is free to convect warm moist air to altitude.
The Earth, as opposed to the models, has a nighttime during which IR bleeds to space. CO2 and water vapor also bleed energy as they convert heat energy to IR which also is lost to space. A bit of downward IR might impinge one the surface, but it is not clear which will cool faster, the air or the surface, but I’ll put money on the air cooling faster, given the heat conductivity of rock being slower than a gas. Thus, even at night, the atmosphere cannot warm the surface.
Nice video, but in my opinion it is a bit mis-informative.
No mention of absorption to extinction for the wavelengths in question and the fact that because of this extinction no further absorption would take by adding more CO2.
…would take place by adding more CO2. Also how is the distance to extinction calculated.
> wmconnolley says: April 27, 2012 at 6:41 am: Makes the standard error most naif folk do.
And on further consideration, I’m being too sniffy. It was the bit at 3:30 in the first video “since these waves are unable to pass through the glass”. They can’t, but that doesn’t much matter, and this has been known for ages (e.g. http://wmconnolley.org.uk/sci/wood_rw.1909.html), and the video corrects itself later.
J says: April 27, 2012 at 8:08 am
“I think the comments here are an interesting study on how subjective science and especially science education is. “
I would second that though. Two quotes come to mind:
“As simple as possible” is, of course, relative. To get the gist of the effect of IR absorbing gases, a simple explanation with a simple model suffices. No actual math is required.
To calculate actual heat flows (like some are asking for in this thread) requires a much more sophisticated model. The calculations for the exchange of IR photons between land and air and space for this model are not simple. This level of detail cannot be adequately be explained or expressed in a 3 paragraph reply to a blog. Frankly, anyone who asks to be tutored from a high school level understanding to understand a PhD-level analysis in a blog doesn’t understand how science works and doesn’t understand enough physics to even be asking the question. A better question would be something like “I made assumptions X & Y & Z, and calculated the heat transfer to be Q. Why does this disagree with the numbers presented in ABC”. Then at least others know the model and the assumptions, and can try to figure out the next level.
##################################
But back to the original video, I thought it was pretty good for the level it was aimed at. There were a few things I would have said differently (eg, the glass in a greenhouse doesn’t “reflect” the IR, but rather absorbs IR and then radiates its own IR due to its own temperature) but for a fun video aimed at a high school audience, I think the knowledge presented is both “useful” and “simple, but not too simple”.
Higley7 said
I recall reading something from Roy Spenser where he pointed out that at certain times of year, frost was common on the ground, on your car, etc. when the air temp had not gone down to 0C.
And from his back-garden experiments, it is clear that solids can lose heat at night by IR much more easily that air (esp dry air).
Jim @ 8:46 am
When you did previously post this explanation I meant to comment on its clarity and thank you – didn’t then; do now.
I have a question and a suggestion. A link to images of molecules that suggest how they react (or don’t react — See wmconnolley’s terse response @8:10 am to Rich) would help.
The question is: You use the terms ‘captured’ and re-radiated. Single quotes yours, but not also on re-radiated. You seem to be suggesting something with ‘captured’ — What? And is it not so that what comes back, that is, re-radiated, is not equivalent to what goes in. The “re-” part seems to say that it is. If what comes out isn’t exactly the same as what goes in then “re-radiated” confuses the process. Hope this question makes sense.
_Jim says:
April 27, 2012 at 8:46 am
Thanks Jim
Your explanation makes great sense…but you kinda lost me at number 11. Converting vibration to temperature? Do you have an equation for that?
steveta_uk says:
April 27, 2012 at 9:24 am “Roy Spenser”
!! Spencer
http://www.drroyspencer.com/2010/07/experiment-to-test-the-temperature-influence-of-infrared-sky-radiation/
In a comment, Mark P., uses “frost on the ground” in the manner you suggest.
I watched the first one. Plus points for being cheerful when there are so many scary and solemn (and, I would add, reprehensible) materials clearly intended to scare children about climate. The undue emphasis given to CO2 in the video is the same ‘mistake’ as committed by such as the IPCC. I put the word in quotes since of course it was a deliberate one. The failure to note the early 20th century experiments on the greenhouse effect in real greenhouse-like structures is a bit odd since they showed the essential irrelevance of the infra-red properties of glass. These experiments have been repeated more recently, and would surely be feasible to set up for use in high schools. The name ‘greenhouse effect’ has had such an appeal for its emotive effect (well exploited for political and financial purposes by many) that it will be hard to discard it, but it ought to be discarded with regard to the atmosphere. Alternative names include ‘Tyndall gases’ for those active in the infra-red, and even the ‘Tyndall effect’ for reference to their role in the climate system, thereby recognising a pioneer of careful measurment in this area. (No scary associations of sweating and discomfort or even death in a closed car or sealed greenhouse, so not so good for campaigners intent on spreading fear). I think the attention towards the end given to the water cycle is promising. The water molecule is so important in our climate system that a marvellous course of materials for high schools could be created around it, and CO2 would be relegated to the minor, mostly secondary role it deserves to have. For example, the climate system in recent decades has been behaving pretty much as it might if the extra CO2 was of negligible importance compared to other factors.
So well done for being cheerful and upbeat. We shall have great need of that once work gets underway to reverse the hideous scaremongering targeted on the young and other vulnerable groups (including many credulous adults). I’m looking forward to watching the other 2 in the series when I get a chance to do so.
_Jim 8.28: you fail to understand my point which is about the most basic theorem in physics.
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If two bodies are at equal temperature and have equal emissivity, the radiation from one to the other is exactly nullified by radiation going the other way. This is Prrevost’s Theory of Exchanges, the oldest Radiation Law, and you also have the associated Kirchhoff’s Radiation Law which is that over any wavelength interval at each body, emissivity = absorptivity.
So, if you were to place a spherical radiometer or spectrometer between the two bodies, it would measure nothing.
Most radiometers/spectrometers aren’t spherical. they consist of a shield which prevents radiation going one way from impacting the detector. So it views part of the flux. That’s when you see the net energy flow and the spectral characteristics but it does not measure any real energy flow, just temperature and emissivity.
Do you get it yet? Because meteorologists donn’t understand what the pyrgeometers actually measure, they have put into the climate models a fallacy about ‘back radiation’ – it’s an artefact of the measurement process and if you take my argument to any professional physicist he/she will confirm my point.
The problem is that radiation physics hasn’t really developed since the 1920s and Planck invented the photon as a throw-away concept. it isn’t real.
Apologies for failing to turn of the bold, also I should add that this argument applies to a detector pointing towards the cooler of the two bodies if they are not at the same temperature.
However, I am totally firm in pointing out that at some time since Manabe and Wetherald’s 1967 paper which assumed IR up = SW down, a gross exaggeration but not incorrect physics, climate science and the modelling has assumed the false S-B B-B argument and imaginary back radiation to justify it.
Hopefully it will soon be accepted that this whole exercise has been a stupid waste of money because the people supposed to be running the programme have failed in their most basic understanding of physics. No IPCC climate model can predict climate and as well as turning BH’s readers, Curry and Spencer I will turn you onto the path of correct bloody physics…………:o)
Russ in Houston says:
April 27, 2012 at 7:39 am
No link. Have you seen any experiment reported where a parcel of air was heated soley by the addition of CO2?
wmconnolley says:
April 27, 2012 at 8:10 am
…”.If you want to pretend that the GHE doesn’t exist, find someone else to talk to.”
=============
Umm, nobody was talking to you, those were voices in your head.
u.k.(us) says:> Umm, nobody was talking to you
When someone starts a comment with “Mr. Connolley please…” I tend to assume they are talking to me. It seems natural. Perhaps there are other Connolley’s known to comment here?
wmconnolley says:
April 27, 2012 at 11:07 am
=====
Sorry, couldn’t resist.
[Moderator’s Note: You didn’t really expect Dr. Connolley to roll over for that, did you? -REP]
Bill Illis says:
April 27, 2012 at 7:25 am
Now how often is cloud cover is present.
Nearly all the *%£$?@# time in England.
The fart at 4.9 made me laugh, fart tax. lol
While the video did a good job with the greenhouse effect, it only tells half the story. What happens to energy in the atmosphere? The GHE relates to energy radiated from the surface. The energy in the atmosphere is ignored. Energy enters the atmosphere from many sources (which was mentioned in passing). This energy gets radiated to space along with the surface energy. The details of that process are essential to understanding how the Earth’s temperature is maintained.
I believe that GHGs act as a thermostat in and of themselves. If the atmosphere gets warmer they act to cool it down. If the atmosphere cools they act to warm it up. This occurs because GHG thermalization is based on different processes than kinetic molecular excitation of GHGs, even though both occur as a result of collisions. Thermalization is primarily based on the amount of energy radiated through the atmosphere. If no energy is absorbed by GHGs there is nothing to thermalize. Excitation is based on the actual temperature of the atmosphere.
Two identical cars.
One filled with Co2 . I’d like to see that one.
RICH says:
April 27, 2012 at 7:53 am
If nitrogen and oxygen “absorb almost no radiation,” how are they warmed then?
Conduction from the ground, and so carrry the heat up by convection thus reducing ground radiation and subsequent back radiation.
(I made that up, not bad for a uneducated person eh?.)
Mydogsgotnonose : “If two bodies are at equal temperature and have equal emissivity, the radiation from one to the other is exactly nullified by radiation going the other way.”
But there are (at least) two ways something can be “nullified” — you can “stop the activity” or you can compensate for it. For example, if I have a pump pumping water through a pipe, I could “nullify” the flow of water by putting an identical pump on the other end of the same pipe, so that no water flows. Or I could get an identical pump and pipe, and pump an identical amount of water back the same way, resulting in no net flow.
You seem to be thinking that the “back-radiation” is like putting the pump on the same pipe, so that no photons move either way. In reality, it is more like two pumps and two pipes, so that photons are flying both ways. There is a “real flow” of photons downward from the atmosphere (which tends to be less than the upward flow from the surface).
PS Even your guy Prevost seems to agree with me. Wikipedia quotes Prevost as saying
This would support the view that equal amounts are going in each direction, and that both are “real”. He does NOT say “receiving no heat from each other”.
wmconnolley says:
April 27, 2012 at 8:10 am
mkelly says:> Mr. Connolley please write a radiative heat transfer equation… Please use 1 atm and 288 K
Read your Wiki link and it was not about heat transfer it was about fluxes.
When you and others get the understanding that in heat transfer when T1= T2 Q/A equals zero, then you will stop this nonsense that radiation from a cooler atmosphere will heat a hotter surface.
That is why I ask you and others to write HEAT transfer equations so you can come to the realization you’re wrong.
I quit after the first video. I can’t stand the factual errors, such as “most of the suns incoming energy is absorbed by the earths surface and radiated as infrared”, or words to that effect.
Ouch! Most of the suns energy is converted to water vapour!
Yikes!
Higley7 said
“but I’ll put money on the air cooling faster, given the heat conductivity of rock being slower than a gas. Thus, even at night, the atmosphere cannot warm the surface.”
Actually, the thermal conductivity of air is much lower than that of rock. Air is an excellent insulator if it is kept from moving. However, air easily moves heat energy from place to place by convection. Fiberglass batting used as insulation works well because it minimizes convective air currents. Air is a much better insulator than the glass.
At night, heat is transferred from the atmosphere to the earth’s surface where it is lost to space thru the atmospheric IR window between 8 to 14 microns. The evidence of this is easily seen on a cloudless still night as the surface temperature will drop several degrees lower than the air temperature due to this radiative cooling process. This temperature difference is minimized when there is even a slight breeze. Turbulent mixing of air near the surface continually provides the surface with supply of atmospheric heat, thus enhancing this nighttime heat transfer.
Calculations of the heat transfer between a gas and a solid usually are done by assuming a stagnant layer of gas exists at the surface whose thickness varies with gas velocity. It is the temperature difference across this boundary layer along with the thermal conductivity of the gas involved that determines the rate of heat transfer.
In reality, there is a barrier to air movement in the atmosphere at the tropopause, where convection currents normally stop. Just like the the roof on a greenhouse so the greenhouse analogy is not as flawed as some make it out to be.
Thanks to all of you for your thoughtful comments and thanks to WUWT for posting my work! Being the first attempt, there is certainly room for improvement in terms of both clarity and production.
Some of the criticisms were based on watching only part 1. I believe most of these were answered later in the program. For those of you who stuck with the program, there was a great emphasis on the dominance of water vapor as a greenhouse gas. As Forrest Mims demonstrated in his AMS article last year, IR sky temp corresponds directly with precipitable water rather than CO2.
The real test will be how this type of video is received by students and educators.
And, by the way, I can’t help it if I look kind of like Bill N– and happen to have the same first name!
Sorry. But I do not like the video. Too many scientific errors. Please educate yourself before you make future videos and please do not show this video to kids. It will only get them more confused.
I enjoyed the videos. To critique it, I would say pick up the pace a bit.
I began to fidget, look out of the window and I thought about making a spitwad. :-).
I have read in a few places where the GreenHouse Effect really doesn’t exist anywhere but in a greenhouse – or in this video.. a green car… one such paper is here:
http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf
In the abstract it states.. “Ac- cording to the second law of thermodynamics such a planetary machine can never exist.”
Although the video is well intended, it really doesn’t do a very good job of giving all ‘scientific’ sides to greenhouse effects…
Hi Tjfolkerts:
Same thing applies: put a plug between the two systems and the net pressure on either side of the plug is real, but nullified by he equal and opposite pressure the other side.
The plug shrinks a bit………
‘Back radiation’ is imaginary…….
Greenhouse analogies are fraught with confusion.
It’s easier to just start with the actual science and experiements
http://nsdl.org/sites/classic_articles/Article3.htm
http://nsdl.org/archives/onramp/classic_articles/issue1_global_warming/n3.Tyndall_1861corrected.pdf
To me it is a very well done misleading propaganda video.
No references to key claims, I am not surprised.
Hi W. M Connolley, since your expertise is to edit wikipedia articles, be sure to correct the one you suggest: http://en.wikipedia.org/wiki/Greenhouse_effect#Real_greenhouses
Where is written:
“In the greenhouse effect, rather than retaining (sensible) heat by physically preventing movement of the air, greenhouse gases act to warm the Earth by re-radiating some of the energy back towards the surface. This process may exist in real greenhouses, but is comparatively unimportant there.”
There’s an error made by some naif people that use to edit wikipedia. Greenhouse gases do not re-rediate some of the energy back towards the surface since the molecules do not have any infinite common orientation that forces the re-emitted radiation only to the surface. Radiation is re-emmited in all directions, including the earth’s surface. The reason why this effect is more intense near the surface it’s because CO2 is more concentrated here and not because it “re-emmits” to the surface. Sorry for my english, but I guess that you’ll understand the physical process. Please edit the Wikipedia article to correct this common “naif” error. The heat transfer processes are a lot more complex than this and this “re-radiation” effect of CO2 is largely over rated.
From a real climate scientist…
montanaconserv writes: “I have read in a few places where the GreenHouse Effect really doesn’t exist anywhere but in a greenhouse … “
One constant problem is that “the greenhouse effect” means different things to different people. I suspect it would not be difficult to find a dozen or more significantly different variations on definitions for “the greenhouse effect.” So before stating whether or not it exists, it is important to state clearly which specific version of “the greenhouse effect” you mean.
Beyond the definitions, people often use analogies, which creates further problems. Saying the atmosphere acts “like a blanket” has some elements of truth, but has a lot of problems, too. The paper you referenced says the greenhouse effect “essentially describes a fictitious mechanism, in
which a planetary atmosphere acts as a heat pump …” which is also a poor analogy (and then makes it easier for the authors to attack the poorly defined “greenhouse effect”.
To me the one key idea in “the greenhouse effect” (as related to the atmosphere, not actual buildings) is that the atmosphere is (mostly) transparent to sunlight, but (significantly) opaque to “earthlight”. This provides a mechanism for the atmosphere to send some energy back to the surface. Many OTHER effects (like evaporation and convection) ALSO affect the temperature at various points, but they are SEPARATE from what I consider to be “the greenhouse effect”.
Maybe I should start a collection of different versions and then let people pick which one they are attacking or supporting….
Sorry Spartacus: CO2 is not concentrated near the surface: it is well mixed.
Your argument is based on the assumption of 100% direct thermalisatin. That is not true: probably it’s indirect at clouds, and bare aerosols.
Mydogsgotnonose writes: “… put a plug between the two systems …”
Ah, but the only way to “plug” the IR would be to put some sort of “IR block” between the sky and your measuring device. That would indeed stop the IR, but now you can no longer claim to be measuring the IR from the sky.
> Spartacus says: http://en.wikipedia.org/wiki/Greenhouse_effect#Real_greenhouses… Greenhouse gases do not re-rediate some of the energy back towards the surface since the molecules do not have any infinite common orientation that forces the re-emitted radiation only to the surface. Radiation is re-emmited in all directions…
Errm, your logic and/or reading comprehension has failed you. The GHG’s do indeed (a) radiate some of the energy back to the surface, but as you so wisely observe, they (b) radiate in all directions. these two statements are not contradictory. Indeed, as the wiki article states “The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions”. Thats, ermm, the first sentence, so I can see how you might easily have missed it.
Perhaps less obviously, since the atmosphere is approximately 2-D (its 10k high but 10000k wide, so to speak) you don’t need to think of “all directions” but only up-and-down.
> near the surface it’s because CO2 is more concentrated here
As Mydogsgotnonose observes, this is wrong. There is more WV near the sfc, perhaps that is what you were thinking of. In fact, due to saturation, the GHE is less important near the surface, not more so.
Hi Tj: clever but I’m not falling for it. I’m a process engineer and for the emissivity of sand with non-forced convection, you need about 100 deg C before radiative flux > convective flux.
The ‘sky’ is an impedance to IR transmission to space. The way you measure its temperature is to use a pyrometer which, by blocking IR energy from the opposite direction, reveals the S-B radiative flux with no opposing flux.
‘Back radiation’ from a colder atmosphere cannot create heat energy at the earth’s surface, To claim this is to claim the existence of a ‘Perpetual Motion Machine of the 2nd Kind’, in thermodynamic terms.
Climate science is dead until it acknowledges its major mistakes. Hansenkoism is dead. Trenberthism may evolve by the missing ‘0.9 W/m^2’, for 18 months maximum.
Mydogsgotononose, almost everything in the atmosphere is more concentrated near the surface, including CO2. The CO2 concentration it’s indeed more constant than water vapour with altitude but all the gases get more rarified with the variation of the pressure gradient. Concentration remains approximately the same but everything follows more or less the PV=nRT variables. The “absolute amount” (not the concentration) of CO2 gas reduces with altitude because atmosphere pressure drops. If you see the patterns of the distribution of CO2 from satellite readings, you will se that the “it is well mixed” its a myth or more a misconception. It’s neither well mixed horizontally nor vertically. There are even more differences between the earth’s hemispheres for instance. I guarantee you you will not get the same absolute amount of CO2 near the earth’s surface or 4000km above your head. Most plants know that too…
See density and pressure profiles from connolley’s favourite wikireference:
http://upload.wikimedia.org/wikipedia/commons/9/9d/Comparison_US_standard_atmosphere_1962.svg
I agree that water vapour, duo to the physical properties of water, drops more rapidly than CO2, but every gas gets more scarce with altitude.
_Jim says:
“7. Should a particular frequency EM field pass by a resonant molecule, the molecule, like a resonant dipole antenna will ‘pick up’ (the field will induce into the molecule) energy from the passing field .. refer to 1. above. “
Are you denying the particle theory of light? There has never been a better proven theory than the particle theory of light … except of course the electromagnetic theory … although it does have a few problems when anything gets moved … which is why we stitched it all together like a torn bit of rags with relativity. But of course, when none of that worked we pretended we could explain it with that new theory called Quantum physics.
Which … says that everything is waves. No, No! … not those old fashioned waves travelling through the ether … no new fashioned waves travelling through a new fashioned ether of time-space. Which really isn’t an ether at all because time space isn’t something its nothing.
And now that everything is completely clear, the argument is over, the science is settled and the theory of light is provable and predictable:
It means we have completely testable science. We can prove the theory is true because we can explain why it doesn’t work when it is supposed to be a wave … because we have the excuse its a particle. And, we can explain why it doesn’t work when it supposed to behave like a particle …by using the excuse that its really a wave.
And we wonder why climate “scientists” think they can make predictions … and if they don’t work they just adjust the causations to include a few added bits and after the experiment is over “prove” they were right because they can swap the theory to suit whatever the result turns out to be.
Isn’t that hilarious!
http://upload.wikimedia.org/wikipedia/commons/9/9d/Comparison_US_standard_atmosphere_1962.svg
If you see from those graphics, the density of the atmosphere drops almost 1kg/m3 from the surface until the Tropopause. Thats a huge amount of less gas re-emmiting radiation, including CO2. This is one of the biggest misconceptions among those that are trying to find hotspots within altitude 😉
Sorry, in one of my last comments, i wanted to write “I guarantee you you will not get the same absolute amount of CO2 near the earth’s surface or 4000 meters (AND NOT KM) above your head.
PS. If you like the video, pass it on!
I’d like to pass it on to Michael Mann, Al Gore, Phil Jones …..
Re my above comments ridiculing the wave-particle theory.
Let me put this in a way most people here will understand. (And just pray the climate “scientists” don’t get any ideas!)
Let us suppose that a climate “scientist” proposes the “drought-flood” theory of climate. This theory says that sometimes the climate behaves to give floods, sometimes drought. We don’t know why or when but it just does. They then offer it to be tested. Asked what they think the climate will do, they say: “I think flood”, there is a drought … is the theory disproven, no! This is because it was behaving like a flood event and not a drought event.
Let us now suggest we create a few more particles (sorry modes of behaviour). Let’s call them the heat-cool particle … sorry event, the flood-drought, the wind-calm … I think you may understand where I’m going.
E.g. the theory predicts the warming of the climate from 1970-2000, then (for reasons they do not need to explain) the other nature of the beast is uncovered and instead of being a heat-event the theory “predicts” (or post-dicts) the cooling event.
The theory is entirely “scientific” like wave particle. It explain everything: there is not a flood, drought, heat-wave, freeze that is not consistent with the theory. Yet strangely it predicts nothing.
First –
Maximum radiative transfer of energy between two non contiguous bodies occurs in a vacuum.
Interposing any matter at all between the bodies reduces the amount of energy received by both.
Where one body is warmer than the other, reducing the efficiency of the energy transfer between the two will not cause the cooler body to increase its temperature above that which is achieved at maximum efficiency.
“Back radiation” is merely cultist obfuscation, attempting to ascribe magical properties to something which exists naturally, and is a property of all bodies above absolute zero – ie all bodies. Every body above absolute zero emits electromagnetic radiation – freezing cold, boiling hot – no exceptions.
Second.
The Earth has obviously cooled since its creation some time ago, if, indeed it was originally a molten blob.
Because it is still a large molten blob, surrounded by a thin solid (or “frozen”) crust, the Earth’s temperature gradient proceeds from the hot inside to the cooler surface. Until the the Earth reaches a point where it has a uniform temperature throughout, it has obviously not finished cooling.
Any calculations purporting to show that the Earth “should have” a temperature of x, are nonsense. The Earth’s surface is at the temperature it has reached as it cooled from several thousand degrees initially.
Third.
Any person claiming to have calculated an “average surface temperature” for the Earth is pulling your leg. Ask what the figure is for say, 0300 UTC on 1/1/2012, and you will find that the figure given comes with caveat or two – a particular refuge is to quote something like 95% certainty. In other words, one chance in twenty that the figure is wrong. Not to mention the fact that whatever is purportedly measured is most certainly not the surface – usually near surface, over land. Not even that over the ocean, which covers most of the planet.
Anyone claiming to measure “global warming” is delusional. They can’t even define the surface that they claim to be measuring. Is it the top of the soil? The top of the rain forest canopy, or the top of the humus beneath it? Maybe the froth on the ocean wave, or the solid water in the trough, a split second later. Does it all “average out,” perhaps? If you believe that, I have a nice bridge you might be interested in buying.
Live well and prosper!
Mike Flynn
Mr. Scientific, or may I call you Bill, check out your humor with your kids’ friends. A good try… but I don’t see a donate button, because I certainly think your in the right space but professional assistance is required.
BTW I am reminded of Zeno’s paradox about the “reflected” radiation… isn’t half of that also “reflected” back to space … half of that back down and half of that back..etc.? In fact, the whole notion is entirely simplistic and childish. Some serious analysis is required before a line of computer code is written…. and I mean serious, not just building on further models and hearsay.
In fact, I think climatologists should just shut up for a couple of thosand years until they have a reliable series of
temperaturesenergy balances.Mydogsgotnonose says: April 27, 2012 at 4:05 pm
“Hi Tj: clever but I’m not falling for it. I’m a process engineer and for the emissivity of sand with non-forced convection, you need about 100 deg C before radiative flux > convective flux.”
Ah, but now you are talking magnitudes of various processes rather than the existence, in principle, of a process. I don’t doubt that in many situations, conduction and/or convection are more important than IR photons for transferring thermal energy. But just because something is small does not make it “imaginary”.
The vast majority of energy in the atmosphere near the surface is transferred from molecule to molecule through collisional exchange rather than emission of photon radiation.
The energy represented by an average IR photon emitted from a hot rock at noon spends time in billions of different atmospheric molecules (99.999% transmitted through collision) before it makes its way to 10 kms high where it starts to have 50% chance of actually being emitted as a photon and making its way directly to space.
Real physics is different than the greenhouse effect explanation. The energy takes a lot of time to make its way back to space and it spends that time in billions of different molecules. It is not “in and out”.
An average 1 sq metre rock on a beach in the tropics receives 2.5 X10^21 solar photons from the Sun each second at noon and emits 1.5 X10^22 IR photons per second at noon. How many of those photons are intercepted by CO2? How many of those interceptions result in a back-radiated photon to the surface? It is a tiny, tiny, tiny fraction compare to the 1.5 X10^22 photons emitted per second. The rock is more likely to receive the energy back after a Nitrogen molecule collides with it and then re-collides with it putting the energy back into a molecule on he surface of the rock.
Climate science is still based on the way we understood physics in the 1896 when Arrhenius did his infamous work. The quantum world is much different.
ozzieostrich says: April 27, 2012 at 5:15 pm
First –
Maximum radiative transfer of energy between two non contiguous bodies occurs in a vacuum.
True, so the maximum transfer between earth’s surface and space occurs with no atmosphere in between. By adding at atmosphere, we reduce the transfer to space. This in turn means the surface must get warmer until it once again radiates enough energy to space to balance the incoming sunlight.
“Second.
The Earth’s surface is at the temperature it has reached as it cooled from several thousand degrees initially. “
No, if the only process involved was the earth cooling by radiation, it would have cooled much more much faster. Estimates put the geothermal heat flux at ~ 0.1 W/m^2. Even if this is off by a factor of 100 and the flux is really 10 W/m^2, this is way smaller than the incoming 340 W/m^2 of sunlight.
“Third.
Any person claiming to have calculated an “average surface temperature” for the Earth is pulling your leg. Ask what the figure is for say, 0300 UTC on 1/1/2012, and you will find that the figure given comes with caveat or two …
This is true. That is one reason people often talk about “changes in temperature” or “temperature anomalies”. It is often quite possible to measure changes quite accurately even when the actual values are not known. For example, I can measure two resistors with the same cheap DMM. Even if the readings are 100.0 Ohms +/- 5 Ohms and 100.5 Ohms +/- 5 Ohms, I know the second resistor is about 0.5 Ohms more, even thought that is less than the uncertainty in either measurement.
If I measure 1000’s of temperatures, it is quite possible to see that they have gone up an average of 0.4 C from one day to the next, even without worrying about what the “average temperature” might represent, and even if the thermometers are only calibrated to +/- 0.5 C.
Tim
Robert of Ottawa says:
April 27, 2012 at 6:02 pm
“…isn’t half of that also ‘reflected’ back to space … half of that back down and half of that back..etc.?”
Very close, but not exactly. At the surface there is a 50/50 chance of a photon being radiated toward the surface or toward space. But the part of the atmosphere that does most of the radiating is above 10 km altitude. Therefore, an emitted photon has a greater than 50/50 chance of being emitted toward space, due to the altitude and the curvature of the earth. So no matter how many billions of re-emissions occur, the net effect is the same: there is more than a 50/50 chance of a photon ending up in space than on the planet, and the odds rise with altitude.
That is why William Connolley tries to reinforce that argument when he says: “since the atmosphere is approximately 2-D (its 10k high but 10000k wide, so to speak) you don’t need to think of ‘all directions’ but only up-and-down.”
“Only up and down” is an attempt to eliminate the ‘more up than down’ scenario. Can’t have that, can we? Because then it might be possible that CO2 has a net cooling effect.
Bill says “How many of those photons are intercepted by CO2? How many of those interceptions result in a back-radiated photon to the surface? It is a tiny, tiny, tiny fraction compare to the 1.5 X10^22 photons emitted per second. “
First, how many of those photons would return with NO greenhouse gases? None!
So we are already at least a BIT ahead of the game.
As for the amount of energy returned, you can “look” up with a cheap IR thermometer (which brings us back to the top post!) and easily measure the “back-radiated” photons. Sure it is typically less than the upward IR from the ground (ie the thermometer reads a lower temperature when aimed at the sky). Much of this is from clouds; some is from H20 vapor; some is from CO2. I would not consider the amount “a tiny, tiny, tiny fraction”.
“The rock is more likely to receive the energy back after a Nitrogen molecule collides with it … “
Except that the nitrogen molecules are about the same temperature as the rock, so on average they neither add nor remove energy much energy. (The “17 W/m^2 Thermals” would mean the surface is, on average loosing energy from collisions with the air, not receiving energy.)
Smokey says:
April 27, 2012 at 6:45 pm
“Only up and down” is an attempt to eliminate the ‘more up than down’ scenario. Can’t have that, can we? Because then it might be possible that CO2 has a net cooling effect.
=========================================================
A net cooling effect is possible, but rather for a different reason: the “greenhouse gasses” block some IR coming from the Sun, this must contribute to cooling. This is a dirty little secret of the warmists.
@tjfolkerts
In response to your comments.
First
By adding an atmosphere, we reduce the radiative transfer between the Sun and the Earth, and vice versa. No ifs, buts, or maybes. This means that the surface of the Earth gets cooler – it is receiving less radiation. Pretending that the atmosphere blocks EMR unidirectionally might be convenient, but is not true. However, if someone can demonstrate experimentally that you can cause a body to become warmer by wrapping it in CO2 (or anything else that is not warmer than the body in question,) I will change my thinking.
Second.
Your response does not make much sense to me. The Earth was molten. It is not now. No ifs, buts, or maybes. Apart from emitting EMR, how would you suggest it cooled? Obviously, (I would think it’s obvious,) the output from the Sun was insufficient to prevent the Earth cooling to where it is now. You can estimate all you like, but it doesn’t change the reality that the Earth has cooled, all by itself. Facts are facts.
Third.
I notice you use your own caveats. This is normal for people who believe in the ability of gases to create warmth out of nothing by some magical process of “one way insulation”. You say ” . . . it is often quite possible . . .” Another characteristic of believers is to use inappropriate analogies. Rather engage in a probably pointless discussion about cheap DMMs, etc, I would merely point out that you assume absolute repeatability, but then add the caveat ” . . . is about . . .” after your statement “. . . I know . . .”
Your assumptions about making thousands of measurements etc., would would carry far more weight if you actually did it, and were than prepared to defend your assumptions relating to how you defined the surface etc.
There is no “greenhouse warming effect” due to CO2 or anything else. Insulators do not warm (or cool) objects in and of themselves – the “blanket effect” does not lead to a rise in temperature, in spite of Mike Mann and Chris Colose. So, sorry, the only source of man made warming is the heat generated by the activities of man. For example –
1. Burn a tree. The action oxidises carbon, creating heat and carbon dioxide.
1. Stay alive. You have oxidised carbon within your cells, creating heat and carbon dioxide.
Creating carbon dioxide by means of combining oxygen and carbon is exothermic, resulting in heat. Go one further, create lots of heat by thermonuclear means – say in a nuclear powered submarine or power station. Lots of heat without carbon dioxide generation. Man creates heat. No ifs, buts or maybes. No caveats to be seen.
Heat cannot be trapped. The perfect insulator does not exist, and all objects above absolute zero emit EMR. No ifs buts or maybes. Given long enough, all matter in the Universe will become isothermal – an assumption shared by much smarter and well educated people than me. Without additional energy input, the earth will continue to cool – slowly and remorselessly
If you want to believe the myth of CO2 greenhouse warming, be my guest.
In the meantime, live well and prosper
Mike Flynn
Now that damned dog with no nose is pedalling his nonsense full time here too?
He won’t ever write you his equations though. That would catch him out. It’s all about how everyone else is wrong, but no actual maths/physics to back it up. With equations.
The problem is that radiation physics hasn’t really developed since the 1920s and Planck invented the photon as a throw-away concept. it isn’t real.
People are already laughing at you Doggie. But saying nonsense like this will make the laughs a lot louder.
Give us your equations that show that every particle physicist for the last 100 years is wrong. No spouting. The equations that replace the photon.
Scottish Sceptic says:
April 27, 2012 at 4:31 pm
“Isn’t that hilarious!”
That pretty funny.
tjfolkerts says:
April 27, 2012 at 6:42 pm
True, so the maximum transfer between earth’s surface and space occurs with no atmosphere in between. By adding at atmosphere, we reduce the transfer to space. This in turn means the surface must get warmer until it once again radiates enough energy to space to balance the incoming sunlight.
OK, I’ll play along. How does the surface get warmer??? This sounds to me like a Maxwell’s demon issue. If the atmosphere keeps the energy in, it must also keep the energy out (If it inhibits energy flow it must inhibit in both directions)
Why not try to show the spectral intensity graphs to their correct proportions. A lower temperature spectral intensity graphs lies completely under a higher temperature spectral intensity graph. In your case you would not even see the lower temperature graph if graphed within the higher temperature graph. There is more long wave incoming than coming from the surface and could be absorbed by water vapor and carbon dioxide before reaching the surface.
Larry
ozzieostrich
1) Certainly the atmosphere absorbs/scatters/reflects some sunlight before it reaches the earth. No one disputes that. The question then becomes how much EM radiation each way is blocked, and how that affects the temperatures. The common answer is that, given current conditions, the net effect is to warm the earth. If you have other calculations, then tell us what temperature YOU predict based on your calculations.
“if someone can demonstrate experimentally that you can cause a body to become warmer by wrapping it in CO2 (or anything else that is not warmer than the body in question,) I will change my thinking.”
It’s called “the earth”. 😉
The challenge to do this in a “laboratory experiment” is that you need
1) a warm object
2) cold walls all around
3) a thick enough layer of CO2 (or other GHG) to absorb a significant fraction of the IR.
Also, on a cold day, my fingers get much warmer by wrapping them in cooler fabric (aka “gloves”).
2. The point is that the earth has indeed cooled by radiation, but the current temperature cannot be inferred solely from the initial conditions as your statement seems to imply: “The Earth’s surface is at the temperature it has reached as it cooled from several thousand degrees initially. ” You seem to imply that the surface is ~ 288 K because that is all it would have cooled from the hot initial conditions. In fact, the surface would have cooled much further than 288 K if the sun was not keeping the earth warmed.
The current temperature is determined 99+ % by sunlight, and less than 1 % by geothermal energy.
3. I can’t speak for “people who believe in the ability of gases to create warmth out of nothing by some magical process”, because I believe in a scientifically based greenhouse effect. 😉
Certainly the “global temperature” is open to numerous questions in terms of calibration, siting issues, lack of coverage, etc. I’m just saying it is not QUITE as bad as you seem to think it is.
“Insulators do not warm (or cool) objects in and of themselves”
Very true. But they don’t have to. If I build two houses that are identical other than insulation and run the furnaces exactly the same on a winter day, the house with insulation will be warmer inside. The furnace provides the thermal energy to each house; the insulation simply makes the one furnace more effective.
Similarly, it is the sun that provides the thermal energy to the earth. The GHGs simply make the sun more effective.
Russ in Houston proposes an insightful hypothesis: “If the atmosphere keeps the energy in, it must also keep the energy out (If it inhibits energy flow it must inhibit in both directions)”
That is the crux of the greenhouse effect. The atmosphere does indeed have to inhibit the flow of photons equally in both directions. But! this applies individually to each wavelength.
* A 0.5 um green photon is block from leaving just as well as it is blocked from arriving. There just happen to be a lot more 0.5 um photons heading down than up.
* A 15 um IR photon is block from leaving just as well as it is blocked from arriving. There just happen to be a lot more 15 um photons heading up than down.
These facts allow the atmosphere to inhibit photons differently in the two directions.
tjfolkerts,
That is a bunch of total crap.
What the heck, let’s try one more ….
lrshultis says: April 27, 2012 at 8:41 pm
“Why not try to show the spectral intensity graphs to their correct proportions. A lower temperature spectral intensity graphs lies completely under a higher temperature spectral intensity graph.”
Once again, this is true as far as it goes. The other point that need to be made is the geometry. The sunlight is indeed more intense at all wavelengths. However the sun only covers about 0.001% of the sky. The other 99.999% is the earth’s atmosphere.
Roughly speaking, the sun is 100,000 times “brighter” than the atmosphere, but covers 1/100,000 as much area, so both provide similar amounts of energy. So drawing the graphs with similar areas is completely legit.
Smokey says “That is a bunch of total crap.”
And as is much too common, Smokey is once again all smoke and no fire.
What SPECIFICALLY do you disagree with? What SPECIFICALLY do you propose as a better answer?
Definitely a ‘don’t try this at home’ moment.
Exhaust fumes from petrol engines contain 1000 to 2000ppm CO and just 667ppm can cause coma, seizure and fatality. CO2 is 14% but it is the ability of CO to bind to haemoglobin in red blood cells and persist, that deprives the victim of oxygen, and could kill.
Not a good example, Bill.
tjfolkerts
1. The “. . . common answer . . .” is wrong. CO2 no more “warms the Earth” than your gloves “warm your hands”. I love a bad analogy combined with an appeal to consensus.
Nobody seems to be able to calculate an “average temperature” for the Earth’s surface which stands up to scrutiny. I have to admit, neither can I. But thanks for the vote of confidence.
I hope I don’t offend you by asking you to measure the temperature of your fingers inside the gloves. Your fingers don’t receive heat from the gloves, they receive heat transferred by the blood stream from cells oxidising carbon. The reason your fingers get cold on the surface is that the heat transfer process cannot keep up with the heat loss occasioned when the temperature differential between the skin surface and the surroundings exceeds the body’s ability to replenish the lost heat.
If you place your glove on the hand of a corpse, the hand will not become warmer. Neither will the Earth by surrounding it with anything at all.
2. I imply nothing. I am stating that the Sun cannot provide sufficient energy to maintain the Earth’s surface temperature at a higher level than exists now. Otherwise, the Earth’s surface temperature would be higher than it is. I trust you agree. Whatever the current surface temperature is, it is – depending on your definition of the “surface”. I assume the Earth will continue to cool until the Earth emits precisely as much EMR as it receives from the Sun.
3. There is no “scientifically based” greenhouse effect that depends on CO2 or any other substance transmitting the total EMR spectrum more efficiently in one arbitrary direction than another. Perpetual motion and infinite free energy are then practical. Unfortunately, there exist plans for perpetual motion or “free” energy generators depending on the application of the principles you appear to believe in. They are nonsense too.
As to insulation, build your houses. Don’t turn on your internal heat generator – that provides, like your fingers, an internal heat source. Which house is warmer? The answer of course, is that they are both the same temperature. If you must use analogies (which I generally see as a device to obfuscate, rather than educate,) then use appropriate analogies. Blankets, insulation etc. do not provide warmth – no ifs, buts, or maybes. Find one that does, and free energy is at your command.
Finally, the maximum radiative transfer of energy is reduced, rather than enhanced, by placing GHGs in the radiation path. So, still no “global warming.”
For a bit of fun, think about why the water in the abyssal ocean depths is around a few degrees C. Interestingly, descending into the ocean results in falling temperatures, while descending into the lithosphere towards the centre of the Earth results in rising temperatures. After you have considered this for a moment or two, you may come to the conclusion that the Earth is still cooling, yourself.
In the meantime,
Live well and prosper.
Mike Flynn.
Keith Minto,
Not meaning to stir the pot, but at CO2 levels above around 7%, the stuff becomes poisonous. I notice a brief look at Wikipedia shows some contradictions. The British Navy was losing divers due to CO2 buildup in the inspired air in rebreathing equipment, even though there was plenty of O2.
Interesting. You probably don’t get the option of deciding whether you will die of suffocation or poisoning, or whether the CO gets you first.
Live well and prosper,
Mike Flynn.
Spartacus says:> almost everything in the atmosphere is more concentrated near the surface, including CO2.
Ah, this rather depends what you mean. If you’re measuring atmospheric constituents as parts-per-million, then no: CO2 (or other minor constituents like Argon) have constant concentration with altitude. If you’re measuring by molecules-per-m3 then yes: everything gets rarified as you go upwards. Your phrasing would normally have the former meaning (and so be incorrect) which is why people misunderstood you.
Mooloo: one of my heroes is Richard Feynman who preferred to teach by conceptual models. You have asked me to ‘write equations’. I could do so and fill papers with them but that does not make the science right. The equation you need is the last one plus whatever working to prove it!
A touching faith in equations is a crutch for people who do not understand physics. The only correct measure of radiative heat transfer in the atmosphere is to have two radiometers with 2 pi viewing angle back to back and use the difference signal.
It is set by S-B1 – S-B2 where 1 is hotter than 2. 1 is normally a composite emitter of the earth’s surface and the air path to the lower detector. 2 is defined by the average temperature of the air in 2 pi angle and its emissivity. The S-B2 ‘back radiation’ is a measure of IR impedance to space, not evidence of an energy source. The use of pyrgeometers is a dead end because they measure atmosphere temperature convolved with average emissivity in the view angle. It is not a measure of energy flow.
You prove this by looking at how the Bedouin make ice. They dig a pit in the desert with water at its base. Overnight it freezes because the pit tends to a black body and the restriction of the view angle reduces the emissivity of the air it sees. So S-B1 – S-B2 increases. Bad physicists and meteorologist [who aren’t taught proper physics] imagine the ‘back radiation’ is lower but this is wrong.
For clouds, the emissivity is much higher than clear air [~0.2], up to ~0.9, and they behave as a grey body. Meteorologists imagine ‘back radiation’ is higher. This is not the case. In reality S-B2 is higher because emissivity is greater. S-B2 is still a measure of IR impedance to space!
Everything would still be fine were it not for the Aarhenius’ claim in the Trenberth cartoon that IR from the Earth’s surface is the S-B level for a B-B in a vacuum. Aarhenius was a bad physicist. In chaos theory this defines an ‘attractor’, a calibration point, which is fundamentally wrong because it converts mostly convective hear transport in the atmosphere to mostly radiative.
The 2-5 times greater prediction of AGW assuming most recent warming has been AGW has to be backed off by making unrealistic estimates of cloud albedo. It would be better to correct the physics back to Manabe, in which case there might be a chance with much lower radiative transport near the earth’s surface of getting the right result. But then you wouldn’t have the scare story. Another issue is the failure to put the real attractor into the models which is the upper ocean temperature of 29 °C.
In short, the physics in the IPCC climate models is appalling and it’s time the discipline stopped fooling itself. It’s the end game.
Some of the objections to the ‘Greenhouse’ effect are semantic. Some people are objecting to ascribing an active action to a passive object. They insist that an object only warms or makes something warmer if it has an internal source of energy.
This despite the colloquial use in common English of phrases like ‘wearing a coat to keep warm’.
The confusion disappears if the actual flows of energy are identified and measured. Expressed as numerical functions the semantic problem vanishes.
Of course empirically we all know that a cloudy night is warmer than a clear night.
Slight mistake above; each IR detector has pi radians viewing angle.
Bill
I think your appoach to teaching young people the ‘Greenhouse Effect’ is probably appropriate for the modern generation. The emphasis given to water vapour as the major greenhouse gas is an often neglected but important aspect for youngsters to be made aware of . The relatively small contribution of CO2 as a greenhouse gas and the even smaller contribution of anthropogenic CO2 from the burning of fossil fuels is also important and is well made. I also liked the points made on the effects of cloud variation.
What I would like to see introduced to the video would be some mention of other sources of CO2. In particular that produced by human and animal respiration. I find that many people young and old do not appreciate that they themselves create CO2 by the mere act of breathing. I saw recently a very good example statement which went something like:-
“The air we inhale contains around 400ppm of CO2. When we breath out it contains 40,000ppm of CO2 i.e. ten times as much”. (I’m not sure of the validity of 40,000ppm but that can be checked). Multiply that by the world population and add to it that created by the breathing of other animals will help your students develop a greater understanding of what CO2 really is.
I don’t think the car exhaust demonstration is useful but if retained you need to explain the difference between the innocuous CO2 and the poisonous CO.
I support your intentions and wish you well
Correction to my post April 28, 2012 at 3:50 am
Third para second line should be ….. CO2 i.e a hundred times as much
fredj: 40,000/400 = 100
tjfolkerts says:
April 27, 2012 at 6:42 pm
You might want to rethink your example, unless you either 1) do not mind claiming that the two resister readings are different with an 8% confidence level or 2) are really just providing the best argument against using anomalies for judging temperature changes.
The fact that there is a non-zero difference in means does not imply that that the difference is statistically distinguishable from zero. The uncertainty in each measurement plays a critical role in determining whether such a difference is meaningful. To a first approximation, we can just propagate the error upon subtraction, which would tell us that resister two is 0.5 +/- 7 Ohms greater than the first. Although the value obtained from subtracting the two means is non-zero, any freshman level science student would readily conclude the two resisters are nevertheless indistinguishable. The source of the non-zero difference is solely due to experimental error. We can apply higher level statistical hypothesis testing to provide us with the exact same answer, unless we are willing to reduce our confidence level from the standard 95% to a paultry 8% level at best.
Fredj says: “What I would like to see introduced to the video would be some mention of other sources of CO2.”
Thanks Fred. That is a very good idea. While I would be inclined to save the details for a video on Global Warming, a brief breakdown of the sources of CO2 (part of the carbon cycle) would have improved the accuracy of the video and removed any mystery surrounding CO2.
Mike says: “If you place your glove on the hand of a corpse, the hand will not become warmer. “
Exactly! So if you shut off the sun, then the atmosphere would cease to warm the surface (after a very short time). But as long as the sun keeps shining, the atmosphere can keep elevating the surface temperature (above what it would be with no atmosphere).
“Don’t turn on your internal heat generator – that provides, like your fingers, an internal heat source.”
Let me say once again, we DO have an “internal generator” generating thermal energy. The sunlight penetrates to the “interior of the atmosphere” (ie the surface) and heats the atmosphere “from the inside” (like the furnace heats the house “from the inside”). You are missing this critical idea, and it then throws off the rest of your thinking. (And no, this is not a perpetual motion machine that violates any laws of thermodynamics).
I assume the Earth will continue to cool until the Earth emits precisely as much EMR as it receives from the Sun.
I don’t think we are really disagreeing here. I acknowledge that the earth is indeed still cooling. My point is that estimates I have seen put the geothermal energy flux at ~ 0.1 W/m^2. So yes, the geothermal energy is helping to warm the surface. And yes, the interior is slowly cooling. But these energies are tiny compared to other energy fluxes and can (for the most part) be ignored.
Finally, I agree that measures of “average temperature” are challenging and problematic. The records have changing coverage and changing instruments and changing times of data collection and changing surroundings. Then there is the whole question of how meaningful “average temperature even is, or whether some sort of “average energy” or average “T^4” would be a more physical thing to calculate. But however you think about it, if there is an upward trend at any given temperature station, then that station has experienced warming. If most stations show increasing temperatures, then there is “global warming”.
Thanks for the discussion. It helps me continue to refine my ideas and explanations.
Tim
PS. Sorry, Bill. We all seem to have hijacked your thread about your video.
W Connelly says:> Ah, this rather depends what you mean. If you’re measuring atmospheric constituents as parts-per-million, then no: CO2 (or other minor constituents like Argon) have constant concentration with altitude. If you’re measuring by molecules-per-m3 then yes: everything gets rarified as you go upwards. Your phrasing would normally have the former meaning (and so be incorrect) which is why people misunderstood you.
Even with my poor English, you know perfectly what I meant and there’s no possible confusion. CO2 is more concentrated near surface as well as any other gas and this is valid in mass concentration or Kg of a compound/ m3 of atmosphere (volume). In simple terms, the number of molecules of CO2 in a m3 of atmosphere declines with the altitude. You can twist, distort, flip it upside down but this is an undeniable truth – There’s more CO2 near the surface, as well as any other gases. The possible GH effect, due to the possible action of GHG, is more intense near the surface because of this bigger density and not because it radiates from above to the surface (or back to the surface as you say). This is a nonsense and it’s in Trenberth’s classic draw. Usually, versions of this Trenberth’s concept drawing, have a small and grayed out layer of greenhouse gases (simulating a imaginary blanket) and, by magic, radiation that comes from earth’s surface is reemitted again, with a perfect reflection angle, towards the earth’s surface. This is a highly misleading scheme and should be corrected. There are comments from other people above that identify correctly what happens at a molecular scale. Almost every wikipedia article about this is misleading and you should learn this effect perfectly and do your wikiedition with honesty.
Even Trenberth should correct his old scheme correcting that fictional “back radiation” because in term of atmospheric physics (even considering that this is only a scheme) it’s almost hilarious. There are other thing to correct in this scheme but this is the most comical one to say the least.
http://iedro.com/blog/wp-content/uploads/2012/04/RBRWuG0086_Trenberth_Radiative_Balance_BAMS_2008.gif
Cheers
Spartacus,
Connolley says: “…CO2 (or other minor constituents like Argon)…”
The amount of the trace gas agron is huge compared with the minuscule trace gas CO2. Argon comprises 1% of the atmosphere, while CO2 comprises less than 0.0004.
Spartacus: the major problem with the Trenberth cartoon is the claim that heat transfer from the Earth’s surface to the atmosphere is [17+80+396=493 W/m^2] when in reality it’s [17+80+63=160 W/m^2], or an exaggeration by a factor of 3.08.
If we include the 78 W/m^2 directly absorbed by the atmosphere, the exaggeration of the total heating is a factor of 2.4. Taking the IR alone, the exaggeration is by a factor of 356/23=15.5.
This is a ‘Perpetual Motion Machine of the Second Kind’ to give it it’s formal thermodynamic definition. it cannot exist because ‘back radiation’ is an artefact of the measurement procedure, as described above. What this false assumption does is the magnify the radiative part of the heat transfer in the atmosphere out of all proportion to reality.
if you want to, you can prove it very simply. On a warm, humid, cloudy night put your hand out, palm down. The back of the hand is a fairly good IR radiation detector and 333 W/m^2, about twice the average SW from the Sun, is about what you get 1/3 m from a 2 kW kitchen heater/ If it exists, you’ll easily feel it. I can’t and neither can anyone else……
Correction 1 and 1/3 m from a 2 kW heater, just over 4 feet.
ZP says: “To a first approximation, we can just propagate the error upon subtraction, which would tell us that resister two is 0.5 +/- 7 Ohms greater than the first. Although the value obtained from subtracting the two means is non-zero, any freshman level science student would readily conclude the two resisters are nevertheless indistinguishable. “
Apparently I expect above-average freshman-level students. 🙂
Let me make it more direct. I hook up a resistor to a poor quality DMM with a 5% uncertainly that reads 100.0 Ohms. I then warm that resistor, and the reading slowly creeps up to 100.5 Ohms. I am 100% sure that the second reading is higher than the first, even though I am not at all sure whether the second resistance is truly above or below 100 Ohms. In fact, I am pretty sure the second reading is 0.5 +/- 0.1 Ohms higher than before. Linearity is a different question than absolute accuracy. If that resistor was being used as a thermometer, I would know the second condition was warmer, even if I didn’t know the calibration curve. I would not be ~ 10% sure that the second one was warmer!
If I measured two resistors with two different poor quality meters, then your conclusions would have been appropriate. And that is precisely why such care must be taken whenever different instruments are compared.
Thank you. Let’s remove “back radiation” from our collective lexicon, shall we? There is no “back radiation”; only radiation. Which, as the person who wrote the above blockquoted bit points out, occurs from any body whose temperature is above 0K. The fact that such radiation may balance out in a bidirectional exchange is irrelevant.
Hi Slarti: I have refined my proof that ‘back radiation’ is an artefact of the measurement process and not as Meteorology imagines, ‘downwelling IR’ from an energy source.
Put two radiometers back to back with no temperature gradient and the difference signal is zero. Take one radiometer away and the shielding at the back of the detector stops the Prevost Exchange signal from the other direction nullifying its signal.
So, poor climate modelling saps only imagine there is a real energy source in the sky – the ‘Sky Dragon’. All the climate models need to be reconstructed – sorry folks but that’s science for you! The net result is that the IPCC has exaggerated AGW by at least an order of magnitude.
Mydogsgotnonose says:
“Spartacus: the major problem with the Trenberth cartoon is the claim that heat transfer from the Earth’s surface to the atmosphere is [17+80+396=493 W/m^2] when in reality it’s [17+80+63=160 W/m^2], or an exaggeration by a factor of 3.08.
I just looked at the paper, and they are rather careful to use the correct term “energy flux”. There is indeed an energy flux of ~ 396 W/m^2 of upward IR, along with the ~ 333 W/m^2 of downward IR, which agrees with their claims. The net IR flux is indeed ~ 63 W/m^2 as you state, but this is a different issue than the individual fluxes that Trenberth is carefully describing.
So you are each right in your own way (but your claim about their claim regarding “heat transfer” is not strictly correct).
“This is a ‘Perpetual Motion Machine of the Second Kind’ to give it it’s formal thermodynamic definition. “
No, sorry, it is not. According to wikipedia (which agrees with other sources):
Where is there mechanical work that was created? Which one heat reservoir do you think we have? Where do we have a system without a cold reservoir to absorb heat?
It is not even any other sort of violation of the laws of thermodynamics. If you think it is, show the calculations of energy and/or entropy that show a specific violation.
Mydogsgotnonose says: ” .. stops the Prevost Exchange signal.. “
I don’t know what you mean by “Prevost exchange signal” or “Prevost exchange energy”. Please give an equation for calculating both of these quantities.
tjfolkerts; I argued with a modeller [I suspect the Met. Office, when they tried to shoot me down]. He claimed ‘back radiation’ is an ‘accounting mechanism’ so I asked him whether he excluded the extra 333 W/m^2 from heating the air near the Earth’s surface. He did not answer.
So it seems to me that it’s a PMM of the second kind because it’s claimed that extra expansion of the air near the earth’s surface is taking place by transferring heat energy from the cooler atmosphere via the Earth’s surface. The work done is PdV hence all the claims about more hurricanes etc.
As for the term ‘energy flux’, the diagram claims 333 W/m^2 ‘Absorbed by Surface’ and 396 W/m^2 ‘Surface Radiation’, So, the ‘back radiation’ merry-go-round’ is needed to make up the S-B BB flux in a vacuum for 16 °C. This has never been measured experimentally. I can say this confidently because I was trained as a process metallurgist and did research with real experts developing pyrometers and designing thermal processes.. For natural convection with steel you need ~100 °C before the radiative heat loss rate exceeds convective, for aluminium it’s ~300 °C. Look it up in McAdams, [McGraw Hill] the process engineer’s bible. Also look up Hottel’s work at MIT:.
Prevost Exchange Energy comes from the oldest radiation law. It’s the S-B flux from the colder body to the hotter body, or both at temperature equilibrium. So it’s S-B2 in the difference equation S-B1 – S-B2 for the net flux with 2 the colder. At equal temperatures, net flux is zero so the Prevost Exchange can do no thermodynamic work. Some physicists call it a ‘photon gas’ and imagine these photons bounce off filled quantum states.
As for the mechanism, there are others besides me investigating what Planck did not work out. it is possible that the modellers don’t use 356 W/m^2 in their near surface GHG absorption in which case I could be wrong. However, if I am not wrong, they have used the PMM to predict CAGW and that’s very naughty, impossible to admit because of the politics.
Also whenever I discuss the issue with ‘climate scientists’ they argue ‘back radiation;’ is real because the pyrgeometers measure it. I have shown above why it is not real, but even if it was, because the detector is shielded from IR from the Earth’s surface, the internal reference isn’t connected in any way to the Earth’s surface. These are astonishingly bad errors.
PS I had a climate scientist argue that the reason why ‘back radiation’ did not heat up passive solar panels at night was because to overcome the thermodynamic limitation of the PMM, you need the external SW energy source, proof I think that they are going through intellectual hoops.
Another issue is that they and I suspect most physicists fail to realise that Kirchhoff’s Law of Radiation only applies at thermal equilibrium and at TOA, where convection changes to radiation, the composite emitter cannot be treated as a standard radiator. This may be new physics.with an effective emissivity to the Earth near zero.
You’re kidding – right?
This simply presents all the misinformation with some stupid inane commentary.
One of the biggest contradictions in climate science is if GHGs emit most of the longwave radiation to space – 165 by atmosphere + 30 by clouds = 195/235 = ~83% of radiation to space it is difficult to comprehend why increasing concentrations of the super emitters will result in less radiation to space.
Seems counter-intuitive – and yes I’ve seen the Nimbus charts – is it not possible the reduction in the radiative temperature implied in these charts could be offset by the increase in radiative units ?
Hell, what would I know?
Mydogsgotnonose says:
April 28, 2012 at 2:00 pm
“Also whenever I discuss the issue with ‘climate scientists’ they argue ‘back radiation;’ is real because the pyrgeometers measure it. I have shown above why it is not real, but even if it was, because the detector is shielded from IR from the Earth’s surface, the internal reference isn’t connected in any way to the Earth’s surface. These are astonishingly bad errors.”
This is basically the same thing as Professor Claes Johnson is saying about “backradiation”.
Good that more and more people is beginning to realise this.
Keep at it, Mydogsgotnonose! The thruth will be known, sooner or later.
tjfolkerts says:
April 28, 2012 at 11:27 am
Well, your example is fairly non-conventional if you using the +/- 5% to refer to accuracy as opposed to precision. It is generally accepted that the “+/-” refers to either the precision (e.g. standard deviation or standard error) of the technique or total uncertainty.
I still disagree with your argument. It does not matter if the reading is with different DMMs or the same DMM. The range for the first reading was 95.0 – 105.0 ohms and the second was 95.5 – 105.5 ohms. You simply cannot conclude that the difference in readings is 0.5 +/- 0.1 ohms, unless you are arguing that the precision of the DMM is +/- 0.1 ohms. The signal readout is not sufficient justification. This fact is independent of whether you anticipate that the resistance changes a specified amount with temperature. You need a sufficient change in temperature to overcome the intrinsic error in the measurement. When the uncertainty in the measurement is larger than the difference, you cannot know the change for certain.
I routinely perform calorimetric experiments that rely on temperature changes due to changes in resistance. We calibrate the linearity (using a range that far exceeds the uncertainty of the DMM) before and after our measurement. And, we ensure that the change in resistance of our measurement is within our calibration range. If we just assumed a change in resistance was statistically significant, then our results would be meaningless. The DMM that we use is research grade with uncertainties far less than 0.1%. Nevertheless, the repeatability of our measurements are always significantly worse than the reported uncertainty of the DMM.
Right now, it appears that you are trying to justify an argument that goes against all current statistical paradigms. You are not going to convince me that your contention has merit without a valid literature reference from a reputable statistics source.
Mydogsgotnonose is right, and a simple experiment with solar cookers proves it-
If the so-called ‘back radiation’ from the cold atmosphere to warm Earth was capable of doing any thermodynamic work, solar cookers pointed at the sky (not the Sun) would produce heating day and night. Instead, experiments show that when a solar cooker concentrates the alleged 324 W/m2 infrared ‘back radiation’ from greenhouse gases, cooling results during both day and night.
http://solarcooking.org/research/McGuire-Jones.mht
Thanks Wikeroy: yes, I am on the same path as Johnson. On Bishop Hill I had a toe to toe fight with people who tried to trick me with a particular radiation calculation. What it came down to was that they used the textbook S-B equation, equal emissivity and absorptivity which you get from Kirchhoff’s Law of Radiation, to ‘prove’ back radiation exists but did not realise that Kirchhoff’s Law only applies at thermal equilibrium and the problem was far from it.
This is why the next step is to show that at TOA, extreme non-equilibrium means the emission towards the Earth’s surface is near zero, another nail in the back radiation coffin because you don’t need it to balance radiative transfer through the atmosphere.
It’s funny how it’s engineers and non Anglos who see through the scam!
Mydogsgotnonose:> Spartacus: the major problem with the Trenberth cartoon is the claim that heat transfer from the Earth’s surface to the atmosphere is [17+80+396=493 W/m^2] when in reality it’s [17+80+63=160 W/m^2], or an exaggeration by a factor of 3.08.
I completely agree with you! But there are more problems in that cartoon…
@tjfolkerts April 28, 2012 at 9:17am
You can see why I am less than enamoured of analogies. Might I suggest we discuss the alleged “greenhouse gas effect”, and not get into endless semantic arguments? I will of course be happy to attempt to point out the fallacies in your analogies if you wish, but this is digression for the sake of digression.
Now when you say ” . . .The sunlight penetrates to the “interior of the atmosphere” (ie the surface) and heats the atmosphere “from the inside” (like the furnace heats the house “from the inside”). . . .”, you can possibly remove extraneous words, and say “the sunlight penetrates to the surface.” I hope we agree on that. When the surface absorbs EMR (of any wavelength – energy is energy), the temperature of the surface and hence of the Earth, will rise. I trust you agree with this also.
But here’s the rub. When the surface “heats the atmosphere from the inside”, it does so by radiating EMR to the atmosphere. This process is exactly the opposite of absorbing EMR causing a rise in temperature, and results in a fall in the temperature of the surface. Wait for night in the desert or any other cloudless still night, and you will notice the temperature drops. The surface loses energy, the temperature drops.
Obviously, the atmosphere will absorb some of the radiation, and its temperature will rise. However, there are unavoidable energy losses when energy is transferred in this fashion. In any case, if you have ever looked at the stars, or across a room, you will notice that the atmosphere is remarkably transparent to a wide range of EMR wavelengths. So the atmosphere, of itself, allows a large amount of EMR to be lost from the surface to space without impediment.
If you examine the maximum surface temperature of the Moon when it is at the same distance from the Sun as the Earth, you will notice that it is much higher than anything that can be achieved at the Earth’s surface without artificial concentration of the incoming energy.
As I have said, anything other than a vacuum reduces, rather than enhances, the amount of EMR transferred between bodies.
So, once again, inducing a rise in temperature by reducing the amount of energy a body receives is nonsense. No ifs, buts or maybes.
Live well and prosper.
MIke Flynn.
Mike, I agree with most of what you say, especially:
Reducing the energy a body (in this case, the surface) receives will indeed reduce the temperature. If the surface could absorb all the sunlight, it would reach an effective black body temperature of ~ 279 K (warmer around noon; lower at night), radiating away 342 W/m^2 to match the incoming 342 W/m^2 of sunlight. Blocking some of the sun’s energy from reaching the surface (clouds reflecting light or air scattering light or ozone absorbing UV or …. ) will lower this effective temperature. The typical number is ~ 255 K (corresponding to 240 W/m^2), depending on exactly how much radiation you block from reaching the surface. Blocking incoming photons did cool the surface — no ifs, buts, or maybes.
But the converse is ALSO true. Reducing the energy a body LOSES will INCREASE the temperature. At an effective BB temp of 255 C, the surface will radiate ~ 240 W/m^2 to balance the income absorbed 240 W/m^2 of sunlight (the rest having been reflected away).
With no mechanism to block those IR photons, that 240 W/m^2 worth of photons will be shot straight out to space, never to return. If, however, there are GHGs that can absorb some of those IR photons, then the energy is NOT lost to space forever. Some of it can return when those GHG molecules emit energy back in random directions. When some of those photons return to the surface, they will get absorbed, adding energy to the surface that would not otherwise have been there.
Reducing the energy a body LOSES will INCREASE the temperature — no ifs, buts, or maybes.
Mydogsgotnonose says:
“PS I had a climate scientist argue that the reason why ‘back radiation’ did not heat up passive solar panels at night was because to overcome the thermodynamic limitation of the PMM, you need the external SW energy source, proof I think that they are going through intellectual hoops.”
Its good to hear that some people understand thermodynamics. This explanation is pretty much spot on.
A heat engine needs a hot reservoir and a cold reservoir, as any good engineer knows. The sun can be the hot reservoir, and the surface is the cold reservoir, with a net flow of heat from hot to cold and some work extracted.
What you seem to be expecting is that you could collect energy from a cold reservoir ( the cool atmosphere) and “focus it” to a hot reservoir ( the warmer surface) and run a heat engine from it. YOUR version would indeed be a violation of the 2nd Law of thermodynamics!
If you don’s see that your expectations are are wrong and the answer you got was right, then you SHOULD jump through a few more intellectual hoops until you understand the fundamental physics better.
“I still disagree with your argument. It does not matter if the reading is with different DMMs or the same DMM. The range for the first reading was 95.0 – 105.0 ohms and the second was 95.5 – 105.5 ohms. You simply cannot conclude that the difference in readings is 0.5 +/- 0.1 ohms, unless you are arguing that the precision of the DMM is +/- 0.1 ohms. ”
Lets make it an old-fashioned analog meter. Are you truly saying that you could watch the pointer moving 2% farther from zero, yet wonder if the resistance is increasing simply because the meter was only calibrated to +/- 5%?
Are you truly saying that you could watch a column of mercury climb 1% farther up a thin tube, yet wonder if the temperature is increasing simply because you don’t know if the starting position corresponded to 20 C or 25 C?
@ Mydogsgotnonose
http://www.flir.com/cs/emea/en/view/?id=41964
Imaging Performance
IR resolution 640 x 480 pixels
Spectral range 7.5 – 13 µm
Image frequency 30 Hz
Focus Automatic or manual
Focal Plane Array (FPA) Uncoooled microbolometer
Measurement
Temperature range -40°C to +500°C (optional up to +2000°C)
Environmental specifications
Operating temperature range -15 °C to +50 °C
This thermal imaging camera will operate at +50C ambient This means the imigaging device (a micro bolometer array) is at at least 50C since it is uncooled.
How can it measure -40C when it is at 50C?
Easy
1 point the camera at a body at -40C and it will lose heat as a black body at 50C but It will gain heat from the cold body at -40C It will produce a voltage developed by the temperature difference set by -40C incoming 50C outgoing
2 point it at a surface at -10C and it will still lose heat as a BB of 50C but now it will receive radiation from the -10C body. It will now produce a voltage set by the -10C incoming and +50C outgoing
I.E. a colder body is warming the hotter body above the value that it would be when pointed at a body at 0K.
tjfolkerts 7:54 pm
Well, almost there.
You say “But the converse is ALSO true. Reducing the energy a body LOSES will INCREASE the temperature. ”
Not at all. Reducing the energy a body loses will slow the rate of temperature drop – that is all. That is how insulators work.
Bear with me. A body at a constant temperature is emitting precisely as much EMR as it is absorbing. As it emits radiation, the amount of energy left in the body drops. Unless the body absorbs enough energy to replace that which is lost, the temperature decreases – at a rate dependent on the energy flux differential.
Eventually after all available EM energy is emitted, then absolute zero is reached. Merely reducing the rate of energy loss will not increase the temperature. For that to occur, the body’s energy needs to increase. Even totally stopping energy loss – say for example, you had a perfect insulator surrounding the body, the temperature will not rise. At best, it will not fall.
So, a great big BUT. Once again, reducing the amount of radiation a body absorbs will not cause a temperature increase.
You are free to believe otherwise if you wish.
Live well and prosper.
Mike Flynn.
SergeiMK: a bolometer is similar to a pyrgeometer in that it measures the temperature difference between a collector in radiative equilibrium with the radiator and a controlled temperature reference
A negative temperature difference means the viewed material is colder.
tjfolkerts: like they you are clutching at straws!.
@- ozzieostrich says: April 28, 2012 at 11:51 pm
“Not at all. Reducing the energy a body loses will slow the rate of temperature drop – that is all. That is how insulators work.”
Have you never worn a coat, or put an extra blanket on the bed?!
Reducing the amount of energy lost from an object, while the the source of energy added remains constant results in the object warming.
The surface is warmed by the sun.
the rate it loses that energy depends on its temperature ~T^4. and the amount of energy any insulator returns to the surface. That is why it is warmer on a cloudy night, the cloud returns much more energy back to the surface than a clear sky.
But even a clear sky returns some energy back to the surface as can be measured with IR sensors. This reduces the rate of cooling so keeping the surface at a higher temperature than would be the case in a vacuum with no returning energy, as with the moon.
Those rejecting the role of the atmosphere as an insulator which modulates the gradient of energy emitted from surface to tropopause thereby increasing the surface temperature above that of a naked surface without an atmosphere are rejecting well established, experimentally confirmed physics. There are areas of the AGW theory that are uncertain, sensitivity and possible feedbacks that react to the warming. But the basic thermodynamics of energy flows in the atmosphere is old science, rejecting it is far more damaging to the credibility of the objectors than the science.
Try this for an equations and numerical explanation of surface warming from back radiation and the 2LoT. –
http://scienceofdoom.com/2011/02/07/understanding-atmospheric-radiation-and-the-%E2%80%9Cgreenhouse%E2%80%9D-effect-%E2%80%93-part-six-the-equations/
Izen,
Yes, I have worn a coat and have put an extra blanket on a bed. As insulators, they both reduce the rate of heat loss from my body, which then does not have to oxidise as much carbon to create sufficient heat to keep my temperature around 37C.
Have you ever wrapped a coat or a blanket around a corpse, (or a concrete block or similar, if you don’t have corpse handy?) No rise in temperature at all.
Now as to your statement which mentions the Moon. I assume you are unaware that surface temperatures on the Moon easily exceed anything that can be achieved on the Earth without concentrating incoming EMR. Likewise, the minimum temperatures on the Moon are lower than anything found on Earth.
This is because there is far more of the Sun’s energy per unit area hitting the Moon’s surface in accordance with maximal radiative energy transfer occurring in a vacuum. The same thing occurs in reverse when the surface of the Moon is radiating directly to space, without the insulating effect of an atmosphere to impede the transfer of EMR energy to outer space.
I am not sure where you obtained your information that the surface of the Moon is colder than that of the Earth when both are in direct sunlight, but I can assure you that your source is wrong.
As I have said a few times on this thread, the atmosphere acts as a relatively poor insulator. I should point out that insulators work both ways, if you like. They retard the rate of both heating and cooling (the insulator doesn’t know what it is insulating). For example, a rather good insulating device is a Dewar flask. It can keep hot things hot, and cold things cold. Amazing, eh? But even a Dewar flask cannot stop the remorseless radiative balancing that Nature dictates. Left long enough, both the cold and hot contents will be at exactly the same temperature, Dewar flask or no.
I agree that the basic thermodynamics of energy flows has been accepted science for a longish time. People who believe in the nonsensical notion that surrounding a body with no internal source of heat, (a corpse or concrete block, say) with an insulator will magically cause the temperature of the body to rise, are likely to believe almost anything.
Anyway,
Live well and prosper.
Mike Flynn.
tjfolkerts says:
April 28, 2012 at 8:21 pm
Lets make it an old-fashioned analog meter. Are you truly saying that you could watch the pointer moving 2% farther from zero, yet wonder if the resistance is increasing simply because the meter was only calibrated to +/- 5%?
Are you truly saying that you could watch a column of mercury climb 1% farther up a thin tube, yet wonder if the temperature is increasing simply because you don’t know if the starting position corresponded to 20 C or 25 C?
OK, it is clear now that you are confusing precision with accuracy.
There is a large degree of misunderstanding shown by many on what the cause and effect of the Earth’s so called greenhouse effect is. The misunderstanding on radiation heat transfer is only part of the problem. A few comments make some of the issues clear:
1) If the storage and transient effects are not large, incoming energy and outgoing energy are nearly equal. If the Earth is rapidly heating, or if the oceans are increasing total energy at a high enough level, the balance is off, but aveage temperature has been essentially constant for about a decade now, and ocean energy increase is fairly slow, so these are not major issues to a basic understanding of the greenhouse effect. For this case, solar energy heating the ground will be transferred by radiation, conduction, and convection, including evaporation and condensation of water. The heat transfer rate will not change at different surface temperatures. i.e., the greenhouse induced warmer Earth does not have a different rate of heat transfer than a planet with no greenhouse effect, but with the same albedo. There is no thermal insulation effect on heat transfer rate for the average steady state case.
2) When the so called greenhouse gases (they shoule be called selective optically absorbing gases or Tyndell gases or something else, as the effect is not at all like a greenhouse) absorb long wave thermal radiation, they will also radiate long wave thermal radiation. The only effect of this is to act as a thermal radiation insulator. However, due to 1), the conduction and convection heat transfer will adjust so that total energy transfer is the same as for no insulation. In the extreme case of the gases bening nearly perfect absorbers of the long wave energy, the radiation component of heat transfer from the surface goes to near zero, but conduction, convection and evaporation folloewd by condensation of water do all of the heat transfer. Talking about back radiation HEATING the surface is wrong. The back radiation would equal the up radiation, and net radiation would be zero. However, unlike with a blanket, the heat transfer would not be changed, since the other forms of heat transfer make up the difference.
3) The temperature gradient (average) is called the lapse rate, and only depends on the specific heat of the gas, gravity, and phase change of water vapor. When clouds are present, it is locally different, but I am referring to average value. The greenhouse gases do not change the lapse rate except for a minor change in average specific heat, and this is very small for Earth.
4) The absorbed solar energy has to eventually escape to space. This can only be done by radiation. There is a variation of altitudes where radiation escapes, but an average altitude can be found. The average temperature can be calculated from this average altitude from the outgoing energy level needed to balance incoming energy. The average temperature at that average altitude plus the average lapse rate times the average altitude of outgoing radiation result in the average surface temperature. That is the sole cause of the so called Earth greenhouse effect. Note that the only effect of the absorbing gases was to RAISE the altitude of outgoing radiation from the surface to a an average location up in the atmosphere. The greater the absorption, the higher you have to go before radiating to space.
Mike (ozzieostrich) says “Not at all. Reducing the energy a body loses will slow the rate of temperature drop – that is all. That is how insulators work.”
Sorry, no.
ΔQ/Δt = k A ΔT / Δx
Or ΔT = (ΔQ/Δt) (Δx) / (k A)
Assume (ΔQ/Δt), the rate of heat production, is constant (for example, running a furnace at a constant level in a house, or shining the sun at a constant rate onto the earth’s surface). Assume the temperature on the “outside” is constant (eg 0C outside the house or 0K outside the earth). Assume the area doesn’t change (no additions to the house; the earth stays the same size).
The difference in temperature between outside an inside, ΔT, then depends on thermal conductivity, k, and thickness of the insulation, Δx. The temperature difference increases (ie the “inside” gets warmer) if either
1) the thickness increase.
2) the thermal conductivity decrease.
So if we increase the insulation (by either of these two methods), the “inside” gets warmer.
THAT is how insulation works!
Having said that, the ability of actual insulation to slow the loss of energy is a different mechanism from GHGs slowing the loss of energy. But the end result in either case is a “warmer interior” while keeping the energy loss at the exterior the same.
“OK, it is clear now that you are confusing precision with accuracy.”
No, I do know the difference. Precision is typically considered how many digits you can read (or some similar measurement), which is different from linearity (and different from accuracy). All three bits of information are important when interpreting a measured value.
Put another way, measurements of DIFFERENCES can be MUCH more accurate (and just a precise) compared to measuring each value separately and subtracting AFTER you have already thrown away information you have about the linearity and repeatability of the meter.
Specifically, if I knew that my instrument was perfectly linear but only accurate to +/- 10%, then an increase from 100.00 +/- 10% to 101.00 +/- 10 % would be an increase of 1.00 +/- 10 %.
Curved Insulation Pipe/Earth Analogy
It would seem at first that the thicker the insulation the less the total heat loss. This is always true for flat insulation but not for curved insulation. For instance considering a pipe with successive layers of cylindrical insulation, as the thickness of the insulation is increased, the surface area from which heat may be removed by air increases and the total heat loss may also increase if the area increases more rapidly than the resistance.
In the case of the pipe the maximum heat loss from its surface occurs when the critical radius from pipe centre equals the ratio of the thermal conductivity of the insulation to the surface coefficient of heat transfer. Perhaps Leonard Weinstein was alluding to this with his statement that for Earth – ‘the average temperature can be calculated from this average altitude from the outgoing energy level needed to balance incoming energy. The average temperature at that average altitude plus the average lapse rate times the average altitude of outgoing radiation result in the average surface temperature. That is the sole cause of the so called Earth greenhouse effect. Note that the only effect of the absorbing gases was to RAISE the altitude of outgoing radiation from the surface to a an average location up in the atmosphere. The greater the absorption, the higher you have to go before radiating to space.’
tjfolkerts says:
April 29, 2012 at 7:40 am
No! Precision is defined as the repeatability of a measurement. The number of digits that you can read from the instrument is irrelevant.
Again, no! Differences will always be less precise than the individual measurements. This fact is commonly referred to as subtractive cancellation and the magnitude can be readily calculated by propagating the errors. As far as the statement “thrown away information… about linearity and repeatability…,” I have absolutely no idea what this means. The general procedure for calibration of an instrument, where one is only interested in relative changes, requires establishment of both repeatability (often referred to as system suitability) and linearity (or establishment of another suitable response curve). In addition, it is critical to establish the LOQ (limit of quantitation) and LOD (limit of detection), which are based on the signal-to-noise ratio. All of these data are vital to interpretation of any measured quantity and to rationally determine whether that measured quantity is meaningful. For time dependent studies, such as those which would be required for establishment of a temperature trend, you also need to establish reproducibility of the instrument, which is defined as the precision obtained from measurements collected on the same piece of equipment on different days and by different operators. Note: reproducibility will always be worse than repeatability. If you are really interested in educating yourself on the subject, I suggest you study the cGLP/cGMP requirements that establish the best practices for collecting analytical data of the highest quality.
I do not understand why you keep using “+/-” to refer to accuracy. If the instrument is inaccurate, it will be off either by a positive deviation or a negative deviation, but not both. If it can be off by either a positive or negative deviation (i.e. +/-), then you are referring to the precision of the instrument.
tjfolkerts says:
“So if we increase the insulation (by either of these two methods), the “inside” gets warmer.”
This use of language is not accidental.
The more thoughtful supporters of IPCC science have enough sense as to not say ‘heat’ the inside.
The less careful supporters like Chris Colose and ‘Eli ‘ Halpern are less inhibited.
tjfolkerts knows fine well that insulation does not heat anything.
It can however reduce the heat transfer to the colder side.
The public are being asked to take a massive dislocation of their economy and standard of living.
The least they should expect is honest answers from their educated professionals who should know better.
Hi Bryan: according to tjf, the extra heat arriving by ‘back radiation’ into the inside of your coat only occurs when the sun is shining but we have to work out the thermodynamics to prove it’s true.
Have you done so? For the life of me, I can’t but probably that’s because I trained as a metallurgical engineer at Imperial College, specialising on process engineering, with a subsequent PhD in applied physics and 30 years experience running international research including CO2 related technologies.
Apparently, to really understand the new physics, you have to qualify in climate science or similar where such changes to 150 years of knowledge are proven solely by modelling!
Leonard, overall I agree with you. The radiation balance from the “top of atmosphere”, along with knowledge of the lapse rate, is probably the best way to understand “the greenhouse effect”.
If I might, I would suggest a few adjustments to what you said.
“The heat transfer rate will not change at different surface temperatures. i.e., the greenhouse induced warmer Earth does not have a different rate of heat transfer than a planet with no greenhouse effect, but with the same albedo. “
At any global temperature, the heat transfer rate is zero (to maintain the constant temperature), which is certainly constant and hence “will not change” . OTOH, specific processes can certainly change (more downward IR with more GHG, for example). When I first read your description, I thought you meant nothing changes with more GHGs, which is clearly false.
“3) The temperature gradient (average) is called the lapse rate, and only depends on the specific heat of the gas, gravity, and phase change of water vapor. ”
The “adiabatic lapse rate” is a theoretical calculation that depends on the factor you state. The actual gradient can and does vary from this value. I tried to give my own explanation of the lapse rate and its relationships to the GHE here: https://sites.google.com/site/sciencestatsandstuff/global-warming/greenhouse-effect/lapse-rate — comments welcome).
ZP … I’ll make you a bet
1) You photocopy a ruler with mm marks — any where from 90% to 110% size. Don’t tell me the scale you used.
2) You make two seperate objects about 20 cm long (give or take a cm).
I think we both agree that I will not be able to tell you the true length of either object to any better than +/- 2 cm.
I bet that I will be able to tell you the difference in length to within 0.3 cm. Would you take that bet?
Hi Mydogsgotnonose
I agree with you that you can test as to whether an energy transfer can be described as a heat transfer.
You are correct to insist that the transfer must be capable of doing thermodynamic work in the given situation
Carnot and Clausius were practical men who thought about the most efficient way to extract work from a heat engine.
They found that work (such as a moving piston output) can only be obtained with a high temperature source and a low temperature sink.
Its clear then that heat is a Macro Quantity
To test to see if an energy transfer qualifies as being HEAT.
1. For a complete cycle extract energy at a higher temperature source do work then dump unused energy to lower temperature sink.
This is a HEAT TRANSFER and happens all the time!
2. From colder to hotter object, spontaneously extract energy do work and dump unused energy to higher temperature sink NEVER HAPPENS.
So this energy transfer CANNOT be called HEAT.
So if HEAT can only BE transferred spontaneously in one direction why do some still insist in calling it NET?
However some continue to use the term NET HEAT for a two way radiative exchange.
This is wrong but understandable as climate science is in a muddle about what exactly the difference is between the terms heat, energy, work and radiation.
There is no heat transfer from colder to hotter object!
However (and this is where we may differ)
1. There is a two way radiative exchange.
2. There is a two way energy exchange.
Take 3 objects in local thermodynamic equlibrium with a vacuum separating them ;
A one at 270K
B one at 300K
C one at 330K
All three will include 10um radiation within their Planck spectrum
We are both in agreement that B can accept a 10um from C.
Some however think that B will reject an identical 10um photon from A
This makes no logical sense.
tjfolkerts 7:15 am
Your equations are correct, as far as they go. You have merely mis-applied them. Unfortunately, like all warmists, you cannot accept that in relation to the Earth, the Sun is not an internal source. It is some distance away from the Earth. To use your poor analogy about houses and furnaces, put your furnace 10 kms away from the house, and tell me how the insulation raises the temperature inside the house. Go a little further, and turn your furnace off 12 hours out of 24. Your analogy doesn’t include the Sun, so no external sunlight allowed. Hmm. Double your insulation. Hmm.
But before that, briefly explain, if you will, why the maximum temperature on the Moon (without appreciable atmosphere) exceeds that of Earth ( with atmosphere.) Ah, I see, you can’t.
Obviously, if you supply energy to a body faster than it can dissipate it, the temperature will rise. That is demonstrably not the case with the Earth. You can walk around on the solidified surface, which doesn’t even get as hot as the Moon.
I would prefer to discuss reality, but I can discuss fantasy all you want.
Live well and prosper.
Mike Flynn
Mydogsgotnonose says: April 29, 2012 at 2:16 am
SergeiMK: a bolometer is similar to a pyrgeometer in that it measures the temperature difference between a collector in radiative equilibrium with the radiator and a controlled temperature reference
A negative temperature difference means the viewed material is colder.
———
The bolometer is hotter than the object. According to you it is impossible for the cooler object to heat a warmer object.
SO
If the bolometer is at 50C then the radiation from any thing below this temperature will have no effect on it. So this would limit its use from 50C upwards. It works down to -20C.
You need to remember that the ir camera produces an image.
Heat from the bolometer will be radiated away in all directions there can be NO imaging of the object from this radiation leaving the bolometer. Radiation leaves the bolometer before it knows where it will land so will be equal from all parts of the bolometer even if it eventually lands on a cooler object beyond the lens.
Unless you postulate negative energy rays (cold rays) (this would be a new concept on me!) from the cold object that can be FOCUSED onto the bolometer then I cannot understand how your statement repeated above explains a bolometer’s operation.
If you assume normal physics applies then the thermal imaging camera can be understood.
Point the camera at 100C the bolometer receives radiation focused on it and its temperature raises above its ambient.
Point the camera at 0K the bolometer receives no radiation so will stay at its ambient.
Point the camera at -20C the bolometer receives radiation focused on it and its temperature will rise but too a lower value than in the 100C case.
A -20C object will therefore produce an image in the bolometer’s output.
“Your equations are correct, as far as they go. “
Glad we can agree on at least that much. 🙂
“But before that, briefly explain, if you will, why the maximum temperature on the Moon (without appreciable atmosphere) exceeds that of Earth ( with atmosphere.) Ah, I see, you can’t.”
I don’t know where you got the idea that this would vex me in the slightest. Incoming sunlight is ~ 1368 W/m^2. Assuming the surface of the moon or earth have an emissivity of 1 for thermal IR, the maximum temperature achievable (without mirrors or lenses or such) would be ~ 121 C. The albedo of actual rocks would lower this slightly; the emissivity of actual rocks would raise this slightly. Overall, 120 C is a pretty good approximation for high-noon on the moon.
Even on a clear day, the noon insolation at the surface of the earth is more like 1000 W/m^2 because some sunlight is absorbed/scattered before reaching the surface. This would put the high-noon temperature (due to sunlight alone) at the surface of the earth more like 90 C. There are couple adjustments to this result. Two big effects are conduction and convection, both of which serve to drain off energy, thereby lowering the temperature that can be achieved. On the other hand, there would still be some downward IR from the sky, which would add some energy. But overall, the max temperature on the earth would be less than on the moon.
That was easy. You apperently have seriously “misunderestimated” my understanding.
“you cannot accept that in relation to the Earth, the Sun is not an internal source. ”
The sun itself is clearly “external” to the earth. But (most of) the energy from the sun can easily get “inside” the boundaries of the earth (ie inside the top of the atmosphere) — about half of it even gets all the way to the surface. Once the energy is inside those boundaries, that energy is “internal”. How is this a difficult concept?
“To use your poor analogy about houses and furnaces, put your furnace 10 kms away from the house ”
Actually if you are trying the make this extension to the analogy, then put a nuclear power plant far away, and find a way to channel the EM energy generated there thru the walls of the house to the electric heater inside. (Of course, the analogy is getting terribly strained, but I am working now with your version of the analogy.)
But the simple fact is that (much) EM energy from the sun easily passes through the atmosphere (similar to the way the electrical energy passes thru the walls of the house). Once at ground level below the atmosphere, the EM energy is converted to thermal energy by a device called a “rock” (similar to the electrical energy being converted to thermal energy inside your house by a resistor).
So the analogy still sort of works. It is better in the end to discuss the actual system. But analogies can be helpful to frame the issues on more familiar settings.
###########################
Finally, the “greenhouse effect” is not about maximum temperatures, but average temperatures. Whether the high-noon moon temperature is higher than the high-noon earth temperature is immaterial. The question is “is the average temperature higher with gases that absorb and emit IR than it would be without those gases?”
“So if HEAT can only BE transferred spontaneously in one direction why do some still insist in calling it NET? …
There is no heat transfer from colder to hotter object!”
By definition, heat *is* the net transfer of energy due to a temperature difference between two objects. The net transfer must always increase entropy (or possibly keep it the same), which guarantees that more energy goes from hot to cold, than from cold to hot.
So, yes, saying “net heat” is a bit redundant, but “net thermal energy exchange” is NOT redundant.
For example, when a warmer piece of metal touches a cooler piece of metal, the transfer of energy is accomplished by collisions of atoms where they are touching. When a fast atom hits a slower atom, the fast atom tends to lose energy and the slower atom tends to gain energy. Often the faster atom is in the warmer object, but not always. Billions of times per second, collisions will transfer energy “backwards” from cooler to warmer. But when averaged out, more collision will transfer energy forward. The net transfer of energy (when averaged over billions of collisions) is always from warmer to cooler, ie the heat is from warmer to cooler.
tjfolkerts 6:34
Nearly there. But, correct me if I am wrong, you are saying that reducing the amount of energy reaching a surface by a ratio of approximately 1000/1368 will cause the average temperature of a body to rise?
You will have to excuse me for thinking that less input of energy means less input of energy. Less energy available within a body results in less EMR emission, and we use temperature as a proxy.
I am reasonably sure you cannot come up with a reasonable analogy showing that a loss of energy results in a rise in temperature.
it’s been fun, but the CO2 house of cards is approaching its “use-by date.”
Live well and prosper.
Mike Flynn.
OK — this is taking too much of my time. We have reached “hydra stage”, where two new questions pop up for everyone that is answered, and I don’t have time to keep going. A few parting comments for this thread.
1) Being careful with language is important. Unfortunately, we are fighting common usage. For example, Dictionary.com defines the verb “heat” as “to make hot or warm” (and has no definition similar to the thermodynamic definition). Since the atmosphere does help to make the surface warm, the atmosphere “heats” the surface according to this definition. But by the strict thermodynamic definition, the atmosphere definitely does not “heat” the surface.
I try to stick to the precise thermodynamic definitions, but I am sure I slip up occasionally.
2) Being able to use equations and numbers is a strong sign of understanding. If you can’t give at least a rough estimate of numbers and the equations involved, you probably don’t understand the science.
I try to give specific numbers or specific equations, so that it is easy for others to address specificis.
3) Thermodynamics is a notoriously difficult and subtle branch of physics. It requires very careful language. It requires advanced mathematics and partial derivatives. It requires the ability to calculate entropy and enthalpy and free energy. Ideally it includes knowledge of microstates and macrostates and advanced topics in probability. If you can’t apply multiple versions of the 2nd Law, then you probably don’t understand the 2nd Law.
I am sure I understand thermodynamics better than most people in this discussion, but I also know I have much more I could learn.
4) Blogs are poor places to discuss advanced science. Limitations of time, typesetting, language and common understanding doom most discussions to run around in circles.
So … enjoy the discussion. Hopefully you all will continue to learn from others and become better informed.
OK — one last comment
“But, correct me if I am wrong, you are saying that reducing the amount of energy reaching a surface by a ratio of approximately 1000/1368 will cause the average temperature of a body to rise?”
That is not quite what I was saying …
1) Reducing the input to a system (keeping other things equal) does indeed lower the temperature of a system (until a new equilibrium is reached).
2) Reducing the output (keeping the input constant) will increase the temperature (until a new equilibrium is reached).
For the system consisting of the surface of the earth (ie put an imaginary boundary right at the bottom of the atmosphere), the atmosphere does BOTH of these things. The atmosphere first reduces the input to the surface by reflecting/scattering/absorbing some sunlight. Given the amount of energy that DOES reach the ground, the atmosphere then reduces the net energy loss by providing some IR photons that get absorbed by the ground. (Fighting this effect are evaporation and convection, which INCREASE the loss from the surface).
So were are left with three cooling effects (for the earth compared to the moon) –> reduced sunlight, convection and conduction. We have one warming effect –> IR photons back from the atmosphere.
There is no a priori way to know if these will have a net warming effect (as measured by some sort of “global average temperature”). Measurements of global temperatures show the earths surface IS warmer than the moon’s surface, so experiment shows the net effect is positive. Estimations of the various effects individually seem to confirm the net effect is positive.
The REAL question is “how big of an effect will ADDITIONAL GHG’s have on the climate”. They should increase the downward IR, but they could also increase the cloud cover, thereby reducing the incoming energy. Here I don’t have a clear answer, because I don’t know enough of the details.
I really shouldn’t bother , BUT –
As you say, the atmosphere reduces input to the surface – no argument.
You go on to say that the atmosphere then ” . . . reduces the net energy loss by providing SOME . . .” (my emphasis.) – once again no argument.
Can you not see that the atmosphere making up SOME of the loss is not the same as compensating for ALL of the loss?
The warming effect from the atmosphere, as you say, does not fully compensate for the amount of radiation initially prevented from reaching the surface – I will accept your nominal 368 w/sq. m. for this purpose. The atmosphere cannot provide more than this figure to the surface (as you say, it provides some of it, not all.)
So yes, you have established that there is less energy reaching the surface than would occur without an atmosphere. I agree with your argument. No “global warming” due to CO2 whatsoever.
Given the fact we both agree that measuring the average temperature of the Earth”s surface at any point in time, the physics at least can determine whether global warming is possible given heat sources both external and internal to the lithosphere, the aquasphere and surrounding atmosphere. It is not.
Live well and prosper.
Mike Flynn.
tjfolkerts says;
” Being careful with language is important. Unfortunately, we are fighting common usage. For example, Dictionary.com defines the verb “heat” as “to make hot or warm” (and has no definition similar to the thermodynamic definition). Since the atmosphere does help to make the surface warm, the atmosphere “heats” the surface according to this definition. But by the strict thermodynamic definition, the atmosphere definitely does not “heat” the surface.”
Why is it that professionally qualified people who should know better jump on the “common usage” bandwagon instead of carefully explaining the proper physical understanding.
The ‘man in the street’ has all sorts of odd notions like;
A whale is a fish
The Sun rises in the East over a stationary Earth
The Earth is flat
Why is it that nobody suggests that because ‘we are fighting common usage’ we should accept these erroneous ideas?
.
_Jim says:
April 27, 2012 at 8:46 am
And so there you have it.
The 12 easy steps to understanding the minor but important (as to moderating the surface temperature of the earth) GHG effect.
Where’s the Water Cycle in all that?
tjfolkerts says:
April 27, 2012 at 3:39 pm
montanaconserv writes: “I have read in a few places where the GreenHouse Effect really doesn’t exist anywhere but in a greenhouse … “
One constant problem is that “the greenhouse effect” means different things to different people. I suspect it would not be difficult to find a dozen or more significantly different variations on definitions for “the greenhouse effect.” So before stating whether or not it exists, it is important to state clearly which specific version of “the greenhouse effect” you mean.
=======
The whole “the Greenhouse Effect is real” propaganda is science fraud – the warmists who claim Carbon Dioxide has The Power to raise the temperature of the Earth 33°C are in agreement that this is what is the “Greenhouse Effect”, but there’s no agreement about how it achieves this. There is ‘apparently’ no agreement on what the “Greenhouse Effect” is because there is no Greenhouse Effect. If there was the warmists would be able to explain it and the explanation would be consistent and the explanation would make physical sense.
You, generic warmists, wave generally in the direction of Tyndall who never proved that Carbon Dioxide raises the temp of the Earth 33°C and Arrhenius who misunderstood Fourier and so believed the atmosphere was like solid glass, but refuse give real science data to show how it is able to do this as you claim.
You, all warmists, are b*llsh*tt*ing.
Where’s the Water Cycle?
Bryan says:
April 29, 2012 at 3:39 pm
Hi Mydogsgotnonose
http://wattsupwiththat.com/2012/04/27/pilot-video-for-a-series-bill-scientific-the-greenhouse-effect/#comment-971089
..
I agree with you that you can test as to whether an energy transfer can be described as a heat transfer.
You are correct to insist that the transfer must be capable of doing thermodynamic work in the given situation
Carnot and Clausius were practical men who thought about the most efficient way to extract work from a heat engine.
They found that work (such as a moving piston output) can only be obtained with a high temperature source and a low temperature sink.
Its clear then that heat is a Macro Quantity
To test to see if an energy transfer qualifies as being HEAT.
1. For a complete cycle extract energy at a higher temperature source do work then dump unused energy to lower temperature sink.
This is a HEAT TRANSFER and happens all the time!
2. From colder to hotter object, spontaneously extract energy do work and dump unused energy to higher temperature sink NEVER HAPPENS.
So this energy transfer CANNOT be called HEAT.
So if HEAT can only BE transferred spontaneously in one direction why do some still insist in calling it NET?
However some continue to use the term NET HEAT for a two way radiative exchange.
This is wrong but understandable as climate science is in a muddle about what exactly the difference is between the terms heat, energy, work and radiation.
There is no heat transfer from colder to hotter object!
===============
In so much of a muddle that they claim shortwave direct from the Sun heats the land and oceans and claim that the direct heat from the Sun, thermal infrared, heat, longwave, doesn’t reach the surface and plays no part in heating land and oceans.
They have no concept of heat.
Because they have a different physical reality from the real world – they have only radiation in empty space created out of the concept of the imaginary ideal gas in a container, they do not have convection or gravity because they do not have real molecules with real weight, volume, attraction.
They have clouds in their fictional atmosphere, but they can’t explain how they got there…
This is the Greenhouse Effect explained by NASA – http://science.nasa.gov/science-news/science-at-nasa/2000/ast20oct_1/
AGWScienceFiction has shortwave visible light heating land and oceans and no heat direct from the Sun warming the land and oceans..
The heat direct from the Sun is thermal infrared, longwave. The direct heat from the Sun, the direct thermal energy of the Sun in transfer, is what directly heats the oceans and lands. NASA used to teach that it was this which warmed the Earth and us..
NASA: “Far infrared waves are thermal. In other words, we experience this type of infrared radiation every day in the form of heat! The heat that we feel from sunlight, a fire, a radiator or a warm sidewalk is infrared.
Shorter, near infrared waves are not hot at all – in fact you cannot even feel them. These shorter wavelengths are the ones used by your TV’s remote control.”
Now NASA is pushing this fictional fisics of the Greenhouse Effect.
How anyone can take this seriously is now quite beyond my comprehension…
Please explain to me how an uncooled thermal imaging camera forms an image of objects below the ambient temperature. There must be something at -20C being focussed on the microblometer at 55C to create an image.
If it is normal physics it is LWIR heating the bolometer (cold heating hot)
If it is your physics how do you explain the -20C image?
Something must be coming through the germanium lens to be focussed on the FPA. What is it?
The camera is sensitive from 7um to 17um approx.
Mike, you are mis-interpreting the situation when you say “Can you not see that the atmosphere making up SOME of the loss is not the same as compensating for ALL of the loss?”
Suppose we start with 342 W/m^2
“Some” of the 342 makes it to the ground. Supppose that is 240 W/m^2 .
“Some” of the 240 gets returned to the surface.
* if “some of 240” = 50, then the IR return by the atmosphere doesn’t make up for the albedo loses by the atmosphere, and the surface is cooler than it would be with no atmosphere.
* if “some of 240” = 102, then the IR return by the atmosphere just makes up for the albedo loses by the atmosphere, and the surface is the same as it would be with no atmosphere.
* if “some of 240” = 150, then the IR return by the atmosphere more than makes up for the albedo loses by the atmosphere, and the surface is the warmer than it would be with no atmosphere.
This much is easy, since all the numbers are hypothetical. It is easy to come up with “some” numbers that lead to either warming or cooling.
The tougher challenge is to estimate what “some” numbers are. Trenberth made some estimates. You are welcome to argue (with numbers and calculations) where he might be off. I am satisfied that the estimates are in the in the right ballpark. The simple fact that the average temperature is above ~ 0 C means that the atmosphere does indeed have a net positive effect.
The REALLY tough challenge is to predict what the numbers would be in OTHER circumstances (for example if CO2 rises to 500 ppm). Here I don’t typically hazzard a guess, since this is pretty much a “wicked problem” http://en.wikipedia.org/wiki/Wicked_problem
tjfolkerts,
Hi.
You have started with 342 W/m^2 insolation.
You remove 102, allowing 240 to impinge on the surface.
I assume instead of “. . . returned to the surface . . .”, you meant to say “returned to the atmosphere”.
To continue. In your first case, you state that the “. . . surface is cooler than it would be with no atmosphere.” I point out that without any atmosphere, the surface would have received 342 – your figure. If you are trying to insist that that surface temperature increases when the incoming energy decreases, we both have a problem. Reducing the energy from 342 to less than 240 increases the temperature by increasing the incoming energy by reducing it?
But no matter. I may have misunderstood.
However, your second point seems to be more definite. You say 240 reaching the surface causes exactly the same result as 342 without atmosphere, which is to say 342, no more no less.
Now your last point just cannot be. Without an additional source of heat, the energy reaching the surface cannot exceed 342. That’s all there was. No amount of bouncing, absorbing, reradiating, or reflecting can increase the amount of radiation that the source emitted.
Trenberth and his motley crew might just now be accepting that they cannot find the “missing heat” because it doesn’t exist.
A common misconception is that the atmosphere (or the supposed GHGs that it contains,) somehow acts as a “one way insulator” selectively reflecting some IR wavelengths, thereby causing an elevation in surface temperatures. Now this cannot be. Suppose you choose a area of the surface such that insolation of 342 causes a temperature rise of 1K. I believe it is fair to say that if that area radiates 342 (regardless of wavelength – we are discussing energy,) then the temperature will drop by as much as it increased. Net energy change – zero.
Using your figures, 240 reaching the surface will cause a rise in temperature of xK.
Radiating 240 causes a drop in temperature of xK. Net change – precisely nil. If part of that 240 is subsequently returned to the surface, then the temperature will rise above nil in proportion to the fraction of the 240 returned, as it were. At night it will radiate that energy away.
To assume that the magical properties of global warming can somehow “reradiate” more than the 240 available is like trying to say 4=3, and then proving that 4 x 0 = 3 x 0, and cancelling out the zeros.
The other minor problems with the selective blocking, in any case, are twofold at least. We know that all visible radiation penetrates the atmosphere containing its wide variety of assorted crud,to space. Pictures of the Earth taken from space support this. Infrared, likewise penetrates rather nicely. Infrared pictures taken from space can distinguish between ice at different temperatures, so IR emitted by objects at least down to 273K travels though the atmosphere with little obstruction. Longer wavelengths, eg radio wavelengths in the SHF spectrum are bounced by amateurs using low powered transmitters off the moon and back to earth.
None of that is particularly relevant, considering that the maximum transfer of radiative energy between bodies occurs in a vacuum.
I believe we have agreed that it is impossible to measure the temperature of something that cannot even be clearly defined – the Earth’s “surface”. If anybody ever figures out a way to do it, they will find that GHGs have precisely nothing to do with any rise in temperature – apart from the heat generated in their creation.
It’s nonsense. Even you are starting to realise it’s nonsense. Join the realist club – you are most welcome.
Live well and prosper.
Mike Flynn.
ozzieostrich : April 30, 2012 at 9:38 pm
compare night and day downward IR at 2 locations:
http://www.patarnott.com/atms749/pdf/LongWaveIrradianceMeas.pdf
http://www.slf.ch/ueber/mitarbeiter/homepages/marty/publications/Marty2003_IPASRCII_JGR.pdf
Look at Upward downward spectrums for signs of GHGs wavelenghts:
http://www.patarnott.com/atms749/powerpoint/ch6_GP.ppt
Answer does a cold body heat a hot body:
See my posts above about thermal imaging cameras.
During the night solar input is zero. But downward LWIR is still within 100 watts of the upward radiation.
It is not coming from warm o2 or n2 (they do not radiate significantly). It is not coming from star/moonlight. So where do you propose this DLWIR is being sourced from.
GHGs is the answer (water vapour/co2 etc)
remember the above documents use real measured figures for IR – not models
So 2 questions:
How doe you explain the thermal imaging camera operation
What do you propose is the source of the DLWIR
Mydogsgotnonose says:
April 28, 2012 at 1:37 am
The “correct” statement would be “2 pi steradians“.
Mydogsgotnonose says:
April 28, 2012 at 2:44 pm
At night, passive solar panels radiate a lot of heat. As a result they get quite cold, much colder than the surrounding air. It is the back radiation that keeps the panels above -80°C.
Mike says: “I assume instead of “. . . returned to the surface . . .”, you meant to say “returned to the atmosphere”.
I could have been a little clearer.
* something like 342 W/m^2 of sunshine shines toward earth (when averaged over the whole surface).
* something like 100 W/m^2 of sunshine reflects/scatters back to space, without ever getting absorbed.
* something like 240 W/m^2 of sunshine gets absorbed.
* something like 240 W/m^2 of thermal IR must be generated to to conserve energy (since we know the earth is pretty close to constant temperature over long time scales). This IR shines outward away from the surface.
NOW we can look at the effect of GHGs.
* with no GHGs, all 240 W/m^2 of thermal lR will pass through the atmosphere and head away to space, never to return. 0 W/m^2 would get returned
* with a little GHG, maybe 50 W/m^2 would get returned due to IR radiation from the GHG molecules toward the surface. This would make a total of 290 W/m^2 heading down, resulting in less surface heating than a perfectly clear atmosphere.
* with a more GHG, maybe 100 W/m^2 would get returned. This would make a total of 340 W/m^2 heading down, resulting in the same surface heating as a perfectly clear atmosphere.
* with a more GHG, maybe 150 W/m^2 would get returned. This would make a total of 390 W/m^2 heading down, resulting in more surface heating than a perfectly clear atmosphere.
This all gets more complicated if evaporation and convection are included, but the principle still applies.
“the maximum transfer of radiative energy between bodies occurs in a vacuum.”
But here one of those bodies is a region of space itself! A region of the atmosphere will transfer NO radiative energy to the surface if that region is 1) a vacuum or 2) a gas with no GHGs. The transfer will increase as more GHG’s are introduced to the region (even if some of the energy is reflected/absorbed/scattered by the non-vacuum between the two. The best transfer is definitely NOT when the “body” is a region of vacuum!
“Infrared pictures taken from space can distinguish between ice at different temperatures, so IR emitted by objects at least down to 273K travels though the atmosphere with little obstruction.
Actually, only specific bands of IR can get through, and only when there is no cloud cover. The sensors have to be tuned to frequencies that are not absorbed by CO2 or H2O in order to “see” the surface. So SOME IR from the surface does get through, but most does not.
Robert Clemenzi says:
May 1, 2012 at 7:17 am (responding to)
Mydogsgotnonose says:
April 28, 2012 at 2:44 pm
I had a climate scientist argue that the reason why ‘back radiation’ did not heat up passive solar panels at night
At night, passive solar panels radiate a lot of heat. As a result they get quite cold, much colder than the surrounding air. It is the back radiation that keeps the panels above -80°C.
??????????
What (airless other world ?) location are you thinking of?
In our real world of air and wind and rain and snow and ice, the temperature of ANY exposed surface to ANY other substance (air, soil, rooftop, or solar panel mount) cannot get lower than that other surface that it touches. Thus, without laboratory conditions of artificially-driven heat exchange and artificially-applied insulation, no surface on earth can get to nor stay at -80 deg C.
Back-radiation in the real-world outdoor environment, compared to conduction and convection, is little. Not nothing mind you (see the ice forming on windshields when conduction and convection (NOTE: the windshield is HEATED by the air flow!) are changed to near-zero under clear skies and low-humidity and no wind.)
Exactly opposite your statement: Thus, it is the air flow (and its subsequent convection and conduction) NOT back-radiation that keeps exposed surfaces at night warmer than theoretical (radiation-only) models predict
Mydogsgotnonose has frequently claimed that
That is not true. Don’t confuse the absorptivity and emissivity (a function of temperature and pressure) with the energy absorbed and emitted. When the temperature is constant the amount of energy absorbed will equal the amount of energy emitted. However, the absorbed spectra and emitted spectra will be identical only at thermal equilibrium. Otherwise, the spectra will be different. That fact that the non-equilibrium spectra are different does not mean that the absorptivity and emissivity are different.
RACookPE1978 says:
May 1, 2012 at 7:37 am
Modern passive solar collectors used evacuated tubes. As a result, conduction and convection have almost no effect on either the daytime high or the night time low temperatures.
And yet, this is a typical winter temperature for the tropopause over Antarctica. Surface temperatures there are typically below -60°C, the record is -89°C.
For exposed surfaces, wind is the only convection that can keep things warm. Lacking wind, isolated surfaces should drop below freezing within an hour of sunset. The fact that they don’t is called the Greenhouse Effect.
I know that the Trenberth radiation diagram confuses a lot of people. What you need to do is to create 2 diagrams – one for day and a separate for night. Assume the day is 4 hours long and multiply the Trenberth solar, convection, and evaporation values by 6. For night, set those values to zero. Then things will make more sense.
ozzieostrich says:
April 28, 2012 at 11:51 pm
I think that if the surface loses 20°C over a long night it would have a higher average temperature than if it lost 50°C over the same time period. Am I missing something?
If the Earth was covered with a perfect long wave insulator but was still able to absorb solar radiation, what would the surface temperature be?
ozzieostrich says:
April 29, 2012 at 5:09 am
That is not correct. Many materials, including Greenhouse Gases, treat long wave and short wave IR radiation differently. As a result, your “Dewar flask” example does not apply here.
No answer to my 2 qustions?
Solar collectors are optimised to use the peak solar spectrum (visible light) but to be a “good” collector, once it has absorbed the visible and converted it to heat then the glass covering should reflect the LWIR back to the collector plate.
LWIR from sunlight and back radiation will be similarly reflected from the glass , but in this case the LWIR will be prevented from entering the collector box.
It would be difficult making a solar collector that utilised LWIR since the glass covering would be required to act differently to LWIR from outside (passes it) to the LWIR from inside (reflects it).
A LWIR collector would lose as much energy that it gained.
Sergei says “It would be difficult making a solar collector that utilised LWIR since the glass covering would be required to act differently to LWIR from outside (passes it) to the LWIR from inside (reflects it). ”
Actually it is even worse than that. The laws of thermodynamics ensure that you cannot focus light so as to warm something above the temperature of the object creating the light (or you would be sending heat from a warm object to an even warmer object). So sunlight (coming from the 5780 K surface of the sun) cannot — even with lenses or mirrors — warm anything above 5780 K. Similarly, if you have radiation from 280 K ground or air or clouds, there is no way to focus that light to warm anything above 280 K.
Think of it this way. The sun is tiny, but can warm things pretty well. With a mirror, I can in effect create a second sun and focus that light onto the collector, doubling the energy heading to the collector. But if are considering thermal IR, it is already coming pretty much every direction. If you put up a mirror to reflect in some IR, the mirror itself will block the same amount IR that would have been coming from that direction.
Anyone who says “if there really were 300 W/m^2 of IR, we should be able to focus it even more effectively than 160 W/m^2 of sunlight” is displaying a fundamental ignorance of thermodynamics.
Robert Clemenzi May 1, 11:51
Sorry. I didn’t notice your comment until now.
To answer your questions in order –
1. Yes. I was talking about an absolute increase in temperature, not a change in rate of cooling. In your ‘think” you lose 20C, or 50C. No warming whatsoever. The amount and/or the rate of cooling is irrelevant. As you have pointed out, there is no warming, as I said.
2. Anything you like. Physically impossible, unless you can adduce experimental evidence to the contrary. If 100 x 0 = 10 x 0, does 100=10? If, if , if . . . . If wishes were fishes, starvation would not exist . . .
3. Energy is energy. If you can point out a filter, or insulator, or some heretofore undiscovered material, that retards the total transmission of energy in an arbitrary direction better than the opposite direction, I will change my thinking. The problem you face is that you can’t. Galling, no doubt, but true.
Until you provide evidence to the contrary (in line with established scientific principals), I see no reason to change my mind.
Over to you.
Live well and prosper.
Mike Flynn.
Tim Folkerts,
Sorry, but I was responding to Robert Clemenzi, and I noticed your comment at 3:00 pm.
If you don’t mind, may I point out that the Sun is not “tiny”, but quite a lot larger than the Earth.
I think I know what you mean, but may I suggest that you make your meaning more precise. There are many people of my level of education (which is to say not much at all) who may take you literally. Maybe I’m wrong. Please let me know if I am.
Live well and prosper.
Mike Flynn.