Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Donate

Twitter Facebook YouTube Pinterest

RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
Keep me logged in
New? Register here
Forgot your password?

Latest Posts

Archives

Climate Hustle

Waste heat vs greenhouse warming

Posted on 27 July 2010 by John Cook

A vigorous discussion has erupted on the waste heat page. Problem is, there's not meant to be a waste heat page! As I encounter new skeptic arguments, I add them to the to-do list and gradually (very gradually) research the peer-reviewed literature then write an explanation of what the science says, usually in order of popularity. I hadn't got around to looking into the issue of waste heat. Nevertheless, one intrepid Skeptical Science user found the empty page waiting to be populated and began a discussion there (j'accuse Doug Bostrom). So let's look at waste heat...

Firstly, what is waste heat? When humans use energy, it gives off heat. Whenever we burn fossil fuels, heat is emitted. This heat doesn't just disappear - it dissipates into our environment. How much does waste heat contribute to global warming? This has been calculated in Flanner 2009 (if you want to read the full paper, access details are posted here). Flanner contributes that the contribution of waste heat to the global climate is 0.028 W/m2. In contrast, the contribution from human greenhouse gases is 2.9 W/m2 (IPCC AR4 Section 2.1). Waste heat is about 1% of greenhouse warming.

Radiative forcing from waste heat vs anthropogenic greenhouse gas radiative forcing

What do these numbers mean? They refer to radiative forcing, the change in energy flux at the top of the atmosphere. Or putting it in plain English, the amount of heat being added to our climate. Greenhouse warming is currently adding about 100 times more heat to our climate than waste heat.

UPDATE 27 July: there is some confusion about the term 'waste heat'. Here, what I'm talking about is all the heat generated by energy use. When humans generate energy, much of it is immediately dissipated as heat. The rest is converted to electricity or energy of some sort (eg - mechanical, chemical, etc). But even this energy eventually dissipates as heat into the environment. So yes, 'waste heat' is not an ideal term. Flanner uses the term "anthropogenic heat flux".

0 0

Bookmark and Share Printable Version  |  Link to this page

Comments

Prev  1  2  3  4  5  Next

Comments 101 to 150 out of 210:

  1. RSVP - I believe I have a better understanding of the issues you are trying to raise.

    The core problem with your formulation, however, is that there is only one account, one collection of energy in the atmosphere, not two separate accounts as you describe here.


    First case: Take a large air mass. Heat in some fashion that only excites, say, just the N2 and O2 (perhaps a magic electrode, perhaps just statistical chance in convection/conduction). Heat it with enough energy to raise that air mass 1oC in temperature. Now the N2 and O2 molecules have high thermal energy, and are moving faster. This is your car radiator case.

    Given that air molecules at surface pressure collide with other molecules 10^9 times per second, this energy is rapidly distributed to all the molecules in the air mass - N2, O2, CO2, Ar, H2O, etc. And once the GHG's in the air mass reach the higher temperature, they will radiate IR at the appropriate rate for that temperature. AND the air mass is now 1oC warmer.


    Second case: Apply a heat lamp to your air mass. CO2 and H2O heat up, N2 and O2 don't since they don't absorb IR. Heat it with enough energy to raise that air mass 1oC in temperature. Some of the CO2 and H2O molecules will just re-emit the IR, which likely gets caught by other molecules in the air mass (i.e., it doesn't leave). If your air mass is over 100m in size, that's almost an absolute certainty; it certainly is for the atmosphere as a whole. The high energy GHG molecules collide at 10^9 times per second, distributing the heat evenly through the air mass. AND the air mass is now 1oC warmer.


    Now what about the IR absorbed/emitted by the GHG's in your air mass? Well, if the surroundings are cooler, a net number of photons will leave, and the air mass will cool - in both cases. If the surroundings are warmer, a net number of photons will enter the air mass, and the air mass will warm - in both cases.

    There is no difference, RSVP. All the energy goes into the same account, whether through conduction, convection, or radiation. It all heats up the entire air mass via thermal diffusion, or cools the entire air mass via thermal diffusion, regardless of the energy pathway.

    There are no separate energy accounts for radiation and convection - thermal diffusion redistributes the energy efficiently and very quickly regardless of energy pathway.
    0 0
  2. As an aside: the mean vibrational equilibrium time for CO2 is ~10^-6 second (1 ms), rotational equilibrium time is ~10^-7 second (100 ns), while time between collisions with other molecules is ~10^-9 second.

    This means that an excited CO2 molecule, on the average, has 100-1000 collisions with other molecules at surface pressure before it has a chance to emit an IR photon. CO2 molecules will be kept at the temperature of the air mass, whether losing or gaining energy for the air mass as a whole.
    0 0
  3. I think y'all have now focused on RSVP's main contention: RSVP contends that the delay of energy getting from non-GHGs to GHGs is sufficiently long that it acts as a bottleneck in that energy escaping via IR radiated by GHGs. RSVP analogizes that with the GHG-induced delay of energy escaping via IR being a bottleneck.

    But as has been pointed out, the delay of energy transfer from non-GHGs to GHGs is inconsequential.
    0 0
  4. NED #100

    "That would cool the Sahara, yes. What happens to the latent heat when the resulting water vapor condenses and precipitates somewhere else? Again, there's a reason it's called the hydrologic cycle.


    Imagine a cubic meter of air heating. Immediately he begins to radiate this thermal energy, respecting the law of Stefan-Boltzmann.
    I wonder, how many feet it can travel up to dispel any ernergia absorbed??
    Already the steam carries the energy packed in the form of latent heat, and will only release this energy whem has its temperature reduced to the dew point. So the task of redistributing the energy the water vapor is the most efficient system.
    Atention....for to divide by 4 is mandatory the distribution before.
    0 0
  5. Another meta-comment since there's nothing fundamental left to say about science here.

    A reasonable person (me, I'm ever so reasonable) might argue at this point-- 104 comments into explaining something that was comprehensively handled with the arrival of Ned's #22-- that RSVP is not practicing skepticism but instead is enjoying a wind-up. If that's the case, he should be thanked for turning the crank because while he's forced the expression of a lot of redundancy he's also managed to uncover several useful mental models for helping people to think about why anthropogenic greenhouse gases warm the planet.

    If I'm wrong, I don't think RSVP is reachable but nonetheless further synthesis of mental models may be helpful. Are there any more? Maybe RSVP is awaiting the arrival of a molecule of thought of just the right shape so as to click into place.
    0 0
  6. RSVP asked: "Can GHG radiated heat from the atmosphere cause heating of something that is hot? ... like an asphalt highway midday? or an air conditioners heat exchanger?"

    I'm not sure how you are defining 'heating' here so I'll explain the full process. Yes, energy which GHGs prevent from leaving the atmosphere does excite the molecules of already heated solids (e.g. asphalt under the noon sun). There is no magical force which prevents photons from approaching an already 'heated' substance. However, all matter also dissipates heat constantly... the hotter the object the more heat it gives off (obviously). Thus, under normal circumstances the heat coming off the asphalt (mostly generated by absorption of visible light) will be greater than the heat retained due to GHG going into the asphalt. The asphalt will be hotter than it would have been without the GHGs (because solar radiation + GHG radiation is greater than solar radiation alone), but it will not continuously accumulate heat ad infinitum. Rather incoming energy and outgoing energy will be equal... and since GHGs increase the incoming energy the 'heat' of the object also increases.

    Also: "Along that same idea, the warmer the air (due to whatever) the less effects GHG have."

    Um... no. The warmer the air the GREATER the effects of GHG. More IR photons inherently means more IR photons being delayed from escaping the climate system by GHGs.

    Finally: "Overall power normally attenuates when it traverses space. If one square KM of ocean water radiates heat upward, and it hits even a perfect mirror, whatever comes back will be a weakened version of that powerwise."

    What? You're suggesting that energy just... ceases to exist? If so, you are VERY mistaken. If X photons hit a perfect mirror then exactly X photons will bounce off of it. The only way your statement could make any sense is if you are suggesting that some of the energy will disperse through the atmosphere... which is of course true, but doesn't change the fact that it is remaining in the climate system regardless of where it originated.
    0 0
  7. RSVP - to address the other direction (CO2 having plenty of time to heat the air mass having been discussed here):

    A heated (high energy) N2 or O2 molecule, given 10^9 collisions/second and 390 ppm of CO2, will strike 390,000 CO2 molecules per second on average, heating them if they are cooler. Temperature therefore equalizes between the N2, O2, H2O, and CO2 molecules.
    0 0
  8. Ned #96

    Thank you very much. I've been trying to get Ken to give me an estimate of what the TOA imbalance means for over a year, in terms of climate sensitivity or other temperature measurements, and for all that time he has refused to answer that question. Now thanks to your digging around, we know why ... it's because the energy balance model shows that the risk of serious climate change is the same as the other available evidence.
    0 0
  9. "we can spread sea water in the desert of the Sahara" - and in doing so lay waste to the whole area so that no vegetation could grow and no animals could live there. Remember how the Romans ensured the Phoenicians would never rise again - they sowed the fields with salt. And after destroying the Sahara (deserts are not empty of biodiversity, they have quite high biodiversity of species adapted to that environment) where do you move on to as temps continue to rise - Australia? Central Asia? Western America?

    The problem with all these "geo-engineering solutions" is that they involve a cloud of unintended consequences. It seems there are people who are content with any solution that involves, say, the destruction of the living contents of the Sahara, as long as it doesn't involve a switch from coal fired power stations and massive SUVs.
    0 0
  10. KR: Great data on collisions and vibrational frequency. I wondered what that data was but didn't know where to find it.
    0 0
  11. The Ville #98
    A point light source spreads out like a cone. Good thing too for the case of the Sun, otherwise we'd be toast.

    doug_bostrom #105
    Very funny. No one is paying me to turn any cranks, but it is sometimes hard not to think about these discussions when driving around town (i.e., helping global warming "one way or the other")... and at some point as I was doing this I did muse on a post that complained about metaphores and analogies. And "since there's nothing fundamental left to say about science here", it would be nice if you could explain what matter really is, that way we dont have to rely on these clumsy models.
    0 0
  12. RSVP says: "A point light source spreads out like a cone."

    Not in my world it doesn't. A point light source sends out light in all directions. The only light source with the behaviour you describe is one with a parabolic reflector round it.
    0 0
  13. John Russell
    You are right. I was just checking to see if you were listening.
    0 0
  14. RSVP
    A point light source spreads out like a cone. Good thing too for the case of the Sun, otherwise we'd be toast.

    Quoting school boy text book physics doesn't help you much.

    You are deviating from the scenario you set up initially.
    Your scenario was an ocean radiating energy and a 'mirror' above it. The assumption was that the 'mirror' was a few miles at most above the ocean.

    That is NOT a point source scenario and your original scenario is different from a school text book concept.

    The energy from the ocean will 'radiate' in different directions from the surface (eg not a 'cone' or 'spherical' from the point). The only case in which your model would be true is once you leave the earths atmosphere and 'view' the ocean from a distance (so that the earth is a point/sphere). At that distance the radiation you see will be from the earths sphere and would have had a chance to disperse outwards along radiating lines.
    What you will 'see' at that point in space are all the photons that happened to have left the planet after a lot of interactions and ended up at your position.

    The issue here is scale and the POV of the observer.

    In the case of an 'atmospheric mirror' around the world.
    If it was a perfect 'mirror' then ALL the energy would be reflected back and there will be NO losses or dispersal. All the energy would return towards Earth, it might end up in a different place on the planet due to refection/incident angles, but it won't be attenuated globally. As I pointed out you may get hot spots and cool spots regionally if the mirror was imperfect.
    If the 'mirror' was 'lossy' then some would not be reflected back.
    0 0
  15. KR 101
    In this narrative, it sounds like CO2's ability to transfers energy to non GHGs is extrememly efficient, if not 100% efficient. Why then does concentration matter, (i.e., the basis of AGW)?

    CO2 only couples a small percentage of the Earth's surface heat, while nearly all of this energy gets out. So in your second case, it takes a lot more energy from the source to get the same air mass up 1 degree centigrade. Your reference to a magic electrode is unwarranted because in heating air only .03% of the energy (or thereabouts) goes into heating the CO2 it contains.

    So in case 1 you make it sound like CO2 is super heat sink, while for AGW a difference of 100 ppm makes all the difference in the world.
    0 0
  16. The Ville #114
    Yes but Sunlight is far from laser quality.
    0 0
  17. Geez.

    Your scenario is radiated heat from the ocean.

    If you are going to use analogies, then keep to the one you started with. If your analogy is incorrect then accept the fact.
    0 0
  18. CBDunkerson #106
    This thing about light dispersing is getting off topic as far as the thread is concerned. You are right, energy cannot be destroyed. Perhaps as far as the IR there could be scattering due to GHG.. why not? (this aside from energy absorption). Perhaps this explains some warming phenomenon.
    0 0
  19. The Ville #117
    You are way off topic.
    0 0
  20. RSVP
    You are way off topic.

    Then I suggest you don't use incorrect analogies!
    But in any case, I accept your answer as acknowledgement of your error.
    0 0
  21. The Ville #120
    The world is not flat, and I dont think I specified how high this mirror is etc. It was a bad choice on my part to focus on the idea of what would happen if absolutely all the IR was reflected back to Earth's surface. I assume you would agree that surface warming would be readily detect, yet in the next chapter, of the 10 items, I did not see this one. It is better that I admit my error. I do. Thanks.
    0 0
  22. RSVP #121: "The world is not flat"

    Hooray! Finally, an aspect of basic scientific reality upon which we can agree.
    0 0
  23. Ned #100

    The 11 year Solar cycle reportedly has a peak to trough of about 0.25 W/sq.m which is about 0.1% - NOT 1% of the 240 W/sq.m of net incoming solar radiation. 1% would be 2.4W/sq.m which is a very large variation compared with Dr Trenberth's 0.9W/sq.m of TOA heating imbalance. Yet Solar variation is being suggested as a flattener for the last 10-12 years of temperatures.

    If that is so, then half the top to btm of 0.25W/sq.m (0.125W/sq.m) must be a large chunk of the warmming imbalance - which looks very small against 0.9W/sq.m of purported imbalance.

    The point is made that human released 'Waste Heat' at 0.028W/sq.m is insignificant when applied to the global surface area; but is quite significant when applied to the 6-8% of the globe from which it emanates. It avearges 0.4W/sq.m over that roughly 7% of the globe.

    Now if most of your temperature measuring land based stations are in that 7% of the globe where humans release waste heat; and this figure is roughly half the 0.9W/sq.m of heating imbalance at TOA, then it is reasonable to expect that temperatures would be affected by waste heat which roughly adds 0.9 + 0.4 = 1.3W/sq.m over those areas.

    I think this is what BP is banging away at in the temperature reconstruction thread. The 'fiddles' which adjust one station to work out a temperature for a point hundreds of km away could indeed be interesting.
    0 0
  24. RSVP - You're still missing the point!

    The point I (and any number of other posters) was making is that energy entering an air mass via conduction/convection heats the entire air mass. Energy entering an air mass via radiation also heats the entire air mass. There are no "separate accounts" as you described.

    What all of this means is that the 2.9W/m^2 GHG forcing and the 0.028W/m^2 AHF simply add to the general energy in the ground/air/water, as described here.

    No distinction once the energy is released into the system, RSVP. None whatsoever. The total energy ends up heating up the Earth, water, and air. Temperature changes are the result of the sum of all forcings and feedbacks.

    And, as you've agreed, the 1% AHF is pretty small change compared to the 99% GHG forcing.

    As to the ppm CO2 changes? I strongly suggest you read up on that here and here. I feel no need to repeat well-written descriptions of the effects of CO2 levels to correct physics errors on your part.
    0 0
  25. Ken Lambert writes: The 11 year Solar cycle reportedly has a peak to trough of about 0.25 W/sq.m which is about 0.1% - NOT 1% of the 240 W/sq.m of net incoming solar radiation.

    You're arguing against someone else, not me. I said that the total variation over the solar cycle is less than 1% not that it is 1%. I was trying to correct another commenter who was IMHO exaggerating the magnitude of solar variation. So I'm glad you agree with me.

    Ken continues: The point is made that human released 'Waste Heat' at 0.028W/sq.m is insignificant when applied to the global surface area; but is quite significant when applied to the 6-8% of the globe from which it emanates. It avearges 0.4W/sq.m over that roughly 7% of the globe.

    Yes, if you assume all 0.028 W/m2 of waste heat is coming from 7% of the globe, it averages 0.4 W/m2 at its source. Of course, the heat doesn't stay there; it moves around. In any case, sure, waste heat can be locally important, but globally it's insignificant.

    That is the point of this thread.

    Ken continues: Now if most of your temperature measuring land based stations are in that 7% of the globe where humans release waste heat [...]

    Please don't muddy the waters. We're doing one thing here, comparing the magnitude of two different forcings.

    If you want to talk about UHI in terms of its (hypothetical) impact on the temperature record, do so in one of the many threads about UHI or the temperature record. (Keep in mind that there are many, many indications that UHI does not have a significant impact on global land/ocean temperature reconstructions.)
    0 0
  26. Ken Lambert #123 wrote: "Now if most of your temperature measuring land based stations are in that 7% of the globe where humans release waste heat; and this figure is roughly half the 0.9W/sq.m of heating imbalance at TOA, then it is reasonable to expect that temperatures would be affected by waste heat which roughly adds 0.9 + 0.4 = 1.3W/sq.m over those areas."

    No, that is not reasonable... because it is not consistent with how global temperature anomalies are computed.

    Essentially, you are arguing that if 50% of all temperature measuring stations are located in the most heavily populated 7% of the globe then that 7% of the planet determines 50% of the global temperature anomaly. Which is simply false. Because the anomalies are computed based on geographic distribution... so those 50% of stations would only account for 7% of the total global anomaly... because they cover only 7% of the planet.

    Ergo, there is no global bias from localized heating.
    0 0
  27. RSVP #128: Creationists aren't twisting science around? Apparently you've never heard of 'intelligent design'.
    0 0
  28. RSVP @115:
    Congratulations! You have learned that the heat transfer in the atmosphere is efficient. The last 200+ posts have not been completely in vain.

    Now one more point: the CO2 in the atmosphere ABSORBS almost ALL of the energy from the surface before it escapes into space. If you want to continue to insist that only 3% is captured you must provide a reference that shows that.
    0 0
  29. RSVP asked "It sounds like CO2's ability to transfers energy to non GHGs is extremely efficient, if not 100% efficient. Why then does concentration matter, (i.e., the basis of AGW)?"

    Answer: Because the higher the CO2 concentration, the more CO2 molecules get in the way of IR photons that are emitted from other CO2 molecules. That causes a longer delay in the energy escaping to space. If the concentration is "low," nearly all the energy from the surface still is absorbed by the atmosphere, but the delay of that energy escaping to space is shorter, meaning the bottleneck of energy escaping to space is wider, so less energy accumulates before the rush of energy trying to escape increases enough to reach equilibrium again.
    0 0
  30. Somewhere up above the statement was made that heat from power plants flows into the ocean from heat exchangers. Since only a fraction of power plants are located on the ocean (Eli is too lazy to look this up) the claim is on thin ice.
    0 0
  31. To EliRabett #129
    If not ocean water, it will be rivers or lakes. What difference does it make?
    0 0
  32. How about another analogy?

    Imagine a pool table (the Earth's atmosphere) where all the pool balls (IR photons) move of their own accord and bounce around until they hit one of the pockets and leave the table (escape to space).

    Now, say that on average it takes 30 seconds for a pool ball to leave the table... but every 30 seconds another pool ball (photons from sunlight, waste heat, et cetera) is added. Thus the system is in equilibrium and will continue that way indefinitely with a relatively fixed number of balls (stable temperature) on the table.

    However, if we then block off one of the pockets (add GHGs to the atmosphere) the pool balls cannot escape as fast and the number on the table begins to increase (it gets hotter). These extra pool balls mean extra collisions and more kinetic energy and thus result in balls hitting the remaining pockets more often... until eventually the average time for a ball to leave the table again reaches 30 seconds and the table returns to equilibrium... just with more balls on it (a higher average temperature).

    An even closer analogy would be if the pool table were three dimensional and different parts of it caused the balls to travel at different speeds (conductivity of solids, liquids and gases the heat is passing through), but essentially that's how it works. There is no great and impenetrable mystery here... and the one white cue ball from waste heat does not behave any differently than all the other balls from solar energy.
    0 0
  33. CBDunkerson at 21:16 PM on 30 July, 2010

    Wow, what a truly wonderful analogy. As a analogyphile myself I admire your creativity (I'm assuming it's not a cut and paste job!).

    If I may, the only thing I could suggest that might improve it is to substitute a crowd in a large stand at a football match looking for one of a number of exits -- with a stream of additional spectators joining them from the tier above. This has that advantage that one doesn't have to imagine balls being self-powered.

    Does that work? Someone ought to collect all the analogies together!
    0 0
  34. Hey John.

    Yeah, I was trying to get across the way that photons bounce around in the atmosphere, but any analogy of things trying to move through constrained exits (e.g. the dam analogy) covers the central concept. They each have benefits. The pool table simulates the 'brownian motion' of the photons, the dam has the increasing pressure at the bottom correlating to the increasing surface temperature, and the stadium crowd helps get across the vast number of individual photons involved.
    0 0
  35. CBDunkerson #126

    "Essentially, you are arguing that if 50% of all temperature measuring stations are located in the most heavily populated 7% of the globe then that 7% of the planet determines 50% of the global temperature anomaly."

    No I am not arguing that. I said "then it is reasonable to expect that temperatures would be affected by waste heat which roughly adds 0.9 + 0.4 = 1.3W/sq.m over those areas."

    "over those areas" refers to the 7% of the globe (land) releasing this waste heat.

    It depends on the 'tricks' used by researchers to correct this 7% of the land area which would have a relatively high number of measuring stations compared with sparsely populated areas.

    Yes - waste heat moves about - but it is an energy flux ie an instantaneous heating power measured in W/sq.m or Joules/sec-sq.m.

    A 3D thermal gradient will be established from source to any remote point. Other sources will add to the complexity and multiple sources will distribute heat from power station stacks, cooling towers, cooling lakes by evaporation, convective and radiative means driven by winds etc.
    0 0
  36. CBDunkerson #131
    "However, if we then block off one of the pockets (add GHGs to the atmosphere"

    Why do you only think GHG work towards warming? They should emit as much as they absorb? No?

    This needs to be established.

    If I am in a dry desert at dusk, temperatures are bound to drop very quickly. Why? I assume IR doesnt have to ask permission from each CO2 molecule it finds on its way upward. You know if this were the case there would no such thing as IR satellite photography. It seems like IR makes it right through for the moment, otherwise there would be no contrasting images.

    But moreover, here is the crux of this issue....

    You could have a situation where if waste heat was equal to 2.9 W/m2, then GHG wouldnt do anything. It would be a "clipping" situation. Another example. Waste heat was 1 W/m2 and GHG in the absense of waste heat was contributing 2.9 W/m2. So in reality GHG only actually added 1.9. Do you see what I am saying? That GHG also serve to emit radiation. They dont push power where it is cant be absorbed. This all has to do with the concept of saturation and a limited amount of surface energy. GHG only warm under certain conditions, and actually cause cooling under others. If you dont believe this, go to the desert at night.
    0 0
  37. If I am in a dry desert at dusk, temperatures are bound to drop very quickly.

    You're missing a GHG there, RSVP. Think about it.
    0 0
  38. One more thing...
    and assuming cloudless skies in two cases, desert and beach... the fact that temperatures drop faster in the desert tells you quite a bit about how water vapor acts as a GHG vs CO2.
    0 0
  39. RSVP #135: "Why do you only think GHG work towards warming?"

    As written that is asking me why this is the only thing I think. Which is obviously inaccurate. Did you intend to ask why I think GHGs cause only warming? I don't think that either... since they cool the stratosphere. Whatever, it bears no resemblance to anything I've actually said so I'm not sure where you are going.

    "They should emit as much as they absorb? No?"

    What about the pool balls aren't you understanding? Pool ball hits a blocked pocket... it bounces off and remains on the table. Photon hits a GHG molecule... it gets emitted back out and remains in the atmosphere. So yes, they emit as much as they absorb... which is precisely why the atmosphere gets warmer. They're bouncing pool balls/photons back onto the table/into the atmosphere rather than allowing them to escape to the pocket/space.

    "If I am in a dry desert at dusk, temperatures are bound to drop very quickly. Why?"

    Because water vapor is a powerful greenhouse gas. Dry deserts don't have alot of water vapor. Ergo, they cool down at dusk more quickly than regions which do.

    "You could have a situation where if waste heat was equal to 2.9 W/m2, then GHG wouldnt do anything."

    False. GHGs work on all IR regardless of its source. Thus, some of that waste heat would be 'bounced' back down towards the surface and prevented from escaping to space longer than it would have been without the GHGs. Yeesh. At least TRY to understand the analogies.

    "GHG only warm under certain conditions, and actually cause cooling under others. If you dont believe this, go to the desert at night."

    This is all nonsense. Not a word of it is true. The laws of physics do not very by geography.
    0 0
  40. RSVP at 00:27 AM on 31 July, 2010 "GHG only warm under certain conditions, and actually cause cooling under others. If you dont believe this, go to the desert at night."

    GHG warm the *atmosphere* under all conditions. Humidity or the lack of it affects the temperature for a few hours or days at individual locations. But this is just the circulation of heat and moisture -within- the atmosphere and the oceans.

    Global warming is about the fact that energy continues to circulate within these systems instead of making orderly progress through the atmosphere and out to space. Adding more GHG to the system increases the amount of energy held and circulating within the system.

    That deserts are cold at night and tropical forests are warm most of the time are simple facts about particular locations on land surfaces. It says little to nothing about the whole system of atmosphere and oceans.
    0 0
  41. #138
    "This is all nonsense. Not a word of it is true. The laws of physics do not very by geography. "

    You mean "vary", and I never said anything about geography.

    The "condition" has to do with energy level or temperature, however you wish.

    What I am bringin up here is a question that would be actually interesting to discuss... perhaps...

    That is... I assume 2.9 W/m2 is the average for the entire planet. Is it higher for places that are normally cooler, or higher for place that are normally warmer, or is it the same everywhere???
    0 0
  42. Someone said way back that radiation does not depend on a difference in temperature. Curiously, it tends to always want to go to the coolest place (i.e. outer space). That to me sounds like the difference matters.

    Likewise, here on Earth, the amount of radiation will depend on the temperature of things. So you wont have radiation happening free just because, especially when things are already getting warmed. So, the GHG will diminish as a function of ambient temperatures especially where something else (like waste heat) is causing a counter force.
    0 0
  43. RSVP:

    Curiously, [radiation] tends to always want to go to the coolest place (i.e. outer space).

    No. It goes in the direction it's emitted which is unrelated to its future destination, does not "want" anything, has no idea of its destiny. You'll need to get past that notion in order to make better progress here.
    0 0
  44. There is a lot of confusion about very basic physics concepts in this thread. There are also a lot of analogies being used that aren't necessarily helpful.

    We could start from ground zero and go over exactly how the greenhouse effect works. But we don't really have to do that, since Science of Doom has already done a far better job of explaining it than we are likely to do.

    RSVP, have you visited that site? Since you seem to be hung up more on the basic principles of greenhouse gases instead of the narrow question of waste heat, you might find it helpful to do some reading over there.
    0 0
  45. doug_bostrom #142
    "You'll need to get past that notion in order to make better progress here"

    I agree that we disagree on this issue. I also noticed this, but hoped it wasnt necessary to go there.

    I dont want to take you or anyone on a wild goose chase, or worse, have someone think that that is my intention.

    If you dont agree with me, please at least respect my "delusion". It might even be interesting to at least hear.

    Photons do in a sense "know" whether they can be launched "before" leaping so to speak. Microwaves for instance require source and load impedance matching. If the load is not matched, the energy does not transmit. How can it "know" this before leaving? Microwave and light and IR are of the same nature, (i.e. electromagnetic radiation).
    0 0
  46. RSVP #144 writes: "If you dont agree with me, please at least respect my "delusion"."

    No.

    Sorry, but I don't respect your belief that radiation somehow magically avoids areas of higher temperature any more than I respect beliefs that the Earth is flat.

    Both of these 'beliefs' are provably, and frankly rather obviously, FALSE.
    0 0
  47. RSVP, I believe you are thinking of the net effect of microwave transmission followed by reflection from the destination back to the source. That process unfolds in time. It does not happen because the microwaves don't leave the source by virtue of knowing what will happen to them.
    0 0
  48. RSVP - If you dont agree with me, please at least respect my "delusion".

    Nope.

    Reality is a harsh critic. Hundreds of years of science cannot be avoided by wishful thinking, 'common sense' arguments, and the like.

    Please - read up on the basic concepts. Roy Spencer, an AGW critic, has an excellent reference on back radiation, and how a cold object can make a nearby warm object warmer. Science of Doom has plenty of introductory material. Wikipedia has tons of useful information on greenhouse effects, climate forcings, and the like, with lots of references.

    But don't expect us to drop the science...
    0 0
  49. Tom Dayton #146
    What exactly happens when the photons "get there", but decide they are not wanted? Do they disturb things in any way? I dont think this has ever been measured.

    The other alternative is to redefine atomic radius as something that goes beyond just the outermost valence shell, at least for photons. When I put out my hand to the Sun, I can "feel" it because I am in "contact" with it (or at least a little bit of it). The Universe is all one big single Thing.
    0 0
  50. RSVP:

    Photons do in a sense "know" whether they can be launched "before" leaping so to speak. Microwaves for instance require source and load impedance matching. How can it "know" this before leaving? Microwave and light and IR are of the same nature, (i.e. electromagnetic radiation).

    That example has nothing to do with the misunderstanding you're expressing with regard to whether radiation knows of its destination. Amplifying and then retransmitting your misunderstanding with paradoxical-seeming knowledge of microwave resonances is a strangely incoherent phenomenon of emission, a sort of epistemological transponder system with severe ringing or the like.
    0 0

Prev  1  2  3  4  5  Next

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.



Get It Here or via iBooks.


The Consensus Project Website

TEXTBOOK

THE ESCALATOR

(free to republish)

THE DEBUNKING HANDBOOK

BOOK NOW AVAILABLE

The Scientific Guide to
Global Warming Skepticism

Smartphone Apps

iPhone
Android
Nokia

© Copyright 2017 John Cook
Home | Links | Translations | About Us | Contact Us