Can Roy Spencer Describe the “Greenhouse Effect”?

· blackbody radiation, climate science

The Blanket Theory

Roy Spencer makes a new try to explain the “greenhouse effect” to the people in More Musings from the Greenhouse by recalling the “blanket theory”:

  • If you are lying in bed and are too cold, you can turn up the electric blanket (increase energy gain), or add a regular blanket (decrease the rate of energy loss). If you add even more blankets, you will gradually make the temperature under the blankets higher…but at the same time you make the temperature of the outer blankets colder.

But is this true? Does Roy Spencer describe a correct “blanket theory”?

Will increasing the blanket effect by doubling the CO2 cause warming of the Earth surface and cooling at the top of the atmosphere radiating to outer space?

To seek an answer consider a house being heated inside with a certain given heat source, and consider the effect of increasing the insulation of the walls of the house, that is decreasing the heat transfer coefficient \alpha of the wall.  Heat balance can be expressed as

  • \alpha (T_i - T_o) = \sigma T_o^4 = Q,

where T_i is the inside temperature, T_o the outside temperature of the wall and Q is the constant heat source.

We see that the outside temperature T_o is determined by the heat source Q assuming the outside radiates according to Stefan-Boltzmann to a surrounding at 0 K.

We see that the temperature gradient T_i-T_o, and thus the inside temperature T_i, increases with better insulation with decreasing \alpha. But we do not see the outside temperature T_o decreasing under better insulation. The flowers outside the house will continue to bloom as before, unless Q is decreased.

The same conclusion is reached in A Skeptic’s Guide to the Greenhouse Effect.

This little exercise illustrates that the “greenhouse effect” is not well described in climate science nor well understood by climate scientists, yet is supposed to require fundamental changes of human conditions.

PS No response from Roy on my comment and questions.

Roy answers:

  • It seems your objection is to the existence of any IR radiation flowing from cooler bodies to warmer bodies as part of the radiative transfer process. Without studying the issue more, I  cannot think of an immediately obvious way to prove you are wrong.
  • But the net effect on radiative transfer might be the same whether you use the concept of back radiation or not…in the usual calculation of radiative flux divergence of radiation in an atmospheric layer, there are radiative fluxes being absorbed by the layer from layers on either side, and there is flux being emitted by the layer. The sum of these is the *net* flux divergence, which you claim is in reality the only flux which is occurring. This is my understanding of your position.
  • If you want to think of it that way, then I cannot immediately think of an example which proves you are wrong. 
  • But all we are discussing here are the details of the mechanism by which IR energy flows from a warmer body to a cooler body. It does not change the fact that making the cooler body a little warmer will then reduce the rate of IR emission from the warmer body to the cooler body, which through conservation of energy means it will change the temperature of the warmer body. One does not necessarily need to invoke “back radiation” to achieve that effect.
  • Since you admit that the presence of an atmosphere reduces the rate of IR emission from the surface to outer space, then you implicitly admit that something like the “greenhouse effect” does exist, at least in terms of its influence on surface temperature. You are just disputing the details of the mechanism usually used to explain the process. Am I correct?

My answer:

How could I possibly object to the statement that something like the “greenhouse effect” does exist? Are we talking science or not?

Can I deny that “something like “creation” does exist”? If not, am I then a creationist?


Comments RSS
  1. mkelly

    “…will then reduce the rate of IR emission…”

    This just isn’t true. The rate of IR emission can stay the same we are talking about heat transfer and the two are not identical.

    A higher energy object does not necessarily absorb lower energy emissions.

    When T1 = T2 the rate of exchange is ZERO but according to this back radiation idea there should be a doubling of T1 or T2.

  2. iceskaterfinland

    Your reasoning for no hotter outside wall when increasing insulation is flawed

    You also need to consider the temperature gradient in air between the wall and the flowers.

    Living in sweden you must know that roofs with poor insulation have melted snow on them before roofs with better insulation. A temperature gradient forms into the snow where snow is a reasonable insulator which is why people in Sweden pile snow against the sides of their house in winter to prevent heat loss from cooling the sides of the house by air

    • iceskaterfinland

      And obviously with sufficient blankets no heat camera will ever detect a person under the blankets

  3. claesjohnson

    No, the reason the snow is melting is that with poor insulation more heat is transported through the wallm if the inside temp is kept constant. Take a trip to Sweden to check out.

    • iceskaterfinland

      So you think the boundary of wall and snow or wall and air are the same temperature regardless of the amount of insulation? Only when the snow is melting can you argue that is true.

      Otherwise there is a gradient thru the wall, then a different gradient thru the snow until the snow air boundary is reached.

      • iceskaterfinland

        if it is a constant -18C for a week outside and 22C inside and you have no insulation then the wall is made of snow and there is a temperature gradient thru the ‘snow’ of 22c to -18C, so at the room snow boundary the snow is rapidly melting – you are living in an igloo for example.

        If you begin adding insulation to the snow at some point the insulation snow boundary is less than 0C, if you keep adding insulation the wall snow boundary falls much lower than 0C eventually the outside wall snow boundary is approaching -18C.

      • iceskaterfinland

        An easier example. Contain some boiling hot water in a copper cylinder. The copper is the insulation and there is a temperature gradient thru the copper. Put your hand on the copper. The thermal detector of your hand indicates it is very hot. Put 10cm of polystyrene on the copper and use your hand. You can no longer notice that the other side of the polystyrene there is a source of heat.

  4. claesjohnson

    The gradient through the snow is constant if the heat source is constant. Hence the outside wall temp is constant if the outside snow wall temp is constant and the heat source is constant.

    • iceskaterfinland

      >>We see that the outside temperature is determined by the heat source assuming the outside radiates according to Stefan-Boltzmann to a surrounding at 0 K

      You are correct for your conditions ***if the insulation is applied to the inside of the house***.

      If you infinitely increase the insulation then the temperature inside rises infinitely and the outside temperature gives the same heat rate loss as before.

      However for spencers example he is adding blankets on the outside so the surface area increases and the blankets are colder for the same heat transfer rate


  5. Richard T. Fowler

    ” Put 10cm of polystyrene on the copper and use your hand. You can no longer notice that the other side of the polystyrene there is a source of heat.”

    This challenge is very easily answered.

    If you put the insulation all around, in equal quantities, except for the bottom on which you put no insulation, then more energy will either exit through the bottom, or not enter in the first place.

    If, on the other hand, you put the heat source inside the cylinder and surround the entire cylinder with the same thickness of insulation, once it reaches equilibrium you will get the same heat, IF AND ONLY IF you measure over the proportional surface area given larger surface area with the insulation.

    Makes sense?


    • iceskaterfinland

      see my reply above. I was not fully realising the nature of the particular house where the internal heating was not turned down as it got better insulated. But obviously the outside wall of a well insulated house is colder for the same internal temperature than a poorly insulated house. Pick up something from the oven at 200C without an oven glove to test that one.

      • Richard T. Fowler

        Again you are not seeing what I am saying.

        First, it makes a difference whether the pan from the oven has its own internal thermal source. My cylinder example, as well as the house, both do. Your cylinder example is somewhat different because you are implicitly keeping energy applied on the bottom, which I am assuming has no insulation or not the same amount. So there is an “escape door” for it to get out, and also through which to influence the ability of new energy to get in by presenting a higher temperature in that direction.

        Second, if the only insulation around the oven pan is right by my hand, that is very different from both the cylinder examples and the house example. With the mostly uninsulated pan, you have many relatively unimpeded avenues for energy to escape, so it is not so motivated to escape in the direction of my hand.

        A third and more minor point, you again did not account for increased surface area, nor for time to reach equilibrium (which of course it won’t do anyway, while it is hotter than the surrounding air, because it doesn’t have its own heat source.)


      • iceskaterfinland

        I understand the point about an internal heat source without thermostat unlike the 200C oven or the domestic hot water tank i illustrated before being aware of that point.

        An unregulated constant heat source and a thermostatically controlled one is of course a very different scenario.

        However an insulated house heated internally with a thermostat has a much lower outside temperature than a heated one. Snow does not melt from my window sills or from the walls in a remarkeable manner. The top layer of insulation in the roof shows no detectable wamth even if you put the thermometer under a piece of wood on top of the insulation. In a house with poor insulation it would feel warm in the roof as soon as you went inside

      • Richard T. Fowler

        If you measure no difference in temperature, with a sufficiently precise thermometer, between the outside of your roof and the inside between roof and insulation, then that means your roof is a perfect conductor.

        You have an interesting roof.


      • Richard T. Fowler

        (“Perfect” to the limit of precision, I mean.)


      • iceskaterfinland

        You misunderstood me.

        If you go into a roof space with no ceiling insulation when it is cold, you immediately feel the heat coming from the ceiling. The ceiling will only be about half an inch of plasterboard for many houses.

        In my situation I feel no heat at all in the roof space when it is -14C and that surprised me. When i left a thermometer under a piece of wood over the *top* of the insulation there was absolutely no difference between the air temperture and next to the insulation under that wood even when i left it there for hours. Get it now?

  6. claesjohnson

    You can cook up as many examples you like, but you miss the point: The inside temp increases with better insulation and constant heat source. The outside temp is fixed because outside is big while inside is small.

    • iceskaterfinland

      Claes, I was aware of that when i mentioned the 200C oven glove.

  7. iceskaterfinland

    Anyway the issue here is that if green house gases increase then we both agree the atmosphere gets warmer as the earth gets warmer

    You have already said you dont object to the Engineering radiation heat loss/cooling rates of cooling from warmer to colder. If the colder gas becomes more absorbant, it becomes warmer and so does the surface because the surface cools more slowly to a warmer atmosphere.

    • Richard T. Fowler

      So, are you prepared to admit that Claes’ theory of blackbody radiation may be valid?


      • iceskaterfinland

        I am not in a position to say anything is impossible. It will be interesting to read what he says about thermal cameras

      • Tor

        That would be a mistake becaose it seems as if Claes Johnson’s theory of one way transfer violates the second law of thermodynamics according to a calculation by Planck.

  8. iceskaterfinland

    However i am still wondering why he wont answer Roy Spencers point about his theory and the existing theory perhaps having the same result for green house gases. Roy seemed to think it made no difference.

  9. Richard T. Fowler

    Have you read Computational Blackbody Radiation?

    Because from what I can tell, Roy gives no indication of having read and understood it. So I’m really not too concerned with what he says. The theories are functionally very different, so how can they be reasonably supposed to give identical results in all scenarios? That just doesn’t make sense to me. I don’t understand how people can say things like that. The theories would perhaps have the same result? That’s like saying two car crashes involving A) two SUV’s and B) an SUV and a dirigible “perhaps” might have the same result — therefore, we should believe that they would. Do you believe that is a reasonable position? It is a scentifically valid position?

    Regarding thermal cameras, I can still refer you to his definitive page about this, if you haven’t been able to find it.


    • iceskaterfinland

      Claes said he has no problem with the engineers heat loss curves. So if Claes wants to say his theory adds more than might be obvious then why not say so? Evidently you guys are talking about a total mind shift so why not make it easier for people to follow what you are thinking?

      Roy observed that Claes must agree a greenhouse effect of some sort must be operating.

      So why respond like this?:

      “How could I possibly object to the statement that something like the “greenhouse effect” does exist? Are we talking science or not?

      Can I deny that “something like “creation” does exist”? If not, am I then a creationist?”

    • iceskaterfinland

      please do refer me to the thermal camera page. I have spent ages looking for it.

  10. iceskaterfinland

    Another aspect of the person under the blanket is that while the heat source is constant quite a bit of heat is lost via breathing in cold air and expelling a much higher energy containing warm *moist* air that contains not just warmed air but also the latent heat of evaporation of water. As the person becomes hotter, after becoming confortable, they will lose more heat via their breathing since this is **primarily** how they are regulating their reasonably constant core body temperature.

    Therefore, if the body temperature remains approximately the same, and does not just keep rising due to a trapped source of heat, because the person breathes quicker to maintain their normal body temperature, adding more blankets makes the outer surface of the blankets colder.

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