söndag 9 oktober 2011

Fiction of Downwelling Longwave Radiation DLR

Pictures of DLR. Because the pictures are real, also DLR must have physical reality, right?

In previous posts, in particular in How to Fool Yourself with a Pyrgeometer I have given evidence that Downwelling Longwave Radiation (DLR), which serves an important role in CO2 climate alarmism, is a fictitious phenomenon without physical reality.

So what is the truth? Is DLR reality or fiction? Is CO2 alarm reality or fiction?

Let us scrutinize the evidence put forward for the reality of DLR with an illustration from recent communication with Prof Grant W. Petty, who states:
  1. We routinely MEASURE it using any of a variety of commercially available instruments (do a search on 'Eppley pyrgeometer', for example;
  2. We routinely and accurately PREDICT its magnitude based solely on knowledge of the temperature, humidity, and cloud structure of the atmospheric column (as exemplified, for example, by a class project I and 15 other students had to complete as first-year graduate students, in which our fairly simple (<200 lines of code) model calculations yield results within a 1-2 W/m^2 of the MEASURED IR flux value for a MEASURED atmospheric profile);
  3. Both Planck's Law and the Stefan-Boltzman Law (the latter is just an integration of the former over wavelength) have been known for generations to accurately predict EMISSION (one-way) from a blackbody. Nothing in either formulation requires one to know the temperature of the body (if any) RECEIVING the radiation. And Planck's Law was itself derived via thermodynamic arguments by a guy who understood the 2nd Law extremely well.
Prof Petty here refers to a Stefan-Boltzmann Law of the form (with sigma SB's constant)
  • R = sigma T^4 - sigma T_b^4 = R_out - R_in,
where R is the radiance from a black body of temperature T into a background of temperature T_b. Petty believes that there is a two-way flow of energy represented by R_out = sigma T^4 and R_in = sigma T_b^4, and that Stefan-Boltzmann's law expresses the net flow R = R_out -R_in as the difference between R_out and R_in.

Prof Petty gives even more weight to his SB law by stating:
  • It is settled science and has been for more than a century.
But Prof Petty is fooling himself and the society. His SB law does not appear in the physics literature. The original SB law has the form
  • E = sigma T^4
under the assumption that the background is at 0 K. This form of SB follows by integration of Planck's law, which is proved in the case of radiation into a background at 0 K.

But there is no proof of Prof Petty's SB law in the literature. Prof Petty's SB law is a free invention outside physics and as such of no scientific significance, a free invention which is used to fool people about the existence of DLR by claiming that it is measured with a pyrgeometer and hence must exist. But what a pyrgeometer effectively measures is temperature and the translation to radiance is done by a SB law without scientific justification.

I have asked Prof Petty abut the original scientific source of his SB Law. I have not received any answer.

Note that what can be proved in the case of a background T_b > 0 is the following SB law
  • R = sigma (T^4 - T_b^4)
with only the net radiance R and not R_in and R_out. Prof Petty would now argue that this law trivially can be written on his form, simply by trivially splitting the right hand side as follows:
  • sigma (T^4 - T_b^4) = sigma T^4 - sigma T_b^4 = R_out - R_in.
But this is fooling yourself by believing that a certain algebraic operation directly translates to physical reality.

As a defense Prof Petty would probably argue that the only thing that matters in the end is the net flow, and that the net flow anyway is the same in both forms of the SB law, and thus that it does not really matter if DLR is reality or fiction. From scientific point of view this argument has an obvious weakness. From political point of view it may not matter if CO2 alarm is reality or fiction, but from scientific point of view it cannot be without importance.

I have asked Prof Petty about a reaction, and will report if I get any.

4 kommentarer:

  1. I've observed and measured downward long wave radiation from the atmosphere myself too. To deny that it exists is literally insane. To try to deny that it exists by using equations is even worse. You could try to mathematically prove that the Sun doesn't exist as well, I suppose, but no amount of badly formatted equations will make it disappear.

  2. The Sun exists yes, because its effects can be directly experienced, but DLR is constructed by the pyrgeometer by a mathematical law without reality.
    What the pyrgeometer experiences is the difference in temperature between itself and the radiating source which directly connects to net radiance, but not to DLR as R_in. Thus your pyrgeometer uses precisely what you hate the most, a mathematical equation. Think of this.

  3. Downward radiation from the atmosphere is a physical fact. You can use all sorts of instruments to detect it. As I say, it is literally insane to deny its existence, every bit as literally insane as if you were to claim that the sun doesn't exist.

  4. Read my above comment and think.