Tuesday, January 04, 2011

What effect

So John Nielsen-Gammon has been trying to explain the greenhouse effect and climate disruption, and not doing a bad job, but Eli has some problems with his trying to rename the greenhouse effect the Tyndall gas effect. Now Eli has some problems with the general idea that "the greenhouse effect is nothing like a greenhouse, basically that both work by restricting the flow of heat out of the system, one by restricting radiation, the other by restricting convection. Of course the details differ, but that is the difference between an analogy and a detailed description. However, as the saying goes, that has nothing to do with this case, which arises from John's invoking Tyndall.

Now true, Tyndall was the first to describe infrared absorption, but a) he already has his effect and b) IEHO the greenhouse effect has more to do with IR radiation, which raised a simple question, who was the first to observe radiation in the infrared from the atmosphere? Eli has asked a few people, and the general answer is good question, don't know. So here is your chance.

11 comments:

Chad said...

From The Discovery of Global Warming,

Beginning with work by Joseph Fourier in the 1820s, scientists had understood that gases in the atmosphere might trap the heat received from the Sun. As Fourier put it, energy in the form of visible light from the Sun easily penetrates the atmosphere to reach the surface and heat it up, but heat cannot so easily escape back into space. For the air absorbs invisible heat rays (“infrared radiation”) rising from the surface. The warmed air radiates some of the energy back down to the surface, helping it stay warm. This was the effect that would later be called, by an inaccurate analogy, the "greenhouse effect." The equations and data available to 19th-century scientists were far too poor to allow an accurate calculation. Yet the physics was straightforward enough to show that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is.

Tyndall set out to find whether there was in fact any gas in the atmosphere that could trap heat rays.


Perhaps it should be called the "Fourier effect" or something like that.

Sou said...

I found this timeline from Google. Don't know how accurate it is and it is an astronomy site. It indicates key players in detecting infrared absorption as William Herschel in 1800 and, in particular, Charles Piazzi Smyth in 1856.

http://www.daviddarling.info/encyclopedia/I/infrared_astronomy.html

Timothy Chase said...

For what it is worth, Tyndall was the first historical figure I added to my webpage. In the bit on Tyndall I link a page that the National Science Digital Library has on their wiki that includes a pdf of Tyndall's "On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connection of Radiation, Absorption, and Conduction" from 1861. At one point Tyndall states in his essay, "It is exceedingly probable that the absorption of the solar rays by the atmosphere, as established by M. Pouillet, is mainly due to the watery vapour contained in the air." (pg. 276) My guess is that it is this Claude Pouillet fellow -- who measured the absorption of solar radiation by the atmosphere.

Claude's analysis was somewhat flawed as it employed Lambert's law to a spectrum whereas Lambert's law is specifically applicable to monochromatic light. Nevertheless his results were relatively accurate. Within 10% of the modern figure.

Please see:

John Charles Drury Brand, Lines of light: the sources of dispersive spectroscopy, 1800-1930 (CRC Press, 1995), pp.84-5

Timothy Chase said...

Correction: I thought you meant absorption of infrared in the atmosphere. But you mean observed infrared in the atmosphere? Like Sou, I would be inclined towards Herschel.

Please see:

"Figure 5.2 The near-infrared solar spectrum, measured by Herschel (1840) (a) and Lamansky (1872)..."

John Charles Drury Brand, Lines of light: the sources of dispersive spectroscopy, 1800-1930 (CRC Press, 1995), pp.83

Neven said...

"Fourier correctly deduced that a planet loses heat almost exclusively by infrared radiation (“chaleur obscure”or ‘dark heat’) and can do so in a vacuum. Infrared had been discovered by Frederick Herschel only 25 years earlier, and the study of its properties occupied much of the attention of nineteenth-century physicists, including Fourier himself."

Raymond T. Pierrehumbert

EliRabett said...

The answer is Anders K. Angstrom. Eli will be posting massively on this tonight

Wiley Coyote said...

Dear Mr. Dr. Professor Rabbit,

I do not wish to come off sounding like an expert on historical photographs, which I most certainly am not, but it appears to me that the gentleman in the picture may be missing a pitchfork.

Sincerely,
Wiley

Jim Bouldin said...

"Now Eli has some problems with the general idea that "the greenhouse effect is nothing like a greenhouse", basically that both work by restricting the flow of heat out of the system, one by restricting radiation, the other by restricting convection."
______________________________

Greenhouses, particularly production greenhouses, restrict both, because they have elevated CO2 concentrations and typically high humidities. There IS a radiation element to it--although admittedly this fact is not the basis for the origin of the "greenhouse" analogy as applied to the atmosphere.

I have to say also, that I'm perplexed by the phrasing of your question. What exactly do you mean by "observed". When the ancients noticed it was warmer at night with cloud cover present, than when it was absent, doesn't that qualify?

Timothy Chase said...

Eli wrote, "The answer is Anders K. Angstrom. Eli will be posting massively on this tonight."

From the above essay itself:

"... who was the first to observe radiation in the infrared from the atmosphere?"

Now I get it.

Not the observation of the absorption of infrared by the atmosphere nor the the observation of infrared through the atmosphere, but the observation of infrared from the atmosphere -- in the sense of being specifically emitted by the atmosphere as thermal radiation. The backradiation.

I still wouldn't have known the answer -- but woulda stood a better chance of finding it. Jeez, I've gotta work on my reading skills!

Jim Bouldin said...

Wait a minute here. Glass is opaque to thermal infrared and transparent to visible, just like GHGs. In addition to the GHG effects inside the greenhouse that I mentioned, this means that there is nothing at all wrong with the greenhouse analogy. It's nearly perfect in fact. John N-G is misguided on this.

EliRabett said...

Well yes, but go talk to John, see also comments by Ray P in the partner post