Friday, December 11, 2009

Greenhouse Effect – Criticism?!

I always criticized the theory of global warming on grounds that left the basic physical science out of the question. I accepted the fact of the greenhouse theory, as it was handed down to us by Arrhenius, upon whose experiments most of this theory builds.

However, the more I actually dwell into the basic foundations, the more I get concerned that 100 year old experiments are believed instead of tested. I was first alerted, when physicist Gerlich et al came up with a strong criticism. In light of the recent scandal over the leaked e-mails, I am even more inclined to give them some credit. Now, I just procured a note by R.W. Wood, who investigated the idea of Infra-red trapping of heat in green houses, and I must say I am inclined to follow his criticism of Arrhenius greenhouse observation.

Now, let’s start at the beginning. The greenhouse theory, albeit it varys from scientist to scientist in the details, is this. You have a hous with glass panels as walls and ceiling. On a bright day the sun shines into this house and warms it. The question is, why does it warm. Greenhouse theory postulates that the warming is due to the trapping of radiated heat inside the green house. The glass panel serves as the atmosphere in this model. They absorb the re-emitted long waves from the ground and re-emit them into the greenhouse, thus trapping the IR-spectrum of light and increasing warming.

Now, this sounds ok, but the question is, are there alternative mechanisms that could also cause the warming and how do we distinguish the degree of warming.

And yes, there is one alternative explanation and that is convection. The air on the ground heats due to the warmer ground and thus changes partial pressure in the greenhouse. The warm air with the bigger volume rises, but is trapped by the walls and ceiling, thus the greenhouse gets warmer, but due to convection and not due to IR radiation trapping.

R.W. Wood now tried to compare the two effects. He designed two greenhouses, one with a glass surrounding and one with non-absorbing surrounding as to let all light specrtums pass. If the IR-trapping is a forceful indication of climate inside the greenhouse, than the difference in temperature should be big. If however, it is convection that drives the climate, then we should see only a small difference in temperature due to extra wavelengths that can pass.

The difference was small and so he concluded that the greenhouse effect is non-existent.

Now, this mustn’t be seen as ultimate prove. After all, with a huge volume of air in the earth atmosphere and a pretty constant base average temperature of 15 °C, a change in greenhouse gases could well be responsible for a small added warming due to IR trappings, but we can’t prove it! We are talking about a supposed IR-trapping force of 0.03 Vol% in the air and about one minor GHG amongst more potent ones like Methane, Water Vapour etc.

Why do we assume that the smallest part has the highest influence on a matter that has been proven to have an unmeasurable influence.

It’s worth, the theory used to connect the analogy of the greenhouse to the Earth climate is pretty weak, because there are no physical equations available that could be used to explain it.

Also, Gerlich et. al. prove that there is a basic mathematical error involved when using Black Body theory. They actually averaged temperatures BEFORE using the fourth square! Everyone knows that you average a value after you have calculated it, not beforehand. The error in these two averages due to their difference is not to be underestimated.

All in all, I am unsure what to make of it. W.M. Conolley replied to this:

“Second, although the troposphere is subject to convection, the stratosphere is not.

Third, in contradiction to his assertion about "the very low radiating power of a gas", the troposphere is largely opaque to infra-red radiation, which is why convection is so important in moving heat up from the surface. Only in the higher (colder) atmosphere where there is less water vapour is the atmosphere simultaneously somewhat, but not totally, transparent to infra-red and thus permits radiation to play a part. “

He is right that the stratosphere is actually a cold place and is the so-called “ceiling” of the greenhouse. Though actually, the higher you go the warmer it gets, because the stratosphere absorbs UV-light (OZONELAYER?!)

And again, the stratosphere is not subject to convection, because it is more akin to the “glass pannel” than to the actuall greenhouse interior. And like the glass of the “greenhouse” it’s colder than the rest, which is though only an anecdotal point.

BUt largely his comment only strengthens the argument, because he himself agrees that Radiation does not play a part in the troposphere! He says that there is radiation between the higher atmospheres (like Mesosphere, Stratosphere) but not passing through the troposphere. He even says that convection is a necessity and thus proves Wood’s point that radiation plays at most a small part in it.

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