RollingThunder
Gold Member
- Mar 22, 2010
- 4,818
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That's your insanity and apparently your delusional mechanism for avoiding coping with reality. Scientists are quite clear about the reality of the greenhouse effect and the physics involved. You're just far too ignorant about science and far too stupid to realize that.Yes, Kooky, we fully realize that China is your ideal environment.
AGW has been proven beyond a reasonable doubt. The consequences are being felt as we post. No amount of inane cartoons are going to change reality.
AGW has not been proven at all. AGW is one assumption upon another assumption upon another. How does a trace gas that has no mechanism by which to trap or retain heat warm the planet.
Ask one of your priests. You have all your cut and pastes lined up, bring one here that describes the mechanism by which it happens and describes the laws of physics that predict it.
My bet is that you will find no such writings in your religious texts because to discuss topics like that is to see your hypotheses fail.
LOLOLOLOL....OK, kiddo, here you go....not that I really expect you to understand it....at least, not without your head exploding like the Martians in "Mars Attacks".
The Greenhouse Effect & Greenhouse Gases
Brought to you by the National Earth Science Teachers Association
Greenhouse Gases
Although Earth's atmosphere is 90% opaque to long wave IR radiation, the vast majority of the atmosphere is not composed of gases that cause the greenhouse effect. Molecular nitrogen (N2) and oxygen (O2) make up roughly 98% of our atmosphere, and neither is a greenhouse gas. So, although the greenhouse effect is very powerful, a very small fraction of Earth's atmospheric gases generate the effect.
What are the main greenhouse gases? Because of all the press coverage it has received in recent years, you may think that carbon dioxide (CO2) is "the big one". Though CO2's role is important, water vapor is actually the dominant greenhouse gas in Earth's atmosphere. Water vapor generates more greenhouse effect on our planet than does any other single gas. Water, in gaseous form (as water vapor) and in liquid form (as tiny droplets in clouds), generates somewhere between 66% and 85% of the greenhouse effect. We'll get back to the issue of the large range that "66% to 85%" represents in a minute; it turns out that separating the impact of individual greenhouse gases is not a simple matter.
After water vapor, what are the most important greenhouse gases? In rough order of importance and size of effect, the major ones are carbon dioxide (CO2), methane (CH4) and ozone (O3). There are a number of other gases that contribute to the greenhouse effect to a lesser extent; we'll mention these here in passing for reference, but not consider them further henceforth. These "lesser greenhouse gases" include nitrous oxide (N2O), sulfur hexafluoride (SF6), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and chlorofluorocarbons (CFCs).


Representations of two important greenhouse gas molecules: carbon dioxide (CO2) and methane (CH4).
Credit: Original artwork by Windows to the Universe Staff (Randy Russell).
How do greenhouse gases (GHGs) "work"? These molecules are capable of absorbing passing infrared photons; the energy of the photon is converted into an excited vibrational state of the GHG molecule. Recall that just as visible light has a range of wavelengths with different energies (that we see as colors!), so too the infrared spectrum spans a range of wavelengths with different energies. The various types of GHGs absorb different wavelength IR photons. In fact, the molecules often have more than one vibrational mode that allows them to absorb IR photons of more than one wavelength. This complicates matters when it comes to determining how much of the greenhouse effect each gas produces.
Here's an example. Water vapor absorbs IR photons with wavelengths of 790 nanometers, 940 nm, and 1,375 NM (and at several other wavelengths, too!). Carbon dioxide also absorbs IR photons with wavelengths around 1,375 NM (as well as at several other wavelengths). So it is difficult to say how much of the 1,375 NM IR radiation is absorbed by water vapor and how much is absorbed by CO2. This brings us back to the "66% to 85%" range of greenhouse effect that is caused by water.
Atmospheric scientists cannot definitively say, based on direct experiments, exactly how much greenhouse effect is caused by each GHG. They cannot simply remove one gas and see how the absorption of IR photons changes. Instead, they must use models of the atmosphere to predict the likely changes. So, they run their models with one GHG removed; say, for instance, water vapor. They might find that this results in a 36% reduction in the greenhouse effect. Note, however, that the absorption of 1,375 NM IR photons by CO2 would increase in this scenario; the CO2 need no longer "compete" for these photons with the water vapor. In essence, the 36% reduction in greenhouse effect computed by this method is a minimum; the impact on the total greenhouse effect from water vapor is actually larger. The end result is that there are rather larger ranges of values associated with the possible contributions of the various GHGs to the total greenhouse effect.
So, given all this, what are those ranges? The table below summarizes the contributions of each of the major GHGs to the overall greenhouse effect. Note that, due to the aforementioned complications, the percentages don't add up nicely to 100%.
Major Greenhouse Gas _____% of Greenhouse Effect
Water vapor _________________36% to 66%
Water vapor & Cloud droplets ___66% to 85%
Carbon dioxide _______________9% to 26%
Methane ____________________4% to 9%
Ozone ______________________3% to 7%
How do greenhouse gases "work"?
Carbon dioxide molecule vibration modes

Vibration modes of carbon dioxide. Mode (a) is symmetric and results in no net displacement of the molecule's "center of charge", and is therefore not associated with the absorption of IR radiation. Modes (b) and (c) do displace the "center of charge", creating a "dipole moment", and therefore are modes that result from EM radiation absorption, and are thus responsible for making CO2 a greenhouse gas.
Credit: Martin C. Doege
If you are up on your chemistry, you may have noticed that all of the greenhouse gas molecules have three or more atoms. Molecular nitrogen (N2) and molecular oxygen (O2), the two most abundant gases in our atmosphere, each have only two atoms per molecule, and are not greenhouse gases. This is not a coincidence. As was mentioned earlier, GHG molecules are capable of absorbing passing infrared photons; the energy of the photon is converted into an excited vibrational state of the GHG molecule. So why don't nitrogen and oxygen molecules absorb infrared photons?
Photons, including infrared photons, are of course a form of electromagnetic radiation. As such, they can also be understood as disturbances, or waves, of electromagnetic energy. Atoms, and the molecules they combine to form, have electrically charged particles (electrons and protons) in them. The gas molecules we are currently considering, nitrogen and oxygen and the various GHGs, have no net charge; they have equal numbers of electrons and protons. However, molecules that are on average neutral (in terms of their electrical charge) can still have localized charges, either some of the time (when they are vibrating) or all of the time. For example, surface tension in water is caused by the tendency of water molecules to stick together because the electrons that the oxygen and hydrogen atoms share are not shared equally. The shared electrons spend more time closer to the oxygen atom's nucleus, which has more protons and thus pulls on the electrons more strongly. The portion of each water molecule that is near the oxygen atom has a negative charge (excess electrons), while the areas around the two hydrogen atoms have positive charges (fewer electrons to offset the protons). Water molecules have localized areas of positive and negative charges, so individual water molecules tend to "stick" to one another (the positive hydrogen segments being attracted to the negative oxygen portion).
Molecules are not, however, rigid ball and stick figures as our chemistry class models may lead us to believe. Molecules are in motion; continuously bouncing around and jiggling and vibrating. Consider first a diatomic nitrogen (N2) or oxygen (O2) molecule. A pair of balls attached by a spring is a good model of such a molecule. Pull the balls apart and release them; they alternately move closer together and further apart. This vibrational mode is extremely symmetric, however; the center of mass of the system always remains at the point midway between the two balls/atoms. Electromagnetic "disturbances" (waves) do not tend to interact with, or transfer energy to, such diatomic molecules (such as N2 or O2).
Molecules with three or more atoms, however, are a different story. The figure (above, right) shows three different vibrational modes of a carbon dioxide (CO2) molecule. The first mode, (a), is symmetric; it is comparable to the vibrational mode of diatomic molecules. The center of mass, and of charge, of the system is not displaced during vibration. However, such is not the case for the other two modes, (b) and (c). In the latter two cases, the "center of charge" moves as the molecule vibrates, creating a "dipole moment". As explained for the the case of water above, electrons are not shared equally between the atoms in the CO2 molecule, so the molecule is not electrically neutral in all places. As the molecule oscillates, the center of charge moves; from side to side in case (b), and up and down in case (c). A passing electromagnetic "disturbance" (wave, or IR photon) can "excite" such a molecule, causing it to vibrate and transferring energy from the photon to the molecule. This is the mechanism by which greenhouse gases absorb energy from infrared photons.
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