2011-01-28 09:24:45Jet Stream Impacts?
John Hartz
John Hartz
john.hartz@hotmail...
98.122.68.19

Here's a question posed to me today on a comment thread.

2. Please detail how CO2, in it's present concentration, can align it's molecules in such a way to reflect significant energy radiated from the earth back in one direction toward the earth and be responsible for the amount of Global Warming attributed to it. Do consider the Jet Stream in your estimates.

I do not recall ever seeing the "jet stream" mentioned in any of the articles and books about climate science that I have perused. What relevance or irrelevance does it have?

BTW, I advised the questioner to read Chapters 3 and 7 of "Global Warming: The Hard Science" by L.D. Danny Harvey, Person Education Limited, 2000.

2011-01-28 14:22:24
citizenschallenge
Peter Miesler
citizenschallenge7@gmail...
166.164.191.149

Isn't that apples and oranges?

CO2 influences the atmosphere's thermo properties,

and the jet stream circulates the atmosphere...

 

just a thought

2011-01-28 14:26:10
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
130.36.27.153

As for jet stream shifts:

http://climatechangepsychology.blogspot.com/2009/04/c-archer-k-caldeira-jet-streams-are.html

 


This may be related: 

 Specific Prediction                                          Predicted by                                                     Confirmed by

Storm tracks move polewardTrenberth and Stepaniak 2003Yin 2005

Source

2011-01-28 16:29:33Some questions
John Hartz
John Hartz
john.hartz@hotmail...
98.122.68.19

I believe that my anti-AGW blogger was inferring that the CO2 in the atomosphere could not be reflecting energy back to Earth if it was wisking around the world in a jet stream. The guy repeatedly uses the "it's only common sense" refrain.

For my edification, how does the greenhouse effect vary by altitute in a column of atmosphere? At what altitude does it become negligible?

Are the above questions directly answered in one or  more rebuttals? If so, which?

2011-01-28 20:35:38
nealjking

nealjking@gmail...
84.151.50.53

Badgersouth:

- The jetstream has no relevance to the greenhouse effect.

- The greenhouse effect (GHE) is an end-to-end result: it has to do with the difference in temperature between the top and the bottom of the troposphere.

It is not the case that upwardly headed photons are directly reflected downward: throughout the atmosphere, infrared photons are absorbed from all directions and emitted in all directions. If you could see only with IR radiation, floating in the atmosphere would be like being lost in an immense foggy cloud, dense but faintly glowing: the glow would come from the photons emitted by the greenhouse gases. The ultimate source of these IR photons is the warm surface of the Earth, but you won't see that: you will only see the photons that are emitted in your immediate neighborhood. Now, what determines the intensity of the glow in your neighborhood is the temperature of the local "fog": the warmer the fog, the brighter the glow. Closer to the ground, the fog is warmer and the intensity is higher; higher in the atmosphere, the fog is cooler and the intensity is lower. At the edge of the fog, the top of the troposphere, it is coolest of all; and this is the point at which the IR photons can actually escape the fog entirely.

It is the temperature, and thus the glow intensity, at the top of the troposphere that determines how much IR power is escaping the Earth's atmosphere. The cooler the top of the troposphere, the less the glow, and the less power is escaping.

When additional amounts of greenhouse gases are added to the atmosphere, they are mixed into the cloud, which becomes a little denser.  This has the effect of expanding the overall extent of the global cloud, so the edge of the cloud moves up and out. But since the temperature of the "fog" depends on altitude (for reasons that have to do with gas dynamics), when the edge of the cloud moves up, the temperature of the edge of the cloud is reduced; so the glow at that critical boundary is reduced, and the escaping radiative power is reduced.

Thus, the impact of adding greenhouse gases is to reduce the amount of power radiated from the Earth. Since this does not change the radiative power impinging on the Earth (which is mostly due to visible light and is not affected by the "cloud"), an imbalance arises between the unchanged incoming radiative power and the reduced outgoing radiative power: this results in a warming. If there is no further change in the amount of greenhouse gases, the warming will continue until the temperature rises throughout the atmosphere and the temperature at the very top is increased to the level it had before the extra "dollop" of GHG had been tossed in.

So it is not appropriate really to think of the IR photons as being reflected back specifically, because they are scattered in all directions. It is probably better to think about it as analogous to adding an extra layer of blanket; but this analogy should not be pushed too far either. The real explanation is in the mathematics of radiative heat transfer, which I have tried to illustrate with the observations in a foggy cloud.

I think Riccardo did a posting or a rebuttal which did a good job laying out a more detailed picture of the GHE.

Does this clarify your question?

2011-01-29 02:23:55@nealjkng
John Hartz
John Hartz
john.hartz@hotmail...
98.122.68.19

 

Your explanation is one of the best narratives on this topic that I have raed. I would like to see it transformed into a blog post for SkS, perhaps under the heading, "The Greenhouse Effect Blanket." 

As I have recommended on prior occaisons, I believe that John Cook should create a new section of SkS titled, "Climate Change 101." Your blog would be one of the key modules for that section.

BTW, have you developed any graphics to accompany your narrative?

2011-01-29 03:13:14
nealjking

nealjking@gmail...
84.151.50.53

I'm glad you find it useful. As I mentioned before, I think Riccardo also had a good discussion somewhere; and just recently I noticed someone else trying to develop a "narrative" somewhere on-site. It might be useful to put them side by side, to see what aspects could be selected for the best story. (There was also a version developed for the question of the applicability of the 2nd law of thermodynamics: but I didn't like that narrative.)

I have no graphics for this.

I will probably not want to get into anything too active for a couple of weeks, due to personal priorities of some weight. But maybe it would be useful if you were to spearhead this by locating the related narratives so we could put together a team of GHE explainers. This is really a key topic, and it's definitely the single hardest concept in global warming. It's notable that the very useful history of global warming by Weart ("The Discovery of Global Warming") skips the topic completely: He just says it's too hard to cover well, despite the fact that he himself has, I believe, a very good understanding of this.

This is also a situation where we would definitely need a more mathematical and a less mathematical version. For people that can digest the math, the more mathematical version is going to be easier to follow!

Probably it would be useful to do this slowly and systematically. At the moment, the pressure is on the specific critiques of the leading deniers, Monckton and the rest; and this seems appropriate.

 

2011-01-29 03:19:33@nealjkng
John Hartz
John Hartz
john.hartz@hotmail...
98.122.68.19
I will follow-up by by locating the related narratives that have been posted on SkS. Should I post the list on this thread or create a new one? 
2011-01-29 03:26:21
nealjking

nealjking@gmail...
84.151.50.53

Recommend a new one, appropriately labeled: "towards a clear narrative for the GHE" or something like that.

If you want to start a project, I would put it in the general "Authors" folder.