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Post by sigurdur on Nov 29, 2009 0:59:38 GMT
There are cyclical cycles of CO2 domes over cities where concentrations exceed 600 ppm, yet they do not exhibit any warming relative to those domes. Why is that? I got it......that is the urban heat island effect! Damn....upon rational thinking that was an easy one!
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Post by nautonnier on Nov 29, 2009 13:05:06 GMT
This could lead to a simple experiment - go downwind of a large CO2 source - the best source looks like volcanic activity from the NOAA graphics but obviously they must be wrong.
Then set up an experiment well clear of any heating effects from the volcano urban heat island but downwind of the volcano city so the wind is carrying the CO2 over the experiment then it should be possible to identify all the 'downwelling IR' that should vary exponentially with the concentration of CO2
As the effect of CO2 concentration is far more apparent below 18000ft or so the result should be well outside the background noise.
One wonders why this has not been done.
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Post by steve on Nov 29, 2009 13:14:49 GMT
There are cyclical cycles of CO2 domes over cities where concentrations exceed 600 ppm, yet they do not exhibit any warming relative to those domes. Why is that? If you took time to understand a little bit of the science, the answer should be obvious. There are two things to consider: The normal amount of radiation at the surface of the earth is measured in hundreds of watts per metre squared Doubling CO2 from 280-560ppm increases the radiation, on average, by about 4W/m^2. That is not a large amount, and would not be noticeable. The second thing is to check how high these "domes" are. The important level in the atmosphere for the enhanced greenhouse effect is 4-6km up. I suspect the 600ppm measurements are lower than this, and by the time you get 4-6km up, the CO2 has dissipated over a wider area. In other words, the 4W calculation applies if the CO2 is uniformally distributed in all levels of the atmosphere. If the CO2 is disproportionately in the lower levels, it won't have much effect as absorption of the relevant spectral regions is high.
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Post by nautonnier on Nov 29, 2009 13:52:01 GMT
There are cyclical cycles of CO2 domes over cities where concentrations exceed 600 ppm, yet they do not exhibit any warming relative to those domes. Why is that? If you took time to understand a little bit of the science, the answer should be obvious. There are two things to consider: The normal amount of radiation at the surface of the earth is measured in hundreds of watts per metre squared Doubling CO2 from 280-560ppm increases the radiation, on average, by about 4W/m^2. That is not a large amount, and would not be noticeable. The second thing is to check how high these "domes" are. The important level in the atmosphere for the enhanced greenhouse effect is 4-6km up. I suspect the 600ppm measurements are lower than this, and by the time you get 4-6km up, the CO2 has dissipated over a wider area. In other words, the 4W calculation applies if the CO2 is uniformally distributed in all levels of the atmosphere. If the CO2 is disproportionately in the lower levels, it won't have much effect as absorption of the relevant spectral regions is high. "The normal amount of radiation at the surface of the earth is measured in hundreds of watts per metre squared"Steve I presume you mean the normal amount REACHING the surface of the Earth? During the day you would be right At NIGHT the only radiation downward to the surface will be from the 'downwelling' IR from water vapor and CO 2So given a dry cloudless night and a large plume of CO 2 this should be measurably different from outside the plume. "In other words, the 4W calculation applies if the CO2 is uniformally distributed in all levels of the atmosphere. If the CO2 is disproportionately in the lower levels, it won't have much effect as absorption of the relevant spectral regions is high"This is an interesting position to take. Logically one would have thought that a high say double concentration of CO 2 in the denser part of the atmosphere would have the most effect - indeed that is what is said in the papers that I have read. Do you have a reference that says GHG are 'more efficient' at scattering IR at lower concentrations in the atmosphere?
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Post by steve on Nov 29, 2009 14:10:22 GMT
On rethinking this, the second part of the answer is probably more relevant. The amount of radiation from the atmosphere as opposed to from the sun is going to be dominated by water vapour near the surface. I did once find a spectrum taken by a building designer looking at engineering aspects, and the comment was that it was difficult to distinguish the water vapour and CO2 emission features.
I didn't say that GHGs are more efficient at lower concentrations, it is that the relative importance of CO2 vs water vapour is higher. At 4-6km or above a) a reasonable proportion of the relevant radiation starts getting to space, and b) CO2 and other greenhouse gases start to be more important than water vapour (because of the lower level of water vapour).
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Post by sigurdur on Nov 29, 2009 17:19:33 GMT
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Post by spaceman on Nov 29, 2009 19:13:07 GMT
Steve wrote "Doubling CO2 from 280-560ppm increases the radiation, on average, by about 4W/m^2. That is not a large amount, and would not be noticeable"
So the temp would not be noticeable? On doubling co2? Do you understand what you are saying here. The temp should be through the roof according to AGW theory.
Now this thing with combining temps. Let's take a city that is 7,000 ft above sea level and the temp is 35 C, (colorado springs,co), are you saying that the real temp, adjusted of course should be around 50 C?
I am sure that there are many places that they could have examined to see if the temp really does rise when the amount of co2 rises. They didn't do that did they? What happened to the feedback? In your own words 'barely noticeable'? A doubling of co2 ? I thought for sure that someone with one of those GRANTS would have measured the amount of co2 off the coast of California and the variation in temp after one of those fires. Of course the air gets very hot anyway with the wind whipping through the valleys. So did all that co2 retain the heat as it pushed off into the Pacific? I would think that the amount of co2 would be a lot higher than just 600 ppm. A perfect opportunity to show how warm it can get with a big increase in co2. I wonder why they didn't do that?
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Post by spaceman on Nov 29, 2009 19:21:01 GMT
who lives at 20,000 ft Steve? And how would that affect temps at lower levels? And there should be co2 at those levels from a volcano, and it comes out very hot indeed. So how is this dome of co2 not important?
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Post by spaceman on Nov 29, 2009 19:26:29 GMT
by a building designer looking at engineering aspects, and the comment was that it was difficult to distinguish the water vapour and CO2 emission features.
Water vapour is around 10,000 to 11,000 ppm and co2 is at most (for round numbers ) 400ppm?
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Post by nautonnier on Nov 29, 2009 19:40:30 GMT
On rethinking this, the second part of the answer is probably more relevant. The amount of radiation from the atmosphere as opposed to from the sun is going to be dominated by water vapour near the surface. I did once find a spectrum taken by a building designer looking at engineering aspects, and the comment was that it was difficult to distinguish the water vapour and CO2 emission features. I didn't say that GHGs are more efficient at lower concentrations, it is that the relative importance of CO2 vs water vapour is higher. At 4-6km or above a) a reasonable proportion of the relevant radiation starts getting to space, and b) CO2 and other greenhouse gases start to be more important than water vapour (because of the lower level of water vapour). That was why I said a DRY area - perhaps I should have been more explicit and said an ARID area and one could wait for an anticyclone so that the air is even drier. That way there should be little water vapor to hide the extremely small ( ) amount of downwelling IR from the plume of CO 2. Surely a plume of CO 2 from the surface to say ~18,000ft raising the atmospheric concentration well above the double current levels if it is that effective should create IR downwelling that should be easily detected and quantified?
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Post by spaceman on Nov 29, 2009 19:54:54 GMT
I'm sure the air is pretty dry when it pushes off the coast of California after a fire. But, for the sake of argument, over land will do. Not like any volcanoes go off over land. There are fires out in Arizona too. I was just thinking how hot the air is in California and whether the co2 retains the heat.
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Post by donmartin on Nov 29, 2009 22:05:26 GMT
Mars probably has the same methane content in its atmosphere as Earth. The Mars atmosphere also is comprised of water vapour. Also, carbon dioxide comprises 95% of the Martian atmosphere. When linear analysis is provided, it indicates the Martian surface atmospheric temperature is at ratio 1.2 to that of Earth's surface atmospheric temperature.
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Post by socold on Nov 30, 2009 2:15:00 GMT
The area of the column would have to be very wide to prevent the column being rapidly broken by high altitude winds - perhaps 10s of kms in radius. It would also have to stretch very high into the troposphere for reasons already mentioned. I reckon just to maintain a column of that size at double co2 level would require rapid release of a few tens of million tons of co2.
Alternatively as the pressure and temperature profile of the atmosphere and absorption properties of co2 are known, we could do a combination of lab experiments and calculations to figure it out instead...
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Post by spaceman on Nov 30, 2009 4:58:41 GMT
One of the co2 concentration maps shows high co2 levels in the northwest part of the US. It looks like it is over a wide area. And I think in either Washington or Oregon, east of the mnts, it is fairly dry
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Post by steve on Nov 30, 2009 13:11:21 GMT
spaceman, Note the original context was CO2 enhanced over a local area. Any small amount of enhanced heating will be small compared to, say, differences in albedo and also to energy use within the urban area. by a building designer looking at engineering aspects, and the comment was that it was difficult to distinguish the water vapour and CO2 emission features. Water vapour is around 10,000 to 11,000 ppm and co2 is at most (for round numbers ) 400ppm? What is water vapour at 5km altitude? Do you really believe the constitution of the atmosphere at 5km cannot affect temperatures at the surface of the earth!
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