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Post by steve on Feb 27, 2009 9:24:03 GMT
Steve, you fail to understand both equilibrium & the quantum nature of energy. The CO2 molecules have the same average kinetic energy as the rest of the atmosphere. I have said that the IR energy absorbed by greenhouse gases is distributed to other molecules such that local thermodynamic equilibrium is reached. What's below is why I misunderstood what you were saying above. No this is wrong! Your book explains it by distinguishing CO2 "internal" energy from M "kinetic energy". M (say an O2 or N2 molecule) has kinetic energy. On collision its kinetic energy will *change* by the amount of the CO2 transition (excitation or deexcitation), but the kinetic energy of a molecule *is not quantised in the same way*. Ignoring GHGs for a moment, the distribution of kinetic energy among O2/N2 molecules will be a thermal distribution. Then introduce CO2 into the mix. The CO2 molecules are excited to CO2* by infrared. A large proportion of them then collide with O2/N2 molecules creating O2*/N2*. The * on the O2 and N2 molecules means is that the kinetic energy of these molecules is slightly higher, on average, than the kinetic energy of the other O2 and N2 molecules. What happens when some molecules are moving faster than average? They get slowed down by all the other molecules, much like a cue ball being hit into the pack. That is, these faster O2*/N2* molecules go on to collide with many other O2 and N2 molecules, and share their energy out. This process results in a slightly higher average kinetic energy once again governed by a thermal distribution. ie. a warmer gas. Yes, if it gets warmer, the CO2 molecules are also more likely to be excited to CO2*. But you don't specifically need an O2* molecule (ie. one that has recently interacted with a CO2* molecule). All you need is an O2 molecule with high enough kinetic energy. The thermal distribution will state what proportion of photons have enough energy. Overall, the balance is reached approx when the IR in at the surface balances out the IR out into space at the top of the atmosphere. CO2 is also responsible for emitting this radiation into space, so is responsible for "cooling the atmosphere". The problem is that as you add more CO2 then the responsibility for cooling the atmosphere goes to higher layers (as emission from the CO2 in the lower layers is now more likely to be absorbed before it gets to space.) But as the higher layers are cooler, there is less CO2* available even though there is more CO2 in total, which is what leads to the loss of energy balance and the warming of the planet. In the above CO2 is interchangeable for any greenhouse gas.
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Post by donmartin on Feb 28, 2009 0:13:57 GMT
I do not wish to sound critical, particularly in light of the fact I do not have the intellectual wherewithal to be so, never mind make positive contribution, but the more I study, the more aware I am of the assumptions being made: hold, collide, attract, excite, and so forth. So, I have one question, when two particles such as O2 and N2 ", both having magnetic fields, "collide," why is not all energy transferred from one molecule to the other? And why would they simply not repel or attract one another?
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Post by steve on Feb 28, 2009 15:23:40 GMT
I do not wish to sound critical, particularly in light of the fact I do not have the intellectual wherewithal to be so, never mind make positive contribution, but the more I study, the more aware I am of the assumptions being made: hold, collide, attract, excite, and so forth. So, I have one question, when two particles such as O2 and N2 ", both having magnetic fields, "collide," why is not all energy transferred from one molecule to the other? And why would they simply not repel or attract one another? At the temperatures we're talking about, a molecule can be approximated to be a particle. The velocities of the particles are very high (hundreds of metres per second) though they actually don't travel far per second because they are continuously colliding with other molecules. Collisions are elastic such that kinetic energy is conserved (except when a greenhouse gas molecule is exited or de-excited such that it changes it's internal energy state). So all the kinetic energy could be transferred from one molecule to another at a collision, but if you calculate the total kinetic energy of the two molecules before and after, the total is the same. Essentially the collisions are elastic because the molecules repel each other at short distances in the same way that two balls colliding would repel each other. Obviously real balls (pool balls or footballs) collide inelastically in that some energy is lost in the collision. These are all approximations to the quantum reality that is impossible to fully resolve. But they are good approximations.
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Post by nautonnier on Feb 28, 2009 20:55:41 GMT
Steve, you fail to understand both equilibrium & the quantum nature of energy. The CO2 molecules have the same average kinetic energy as the rest of the atmosphere. I have said that the IR energy absorbed by greenhouse gases is distributed to other molecules such that local thermodynamic equilibrium is reached. What's below is why I misunderstood what you were saying above. No this is wrong! Your book explains it by distinguishing CO2 "internal" energy from M "kinetic energy". M (say an O2 or N2 molecule) has kinetic energy. On collision its kinetic energy will *change* by the amount of the CO2 transition (excitation or deexcitation), but the kinetic energy of a molecule *is not quantised in the same way*. Ignoring GHGs for a moment, the distribution of kinetic energy among O2/N2 molecules will be a thermal distribution. Then introduce CO2 into the mix. The CO2 molecules are excited to CO2* by infrared. A large proportion of them then collide with O2/N2 molecules creating O2*/N2*. The * on the O2 and N2 molecules means is that the kinetic energy of these molecules is slightly higher, on average, than the kinetic energy of the other O2 and N2 molecules. What happens when some molecules are moving faster than average? They get slowed down by all the other molecules, much like a cue ball being hit into the pack. That is, these faster O2*/N2* molecules go on to collide with many other O2 and N2 molecules, and share their energy out. This process results in a slightly higher average kinetic energy once again governed by a thermal distribution. ie. a warmer gas. Yes, if it gets warmer, the CO2 molecules are also more likely to be excited to CO2*. But you don't specifically need an O2* molecule (ie. one that has recently interacted with a CO2* molecule). All you need is an O2 molecule with high enough kinetic energy. The thermal distribution will state what proportion of photons have enough energy. Overall, the balance is reached approx when the IR in at the surface balances out the IR out into space at the top of the atmosphere. CO2 is also responsible for emitting this radiation into space, so is responsible for "cooling the atmosphere". The problem is that as you add more CO2 then the responsibility for cooling the atmosphere goes to higher layers (as emission from the CO2 in the lower layers is now more likely to be absorbed before it gets to space.) But as the higher layers are cooler, there is less CO2* available even though there is more CO2 in total, which is what leads to the loss of energy balance and the warming of the planet. In the above CO2 is interchangeable for any greenhouse gas. Of course CO 2 only gets excited by IR in 3 bands making up around 8.5% of the IR spectrum so more than 90% of the IR passes straight by CO 2 without any effect. CO 2 has a very small radiative forcing effect. Also if any energy results in greater kinetic energy for molecules in the atmosphere - the density of that volume of gas lowers as it 'heats up' and it starts to rise transporting the heat upwards. It is convection that carries most of the heat to the tropopause.
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Post by socold on Mar 1, 2009 0:56:18 GMT
A lot of posts in this thread professing to explain how the climate works are essentially describing mini-climate models. They haven't been implemented or run but the promise is that these mini-climate models would show co2 doubling doesn't result in significant warming.
Well that doesn't make sense at all. If it is so easy to show co2 doubling doesn't cause significant warming by running the physics then how come noone has done it?
How can you claim these simplistic non-run climate models can be used to show co2 sensitivity is low while dismissing the results of the big in depth climate models that show co2 senstivity is high?
It's a glaring contradiction. If you are a skeptic then the only logical argument on the subject of climate modelling is that it can't tell us anything about co2 sensitivity.
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Post by poitsplace on Mar 1, 2009 2:37:34 GMT
A lot of posts in this thread professing to explain how the climate works are essentially describing mini-climate models. They haven't been implemented or run but the promise is that these mini-climate models would show co2 doubling doesn't result in significant warming. Well that doesn't make sense at all. If it is so easy to show co2 doubling doesn't cause significant warming by running the physics then how come noone has done it? How can you claim these simplistic non-run climate models can be used to show co2 sensitivity is low while dismissing the results of the big in depth climate models that show co2 senstivity is high? Ummm... (1) since we obviously don't have a working knowledge of climate the complex models are a waste of time... (2) the straight physics of absorption is the only thing we do know with any certainty (although even the 1.5C ignores some things we know that would stop it doing that 1.5C) and....this is the biggie... (3) Even assuming all the supposedly "extra" warming we've seen was caused by man...any projection based on the observed data only seems to support an additional "increase" of maybe .8C by 2100. HOWEVER...due to the normal warming/cooling phases the temperature within that timeframe would likely peak around 2070 at .5C warmer than our recent peak. Heh, by 2100 the temperatures would have dropped by .2C again. (Excuse the graph, it's several tacked together crudely) poitsplace.com/images/08/warming_projections.png
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Post by socold on Mar 1, 2009 2:44:51 GMT
point 1+2: Simple models (radiation-convection), complex models (GCMs) - all show signifcant warming from co2.
My point stands that it's inconsistant for skeptics to push some personal model of climate that's even rougher than back of envelope while dismissing implemented climate models that have actually been run with numbers.
point 3 is irrelevant to my point
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Post by nautonnier on Mar 1, 2009 3:08:16 GMT
point 1+2: Simple models (radiation-convection), complex models (GCMs) - all show signifcant warming from co2. My point stands that it's inconsistant for skeptics to push some personal model of climate that's even rougher than back of envelope while dismissing implemented climate models that have actually been run with numbers. point 3 is irrelevant to my point "Simple models (radiation-convection), complex models (GCMs) - all show signifcant warming from co2."Absolutely correct this is what the models show It is also true that the concentrations of CO 2 and other so called green house gases have increased faster than forecast. BUT The global temperatures have NOT shown "signifcant warming" over the last 8 years and Had crut is reporting sea temperatures dropping. So the "Simple models (radiation-convection), complex models (GCMs)" showing " significant warming" have all been shown to be incorrect. Read that again - slowly - all the models show SIGNIFICANT WARMING - that has NOT occurred. They did not forecast slight warming or stable temperatures but SIGNIFICANT warming. They are INCORRECT. Yet we are to see industries sacrificed because of these incorrect models.
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Post by donmartin on Mar 1, 2009 3:59:20 GMT
Moreover, Mars would be a hothouse.
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Post by socold on Mar 1, 2009 4:13:03 GMT
The models show significant warming from co2. Not significant warming over every 8 year period. Neither do they imply Mars should be a hot house.
The models are the best physical calculations of long term climate we have. All the discussion about IR absorption of co2 and convection as if they can somehow make co2 insignificant seem to miss the fact that this stuff is already in the models.
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Post by ron on Mar 1, 2009 5:20:00 GMT
All the discussion about IR absorption of co2 and convection as if they can somehow make co2 insignificant seem to miss the fact that this stuff is already in the models. ...and the clouds?
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Post by poitsplace on Mar 1, 2009 5:23:01 GMT
point 1+2: Simple models (radiation-convection), complex models (GCMs) - all show signifcant warming from co2. My point stands that it's inconsistant for skeptics to push some personal model of climate that's even rougher than back of envelope while dismissing implemented climate models that have actually been run with numbers. point 3 is irrelevant to my point LOL, it may not be relevant to skeptics use of very rough estimates on climate projections but you fail to address the reality...the real-world data doesn't support warming at the silly rates projected by alarmists. The alarmism was sparked ENTIRELY by the stupid assumption (given the temperature record) that temperatures would continue to ramp up at the same rates. They didn't. Deal with it. Looking back at the temperature record, anyone with half a brain should have expected the warming to stop for a while. While I'm on the subject of "looking back"...here's a crazy thought. You guys say the current warming is completely outside of what can be explained...and that my projection is terrible? Fine...I'll do a hindcast of the 1940-2000 cycle by cutting and pasting the previous cycle (shown here in yellow...again, excuse the poorly assembled graph)
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Post by socold on Mar 1, 2009 10:49:50 GMT
The warming forcasts are based on physics, not line fitting.
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Post by poitsplace on Mar 1, 2009 14:31:54 GMT
The warming forcasts are based on physics, not line fitting. What the heck, man...the earth isn't as good a model of its self as our computer models? Do you not see the the lunacy in your overall position? Forget models! If the warming is alarming/unprecedented and must therefore be attributed to man's CO2 (piss-poor logic here) then why do you consider that amount of warming to be so insignificant? The 1915-1980 trend is only .1C lower. For that matter, if you ignore what is obviously another super El Nino year around 1880, the projection using the 1880-1940 trend comes up only .2C lower. The current warming forecasts are based on FANTASY and alarmist misconceptions. The problem is that the alarmists ASSUMED that 100% of the last warming phase was from CO2 and that's simply not true. The earth's own climate systems are currently the BEST analog to themselves. Projecting the WORST phase of the warming period should give us a very good indication of what increased CO2 emissions will do if indeed the CO2 is actually what's driving the temperature up. I'm sorry but if the "alarming" warming we've experienced isn't alarming enough for you that's just too bad.
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Post by ron on Mar 1, 2009 19:28:13 GMT
I wonder if you carry out the physics model to the year 2200 how hot the climate gets. I wonder if you carry it out to 2500 how hot the climate gets.
Anyone ever let them run on?
I haven't seen really long term projections that I can recall.
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