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# Declining global average cloud height: “A significant measure of negative feedback to global warming”

Guest post by Dr. Pat Michaels – reposted (with permission) from World Climate Report

A new paper just published in Geophysical Research Letters by Roger Davies and Mathew Molloy of the University of Auckland finds that over the past decade the global average effective cloud height has declined and that “If sustained, such a decrease would indicate a significant measure of negative cloud feedback to global warming.”

Davies and Molloy are quick to point out that part of the decline from 2000 to 2010 in cloud height is due to the timing and variability of El Niño/La Niña events over the same period, however, there still seems to be evidence that at least part of the decline may remain even when El Niño/La Niña variability is accounted for.

Figure 1 (below) shows the history of the effective cloud height, as determined by Davies and Molloy from satellite observations, from March 2000 through February 2010.

Figure 1. Deseasonalized anomalies of global effective cloud-top height from the 10-year mean. Solid line: 12-month running mean of 10-day anomalies. Dotted line: linear regression. Gray error bars indicate the sampling error (±8 m) in the annual average (source: Davies and Molloy, 2012).

The dotted line is the linear trend through the data as determined by Davies and Molloy and has a value of -44 meters per decade (+/- 22m). However, clearly the trend is influenced by the large negative departure centered around the beginning of 2008 that was related to a moderate La Niña event in the Pacific Ocean. To avoid the influence of the this event, Davies and Molloy calculate the difference between the cloud heights during the first and last years of their record and still find a decline of 31 m/dec (+/- 11m). Although this latter technique doesn’t fully account for the El Niño/La Niña signal in the record, it does at least give some indication of the influence of the large negative departures in the latter half of the record, and indicates that the overall decline is not simply an artifact of a single event.

The average global cloud height is linked to the average global temperature—generally, the higher the average cloud height, the higher the average surface temperature, and vice versa. The tie-in is related to the height in the atmosphere from which clouds radiate long-wave radiation to space. The higher up they are, the cooler they are, and thus the less radiation they lose to space, which means the surface stays warmer.

Davies and Molloy calculate that on a decadal basis, the radiative forcing from increasing greenhouse gases is the same as that caused by either a decrease in the total global cloud amount of ~0.3% (which would allow more short wave radiation from the sun to hit the earth’s surface) or an increase in the global average cloud height of ~19 meters (about 62 feet). All to say, that clouds play a major role in the earth’s climate and that small changes in cloud characteristics can add to (via positive feedbacks) or offset (via negative feedbacks) the warming pressure put on the climate from increasing greenhouse gases. A point well-recognized by Davies and Molloy when they write “Changes in cloud properties in response to rising surface temperatures represent some of the strongest, yet least understood, feedback processes in the climate system. “

Davies and Molloy hoped to better our understanding of cloud behavior by quantifying changes in cloud heights as determined from data obtained from the Multiangle Imaging SpectroRadiometer (MISR) carried aboard the Terra satellite. The MISR data provides stereo imaging that can be used to determine the heights of clouds. The MISR data is not perfect, as it misses very thin clouds (like high level cirrus) and very homogeneous clouds (like some cirrus from thunderstorm anvils), but perhaps its biggest shortcoming is that the period of available data is still pretty short (i.e., only begins February 2000). Nevertheless, an investigation of what data is available from the MISR instrument can provide some insight as to the variability of cloud heights and their relationship to the earth’s climate.

Which was the main purpose of the work of Davies and Molloy.

In full recognition of the limitations of the data, here is how Davies and Molloy conclude their paper, in their own words:

Finally, we note that the climate data record of [effective cloud height] anomalies may ultimately indicate a measure of long-term cloud feedback that may be quite separate from the correlations discussed above [i.e., correlations with El Niña/La Niña]. Ten years is unfortunately too short a span for any definitive conclusion, as the linear trend in global cloud height of -44 +/- 22 m over the last decade is partly influenced by the La Niña event, and may prove ephemeral. The difference between the first and last year of the decade, not directly affected by the La Niña event, is -31 +/- 11 m. If sustained, such a decrease would indicate a significant measure of negative cloud feedback to global warming, as lower cloud heights reduce the effective altitude of emission of radiation to space with a corresponding cooling effect on equilibrium surface temperature. Given the precision of the MISR measurements, we look forward to the extension of this climate data record with great interest.

According to the calculations of Davies and Molloy, the negative climate forcing from a decrease in the average global cloud amount during the past 10 years has more than offset the positive forcing from an increase in greenhouse gases from human activities. It is little wonder that the rate of global temperature rise during this period has been so paltry!

Davies and Molloy write that they “look forward to the extension of this climate data record with great interest.” We want to be the first to second that sentiment.

Reference:

Davies, R., and M. Molloy, 2012. Global cloud height fluctuations measured by MISR on Terra from 2000 to 2010. Geophysical Research Letters, 39, L03701, doi:10.1029/2011GL050506.

## 99 thoughts on “Declining global average cloud height: “A significant measure of negative feedback to global warming””

1. Alan S. Blue says:

Could we have a plot of the ‘ENSO Meter’ for the same time period?

Just switching back and forth from the page in the sidebar … not sure how well they correlate, really.

2. “more than offset the positive forcing from an increase in greenhouse gases from human activities. ”

This is, f course, assuming that these GHGs are really doing anything. We know that CO2 is pathetic and ineffective and that the IPCC insists on water vapor being a slave to CO2. As we know that this is not true, then the question is still real that regarding rising CO2 having any effect at all on temperatures. It really is not a GHG, only by the strange definition given it by the IPCC. N2 and O2 trap heat as they have no way to emit IR. CO2 and water vapor can emit IR just fine and thus serve to bleed IR to space, particularly at night. In the land of the IPCC there is no night.

3. Compare that graph to the sunspot numbers of 2008. Hmmmmm.

4. Olavi says:

Count this paper, Spencer’s Cloudfeedback paper and Svensmark’s Cern experimet 1+1+1= 3
1 + Sun 1 + Controls 1 + Climate = 3 Climate sensitivity to CO2 is 0 it wont warm a thing.
CO2 ice is good for cooling icecream. :)

5. Kasuha says:

I see no statistically significant trend in Figure 1.

6. Stephen Wilde says:

“a decrease in the average global cloud amount during the past 10 years”

Is that a typo ?

Average cloud height has declined or so they say but according to other sources cloud amounts have increased over the past ten years.

7. The length of daylight in the Northern Hemisphere is increasing. This increase has been going on for at least two months. If sustained, this increase will inevitably lead to 500 hours of daylight and -476 hours of night in each 24-hour period. We need to stop breathing RIGHT NOW!

8. JohnBUK says:

Polistra

“We need to stop breathing RIGHT NOW!”

That isn’t strictly necessary – we can keep breathing in as long as we don’t breathe out. ;-)

9. Ed Caryl says:

Gaia knows best!

10. Louis Hooffstetter says:

Davies and Molloy… point out that part of the decline… is due to the timing and variability of El Niño/La Niña events…, however, there still seems to be evidence that at least part of the decline may remain even when El Niño/La Niña variability is accounted for.

Correlation does not necessarily equal causation; however, this may be additional evidence supporting Svensmark’s theory.

11. Theo Goodwin says:

‘All to say, that clouds play a major role in the earth’s climate and that small changes in cloud characteristics can add to (via positive feedbacks) or offset (via negative feedbacks) the warming pressure put on the climate from increasing greenhouse gases. A point well-recognized by Davies and Molloy when they write “Changes in cloud properties in response to rising surface temperatures represent some of the strongest, yet least understood, feedback processes in the climate system. “’

Yes, yes, yes!!!! The claim that human made CO2 can cause rising temperatures turns crucially on the claim that the effects of rising CO2 cause positive “feedbacks” in phenomena such as cloud behavior. In turn, the latter claim depends on the existence of well confirmed physical hypotheses which can be used to explain and predict cloud responses to rising CO2. As of this date, no mainstream climate scientist has produced such hypotheses. They seem not to be interested.

Davies and Molloy provide data and data analysis that takes us ever closer to such hypotheses. But surprise oh surprise, the “feedback” is negative. The response of cloud behavior lowers temperatures.

This is the kind of work that promoters of either AGW or CAGW need to be doing. Yet these scientists remain closeted within their computer models and seem completely averse to empirical research. I think that all of us should take every occasion to ask them why. With all the government money flowing into climate research, why is there no system for the atmosphere thqat is comparable in its capacities to the ARGO system for the oceans?

12. I’m glad to see this stuff start to be published more frequently. When I say “this stuff”, I’m referencing mechanisms and phenomena which up until recently were associated with our actual climate.

The sun and clouds, throw in some wind and ocean currents and they might have a good general idea about what comprises our climate……… naaw….. let’s go chasing around some trace gas or two and attach meaning to every cow fart we detect.

13. gyptis444 says:

What is quite extraordinary is how much is NOT known about the physics of clouds.
Graeme Stephens delivered the Charney Lecture recently at the Fall Meeting of the AGU (American Geophysical Union). Video of that lecture is available at

http://sites.agu.org/fallmeeting/scientific-program/lectures/bowie-and-named-lectures/6dec/

I strongly recommend this as it is extremely enlightening as to the specific details of cloud physics which have not been adequately characterised.

14. I simply cannot agree with this logic about clouds “The higher up they are, the cooler they are, and thus the less radiation they lose to space, which means the surface stays warmer.”

One could say the higher they are the sooner they will reflect incident radiation back to space before it warms some of the atmosphere below it.

Less radiation to space may well mean the atmosphere gets a little warmer, but then we do still have carbon dioxide to help with the radiation to space and thus cool the atmosphere.

But my main point is that there is only one way in which thermal energy from the atmosphere can get back to the surface. It does not “fall” out of the sky by downward convection. It does not get radiated back down because radiation from a cooler source cannot transfer thermal energy to the warmer surface. The only way it can transfer back to the surface is by being transported downwards in precipitation. Yes, cooler clouds mean cooler rain and more hail and snow.

The fact that the clouds are getting lower and warmer may well be a reason why the world is perhaps not cooling quite as much as the 60 year cycle would appear to cause. But then, there is still a slight rise in the ~1,000 year cycle of about half a degree C per century and that may still have one or two centuries before reaching its maximum.

And, by the way, there is absolutely no “positive forcing from an increase in greenhouse gases from human activities.” The author needs to catch up with the fact that, as Prof Claes Johnson has proved in Computational Blackbody Radiation, (summarised on my site) radiation from the atmosphere has a frequency which is below the cut-off frequency for absorption by the surface, so it is merely reflected or scattered without slowing the rate of cooling or increasing the rate of warming of the surface one iota.

15. Pete in Cumbria UK says:

Surely its intuitive isn’t it that Global Warming will alter cloud height..
Imagine a (liquid) water molecule at the surface. It takes a huge amount of energy (~2200Joules per gram) to turn it into a vapour. Once airborne, it has nowhere else to go but up, pushed by convection and also diffusion and its own partial pressure amongst the other atmospheric gasses.
Being very sticky stuff as it is (hence the huge Latent Heat of evaporation) it will want to condense, to join back together with all its other airborne siblings. But, if there is a significant energy flux at whatever height it chooses to do its condensing, that flux will prevent condensation. Therefore it will keep on rising until it finds a place/altitude where it can get peace and quiet and actually condense. By definition, it will then be out of the way of any energy flux, especially coming from other GHGs and all the photons of Latent Heat it emits as it condenses get a ‘free run’, upwards and outwards. Water is constantly punching holes through the insulating envelope of GHGs and will go to whatever lengths (altitudes) necessary to lose its Latent Heat.
Hence, less energy, less greenhouse effect means lower clouds. Simples.

Trenberth’s missing heat has all gone, its way out past Alpha Centauri and a good way towards Betelgeuse by now and is moving at 3 times 10 to the eight metres per second. Not even Al Gore can bring it back now.

16. Dr Burns says:

Doug Cotton wrote:
>>But my main point is that there is only one way in which thermal energy from the atmosphere can get back to the surface. It does not “fall” out of the sky by downward convection.

The primary heat transport mechanism between clouds and the Earth’s surface in convection, evaporation and condensation. Radiative transfer is very small because of relatively small temperature differences (30 degrees C or so). This applies to the 70% of the Earth’s surface covered by clouds.

17. Don Keiller says:

The sky is falling!
It’s worse than we thought!

18. This is, f course, assuming that these GHGs are really doing anything. We know that CO2 is pathetic and ineffective and that the IPCC insists on water vapor being a slave to CO2. As we know that this is not true, then the question is still real that regarding rising CO2 having any effect at all on temperatures. It really is not a GHG, only by the strange definition given it by the IPCC. N2 and O2 trap heat as they have no way to emit IR. CO2 and water vapor can emit IR just fine and thus serve to bleed IR to space, particularly at night. In the land of the IPCC there is no night.

Truly, this merely indicates that you don’t understand how the GHE works, or the importance of the work in this paper. As the paper states, the major factor in the GHE is the temperature at which atmospheric heat is lost. It has nothing to do with “trapping heat” — it has to do with how rapidly they lose heat. O2 and N2 lose heat by transferring it to the CO_2 and H_2O which can then radiate the heat away, the only way any part of the upper atmosphere can lose heat. If the CO_2 is cold when it radiates the heat away, it dissipates the heat slowly and overall temperatures underneath rise. If it is warmer, it loses it more rapidly and overall temperatures fall. Ditto water and radiation from the cloud tops.

The point of the paper is that lower cloud tops mean warmer clouds doing the radiation, hence faster cooling, hence lower temperatures. However, the evidence for this is not yet compelling, even to the authors. It is merely suggestive and plausible. The hypothesis would be strengthened if the trends and response to the trend continues, or it might be strengthened with a more precise, less heuristic assessment of the feedback. The authors do not address, for example, what the effect of water vapor above the cloud tops might do to the outgoing radiation from the cloud tops. One possibility is re-absorb it and emit it again from higher and colder, negating the effect. The other thing the authors do not address is the confounding observation that stratospheric H_2O has dropped by some 10% over the last decade plus, significantly opening a hole there that in principle also permits more radiation from water vapor to escape from higher temperature, lower collections of water vapor. They aren’t really to blame for this — it is a very complicated system and everybody is doing all they can to look at a linearized (possible) effect from changes in just one small part of it.

In the end, the best conclusion is indeed that it suggests that there is more negative feedback in the system than previously believed, but it isn’t clear why cloud tops are dropping now but might have been rising before when CO_2 levels and temperatures were still rising. It’s unlikely that the cloud top movements are the proximate cause, in other words — they are more likely themselves an effect.

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19. ShrNfr says:

I would hate to have to tease out the AMO and ENSO effects along with the effects of lower solar activity.

20. DesertYote says:

10 years is not enough time to indicate anything at all.

21. Bernie says:

Global temperatures are falling with a big dip in 2008, cloud height is decreasing with a big dip in 2008. What is the mystery? Why are they talking about global warming?

22. Robert Brown says:
February 9, 2012 at 3:18 pm

The other thing the authors do not address is the confounding observation that stratospheric H_2O has dropped by some 10% over the last decade plus, significantly opening a hole there that in principle also permits more radiation from water vapor to escape from higher temperature, lower collections of water vapor.
==================================================
That would be confounding. Do you have a link for the reference? I’d be most interested in seeing that. If this can be stated with reasonable confidence, then we have a huge problem. Because sea-level rise hasn’t just slowed, it has been reversing itself. In spite of the Himalayas remaining the same, we’re told that much melt is occurring on Greenland and Antarctic is supposedly shedding ice.

23. Third Party says:

Peak Fog is on the way.

24. HR says:

ShrNfr says:
February 9, 2012 at 3:20 pm
I would hate to have to tease out the AMO and ENSO effects along with the effects of lower solar activity.

The paper above has a first go at that. The good thing from that paper is the sense they give that the instruments in space have the potential to get to the bottom of the problem of clouds.

25. GeoLurking says:

Alan S. Blue says:
February 9, 2012 at 12:21 pm

“Could we have a plot of the ‘ENSO Meter’ for the same time period?

Just switching back and forth from the page in the sidebar … not sure how well they correlate, really.”

Dunno. But it would look a bit like this.

26. Gary Pearse says:

“the negative climate forcing from a decrease in the average global cloud amount during the past 10 years has more than offset the positive forcing from an increase in greenhouse gases from human activities. ”

Something wrong here. Why are the clouds declining? Because it is cooling! In the polar regions cummulus are about 600 feet; at the equator its 6000 feet or more. You cant have global warming going on with the clouds declining in height, so you can’t say increased forcings from GHG are being neutralized by negative feedbacks from declining cloud height. Have I got this right?

27. John M says:

GeoLurking: Just curious what software you used to digitize the graphic data (of Fig 1). It looks like you’re using DPlot (great program); are you using one of their recommended program?

28. Bart says:

Robert Brown says:
February 9, 2012 at 3:18 pm

“O2 and N2 lose heat by transferring it to the CO_2 and H_2O which can then radiate the heat away, the only way any part of the upper atmosphere can lose heat.”

Not the only way. I’d be tempted to give it a pass if you had wedged “significant” in there somewhere. O2 and N2 both radiate and absorb, too, though at much lower rates. But, NO and O3 are produced in the upper atmosphere from these constituents. Production of NO causes airglow, and O3 is a GHG at relevant wavelengths.

You are also neglecting another very significant GHG: CH4, which exists in the stratosphere at significant concentrations.

29. Robert Brown says:
February 9, 2012 at 3:18 pm

“O2 and N2 lose heat by transferring it to the CO_2 and H_2O which can then radiate the heat away,”

I used to think that too, as indeed old text books indicate oxygen and nitrogen don’t radiate at atmospheric temperatures. Well, they don’t as a result of quantum energy level jumps. But the downward radiation is full spectrum blackbody radiation and it now seems apparent that oxygen and nitrogen do in fact radiate as a result of electron acceleration during collisions – nothing to do with quantum energy steps.

“If the CO_2 is cold when it radiates the heat away, it dissipates the heat slowly and overall temperatures underneath rise”

The atmosphere may well retain extra thermal energy, but temperatures underneath can only rise if there is an actual transfer of thermal energy downwards. No amount of downward radiation will be converted to thermal energy in cooler layers, as per Johnson’s Computational Blackbody Radiation.”

The rate at which thermal energy leaves the surface is not affected by what happens up in the atmosphere. The adiabatic lapse rate is affected by the relative humidity, not the amount of carbon dioxide.

Now, the relative humidity has been falling this last decade as we have seen in another WUWT article. This increases the adiabatic lapse rate. You might think that this would make the clouds colder, but they have been falling too we now learn. So perhaps they are still about the same temperature.

The only transfer of thermal energy to the surface is in precipitation. Thus, if the clouds are staying at about the same temperature this last decade, we should see no significant change in temperatures – which is the case – QED

30. Sorry – correction: No amount of downward radiation will be converted to thermal energy in warmer layers, as per Johnson’s Computational Blackbody Radiation.”

31. Keith Minto says:

Svensmark’s theory suggests low level cloud formation during times of cosmic ray flux.

http://physicsworld.com/cws/article/news/45982

I am not convinced about that trend line in Fig1 from 2003 onwards, it looks fairly flat.

32. Bart says:

Doug Cotton says:
February 9, 2012 at 6:39 pm

“The atmosphere may well retain extra thermal energy, but temperatures underneath can only rise if there is an actual transfer of thermal energy downwards.”

There is a continual transfer of thermal energy downwards. It comes from the Sun. When it is impeded from leaving, it pools up until equilibrium between incoming and outgoing can be reestablished. That pooling up leads to a rise in temperature.

It is not unlike a dam across a river. Putting a dam across a river, which has a constant source pouring water into it, will cause the water to pool up until it overflows the top of the dam, and equilibrium is reestablished. The water level behind the dam is higher, even though the dam itself is not a source of water.

33. David A. Evans says:

Robert Brown says.

Sorry, I call BS!

Surely, if O2 & N2 can absorb energy by conduction, they can radiate in their respective absorptive/emissive frequencies.

RGB is an appropriate initial btw as I do consider you as a white knight.

34. Bart says:

Bart says:
February 9, 2012 at 7:04 pm

Doug Cotton says:
February 9, 2012 at 6:39 pm

Since you’ve broadcast your crackpottery here for all to see, it is only fair that I take it as an opportunity to broadcast mine . ;-)

This is where the analogy gets interesting. Suppose the dam is infinitely high, but it has two rows of floodgates in it. One, at low level, we will call the CO2 floodgates. One, at higher level, we will call the CH4 floodgates.

The water rises until it starts flowing out of the CO2 floodgate. But, the outflow isn’t enough to establish equilibrium before this row is saturated, so the water keeps on rising. Eventually, it reaches the level of the CH4 floodgates. Here, the water has enough of an outlet that the level stabilizes.

Now, we add more CO2 outlets. To make the analogy fit, let’s assume that we had to raise the level of the CO2 floodgates a bit to fit more in. If the CO2 floodgates had previously been sufficient to allow an equilibrium level to be established, that equilibrium level would be pushed higher.

BUT, since the level previously rose to the CH4 gates, and we put more CO2 gates in below that level which are now able to remove higher volumes of water, the equilibrium level will go down.

I hope maybe this analogy will get a read from some people who did not understand what I was talking about on an earlier thread.

Adding CO2 does not necessarily raise surface temperature, because there are other radiative emitters in the atmosphere which have interacted to create the equilibrium temperature.

35. jeef says:

Good,honest research.

36. Austin says:

Maybe the clouds are getting shorter because there is less heat to go around?

Or, there are more clouds nearer the ground?

37. Clouds look different in the IR at say 15 micron than they do in the visible at say 0.5 micron. Also, transparency is wavelength dependent. To save a literature search, does anyone know the wavelength used to estimate the height of clouds as reported here?

38. richard verney says:

This is why computer models have no prospect of working. The behavior of clouds has a huge impact on the amount of solar irradiance received at the surface, Changes in cloud pattern alter both the albedo and the amount of solar irradiance absorbed by the atmosphere

The variations are all but infinite since variation occurs depending upon the size of the cloud both 2 dimensionally and 3 dimensionally,the composition of the cloud, the altitude at which the cloud forms, the location where the cloud forms, the time of day the cloud forms and dissipates, the day & month when the cloud forms.

This is infinitely more complex since a cloud forming say over the snow covered Himalayas will have a significantly different impact on albedo than a similar sized cloud forming over a tropical rain forest So one has to look at the ground surface albedo that is being interrupted by the cloud to get a proper appreciation of albedo change. Of course, surface albedo is often seasonal and therefore the changes in albedo change also with the season.

The latitude of cloud formation and the date and time of day is very material to azimuth issues, quite obviously a cloud forming at say 11 am and dissipating at say 4pm in the tropics has a significantly different effect to a similar cloud forming say at 2pm and dissipating at 5pm over mid Canada.

There is no such thing as average cloudiness and our estimate of cloudiness conditions need be out by just 1 or 2% to fully explain the 20th century warming.

Since the process by which clouds form, dissipate and how and why they take the composition they take is not sufficiently well understood to have a reasonable stab at modelling. . .

39. Theo Goodwin says:

gyptis444 says:
February 9, 2012 at 2:23 pm

Thanks much.

40. GeoLurking says:

John M says:
February 9, 2012 at 6:05 pm

“GeoLurking: Just curious what software you used to digitize the graphic data (of Fig 1). It looks like you’re using DPlot”

Yes, I set the params of the plot after measuring the extent of the the graphic and setting it at as the background. A little tedious, but it works.

I’ve used it for about two years now… great program. What I liked about it was it’s integration to Excel. (OT: I even managed to get the coordinator of Involcan (El Hierro) pissed off at me for my interpretation of GPS data (quadratic sheet) for his “volcanic crisis.” Had to yank a few vids off of my Youtube channel… most of the vids were done using Dplot and a video capture program)

41. My head spins. Is it CO2 that drives the climate? Is it sun spots? Is it total solar irradiance? Is it the pacific decadal oscillation? Is it Cosmic Rays? And on and on and on and….. Now cloud height? WUWT?

Seriously, if the climate is this complicated (or MIGHT be this complicated), what makes us think we have an idea whatsoever that we have the faintest idea of where it’s going?

42. I would like to embarrass gyptis444 by seconding the recommendation to watch:

http://sites.agu.org/fallmeeting/scientific-program/lectures/bowie-and-named-lectures/6dec/

g444 says “I strongly recommend this as it is extremely enlightening as to the specific details of cloud physics which have not been adequately characterised.”

I strongly recommend this for that reason, and ALSO because it implicitly indicates how much has been achieved already. In addition, it indicates how climate scientists really talk to each other, and what one of the key roles of simulation models is in the actual practice of climate science.

Indeed, the availability of the principal AGU lectures online is a wonderful thing. In future I’ll attend the less prominent sessions and watch most of the big name lectures after the fact.

43. G. Karst says:

re: richard verney says:
February 9, 2012 at 8:11 pm

The problem with clouds is compounded by natures trick of camouflaging a cloud’s complexity, behind such a simple outward appearance. We have been underestimating them since modern science began. As everyone knows, almost everything can influence cloud formation, and cloud formation steers climate. Smoke, cosmic rays, dust, pressure waves, electrical charge, chemistry, etc. etc. all dance within them. We have been chasing our tails for a century, trying to manipulate one factor or the other, in order to manipulate clouds (usually to induce precipitation).

As this cloud altitude observation demonstrates, it is still confounding us all today. As usual, quantification and assigning direction of effect, prove difficult. Still, the prize is worth the effort. GK

44. wayne Job says:

Our little watery blue ball, held captive by old Sol, and perturbed by a captive moon, and various other divers influences. Fights back to reset the thermostat for the passengers. Reset takes a while and the rampant sun experienced for a few cycles has reset our world to cold, thus the change in clouds. The rather sudden holiday old Sol decided to take will mean an over shoot of temperature toward cold. If old Sol does not wake up. there will be no reset signal to warm, and our thermostat will be set at cold. I do not like cold.

45. M Courtney says:

DesertYote says:
February 9, 2012 at 3:24 pm
“10 years is not enough time to indicate anything at all.”

I quite agree. You are a sound voice of caution.
But surely it’s long enough to hint at where to look?

46. richard verney says:
February 9, 2012 at 8:11 pm
“…The variations are all but infinite since variation occurs depending upon the size of the cloud both 2 dimensionally and 3 dimensionally,the composition of the cloud, the altitude at which the cloud forms, the location where the cloud forms, the time of day the cloud forms and dissipates, the day & month when the cloud forms…”

Amen to that brother – great post!!!

The massive reduction in global cloud hight in 2008 is a fascinating event, about which the authors of the paper conjecture was caused by the ‘moderate La Niña’ in the Pacific. However, this period was also the time of a prolonged period of low solar activity, and I wonder if this is another possible candidate for the observed cloud effect. Graph of sunspot number, courtesy Solen.info, available here…

47. Bart says:
February 9, 2012 at 7:04 pm

Doug Cotton says:
February 9, 2012 at 6:39 pm

“The atmosphere may well retain extra thermal energy, but temperatures underneath can only rise if there is an actual transfer of thermal energy downwards.”

(1) There is a continual transfer of thermal energy downwards. It comes from the Sun.

(2) When it is impeded from leaving, it pools up until equilibrium between incoming and outgoing can be reestablished. That pooling up leads to a rise in temperature.
________________________________________________________

(1) Yes, the Sun is what keeps you warm. It’s been happening for a few billion years without getting too hot. But the IPCC hangs its hat on a thing they inappropriately call the greenhouse effect – due to what they also inappropriately call “backradiation.” So let’s keep to the topic I was talking about, shall we?

(2) Yes, maybe the atmosphere gets a little closer to freezing point until a fraction of a second later when more radiation is emitted from the atmosphere and eventually makes its way to space, perhaps after being rejected by the surface and a billion other warmer air molecules it visits.

48. DirkH says:

Michael Tobis says:
February 9, 2012 at 9:40 pm
“In addition, it indicates how climate scientists really talk to each other, and what one of the key roles of simulation models is in the actual practice of climate science.”

Michael, we already know how they talk to each other. They are full of doubt. We have read the ClimateGate e-mails. And we know that the key role of the models is not predicting the future climate; but that they only pretend to do this to ensure ongoing funding. All this is known. The MSM is currently playing catch-up and starts to explain it to their customers.

The public image of scientists will never recover from this; they will lose their aura of objectivity forever.

49. Dr Burns says:
February 9, 2012 at 2:36 pm

Doug Cotton wrote:
>>But my main point is that there is only one way in which thermal energy from the atmosphere can get back to the surface. It does not “fall” out of the sky by downward convection.

(1) The primary heat transport mechanism between clouds and the Earth’s surface in convection, evaporation and condensation.

(2) Radiative transfer is very small because of relatively small temperature differences (30 degrees C or so). ….
____________________________________________________________

(1) Condensation pf course leads to the precipitation I was talking about. Did you really mean to include convection and evaporation in the downward transfer of thermal energy?

(2) You seem to be talking about net upward radiation (not downward as I was discussing) for why else are you referring to a temperature difference of 30 degrees? Even the good old Stefan-Boltzmann Law would expect the warmer temperature to be the source of net radiation. Indeed such radiation from the surface is not large because there is often a temperature difference of less than 3 degrees (never, well hardly ever 30 degrees) between the surface and the first millimeter of the air – and that’s all that counts. Most thermal energy leaves the surface by diffusion, conduction, convection, evaporation and chemical processes, not by radiation – which is why that -18 deg.C figure is garbage if you follow me.

50. Kelvin Vaughan says:

The average global cloud height is linked to the average global temperature—generally, the higher the average cloud height, the higher the average surface temperature, and vice versa.

We are cooling down.

51. DEEBEE says:

Could we stop plotting lines through scattered data. Except for the four year dip the plot essentially flat. I clearly do not understand the tendency in things climatological to do so. It just makes it hard to consider this science instead of reading tea leaves. In most other hard sciences a value that has plus minus bars of 50% would be a dead giveaway of the randomness and a reason to hit the thinking chair some more.

52. Bart says:
February 9, 2012 at 7:04 pm

I note that you like to talk about dams as if thermal energy stacks up like a traffic jam or a river.with a dam. That’s not what actually happens.

Take a look at what’s really going on up there around the tropopause above which the temperature then starts to rise with increasing altitude in the stratosphere, so there’s a nice little “valley” for all your extra “heat”.

But check out what NASA satellites found up there at say 56,000 feet. Then compare 2003 with 2011 – both almost precisely the same around the -63 deg.C value. Here’s the link: http://discover.itsc.uah.edu/amsutemps/ Check all the records available (from 2002)and see how little variation there has been. Then tell me what would happen on Earth if it warmed up to, let’s say, -60 deg.C.

53. Say this loud and clear to every warmist you encounter: “The climate is subject to negative feedback. It is self-correcting. This means that there is no such thing as a ‘Tipping Point’ “.

54. Steve Keohane says:

The atmosphere shrank quite a bit over the past few years. I suspect this is related to the cloud deck change, sorry I don’t have a link, here is the full article from AGU 2010. One question that I have re: this article is the claim of the thermosphere cooling considerably, yet having a significant drop in density ~30% as well…does not compute to me, especially if altitude is lower.

AGU Release No. 10–28
26 August 2010
For Immediate Release

WASHINGTON—Large changes in the Sun’s energy output may cause Earth’s outer atmosphere to contract, new research indicates. A study published today by the American Geophysical Union links a recent, temporary shrinking of a high atmospheric layer with a sharp drop in the Sun’s ultraviolet radiation levels.

The research indicates that the Sun’s magnetic cycle, which produces differing numbers of sunspots over an approximately 11-year cycle, may vary more than previously thought.

“Our work demonstrates that the solar cycle not only varies on the typical 11-year time scale, but also can vary from one solar minimum to another,” says lead author Stanley Solomon, a scientist at the National Center for Atmospheric Research’s High Altitude Observatory. “All solar minima are not equal.” Researchers from the University of Colorado at Boulder (CU) also contributed to the project.

The findings may have implications for orbiting satellites, as well as for the International Space Station. The fact that the layer in the upper atmosphere known as the thermosphere is shrunken and less dense means that satellites can more easily maintain their orbits. But it also indicates that space debris and other objects that pose hazards may persist longer in the thermosphere.

“With lower thermospheric density, our satellites will have a longer life in orbit,” says CU professor Thomas Woods, a co-author. “This is good news for those satellites that are actually operating, but it is also bad because of the thousands of non-operating objects remaining in space that could potentially have collisions with our working satellites.”

The Sun’s energy output declined to unusually low levels from 2007 to 2009, a particularly prolonged solar minimum during which there were virtually no sunspots or solar storms. During that same period of low solar activity, Earth’s thermosphere shrank more than at any time in the 43-year era of space exploration.

The thermosphere, which ranges in altitude from about 90 to 500 kilometers (55 to more than 300 miles), is a rarified layer of gas at the edge of space where the Sun’s radiation first makes contact with Earth’s atmosphere. It typically cools and becomes less dense during low solar activity. But the magnitude of the density change during the recent solar minimum appeared to be about 30 percent greater than would have been expected by low solar activity.

The study team used computer modeling to analyze two possible factors implicated in the mystery of the shrinking thermosphere. They simulated both the impacts of solar output and the role of carbon dioxide, a potent greenhouse gas that, according to past estimates, is reducing the density of the outer atmosphere by about 2 percent to 5 percent per decade.

Their work built on several recent studies. Earlier this year, a team of scientists from the Naval Research Laboratory and George Mason University, measuring changes in satellite drag, estimated that the density of the thermosphere declined from 2007–2009 to about 30 percent less than that observed during the previous solar minimum in 1996. Other studies by scientists at the University of Southern California and CU, using measurements from sub-orbital rocket flights and space-based instruments, have estimated that levels of extreme-ultraviolet radiation—a class of photons with extremely short wavelengths—dropped about 15 percent during the same period.

However, scientists remained uncertain whether the decline in extreme-ultraviolet radiation would be sufficient to have such a dramatic impact on the thermosphere, even when combined with the effects of carbon dioxide.

To answer this question, Solomon and his colleagues used a computer model to simulate how the Sun’s output during 1996 and 2008 would affect the temperature and density of the thermosphere. They also created two simulations of thermospheric conditions in 2008—one with a level that approximated actual carbon dioxide emissions and one with a fixed, lower level.

The results showed the thermosphere cooling in 2008 by 41 kelvins (about 74 degrees Fahrenheit) compared to 1996, with just 2 K attributable to the carbon dioxide increase. The results also showed the thermosphere’s density decreasing by 31 percent, with just 3 percent attributable to carbon dioxide. The results closely approximated the 30 percent reduction in density indicated by measurements of satellite drag.

“It is now clear that the record low temperature and density were primarily caused by unusually low levels of solar radiation at the extreme-ultraviolet level,” Solomon says.

Woods says the research indicates that the Sun could be going through a period of relatively low activity, similar to periods in the early 19th and 20th centuries. This could mean that solar output may remain at a low level for the near future.

“If it is indeed similar to certain patterns in the past, then we expect to have low solar cycles for the next 10 to 30 years,” Woods says.

The study, published in Geophysical Research Letters, was funded by NASA and by the National Science Foundation.

55. Bart says:

Doug Cotton says:
February 10, 2012 at 2:47 am

‘But the IPCC hangs its hat on a thing they inappropriately call the greenhouse effect – due to what they also inappropriately call “backradiation.” ‘

The “backradiation” paradigm is just an equivalent way of looking at the result in equilibrium. If you don’t like it, look at it the other more proper way, as atmospheric impedance to heat dissipation. Water cannot flow from a low point to a high point, either. Yet, a dam raises the water level upstream. You are arguing that it cannot, but I am certain that it can.

“So let’s keep to the topic I was talking about, shall we?”

Let’s not, because you are advancing a crackpot thesis: essentially that the atmosphere cannot retain heat. Atmospheric retention of heat, and consequent raising of temperature at the surface due to it, is a slam dunk. There is no doubt at all that the Earth’s surface is hotter than it would be without an atmosphere and, ignoring other processes, the addition of heat trapping gases to a homogenous unsaturated atmosphere would tend to heat it more.

BUT, I have imposed very specific conditions, here. The situation is complex. There are other processes occurring which cannot be ignored, as the IPCC wants to do. Feedback effects, e.g., from clouds, can mitigate the effect, and alter the characteristics. In addition, the atmosphere is not homogeneous and CO2 radiative emissions are nearly saturated.

Inhomogeneity and saturation mean that the partial derivative (sensitivity) of temperature with respect to added CO2 can be negative, i.e., adding CO2 can actually tend to cool, rather than heat, the surface. I believe that my little thought experiment above demonstrates that adding more CO2 to the Earth’s atmosphere should, in fact, reduce the amount needed to be radiated out by CH4 to establish equilibrium, and therefore the sensitivity of Earth’s surface temperature to additional CO2 is actually negative.

And, other negative feedback effects can (and almost certainly do) reduce the magnitude of the sensitivity in the closed loop, and alter the steady state conditions.

I am not carrying the IPCC’s water here. I am not defending their position in toto. I am very specifically stating that they have simplified the situation to the point that it no longer reflects reality. But, the fallacy does not disprove the premise. The greenhouse effect being wrong would invalidate the IPCC’s postion. But, the invalidity of the IPCC’s position does not prove that the greenhouse effect is nonexistent.

56. Bart says:
February 10, 2012 at 8:53 am
“There is no doubt at all that the Earth’s surface is hotter than it would be without an atmosphere “
__________________________________________________________

You are obviously unaware of the results of mathematical calculations by Claes Johnson (well-published Professor of Applied Mathematics) in his Computational Blackbody Radiation” which is linked and summarised on the ‘Radiation’ page of my site http://climate-change-theory.com .

There is no physical process whereby atmospheric impedance to heat dissipation can cause thermal energy to be transferred back to the surface, (or even the air we stand in) other than, to a negligible extent contained in precipitation. As Johnson and I have stated many times, radiation cannot transfer thermal energy from a cooler source to a significantly warmer surface of atmospheric layer.

I am not ruling out any accumulation of thermal energy in the atmosphere, but I am saying that such will not affect climate. If there had been any such accumulation, then it would surely show up in the tropopause – the temperature “valley” where temperatures stop declining and start to rise with increasing altitude. Check NASA satellite data at 56,000 feet for every year since 2002 on their site http://discover.itsc.uah.edu/amsutemps/ and you will see that it has been consistently around -63 deg.C every year with less than a degree of variation and certainly no rising trend.

The atmosphere does more in the way of cooling the Earth’s surface (by insulating it from solar radiation) and even the carbon dioxide actually also insulates and thus cools the surface. You can see how ineffective it is at keeping Antarctica warm. Surely the difference between the South Pole and the Equator shows that it is all about indicent solar raditaion levels. And you have only to consider that the Moon’s surface can go about 100 deg.C to realise that our atmosphere insulates us from solar heat. (I know it also goes below -150 deg.C on the Moon but that is partly to do with not having core heat like the Earth and also the long 13 day cooling off period in the Moon’s night.) http://www.universetoday.com/19623/temperature-of-the-moon/

The earth’s adiabatic lapse rate is primarily determined by the mass of air in the atmosphere and the relative humidity, both of which mankind has no control over. This rate sets a temperature trend line in the atmosphere. That trend is actually an extension of the trend from the core to the surface. If the atmospheric trend were to rise to a new equilibrium at the surface end for some reason, probably greater solar radiance due to orbital variations, or variations in cloud cover, then the whole temperature plot from the core would also have to rise at the surface end because thermal equilibrium will be maintained at the surface/atmosphere interface. It would take a huge amount of energy to fill the gap under the new sub-surface plot, wouldn’t it. So, for a start, we would be seeing net flow into the surface rather than out of it as is currently observed. I am not saying it could not happen, and it obviously does in long natural cyclic patterns, but I am saying it takes a long time.

So, I repeat that there is no mechanism whereby any warming of the atmosphere will then warm the surface. All surplus energy above the well-embedded temperature trend line will be simply radiated away. Only when the surface itself is warmed, by stronger solar insolation or even by variations in thermal energy generated under the surface, and only when a new equilibrium is established in the core to surface plot will be see a new equilibrium at a higher surface temperature. Processes like this appear to happen naturally in long term natural cycles beyond the control of man.

It has absolutely nothing to do with radiative feedback from WV or any atmospheric trace gases.

57. PS – Bart (and others)

We have seen here at WUWT that there has been a reduction in relative humidity this century which should indicate that there is no radiative feedback from water vapour having any positive effect. That in itself demonstrates what Prof Johnson is saying that any radiation from a cooler atmosphere cannot transfer thermal energy to the warmer surface or to any (significantly) warmer atmospheric layer. This does more than just negate any amplification of any carbon dioxide forcing: it also negates the possibility of any GHG forcing whatsoever, which is in accord with what Johnson has proved. If WV does not warm with “backradiation” neither will any GHG.

If and only if there is conversion to thermal energy will there be any effect on the rate of warming or cooling of the target. So climate cannot be affected by radiation from the atmosphere.

Now, finally, there is considerable doubt that the capture of photons by carbon dioxide will necessarily lead to sharing of that energy among O2 and N2 molecules. These have different quantum energy steps for a start. Collisions may appear to transfer KE, but they in themselves can generate low amounts of radiation due to acceleration of electrons. What happens appears to depend very much on temperature also. If there is warming then there will be a greater propensity to radiate anyway. So, either radiation happens before any warming, or any warming causes more radiation. All radiation from the atmosphere eventually gets to space because the surface and warmer molecules lower down will not accept it.

58. Bart says:

Doug Cotton says:
February 10, 2012 at 1:55 pm

“There is no physical process whereby atmospheric impedance to heat dissipation can cause thermal energy to be transferred back to the surface…”

For the last time, the energy flux to the surface is coming from the Sun. The IR emitters in the atmosphere do not heat the surface, the Sun does.

The GHGs do not have to transfer thermal energy to the surface. They only have to impede the energy that gets there from leaving, because there is more coming in every infinitesimal unit of time.

The surface temperature is a result of retained energy from the Sun. The atmosphere also retains energy, and with more energy retained, the temperature increases. And, it will keep increasing until atmospheric radiation allows an equilibrium to be attained.

At that point, a steady state adiabatic lapse rate can be established. Without such a radiative heat sink high in the atmosphere, there can be no stable non-zero lapse rate.

In equilibrium, the incoming solar flux plus backradiation balance with the outgoing surface radiation. Only in that narrow sense can the backradiation be said to be heating the surface. But, it isn’t really. It’s just an equilibrium condition.

59. Richard M says:

Kelvin Vaughan says:
February 10, 2012 at 3:09 am

The average global cloud height is linked to the average global temperature—generally, the higher the average cloud height, the higher the average surface temperature, and vice versa.

We are cooling down.

Yes, the cloud height is a proxy of the average strength of convection which itself is a proxy for the energy in the system. Less energy = cooler.

60. Bart says:

Doug Cotton says:
February 10, 2012 at 2:57 pm

“Is there any evidence of waves from a radio broadcasting tower actually warming something nearby?”

I have a little box in my kitchen which has a little radio broadcasting tower in the top. When I put food in the box, it gets hot.

61. The very cold temps at 400 mb the infamous level of trapping the IPCC is looking for, would also argue for lower cloud tops, at least over the last year. Interestingly enough.. the cool enso, then rapid drop off in mid trop temps and now the rapid drop off in the lower trop temps ( the air above the boundary layer would cool first) goes hand in hand with the idea that global temps respond to the large natural cycles ( in this case the turn of the PDO and the cool enso) than the fiction the AGW side is trying to push

62. Bart and others. Don’t joke with me about putting something on top of a radio wave generator. Try a bit to one side.

63. The atmosphere can violate physics? Whatever radiation meets the surface from the atmosphere, whatever the intensity or wavelength, if it came from a cooler source it cannot add thermal energy to the surface.

See section 3.9.3 regarding the Second Law of Thermodynamics applying to heat transfer by radiation.

http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf

Prof Claes Johnson proves computationally how and why it applies. If he were incorrect there would be a violation of the law.

This paper also mentions on p.74 the role of the core heat in climate, something which I have written about long ago on the ‘Explanation’ page of http://climate-change-theory.com I am relieved to find a paper that mentions such.

64. Well, try a question mark after that: The atmosphere can violate physics? /sarc

65. Bart says:
February 10, 2012 at 3:06 pm
Doug Cotton says:
February 10, 2012 at 1:55 pm

“There is no physical process whereby atmospheric impedance to heat dissipation can cause thermal energy to be transferred back to the surface…”

For the last time, the energy flux to the surface is coming from the Sun. The IR emitters in the atmosphere do not heat the surface, the Sun does.

________________________________

I stand by my statement and I couldn’t agree more with yours in italic above.

So how does any thermal energy trapped up somewhere in the atmosphere (or slowed down in its inevitable exit to space) have any effect on what we call climate down here?

So at night how does radiative flux from the atmosphere add thermal energy to the surface in order to slow the rate of cooling? (Sorry, but we need to take the Sun out of the picture to focus on this nocturnal system.) Do try to remember that the Second Law of Thermodynamics also works at night.

Try reading p.74 at least from this peer-reviewed published paper. http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf

You also said: They only have to impede the energy that gets there from leaving, because there is more coming in every infinitesimal unit of time.

The impeding will have no effect on climate as I said in the statement I stand by above.

Oh, and sorry, but the Sun doesn’t shine here in Sydney “in every infinitesimal unit of time.” I find things cool off at night, don’t you?, Back to about where they were the night before.

Funny how the temperature at 56,000 feet is still the same as it was a decade or so ago, namely about -63 deg.C. That must be having a huge effect on us all down here.

66. Bart says:
February 10, 2012 at 3:06 pm

“The IR emitters in the atmosphere do not heat the surface … Only in that narrow sense can the backradiation be said to be heating the surface. But, it isn’t really. It’s just an equilibrium condition.”
_____________________________________________

Make up your mind. EIther the radiation from the cold atmosphere is converted to thermal energy in the surface or it isn’t.. Which, my friend?

If it isn’t (which it isn’t because it’s scattered) then its effect energy-wise is exactly the same as being reflected and it can have absolutely no effect. It certainly cannot slow down other radiation or the rate of cooling of the surface in the evening or increase the rate of warming in the morning sunshine.

Now go and read what a proper published paper by German physicists has to say and I’d be happy to discuss any point in the paper – just quote section or page.

http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf

“Unfortunately, there is no source in the literature, where the greenhouse effect is introduced
in harmony with the scientific standards of theoretical physics ”
.

67. Bart says:

“EIther the radiation from the cold atmosphere is converted to thermal energy in the surface or it isn’t.”

You’re just thinking about this all wrong, Doug. I think you have in mind a sort of pseudo-static situation where various entities are independently bombarding the surface with energy bundles, and the Earth is, in turn, sending them back out toward the sources. According to the 2nd law, the atmospheric particles, in this scenario, will receive back more radiation than they put in, so the net flow is outward.

That is entirely true. The net flow between the surface and the atmosphere is outward. But, all of the energy is coming from the Sun. It is coming in constantly on the day side of the planet. It is re-emitted up into the atmosphere, and some of it is re-emitted back down, and then the surface re-emits it back up again, and so on. Then net result is that more energy puddles near the surface, and so the temperature rises. But, the net flow between the surface and the atmosphere is still upward, so there is no 2nd law violation. What is left is a little larger pool of energy near the surface, and that raises the temperature.

On the night side, the net flux is still out, so there is no 2nd law violation. The only thing affected is the rate of thermal emission from the combined surface/atmosphere, which slows (not the speed of the photons, of course, but the number of emissions per unit of time which result in photons escaping the system), so the surface cools less quickly than it otherwise would have.

I don’t harbor much hope I am going to get through to you. But, in the off chance that I do, I want to point out to you how complex this really all is, which is widely unappreciated. Don’t bother reading beyond here if you are not interested.
————————————————————
All of this back-radiation and thermal energy accumulation is a positive feedback. A temperature rise causes atmospheric absorption by GHG gases, which reduces the rate of outward energy flow, which raises the surface temperature, which causes more atmospheric absorption, and so on it a self-reinforcing cycle. This will continue until the rate of surface emission outside the GHG bands of absorption plus the outward bound atmospheric emissions balances the incoming solar radiation flux.

It is exactly like my analogy of the dam and the floodgates. And, as I showed with that analogy, it is entirely possible for the addition of lower energy emitters like CO2 to cause the equilibrium temperature to go down rather than up. in fact, when you are in an equilibrium situation, as we are, in which a higher energy emitter like CH4 is producing significant emissions to balance everything out, then I believe it is even very likely that the addition of more CO2 would tend to lower the surface temperature.

There is an additional potential for a saturation effect to create more cooling. In that case, adding more CO2 would tend to broaden the peak at which absorption and subsequent radiation occurs. In my dam analogy, that would be like adding additional floodgates below the level of the previous ensemble.

SO, to sum it all up:

1) The GH effect is real

2) But, adding GH gases does not necessarily increase the surface temperature

3) In the case where there are higher energy emitters which are significantly stimulated, and/or the absorption/emittance distribution is broadened, it is quite likely that increasing the concentration will lead to cooling

4) Not discussed here, but additional feedbacks in the system (e.g., cloud dynamics) can suppress the GH effects and make any warming/cooling insignificant – this would be akin to having a spillway that circumvents the dam

68. Bart: You display a distinct lack of knowledge about radiation when you say “In the case where there are higher energy emitters which are significantly stimulated,.”

No spontaneous radiation from the atmosphere can have radiated energy high enough to deposit thermal energy in a warmer surface, as official explanations of the GHE speculate happens. There are several different official explanations I know, which just demonstrates the confusion, but the IPCC says backradiation leads to warming somehow.

Why are you wrong in the above statement? Because peak frequency is proportional to absolute temperature according to Wien’s Displacement Law and the energy of a photon is proportional to its frequency and thus to the temperature of the emitter. Below the mesopause the atmosphere is colder than the surface, so any photons it emits have lower energy than the photons being emitted by the surface. And if any heat were transferred it would be in breach of the Second Law. And if no heat is transferred, there is no greenhouse effect causing any warmer climate down here. It’s that simple.

It is not I who “has it all wrong.”

My belief and understanding are exactly in accord with the published physicists who wrote this paper and made this statement therein.

http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf

“Unfortunately, there is no source in the literature, where the greenhouse effect is introduced in harmony with the scientific standards of theoretical physics.”.

So if you, Bart, disagree with anything in the 100+ pages therein, write and publish an official rebuttal, or try to find one – which I would love to see.

69. Bart you really put your foot in it here: “the net flux is still out, so there is no 2nd law violation” because the Second Law has nothing to do with net radiative flux. It has to do with heat transfer. The IPCC tries to say there is heat transfer into the surface (thus slowing the rate of cooling in the evening and increaing the rate of warming in the morning and the maximum temperature for the day), whilst all the time there is net flux out of the system. This does not make it OK to break the Second Law by transferring heat into the surface from a colder atmosphere, No transfer of heat inwards means no greenhouse effect.

70. (continued)

Just to clarify … Imagine three metal plates in parallel planes at equal separation in a vacuum.

1. The plate on the left is 100 cm^2 and is at 28 deg.C
2. The plate in the middle is 1 cm^2 and is at 30 deg.C
3. The plate on the right is 10 cm^2 and is 32 deg.C

(a) Net total radiative flux is left to right because the difference in surface areas dominates in S-B calculations.
.
(b) Heat flow is from right to left because of the temperature differences.

(c) The middle plate is not warmed by the cooler plate on the left despite the large flux.

71. Bart, you’re about a year and a thousand hours of study behind me. I wrote stuff like this on my website a year ago: “It is re-emitted up into the atmosphere, and some of it is re-emitted back down, and then the surface re-emits it back up again, and so on. “

In fact the atmosphere is 3D and radiation “bounces” around being re-emitted millions, perhaps billions of times in random directions. But, whenever it encounters a warmer molecule than is represented by its own frequency it is scattered without being absorbed and without leaving any energy behind in any little “pool” near the surface or wherever. Even when it strikes a cooler molecule when heading toward space it usually gets re-emitted without causing warming of any other molecule. Even if does happen to warm some other molecule, that molecule will then have a greater propensity to emit radiation. The probability is that it will escape to space sooner or later, and in fact at least 99.5% of incident radiation does go back to space, sometimes 100.5%.

The main factors influencing climate are

(a) total solar insolation which can vary with solar distance plus
(b) to some extent, relative humidity and
(c) cloud levels and cover.

Of course there are many other natural variables, volcanoes etc. But carbon dioxide levels are not among the factors involved, other than a very slight cooling effect due to absorption of incoming IR radiation from the Sun. What the IPCC never mentions is that about half the Sun’s radiation is in the infra-red spectrum and there are pockets in the spectrum where CO2 and WV are absorbing and so reducing the warming effect of the Sun..

Now spend at least two hours reading that paper by the German physicists!

72. shawnhet says:

Doug,

Respectfully, you’re not getting it. No one is saying that the atmosphere is transferring heat from the atmosphere to the surface (on average). They are saying that the GHGs in the atmosphere prevent the surface from cooling as quickly as it OTW would do.

It may be obvious but it bears laying out in detail. Given intermittent periods of heating and cooling, a plate surrounded by an insulating material will, on average, be warmer than a plate surrounded by a non insulating material. When you talk about heat transfer from a colder object to a warmer one, you are talking a different language than the folks you are disagreeing with.

Cheers, :)

73. It seems some like shawnhet need to learn some basic facts of physics, rather than what they have been fed by climatologists…

It is physically impossible to slow the rate of anything cooling without adding thermal energy, and iIt is physically impossible to add thermal energy by conduction or spontaneous radiation from a cooler source.

The language I speak is that of physics, not that of the IPCC.

Go and read 100+ pages of the peer-reviewed published paper by those two German physicists which I linked above, but link again http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf

There is absolutely nothing in that physics paper which contradicts anything I have written on my website http://climate-change-theory.com or in recent posts, even though I have just found the paper yesterday.

The Second Law of Thermodynamics does apply for radiation and you need to remember that radiation is not itself thermal energy. It is only converted to thermal energy when it strikes a target which is cooler than its source – which is why heat only transfers from hot to cold and not from a cold atmosphere to a warmer surface. The target detects the temperature of the emitter by way of its peak frequency which is proportional to its absolute temperature. Radiation which is neither reflected nor converted to thermal energy is merely scattered and thus has no more effect than that which is reflected.

So there is no heat transfer from the cooler atmosphere (as per Second Law) and without any heat transfer from the atmsophere, there can be no slowing of the cooling rate of the surface.

I will not be replying to anyone who does not show evidence of reading the above physics paper at least in part. I am happy to explain any part of it, but will be unavailable for the next 24 hours.

74. Strictly speaking I should have said it is impossible to slow the rate of cooling of anything in a vacuum without adding thermal energy. In practice, however, when the Earth is cooling at night the atmosphere at the surface is cooler and cooling faster than the surface, so no significant insulation is happening. Even more so, when calculating average rates of cooling over a 24 hour cycle it should be obvious that the rate of warming would also have to increase by whatever radiation process was slowing the cooling at night. It is perhaps easier to understand that this rate of warming requires addition of thermal energy, but it does also require addition of thermal energy to slow the rate of cooling once there is any significant difference in temperature at the interface.

75. MartinGAtkins says:

Doug Cotton says:

It is physically impossible to slow the rate of anything cooling without adding thermal energy, and iIt is physically impossible to add thermal energy by conduction or spontaneous radiation from a cooler source.

The language I speak is that of physics, not that of the IPCC.

The language you speak is neither that of physics nor that of the IPCC.

You don’t understand the difference between radiative physics and kinetic physics.

76. Bart says:

Doug Cotton says:
February 11, 2012 at 3:54 am

“The probability is that it will escape to space sooner or later…”

That is the whole point. If it is later rather than sooner, more energy will be deposited before equilibrium is established.

Doug Cotton says:
February 11, 2012 at 5:23 am

“It is physically impossible to slow the rate of anything cooling without adding thermal energy…”

So, Thermos bottles are one big fraud.

The blankets on your bed are just for show (Yes, there is a heat source: you. But, the Earth-Atmosphere system has a heat source, too: the Sun.)

“…and it is physically impossible to add thermal energy by conduction or spontaneous radiation from a cooler source.”

Nobody is talking about adding anything. Just like a river with a dam. No water is “added” that isn’t already coming in, yet the water pools up.

77. George E. Smith; says:

“”””” Stephen Wilde says:

February 9, 2012 at 12:53 pm

“a decrease in the average global cloud amount during the past 10 years”

Is that a typo ?

Average cloud height has declined or so they say but according to other sources cloud amounts have increased over the past ten years. “””””

Tut tut Stephen; the higher you go, the less atmospheric mass there is, the less moisture there is, the less clouds there is. It follows logically, that exactly the opposite happens the lower you go, lower = more clouds.
Quite Easily Done !

78. George E. Smith; says:

“”””” Bart says:

February 9, 2012 at 7:04 pm

Doug Cotton says:
February 9, 2012 at 6:39 pm

“The atmosphere may well retain extra thermal energy, but temperatures underneath can only rise if there is an actual transfer of thermal energy downwards.”

There is a continual transfer of thermal energy downwards. It comes from the Sun “””””

Sorry Bart,and Doug,

But there is no medium to conduct or convect thermal energy from the sun to earth; well not enough to write home about; so we get ZERO thermal energy from the sun.

What we get from the sun is Electromagnetic radiation energy, that theoretically, if perhaps not practically, can be all converted to electricity here on earth. Well large amounts of it are converted to biotic materials and organisms.

We MAKE ALL OF OUR HEAT right here on earth, by simply wasting MOST of the good radiant EM energy the sun sends us.

79. George E. Smith; says:

“”””” DesertYote says:

February 9, 2012 at 3:24 pm

10 years is not enough time to indicate anything at all. “””””

Well ten years is ample time to observe whatever happens in ten years. I agree that five years is not enough time to observe what happens in ten years, but ten years is plenty of time to do it.

80. George E. Smith; says:

As it turns out, I will be in Auckland in about 4 weeks, and plan on visiting the Physics Dept at the UofA.

I’m hoping I can catch up with Professor Davies, and talk with him about this. The Physics Dept seems to be 10 times bigger than when I was there, so it is likely to be, not so easy to catch up with him; but maybe I’ll get lucky.

81. shawnhet says:

“Doug Cotton says:
February 11, 2012 at 5:23 am
It seems some like shawnhet need to learn some basic facts of physics, rather than what they have been fed by climatologists…

It is physically impossible to slow the rate of anything cooling without adding thermal energy, and it is physically impossible to add thermal energy by conduction or spontaneous radiation from a cooler source.”

This has already been responded to a couple of times but since it is addressed to me, I will respond briefly. To me, this statement is obviously wrong and one doesn’t even need to know any physics to show it. It’s about -20C outside where I am and I can assure you that I can *feel* a difference when I walk out in a T-shirt as compared to my winter coat. Now, I’m sure that you know this. I’m also sure (unfortunately) that given enough effort you can *torture* the English language so that it seems that the above statement is not wrong so I won’t go further on this point.

IAC, regardless of what you finally decide on whether or not something can cooled slower, hopefully you have learned enough to stop making the straw man argument that the GHE is about sucking heat from the colder air into the warmer surface. This is not how the GHE is hypothesized to work.

Cheers, :)

82. David says:

Robert Brown,

“The authors do not address, for example, what the effect of water vapor above the cloud tops might do to the outgoing radiation from the cloud tops.”
——————————————————————————-

True Robert, yet they also do not addrsss what effects the same w/v does to incoming solar radiation where ground level (air Mass once) spectrum readings show the amounts of that energy taken out by primarily O2, O3, and H2O, in the case of H2O which absorbs in the visible and near IR perhaps 20% of the total incoming solar energy is captured by water VAPOR (clear sky) clouds are an additional loss over and above that.

83. It’s a mystery to me how anyone can claim that the atmosphere has a cooling effect on the surface, when the fact is, the higher we go in the atmosphere the cooler we find the surface. –AGF

84. G. Karst says:

agfosterjr says:
February 12, 2012 at 10:56 am

It’s a mystery to me how anyone can claim that the atmosphere has a cooling effect on the surface, when the fact is, the higher we go in the atmosphere the cooler we find the surface. –AGF

Think of a large rock in the sunshine as being the earth’s surface. It is being heated by the sun but as it get’s hotter than the air – the air scrubs heat (conduction to air, then air convects away) from the rock. The more wind, the more scrubbing ==> the rock T, is reduced. GK

85. Let’s call the top of Everest your rock. –AGF

86. George E. Smith; says:

So I have a confirmed meeting with Professor Roger Davies at the UofA Physics Dept, to talk about the ramifications of his new paper . Matthew Molloy is currently offsite, so I won’t get to neet him, but I can get to talk with Prof Davies about a number of climate issues besides his new cloud falling discovery. I plan to get some definitive answers from somebody there on the thermal radiation from ordinary atmospheric gases. My prof went through the derivation of Planck’s formula for BB radiation, and nowhere was it necessary to talk about atomic structure or energy levels; the physical origin of the BB radiation is not even a part of the derivation which is purely classical physics; statistical mechanics, and the equipartition principle applied to the equipartition of mean energy to each emission frequency subject to the Planck restriction that E = h. f which requires fewer possible energy values for higher frequencies, thus escaping the ultra-violet catastrophe of Raleigh-Jeans.

I’ll file some sort of report on what extra I can discover from Prof Davies about the cloud height issue.

87. That would be confounding. Do you have a link for the reference? I’d be most interested in seeing that. If this can be stated with reasonable confidence, then we have a huge problem. Because sea-level rise hasn’t just slowed, it has been reversing itself. In spite of the Himalayas remaining the same, we’re told that much melt is occurring on Greenland and Antarctic is supposedly shedding ice.

Scientific American no less:

http://www.scientificamerican.com/article.cfm?id=is-water-vapor-in-the-stratosphere-slowing-global-warming

or

http://www.sciencedaily.com/releases/2010/01/100131145840.htm

This summarizes the following article in Science:

http://www.sciencemag.org/content/327/5970/1219.abstract

I’d say it can be stated with quite a bit of confidence. One of a whole lot of things that are interesting about this paper is that it makes a mockery out of the “settled science” assertion of the Warmists, who failed to predict this.

Another is that I don’t believe that anybody knows why atmospheric water vapor is increasing or decreasing. Even warm-biased Science magazine has published the article with a statement that the observed 10% modulation of water vapor might have been responsible for 35% of the supposed temperature anomaly.

Interesting hypothesis: a less active sun permits more GCRs to penetrate. This has a quadruple effect on the climate — radiation cascades nucleate clouds at lower saturations, much as do aerosols. The clouds have a high albedo (net cooling). The clouds form at lower altitudes, so that outgoing cloudtop radiation in the water window is warmer than it would be otherwise (weaker GHE). When clouds form lower, less water vapor is left over for transport to the stratosphere, which then becomes more transparent to outgoing GHGs radiating at the top of the troposphere, which in turn lowers the optical depth and raises the temperature where the Greenhouse cooling occurs, which in turn further lowers the tropopause (shifts the entire lapse rate downwards) as the atmosphere underneath is less buoyant.

A change in the mean albedo of the Earth of 0.01 implies a change in mean temperature of around a degree K. From the links above, the 10% variation in stratospheric H_2O may be responsible for anywhere from 0.1 to 0.2 of the temperature anomaly over the last 30 years (although resolving that is nearly impossible, given all of the factors). The lowering of clouds and the troposphere may have a bigger effect in the long run than either of the above. Even solar irradiance itself drops some with lower magnetic activity.

What we could see is that solar modulation of climate is by far and away the largest factor, literally dwarfing the other factors. Since the twentieth century contained a 9000 year Grand Solar Maximum, it could well be that almost all of the heating observed in the latter part of the twentieth century can be attributed directly to the Sun, with only a few tenths of a degree attributable to increased CO_2. If one looks at the speed with which the climate has changed in the past in response to solar state and the magnitude of the variations, this becomes a rather plausible possibility.

Another question: It took decades for stratospheric water vapor to build up and peak in the 80’s and 90’s. It’s dropped 10% in around a decade since. Is it finished dropping? Since we don’t know why it went up we can hardly predict when it is finished going down. Since we have no good measurements that stretch further back than the satellite era, we literally have no data from a non-active sun and cannot computer the relaxation time of the system in any reliable way. If the solar hypothesis above is correct, we may not be particularly close to finished — stratospheric H2O could drop another 20-30% as the anemic sun limps through the rest of this cycle and into the next, probably even less active one. This in turn could drop global temperatures buy — how much? 1-2K from albedo, 0.3-0.4K from extending radiative cooling of CO_2, farther down into the troposphere, 0.5K-0.1K from the shrinking of the thermosphere itself due to cooling and alteration of the lapse rate. — we could see global temperature drops from 1 to as many as 3 or 4 degrees Kelvin — back to levels not seen for 160 years.

Perhaps not quite a new “LIA”, but a new Dalton minimum, complete with radically lowered temperatures.

Settled science, yeah, sure.

rgb

88. IAC, regardless of what you finally decide on whether or not something can cooled slower, hopefully you have learned enough to stop making the straw man argument that the GHE is about sucking heat from the colder air into the warmer surface. This is not how the GHE is hypothesized to work.

Hear, hear!

rgb

89. The Second Law of Thermodynamics does apply for radiation and you need to remember that radiation is not itself thermal energy. It is only converted to thermal energy when it strikes a target which is cooler than its source – which is why heat only transfers from hot to cold and not from a cold atmosphere to a warmer surface. The target detects the temperature of the emitter by way of its peak frequency which is proportional to its absolute temperature. Radiation which is neither reflected nor converted to thermal energy is merely scattered and thus has no more effect than that which is reflected.

So there is no heat transfer from the cooler atmosphere (as per Second Law) and without any heat transfer from the atmsophere, there can be no slowing of the cooling rate of the surface.

I’ve been whacked for this myself, so permit me to whack you, because here it matters. You mean to say no net heat transfer. Net heat. Otherwise your statements are laughably wrong. You are also making a straight up error regarding “targets detecting temperature of emitters”. Piffle. A photon does not come with a label for the process that created it, and even blackbody radiation viewed as a semiclassical continuum, once emitted, just becomes “radiation”.

Finally, you are horribly misrepresenting the nature of the GHE. Forget about upwelling and downwelling radiation. I agree that the way that is described is a nightmarish mess — it is filled with incorrect heuristics and oversimplifications. But the GHE does not rely in any intrinsic way on that. All you need to know to understand the GHE is what the top of atmosphere radiation spectrum looks like.

Here is the GHE in a nutshell:

To the extent that the Earth’s outgoing radiation budget comes from greenhouse gases in the cool upper atmosphere — in e.g. the CO_2 band at 150-200K — it must come from warmer sources in the non-CO_2 band(s) in order for the total outflow to equal the average inflow and maintain roughly constant temperatures.

Honey Badger just don’t care how the heat redistribution happens to manage this. Make up any story you like about upwelling or downwelling radiation, conduction, convection, storage in the ocean, or invisible fairies moving it around. At the end of the day, the non-CO_2 radiators have to be hotter to compensate for the colder CO_2 radiators in order to get just as much energy out of the Earth, on average, per day, month, year, whatever.

It’s really that simple. If you have a hose and put your finger over the end to slow the flow over one part of the end, it has to speed up elsewhere to maintain the same flow and the pressure inside the hose has to go up to provide the force that speeds it up. The exact same thing describes the GHE. The Sun is the input of the hose, the upper atmosphere CO_2 is the finger, and it gets warmer on the surface to provide the additional pressure in the non-obstructed channels.

rgb

90. George E. Smith; says:

“””””
Doug Cotton says:

February 11, 2012 at 5:23 am

The Second Law of Thermodynamics does apply for radiation and you need to remember that radiation is not itself thermal energy. It is only converted to thermal energy when it strikes a target which is cooler than its source – which is why heat only transfers from hot to cold and not from a cold atmosphere to a warmer surface. The target detects the temperature of the emitter by way of its peak frequency which is proportional to its absolute temperature. Radiation which is neither reflected nor converted to thermal energy is merely scattered and thus has no more effect than that which is reflected. “””””

So Doug, this is some new Physics which was previously unknown to me.

Radiation only converts to thermal energy when it strikes a target that is cooler than the source.

So precisely WHAT does radiation convert to when it strikes a target, that is NOT cooler than the source ?

If I have a 250 feV photon, with a wavelength of 5,000 km, emitted from a 60 Hz power transmission line, which is at say 300 Kelvins (about 27 deg C) and it strikes the radiator of my car which is starting to cool down from around 350 K, what will happen to that photon ?

What if that 250 feV photon came from the sun at 6,000 K; what happens if that one hits my radiator ?

How about if the photon is 1 MeV instead of 250 feV ?

How do you tell what the source Temperature was, if all you know about the photon is its energy ?

Any object at any Temperature above zero Kelvins, is capable of emitting both a 250 feV photon, and a 1MeV photon at the same time; how do you tell what Temperature the source was ?

91. George E. Smith; says:

Looked at “YOUR” website Doug; and I noticed that all of “YOUR” climate research is copyrighted; well that’s what it says at the bottom of your site.

Some of “YOUR” research results look remarkably like ones already well known from other authors.

So what, if any of that stuff on your site is your own work that you are entitled to protect.

I presume that you have authorization from the authors of the other stuff to use their materials without attribution.

92. The Second Law of Thermodynamics does apply for radiation and you need to remember that radiation is not itself thermal energy. It is only converted to thermal energy when it strikes a target which is cooler than its source

Absolute piffle. On both counts. The second law applies just fine to radiation, in contexts where thermodynamics makes sense. Blackbody radiation is thermal energy — just not thermal energy that happens to be in matter at the time. You can integrate over it, sum over its density of states, do statistical mechanics with it. In fact, it was one of the earliest places statistical mechanics was done, and doing it correctly led to the discovery of the photon and quantum mechanics.

As for radiation not being absorbed by a target that is “cooler than its source” — you have to be kidding me, right? Electromagnetic energy does not come labelled with the temperature of its source. The “temperature” of a laser can be thought of as being anything from ambient to (in the relevant energy levels)negative — lasers operate with an inversion, see:

http://en.wikipedia.org/wiki/Negative_temperature#Lasers

Are you suggesting that laser light is never absorbed by any target, because every single bit of matter in the Universe is “hotter” than the source?

Here’s a hint for you. z-directed monochromatic electromagnetic radiation is, classically (which is more than adequate for this discussion) e.g. $\vec{E}(z,t) = \hat{x} E_0 \sin(kz - \omega t)$, $\vec{B}(z,t) = \hat{y} \frac{E_0}{c} \sin(kz - \omega t)$ — (simple x-polarized plane wave). This plane wave can be produced an infinity of ways, by sources at any temperature you like. It can be — and will be — absorbed to some degree by any ordinary matter. How much is absorbed depends on many things, and temperature is certainly one of them — absorption by a plasma, a solid metal/conductor, a solid insulator, a liquid (conductor or non-conductor) and a gas will all usually be quite different and functions of the wavelength (associated with something called “dispersion”). You might want to actually take a course in electrodynamics where you learn about things like Kramers-Kronig relations:

http://en.wikipedia.org/wiki/Kramers%E2%80%93Kronig_relations#Electron_spectroscopy

and the complex part of the dielectric constant for ordinary dispersive matter before making absurd statements. I, on the other hand, have taught such courses at the graduate level for years and have written a textbook on classical electrodynamics to support this activity:

http://www.phy.duke.edu/~rgb/Class/Electrodynamics.php

You are welcome to use this text to learn, although you might find it easier to start with e.g. Griffiths first instead. In the meantime, permit me to make a categorical professional pronouncement:

Ordinary matter can and does absorb electromagnetic energy from sources that are hotter, colder, and at the same temperature as the absorbing matter (where absorbed energy is almost always mostly or partly converted to “thermal energy”, although most thermodynamics textbooks shy away from such terminology because how much actually gets so converted depends, does it not, on how much work the absorbing system does in the process). Come to think of it, you could probably stand a refresher in thermodynamics as well.

rgb

You, sir, are simply wrong.

rgb

93. Phil. says:

Doug Cotton says:
February 11, 2012 at 5:53 am
Strictly speaking I should have said it is impossible to slow the rate of cooling of anything in a vacuum without adding thermal energy. In practice, however, when the Earth is cooling at night the atmosphere at the surface is cooler and cooling faster than the surface, so no significant insulation is happening.

In practice the surface is frequently cooling faster than the atmosphere at night, causing an inversion!
Yet another area of physics that you’re wrong about.

94. Australian Gov Radio (ABC) spins this into a story about the sky falling in. The story is introduced thus:

This is a story for anyone who’s ever been accused of having your head in the clouds. It now appears there’s evidence that the sky could actually be falling in. Research on changes in cloud height has found that clouds are lowering now than ever in the past and this could be the earth’s way of dealing with global warming.

http://www.abc.net.au/news/2012-02-25/clouds-falling-according-to-nasa-research/3852450


text:
Compute plant number

plant_number(acres, plant_spacing, row_spacing)

## Arguments

acres The area of the crop in acres. The plant spacing of between plants in a row in metres. The row spacing between rows of plants in metres.

## Value

The number of plants in the field.

format: plain


text:
Department of

Mathematics

Seminar Calendar
for Hani events the day of Tuesday, November 14, 2017.

.
events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
     October 2017          November 2017          December 2017
Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa
1  2  3  4  5  6  7             1  2  3  4                   1  2
8  9 10 11 12 13 14    5  6  7  8  9 10 11    3  4  5  6  7  8  9
15 16 17 18 19 20 21   12 13 14 15 16 17 18   10 11 12 13 14 15 16
22 23 24 25 26 27 28   19 20 21 22 23 24 25   17 18 19 20 21 22 23
29 30 31               26 27 28 29 30         24 25 26 27 28 29 30
31

Tuesday, November 14, 2017

4:00 pm in 245 Altgeld Hall,Tuesday, November 14, 2017

Nonlinear dispersive equations on large domains and wave turbulence

Zaher Hani   [email] (Georgia Institute of Technology)

Abstract: In this talk, we will be mainly concerned with the following question: Suppose we consider a nonlinear dispersive or wave equation on a large compact domain of characteristic size L. What is the effective dynamics when L is very large? This question is relevant for equations that are naturally posed on large domains (like the water waves equation on the ocean), and in turbulence theories for dispersive equations. It’s not hard to see that the answer is intimately related to the particular time scales at which we study the equation, as one often obtains different effective dynamics on different timescales. After discussing some relatively “trivial” time scales (and their corresponding effective dynamics), we shall attempt to access longer times scales and try to describe the effective equations that govern the dynamics there. The ultimate goal is to reach the so-called the “kinetic time scale” over which it is conjectured that the effective dynamics are described by a kinetic equation called the “wave kinetic equation”. This is the main claim of wave turbulence theory. We will discuss several results that are aimed at addressing the above problematic for the nonlinear Schrodinger equation. Recent results are joint works with Tristan Buckmaster, Pierre Germain, and Jalal Shatah.


text:
Physics Help Forum Heat Equation with Neumann Boundary conditions
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 Sep 24th 2010, 03:48 PM #1 Junior Member   Join Date: Sep 2010 Posts: 1 Heat Equation with Neumann Boundary conditions I posted this in MathHelpForums, so I figured I'd post it here as well (since some one here has to know about calculating a heat equation) As I can't seem to get latex to work here, I'll just post a link My Post

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