A paper published Friday in the Journal of Geophysical Research (GRL) finds that a known and natural atmospheric oscillation, the Southern Annular Mode or SAM, is correlated with observed increases in cloud cover resulting in regional cooling of approximately -2.5C. See for example this comparison from the paper with MODIS satellite data:
From UCAR:
The Southern Annular Mode (SAM), which is defined by changes in the westerly winds that are driven by temperature contrasts between the tropics and southern polar areas. The annular modes generally take a circular pattern (‘annular’ means ring-shaped) and see-saw between positive and negative phases for weeks or months. In the SAM’s positive mode, the ring is stronger and further south, inhibiting Antarctic air outbreaks. In the negative mode, a weaker, more variable vortex allows Antarctic air to spill north more easily.
The Southern Annular Mode has steadily trended positive in recent decades. Computer models indicate this trend is related to ozone depletion above Antarctica and increases in greenhouse gases. (Image courtesy Jianping Li, China Institute for Atmospheric Physics.)
As presently programmed, climate models assume clouds result in net positive feedback and increased temperatures, however this new paper and several others that have recently been published show that clouds instead result in net negative feedback and cooling.
Key Points of the paper:
- Sudden regional increases in cloud cover are detected over S. America
- Changes linked to the Southern Annular Mode
- The cloud changes are associated with regional temperature reductions
The paper and abstract:
Understanding sudden changes in cloud amount: The Southern Annular Mode and South American weather fluctuations
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 117, D13103, 7 PP., 2012
doi:10.1029/2012JD017626
Benjamin A. Laken Instituto de Astrofísica de Canarias, La Laguna, Spain, Department of Astrophysics, Faculty of Physics, Universidad de La Laguna, La Laguna, Spain
Enric Pallé Instituto de Astrofísica de Canarias, La Laguna, Spain, Department of Astrophysics, Faculty of Physics, Universidad de La Laguna, La Laguna, Spain
This work investigates the cause and effects of extreme changes in synoptic-scale cloud cover operating at daily timescales using a variety of satellite-based and reanalysis data sets. It is found that the largest sudden increases detected in globally averaged cloud cover over the last ten years of satellite-based observations occur following positively correlated shifts in the phase of the Southern Annular Mode (SAM) index. The associated pressure anomalies are found to generate frontal cloud formation over large areas of the South American continent, increasing regional cloud cover by up to 20%; these changes are correlated to statistically significant reductions in local temperatures of approximately −2.5°C with a +1 day time lag, indicating the SAM index is associated with large scale weather fluctuations over South America.
It’s no surprise that clouds are a negative (cooling) feedback. A warming cloud feedback is just a fiddle in the models.
A positive correlation with the Southern Annular Mode (SAM) index surprises me. I’d expect a negative correlation. More polar outbreaks = more clouds.
What strikes me is the fact that a paper so trivial is considered “novel”.
Pure logic will tell you that clouds cannot have a positive feedback, since if they had, the Earth would have been destroyed long time ago. And if they do not have a positive feedback they must have negative one.
I am hoping to put together an article on the site I post to, about all the various negative feedback research papers which seem to have come out in the past year (hints would be appreciated! 😛 ), in regards to their clearly opposite nature to the Positive feedbacks figured for the same, in the climate models.
So if ya’ll don’t mind, two questions:
1. Are there NO negative feedbacks at all, in the models?
2. I don’t understand how clouds could possibly be a positive feedback- it just seems to me to suggest, that they posit some kind of roof over the atmosphere, as though Nothing could escape into space…
I rather like this understated way of suggesting the the models “indicate a trend” rather than prove that we’re all doomed
@Eyal Porat says “Pure logic will tell you that clouds cannot have a positive feedback, since if they had, the Earth would have been destroyed long time ago.”
That may be pure logic, but it is wrong. The largest feedback is the increase in longwave IR radiation from the earth caused by an increase in temperature. The system remains stable, with net negative feedback as long as the sum of the various positive feedbacks are less then this dominant Stefan–Boltzmann. In most climate science literature, a “net positive” feedback refers to only those terms other than the overwhelming Stefan–Boltzmann feedback term. It’s a confusing choice of terminology, but climate scientist often use different terms for things well know I other fields.
If clouds were a positive feedback it would follow that if clouds were made to completely cover the earth the global average temperature would increase.
Who can justify why this should be true?
I can envisage that cloud cover at night would slow cooling as in the day it would slow warming but I find it difficult to understand how the slowed cooling could be greater that the slowed warming.
Just one of the reasons I’m a sceptic when it comes to CAGW.
Seems some people have confusion about the warming and cooling roles of clouds … lots of technical references on this, but a simple statement from Wikipedia: “Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect.”
Edits:
negative cloud feed associated with SAM — feedback ??
climate scientists … well known in other fields ??
otter…i would LOVE to see that when you are finished. can you tell us what site you post to?
These scientists,
http://www.agu.org/pubs/crossref/2010/2009GL041320.shtml
estimate an increase in wind speed of less than half a metre per second per decade since early 1980s has made these seas choppier, resulting in more aerosols which give more cloud nuclei, resulting in an 85% increase in some regions.
Would that be more cloud cover or more intense weather systems?
Either way wouldn’t in result in an intensification of pressure systems and so more aerosol production?
They say it results in a substantial negative climate feedback.
“The change in cloud drop concentrations causes an increase in cloud reflectivity and a summertime radiative forcing between at 50 and 65°S comparable in magnitude but acting against that from greenhouse gas forcing over the same time period, and thus represents a substantial negative climate feedback.”
Bradley
In the SAM’s positive mode, the ring is stronger and further south, inhibiting Antarctic air outbreaks
http://virakkraft.com/SAM-temp-SH.png
Otter says:
Yes…There is the lapse rate feedback. That feedback says that the temperatures at the altitude most important for radiating infrared radiation back out into space tend to increase more rapidly with warming than the temperature at the surface and hence that it takes a smaller surface temperature warming to counteract a certain forcing than would otherwise be the case.
This negative feedback involves a lot of the same physics as the water vapor feedback (a positive feedback). Hence, models that have a larger (in magnitude) lapse rate feedback tend to have a larger in magnitude water vapor feedback. This means that although there is a fair bit of variation in the lapse rate feedback between models, there is much less variation in the sum of the two feedbacks.
There seems to be a constant confusion among AGW skeptics between the radiative effect of clouds and the feedback from clouds. To determine the feedback due to clouds, you have to know both the radiative effect and the effect of increasing temperature on clouds. (And, it is not intuitively obvious how clouds vary with temperature. You might think that since water vapor increases with temperatures, clouds do too. However, the saturation vapor pressure also increases with temperature. And, in fact the water vapor is expected to increase with temperature in such a way that the average relative humidity will stay pretty close to constant or more even decrease slightly.)
So, even though the net radiative effect of clouds is negative (i.e., clouds on average cool due to increasing albedo more than they warm due to a greenhouse effect of reducing the escape of IR radiation from the Earth to space), if the effect of increasing temperature in the current climate is to reduce cloudiness rather than increase it, then this could be a positive feedback…i.e., cause additional warming.
As it turns out, there is the additional complication that although the net radiative effect of all clouds is cooling, the sign of the effect can vary with the type of cloud: Low clouds tend to have a net radiative cooling effect (because the albedo effect wins out over the greenhouse effect) but high clouds tend to have a net radiative warming effect (because the greenhouse effect wins out over the albedo effect). [These basic principles are not controversial, by the way: Skeptical atmospheric scientist Richard Lindzen’s iris hypothesis proposed that warming in the tropics would decrease high clouds and therefore produce a negative feedback.]
Truth is an iterative process. First you admit that clouds cool by day. Then you admit the same cooling occurs with only the slight delay of OLR at night. Finally you admit that ‘slower cooling’ is NOT warming.
Clouds are not static stage props. The multiple layers of vertical wind shears within a cloud come from the very nature of clouds, ‘boiling’ in mid air with high velocity invisible water vapor rising past colums of newly condensed cold droplets falling inside clouds.
In my article “Science Goes Over-Under, Inside-Out” I describe my thoughts on clouds while sitting alone….inside a cumulus cloud….in a Cessna 150. This massive convective energy transfer from cloud bottoms to cloud tops has NO radiative component and is hence not in the non sequitur K-T budget. Be a Joanie Mitchell and “Look At Clouds from Both Sides Now”.
charliexyz says:
July 7, 2012 at 3:52 am
@Eyal Porat says
The IR radiation could not have happen if the clouds covered the earth completely. They may hold some of the radiation from going back to space, but the initial cause of the IR radiation (i.e. the sun) is the existence/lack of clouds.
So they are a mitigating factor = negative feedback.
Hence their feedback is not net negative, but the overall effect is: more clouds -> less heat reaches the earth -> cooling, and vice versa.
I seriously doubt and contest that ozone has anything to do with climate. It is too high and to thin to have the effect or abilities that they attribute to it. Just as with CO2, they have this gas bias and give it superpowers.
fredb says: July 7, 2012 at 4:12 am
“Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect; ”
Er, No. The IR radiated downward has no effect on the surface as those energy levels are already full. It has to be reflected back upward. Clouds simply slow the loss of IR to space, but back radiation does not exist as a factor that does anything.
The paragraph that begins “As presently programmed…” does not seem to be from the UCAR cite. Perhaps this was an editing error.
https://www2.ucar.edu/news/backgrounders/weather-maker-patterns-map-text-version
Is this the same as the paper on ‘The Iris Effect’ ?
Hey! What about the recent contiguous continental US heatwave? Is this related to a DECREASE in cloud cover over the region?
There has been a noted 5% or so reduction in cloud cover globally over the past 50 years (the data is poor from what I’ve seen, like the CERES project). If things like SAM increase cloud cover by 20% in South America, there must be equal areas that have decreases of 15% to maintain the average (if S.America is the only area of net increase).
I worked up a paper on cloud cover changes in the central UK that accounted for the central UK temperature changes (plus PDO/AMO patterns) (NothingSettledNothingCertain.com). My work and this paper (and others) confirm to me the suspicion that most of global warming was not global but regional. Global warming is an aretefact of addition and division. The human tendency to generalize from the specific, and to bias all thoughts to support personal experience, means that Americans seeking refuge from a heatwave see the world warming catastrophically. If – as in the early ’70s? – the American Heartland was plunged into a freezer while Europe broiled, America would be worried about (again) a returning Ice Age.
The Russian heatwave and the current American heatwave: is this a cloud cover effect or a “global warming” effect? I’m betting on cloud cover. I recall grandparents who spoke of their mothers crying on the farmhouse steps because another day had started out with beautiful, blue skys – a routine, I was told, that lead to 7 years of failed crops in southern Saskatchewan.
It always seems to come back to clouds. Svensmark clouds, that is.
The important thing is convection, which serves as a kind of “end run” around the greenhouse effect. Clouds are incidental to convection. The significant effect of clouds is to moderate temperature swings, which should theoretically result in some warming because outgoing radiation goes as the fourth power of surface temperature. Also, assuming that increased albedo will result in cooler surface temperature ignores the fact that both the surface and the cloud are approximately greybodies and so should behave nearly the same with respect to incident radiation.
The big negative feedback is simply convection, which causes a parcel of air that is heated above a temperature given by the adiabatic lapse rate to rise to a level where it can “see” space and get rid of the excess heat. The presence of moisture augments this process because now phase change (rain) helps to move the heat upward and overcomes any tendency of clouds to warm the surface. Incidentally, the moisture content of the atmosphere is also set by the adiabatic lapse rate, so assuming any positive feedback on surface temperature from moisture content is questionable ab initio. Any process that does not help the earth to reject heat is not energetically favorable because it retards the increase in entropy that the universe is trying so valiantly to achieve. Perhaps that’s why CO2 concentrations have been so low for so long, before we arrived.
Yes, greenhouse gases will produce backscattered radiation at the surface and feed thousands of climate scientists with no other means of support, but convection will reduce the effect to insignificance.
Joel Shore:You might think that since water vapor increases with temperatures, clouds do too. However, the saturation vapor pressure also increases with temperature. And, in fact the water vapor is expected to increase with temperature in such a way that the average relative humidity will stay pretty close to constant or more even decrease slightly.)
Yes, but the problem with the above is that air does not stay at one average temperature typically over the course of a day(or a year). Rather it warms, then cools in sequence. Given a more or less constant RH, per the Clausius-Clapeyron relationship, then a warmer on average air mass will condense a greater amount of moisture than a cooler one.
It is pretty hard to square this relationship without assuming that cloud feedback is negative with regard to temperature.
Cheers, 🙂
pochas says:
This does not make sense. Convection can’t do an “end run” around the greenhouse effect because ultimately the energy has to escape the Earth system via radiation. To the extent that one can make something sensible out of your argument, what it would imply is the notion that the mid- and upper- troposphere can heat up without the surface temperature heating up too…but, to the extent that this is true, it is already accounted for by the lapse rate feedback. There is no evidence that this effect is being underestimated. (In fact, some people claim that the supposed lack of the so-called “tropical hotspot” in the troposphere is evidence that it is being overestimated, although the wiser money is probably on the notion that it reflects residual problems with long-term trends in some of the satellite and radiosonde data analyses. Still, the notion that the amplification is actually much larger than the models predict certainly is something with no experimental support.)
Shawnhet says:
My point is simply that the complexity of the issues defies attempts to reach very simple conclusions about how clouds will behave in a warming climate. Your intuition that cloudiness will increase contradicts Lindzen’s intuition that at least some types of clouds (high clouds in the tropics) will decrease. That ought to give you pause if you think that you can come to a conclusion on the basis of any extremely simple ideas.
charliexyz says:
July 7, 2012 at 3:52 am
You do realize you haven’t one iota of evidence for any of the garbge you regurgitated?
“So, even though the net radiative effect of clouds is negative (i.e., clouds on average cool due to increasing albedo more than they warm due to a greenhouse effect of reducing the escape of IR radiation from the Earth to space), if the effect of increasing temperature in the current climate is to reduce cloudiness rather than increase it, then this could be a positive feedback…i.e., cause additional warming.”
1) You’re defining the “greenhouse effect” as a reduction in the escape of IR radiation from the Earth into space, yet in a real greenhouse the warming (inhibition of cooling) seen is due to an inhibition of air movement rather than an entrapment of IR radiation. (Empirical experimentation has demonstrated this time and again.) In the real world atmosphere air movement results from temperature differentials. One can empirically measure the fact that when it is cloudy at night the temperature differential between the ground and the air is reduced by about 1/2. This significantly decreases the vigor of nighttime upward convection currents and naturally results in a slower rate of nighttime ground cooling. This is, indeed, a quasi-greenhouse effect, but it is caused by a reduction in air flow rather than the entrapment of IR radiation. In the absence of clouds regardless of the level of humidity (the primary greenhouse gas) the temperature differential between the air and the ground *increases* during the course of the night, which is an anti-greenhouse effect. This anti-greenhouse effect seen on cloudless nights is a repetitive, observable phenomenon that can be measured by anyone anywhere in the world with two thermometers; one about 1.5 meters off of the ground and one placed at ground level. After placing the thermometers take readings every thirty minutes during the night and you will observe that as the cloudless night progresses the temperature differential between the ground and the air will widen, regardless of how humid it is. An extreme form of the quasi-greenhouse effect that low-level nighttime clouds create can be seen during a nighttime temperature inversion. Such temperature inversions are invariably accompanied by a dead calm.
2) The hypothetical warming affect of increased CO2 levels is said to be augmented by a resultant increase in humidity, which further warms the atmosphere, which leads to further evaporation of water and even more humidity. Within which empirical study of the climate has an increase in humidity led to a decrease in cloud cover?
According to the “greenhouse effect” hypothesis even the lessor GHG’s, like CO2, require the presence of water vapor, i.e., water vapor feedback, to have a significant affect on the temperature. Therefore, when and where it is both hot and dry the heat cannot be the result of the “greenhouse effect” since the hypothetical “greenhouse effect” is dependent upon water vapor for its operation. Ergo, the humidity in Huntsville, Alabama cannot be the cause of the heat present in Death Valley, CA., which is on average several degrees C warmer than Huntsville. So, Huntsville, whose air is flooded with the greenhouse gas water vapor, is not only cooler; it is also teaming with life, while arid Death Valley, which is greenhouse gas deficient, i.e., very little water vapor, is not only hotter; it’s ability to support life is severely limited. The “greenhouse effect” hypothesis asserts that it would be a climate catastrophe if the world becomes more and more like Huntsville and less and less like Death Valley; that is, becomes more and more humid.
Carl
Joel Shore:”My point is simply that the complexity of the issues defies attempts to reach very simple conclusions about how clouds will behave in a warming climate. Your intuition that cloudiness will increase contradicts Lindzen’s intuition that at least some types of clouds (high clouds in the tropics) will decrease. That ought to give you pause if you think that you can come to a conclusion on the basis of any extremely simple ideas.”
Well, it seems to me that simple conclusions are reached one way or another here. You can either assume that cloud feedback is 0, negative or positive. My point, however, is that by using *the very same logic* that assumes the RH will be more or less constant, you will also be led to the conclusion that a warmer atmosphere will condense more than a cooler one.
See here:
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/relhum.html#c4
I don’t recall the precise details of the Iris hypothesis but doesn’t it go something like this? Drier conditions decrease precipitation efficiency which allows moisture to “survive” in the atmosphere for a longer period before raining out. Low precipitation efficiency is directly related to the formation of cirrus clouds which act to raise surface temps. As such, I don’t necessarily see any contradiction between what I am saying and the Lindzen hypothesis.
Cheers,:)
joeldshore says:
“This does not make sense. Convection can’t do an “end run” around the greenhouse effect because ultimately the energy has to escape the Earth system via radiation.”
Your comment defies common sense. Of course heat can rocket upwards via convection and get above 95% of the radiation blocking CO2. That is what I would call an end run. The only question is, why are climate scientists not including this real effect into their models? I LOL when I watched thos professors lecture at U of Chicago on radiative physics. It was a static model! I cannot imagine any student being so dumb as not to see through that charade!
joeldshore says:
My point is simply that the complexity of the issues defies attempts to reach very simple conclusions about how clouds will behave in a warming climate. Your intuition that cloudiness will increase contradicts Lindzen’s intuition that at least some types of clouds (high clouds in the tropics) will decrease.
Reduction in high cloudiness has occurred,
And that also has a cooling effect!!!!
A consistent reduction in cloud height would allow Earth to cool to space more efficiently, reducing the surface temperature of the planet and potentially slowing the effects of global warming. This may represent a “negative feedback” mechanism — a change caused by global warming that works to counteract it.
http://www.auckland.ac.nz/uoa/home/news/template/news_item.jsp?cid=466683
Carl B can have some of my tax money. I don’t want Joel S to have a cent–he should go find a productive job.
[Moderator’s Note: Ken, that was not really called for. Joel does have a productive job and is easily located on the internet. Maybe we can stick to substantive arguments? -REP]
Dear Moderator. I disagree. Joel is an academic and gets a paycheck that is partially funded by tax dollars. In my opinion, he does a lot of damage supporting wrong-headed ideas about human-caused global warming. As long as he sticks to his OLEDS, I have no problem, but he’s a vocal supporter of AGW. What is he saying in the classroom? Does he present both sides of our ongoing argument? I doubt it. I pay a lot in Federal Income taxes and I object to any of it going in his direction. That’s fair enough, isn’t it?
[REPLY: Ken, RIT is a private institution. I am not aware of any private institution that does not take government dollars in one form or another. Do you really want the government deciding what can or cannot be taught because they fund some of the programs? Asking for a level playing field means that Joel gets to teach the subject as he understands it, just as I, in another life, get to teach my subject as I understand it. Criticism is the name of the game. Joel does real work, and if you disagree with his perspective, as I do, engage it substantively or expose the errors. My university accepts Federal dollars and we would all be upset if someone objected to my society and environment lecture and demanded I go out and get a real job. -REP]
I do get your point and if you want to edit my comment as follows, I understand. Your house, your rules.
Carl B can have some of my tax money. I don’t want Joel S to have a cent–[Snip].
In the last three decades there has been on average a 22% increase in cloud condensation nuclei between 50 and 65 deg South due to increasing wind speed.
“These fractional increases are similar in magnitude to the decreases over many northern hemisphere land areas due to changes in air pollution over the same period.”
http://www.agu.org/pubs/crossref/2010/2009GL041320.shtml
Changing aerosol concentrations appear to be the factor which dictates the amount of cloud cover. Salt aerosols make effective water attracting, cloud forming c.c.n. whereas dark silt aerosols might be more heat absorbing and less likely to act as c.c.n. and there is a plethora of different forms of aerosol in between.
Regional and seasonal variations in aerosol concentrations must play an important role in dictating how climate changes. They may have short lifetimes but there is a constant supply, they can be wet (in clouds) or dry, either way they are shifting energy about.
Is my view of their major climatic influence misguided?
Re positive/negative feedback
I also have been bemused by the question of clouds and negative v. positive feedback.
I have posed a thought experiment for myself –
1. Assume a steady temperature, evaporation rate etc etc.
2. Now suppose that there is a rise in temperature from some cause
3. That causes an increase in water vapour in the atmosphere
4. That in turn causes an increase in temperature
5. And so forth and so on (and not a sign of CO2…after all it’s only a thought experiment).
What is wrong with this picture?
I compare this with the theory that CO2 causes some warming, which is ‘amplified’ by water vapour, which increases warming….
And so I wonder: “Why has the planet not overheated long ago?”
As an engineer, I am constantly seeking and applying forces and materials and effects that are useful…that do work. It troubles me when academics put such faith in their models and constructs. Literally, they invent things out of thin air. Don’t you know how useful if would be to heat something by an average of 33C (GHE)? Or, how useful it would be to heat something by an average of 66C (by doubling the GHE)? Or, how useful it would be to cool something by an average of 33C (by blocking or defusing the GHE)? However, the activists say, you can’t make this powerful force of nature work on command in your living room–you must have thin layers of cold, rarefied gases to make this powerful heating engine work.
It would be easy to shut me up. Just tell me how long the GHG delay is for energy leaving our system. What is the median delay? What is the distribution of this delay? Is the delay uniform from the tropics to the poles? How does a small delay in OLWR change an average temperature in a diurnal system? How long must the delay be to contribute positive feedback: 9 hours or so? 12? Is that how long it takes for photonic energy to leave our system? The incoming delay is something like 2 hours for materials (land and water) with greater thermal mass and a longer thermal time constant than air. The outgoing delay is longer than that? Prove it.
There is nothing wrong with the picture except that you seem to have failed to understand the fact that an infinite series does not necessarily diverge. For example, if 1 C of warming due to CO2 causes 0.5 C of warming via the water vapor feedback, then the feedback on that amount will cause an additional 0.25 C of warming, and the feedback on that will cause an additional 0.125 C of warming. The geometric series 1 + (1/2) + (1/4) + (1/8) + … does not get larger and larger without bound; rather, it approaches 2 as you approach an infinite number of terms.
Ed_B says:
The climate models incorporate both radiative and convective effects as understood by the laws of physics. So, that means your “rocketing effect” is either included…or it is not included because there is no known law of physics that includes. It is easy to talk in words of magical effects when one is unconstrained by having to actually create physical models constrained by the known laws of physics. People like Stephen Wilde over at tallbloke’s blog have made this into a high art form. As art, its impressive; as science, not so much.
Ken Coffman:
Ken: I think history has proven that nothing can shut you up, as you have had the greenhouse effect explained to you many times by AGW skeptics and those who agree with the scientific consensus alike and it has completely failed to register. We have told you that the issue is not one of delay. It is an issue of the rate in and rate out. You have energy coming in at a certain rate and you have to have energy going out at the same rate. If you do something that decreases the rate at which energy leaves the system, like increasing greenhouse gas concentrations, then the rate at which energy leaves the system will be lower than the rate at which it enters. The system responds by increasing its temperature until the rate out again matches the rate in (which occurs because the rate at which energy escapes is an increasing function of temperature).
This ought not be something that a reasonably competent engineer should have a problem understanding unless they are so ruled by their ideology that they cannot understand anything that challenges it.
Can anyone tell me if what seems obvious to me is actually true? Do sunshine hours recorded act as a proxy for cloud cover in general? This obviously only has daytime relevance but are sunshine hours a good enough indicator of cloud trends overall?
I have the monthly and annual weather means for my area (Palmerston North, New Zealand) going back to 1928. The sunniest years and decades were the 1930’s & 1940’s, although the Noughties came in third overall. The worst period was from 1979 to 1993, with 1980, 1983 and 1992 being the worst individual years.1983 suffered from the effects of El Chichon and Mayon, while 1992 was obviously affected by Mt Pinatubo, so I would surmise from the graph supplied by Jiangping Li that the 1980 low figure was as a result of a positive SAM at the time. The period 1952 to 1968 was also a time of average or below average annual sunshine figures with a few exceptions courtesy of strong La Nina events, in my part of New Zealand strong La Ninas have a positive affect in sunshine hours.
The last three years have seen a return to average and below average sunshine. This last southern summer saw the North Island covered in cloud for long periods while the lower South Island was bathed in sunshine.
As an example of natural oscillation, the first three months of the year here were the 3rd worst for that period while the last three months were the 3rd best on record for sunshine!
Looking at the data for Relative Humidity which I have up until 2000, this has been increasing through the 80’s & 90’s. I must track down the data since 2000 to see how it is running.
The article focusses on what happened in South America last winter but a significant snow event occurred over New Zealand last winter as well. Snow in many places right to the top of the North Island which was last seen in 1939, and to levels and thicknesses not seen in a lifetime. For Palmerston North snow of this nature hadn’t been seen since the winter solstice of 1912, and another big event in August 1904, although there have been other significant events in the valleys to the north which are at a higher elevation.
From what I can tell the oscillating positive/negative phases of SAM are the route cause of the bad weather/good weather patterns that dominate the short term weather patterns. When a negative SAM combines with a strong La Nina we have hot, sunny & dry summers. When a positive sam combines with a strong El Nino phase we have the opposite result.
Cheers
Coops
joeldshore says:
July 7, 2012 at 12:45 pm
“This does not make sense. ”
I’m not surprised; convection is unknown to the IPCC.
joeldshore says:
There is nothing wrong with the picture except that you seem to have failed to understand the fact that an infinite series does not necessarily diverge.
Let us agree immediately that not all infinite series diverge. That is trivial.
But that doesn’t answer the point of the thought experiment.
a) If you look to that part of my comment which follows the thought experiment you will note that my musings are intended to explore the notion that CO2 is responsible for current warming due to the ‘amplifying’ effect of water vapour. (Warming by CO2 alone simply doesn’t account for the extent of warming which some people report that they ‘see’).
It seems to me that what you have argued in relation to warming by water vapour must also apply to warming due to CO2?
b) Where do you get the idea that warming due to water vapour (or CO2 or anything else) is (i) incremental and (ii) most conveniently occurs in just such increments as to form a converging series?
Doug proctor says:
It always seems to come back to clouds. Svensmark clouds, that is.
And aerosol seeded clouds, which have decreased in recent decades over much of the Earth’s land surface, including the UK.
Philip Bradley says:
“And aerosol seeded clouds, which have decreased in recent decades over much of the Earth’s land surface, including the UK.”.
All cloud formations are the result of water vapour condensation on aerosol of some description. Salt and dust being the most prolific. If wind speeds are increasing in the Southern Hemisphere you would expect more salt spray and so more clouds.
I suspect more dust aerosol formation in the NH due to there being more land surface and that this could be playing a role in suppressing cloud formation due to there being more dark, heat absorbing silt aerosol and less light scattering clay aerosol than currently estimated.
http://sitemaker.umich.edu/jasperkok/files/kok2011_pnas_scalingtheorydustpsd.pdf
I think seasonal and regional variations in aerosol concentrations play a part in shaping weather systems.
Many people here are making a major mistake.
One cannot compare regional cloudcover increase with a global trend. The global trend is not a sudden 20% increase in cloudcover. Besides the paper never speaks of a relation between CO2 increase and cloudcover effects, but about an effect caused by the SAM which was probably also there before humans existed on the planet. A natural process.
It is generally known and accepted throughout the scientific community that more clouds will cause cooling, but it remains a mystery so far if cloudcover increase will negate AGW.
However it is funny though that a paper like this is easily projected onto global climate by a lot of posters here (Eyal Porat, Kohl, son of mulder, etc.) and the text of this piece also would like to suggest that cloud cover increase is a big negative feedback (in the >20% range yes, but this increase will never happen globally in the nearby future), while other papers are scrutinezed here to the minute detail for doing exactly the same:
http://wattsupwiththat.com/2011/06/23/reduce-your-co2-footprint-by-recycling-past-errors/
Another funny detail perhaps: If you need a >20% increase in cloudcover to cause a net reduction in temperatures of approximately 2.5°C. What do you think a cloud cover increase of just 1 or 2% will cause for a cooling? That’s the range we are talking about globally. The net effect would still be a good deal of warming.
pochas says:
That is a complete and utter falsehood…but I am sure you had fun saying it.
Kohl says:
I don’t understand the first part of your question…If the warming is not incremental, what is it? The point of this picture is to understand how an incremental view of things (which you adopted in your original post) yields a finite result. It is not necessary to think in this incremental way. One could simply say that the total effect of the entire water vapor feedback is to double the original effect. Or, one can look incrementally and see how that naturally arises for a feedback of the strength where the temperature rise due to the direct first-order feedback effect on a certain temperature increment is to add half again as much of an additional increase in temperature.
The converging series has to do with the strength of the water vapor feedback. The point is that the feedback is not strong enough to produce a divergence. If the first-order effect of water vapor on the original temperature increment were larger than the increment itself, you would get a diverging series. Because it is smaller than the original temperature increment itself, you get a converging series.
pochas: Just to bring you up to speed in regards to the actual science regarding convection and the greenhouse effect – The reason convection does not negate the greenhouse effect is that convection proceeds only as far as driving the temperature distribution with altitude (“the lapse rate”) down to the (appropriate, dry or moist) adiabatic lapse rate. If it were able to drive the temperature distribution all the way to an isothermal distribution with altitude (zero lapse rate) then it would indeed negate the entire greenhouse effect (as was well-known already and most recently re-discovered by Nikolov and Zeller who mistakenly put convection into a simple model in exactly this incorrect way).
Because of this limitation, convection does not cancel out the greenhouse effect, although it does reduce the natural greenhouse effect on Earth by a significant amount from what it would be with no convection. (As I recall, calculations show it would be about a factor of two larger in the absence of convection but all else equal.)
Kohl says:
July 7, 2012 at 3:49 pm
Re positive/negative feedback
I also have been bemused by the question of clouds and negative v. positive feedback.
I have posed a thought experiment for myself –
1. Assume a steady temperature, evaporation rate etc etc.
2. Now suppose that there is a rise in temperature from some cause
3. That causes an increase in water vapour in the atmosphere
4. That in turn causes an increase in temperature
5. And so forth and so on (and not a sign of CO2…after all it’s only a thought experiment).
What is wrong with this picture?
I compare this with the theory that CO2 causes some warming, which is ‘amplified’ by water vapour, which increases warming….
And so I wonder: “Why has the planet not overheated long ago?”
You have only included part of the system (as has Joeldshore).
Step 3 is incomplete. There may be a rise in evaporation from the surface which:
a. Cools the surface due to latent heat of evaporation
b. Takes that latent heat upward by convection – humid air is actually less dense than dry air at the same temperature and pressure – and eventually as the air cools with the lapse rate it reaches 100% humidity and water condenses out releasing latent heat which warms the volume of air which continues convecting upward this time with small water droplets – eventually these water droplets freeze releasing latent heat which warms the volume of air which continues convecting upward this time with small ice crystals the volume cools due to the pressure drop (number of molecules per unit volume). At the same time as this is happening the clouds of droplets and/or ice crystals are reflecting the incoming sun’s radiation reducing the input warming.
4. Might not be the case at all…. the only increase in temperature possible is before clouds form… you _have noticed it gets cooler when a cloud goes between you and the sun haven’t you? and once the clouds get dense enough to rain then the atmospheric temperature can really drop. Any returning long wave radiation will not heat water but may excite surface molecules enough to increase evaporation COOLING the surface.
Your thought experiment did not extend to clouds and rain only to mathematically simple radiation. The majority of heat transport to the Tropopause is convective – once there yes it radiates but the atmospheric density is so much lower that the effect of the increased presence of CO2 is probably more to radiate heat rather than trap it.
5. We don’t get to 5 as 4 was not totally true.
This convective cooling is seen everywhere as part of the water cycle it is why the Earth is largely homeostatic. Initially, the feedback is positive then as the water content of the atmosphere increases its enthalpy increases requiring more heat to raise the atmospheric temperature at the same time the humid less dense air will start rising taking heat upwards in the atmosphere and cooling and the feedback is almost zero – then as clouds form and eventually precipitate the albedo increase and the cold precipitation result in negative feedback to the heating. You can watch this as a daily cycle in the sub-tropics and tropics all the time.
Stefan-Boltzmann does not apply inside layers of convecting fluids with energy dependent state changes in the gaseous fluid with sensible heating from below. You have to be outside the hohlraum.
“Robbie says:
July 8, 2012 at 5:27 am
……… It is generally known and accepted throughout the scientific community that more clouds will cause cooling, but it remains a mystery so far if cloudcover increase will negate AGW.”
I’m glad you recognize that more clouds cause cooling but no one is suggesting that cloud cover increase will negate AGW simply that it will reduce the impact of CO2 increase ie it is a negative feedback and the debate is about CAGW (C=Catastrophic) not about the AGW component derived from anthropogenic CO2 which is approx 1.2 deg C (fairly uncontroversially) without positive or negative feedbacks for a doubling of atmospheric CO2.
Joeldshore says (inter alia)
“The converging series has to do with the strength of the water vapor feedback. The point is that the feedback is not strong enough to produce a divergence. ”
Well yes…. that’s a good part of the point I am making.
IF the ‘greenhouse’ effect was as advertised, then the earth would already be ‘too hot’ (whatever that might mean)
Exactly the same criticism you level at my thought experiment considering water vapour MUST apply to warming caused by CO2. Theoretical considerations would seem to show that this is only a problem if you think that direct warming caused by CO2 is ‘amplified’ by the effect of water vapour.
And again, Joel, you have not answered this part of my original post
As for my answer b) – I suppose it is unfair to berate you for ‘incrementalising’ warming after I set it up that way in my thought experiment. So… I will concede your criticism of that part of my answer to you. However, the rest stands – why should the warming be of just such a value that it supports your convergence example. Might it not be of such a value that you get a diverging series? But that’s not what I am proposing. In fact I agree that the facts show that the figure, whatever it is, is not diverging.
The point is that the earth has not, in 5 billion years, progressed to the ‘hot’ endpoint envisaged by those who are worried about the effect of CO2. My thought experiment underlines that fact – it invites a conclusion per contra. The heating supposed to have occurred has not happened. Therefore there is something wrong with the premise(s) of the experiment. I think the error is in supposing that the heating can be viewed as a diverging series (as you have pointed out). I think that whatever heating is going on now or in the recent past has effects that regulate the extent of the warming. I think that this has been going on in one way or another for eons and that there is nothing special in what we now observe.
Ian W says:
“Step 3 is incomplete. There may be a rise in evaporation from the surface which:
a. Cools the surface due to latent heat of evaporation
b. Takes that latent heat upward by convection”
Well of course! But the thought experiment is, after all, rather artificial.
Nevertheless, it raises a problem with the view that CO2 warms the atmosphere and this degree of heating is amplified by the effects of water vapour and in the not too distant future temperatures will get very uncomfortable indeed. And the punch line? All because mankind has been and continues to emit great clouds of CO2.
Now it seems to me that if that were true, then the atmosphere should long ago have reached some much higher temperature due simply to the effect of water vapour alone. The fact that it hasn’t points to other factors some of which may be the ones to which you draw attention.
It all boils down to the net magnitude and sign of the feedbacks. Because of the complexity, you can’t compute it empiracally. It’s knobs in the models that get tweaked to make the models align with past climate.
That’s where Hansen comes in with his series (and, the manipulation, therof). That’s where the paleoclimate folks come in with their debunked hockey sticks (“we have to make the MWP disappear”). Thats where climate-gate and Team tactics come in. That’s where Yamil and “hide the decline” come in. It’s all about justifying that the feedback is anywhere near high enough to justify even the weakest IPCC projections. Well, they failed to make the MWP disappear. Or, rather, they made it disappear; but, it came back.
The result of their failure to keep the MWP disappeared is that all model predictions have and will diverge from realtiy.
***
joeldshore says:
“This does not make sense. Convection can’t do an “end run” around the greenhouse effect because ultimately the energy has to escape the Earth system via radiation.”
***
“End run” is a reasonable description, joel. By nature, the top of the upward-moving convection column is warmer than the surrounding air. If it’s high enough for radiation to escape (near the tropopause) and additionally contains aerosols (condensed water/ice), it radiates outward to space as a warmer “surface” than a standard column. That’s increased heat-loss & less “insulation” effect.
This is basic. Why deny/obscure it?
Kohl says:
This is simply not correct. There have been fairly considerable variations in temperatures over the Earth’s entire history (and correspondingly huge variations in sea levels) and the IPCC projections do not place the Earth outside of this range of temperatures. They do, however, predict temperatures that would likely be higher than anything experienced for millions of years (and higher than anything experienced in the geological blink-of-an-eye that homo sapiens have beeen around).
[Only a very few scientists, like James Hansen, have claimed that we could set off some sort of runaway effect that would bring temperatures to truly unprecedented levels for essentially all of the Earth’s geological history. These claims are very speculative and it is reasonable to be quite skeptical of them (as I think most climate scientists are currently) although Hansen has made arguments why such an unprecedented occurrence could happen when it never has before.]
I am not sure why you believe this. The very same climate models that predict the response to rising CO2 levels with a water vapor feedback (a feedback which is now well-verifed by empirical data, see http://www.sciencemag.org/content/323/5917/1020.summary or http://www.sciencemag.org/content/310/5749/841.abstract ) allow for spontaneous variations in water vapor concentrations and yet they do not predict that these levels will spontaneously rise in the way that you are talking about. Clearly, your intuition here is not very good.
One of the big advantages of physical modeling is that it allows you to consider “What if…” scenarios and none of the models provide support for your hypothetical…and, in fact, the models show that a positive water vapor feedback is necessary to get good agreement with current climatology in various ways.
mike g says:
Not really. To the extent that there are knobs that can be adjusted, they are mainly adjusted to get some basic things in the current climate right, like the cloud fraction or what have you.
Every analysis of the instrumental temperature record has shown essentially the same thing, whether it be NASA GISS, Hadcrut, BEST, or various “lukewarmers” like Steven Mosher.
Actually, what you are throwing out here are just a bunch of debunked “skeptic” talking-points. You might endeavor to learn why the scientific community does not agree with your conclusions here. But, because of what I say below, they are also besides the point.
The strength of the MWP in the data has essentially nothing to do with the model predictions because, as noted, the models haven’t really been adjusted to agree with the temperature reconstructions over the last 2000 years. In fact, such a task is essentially impossible because not enough is known about the forcing variations over the last 2000 years (e.g., there is considerable uncertainty in the proxy data for solar variability over that timescale). So, while there has been some work comparing models and temperature reconstructions, the uncertainties tend to be too large to make very definitive conclusions, let alone to tune the models!
Better tests of the model estimates of climate sensitivity are provided by looking at the temperature change and forcing change between the Last Glacial Maximum (roughly 20,000 years ago) and now…Or by looking at the response to the Mt Pinatubo eruption…Or, the best by combinations of various such things.
The best way of tuning what free parameters there are in the models is provided by comparing the details of current climatology with what the models produce.
beng says:
I have clearly explained why that there is no empirical evidence or physical basis for believing that any such magic exists beyond what is already incorporated into climate models. It is incumbent on those proposing such magic to explain how it occurs and how it agrees with the empirical data.
As I noted, ultimately the only way a significant amount of radiation escapes to space is by radiation. And, how much radiation is emitted depends on temperature. Such hypotheses seem to imply something about the temperature structure of the atmosphere that there is no observational evidence to support (at least if you interpret them as implying something beyond what is already included in the models).
Joel,
“Getting rid of the MWP” is a metaphor for what they’ve done, which is to assume temperatures to have been flat back in time from the most recent minimum (70’s – 80’s) and attribute all warming since then to CO2 and feedbacks, and tweak the knobs accordingly. Which is why the model predictions fail so miserably.
Climategate wasn’t debunked. It was whitewashed.
joeldshore says:
July 8, 2012 at 6:58 am
“pochas: Just to bring you up to speed in regards to the actual science regarding convection and the greenhouse effect – The reason convection does not negate the greenhouse effect is that convection proceeds only as far as driving the temperature distribution with altitude (“the lapse rate”) down to the (appropriate, dry or moist) adiabatic lapse rate. If it were able to drive the temperature distribution all the way to an isothermal distribution with altitude (zero lapse rate) then it would indeed negate the entire greenhouse effect (as was well-known already and most recently re-discovered by Nikolov and Zeller who mistakenly put convection into a simple model in exactly this incorrect way).
Because of this limitation, convection does not cancel out the greenhouse effect, although it does reduce the natural greenhouse effect on Earth by a significant amount from what it would be with no convection. (As I recall, calculations show it would be about a factor of two larger in the absence of convection but all else equal.)”
————————–
I did not say convection negates the greenhouse effect. I said that it reduces it significantly, and you appear to agree. It is the feedbacks on temperature change that are in dispute. So, only a minor effect from CO2, and the amplifying effect from water vapor is missing (no hot spot).
The reason it is missing is that the lapse rate is in control of the atmospheric temperature profile, and hence limits the vapor pressure of water in the moist sectors of the atmosphere. This is evident from the 30 degree “flat top” in the water surface temperatures over the oceans at the equator that Willis pointed out here. Now, dry descending air is just that: dry. So water vapor is limited by the carrying capacity of the ascending air columns in the convective zones, and higher surface temperature just intensifies the convection while the dry zones stay dry. The naive use of the Antoine equation by the IPCC and others is part of their fragile fabric of incorrect physics.
You might expect that intensified convection would result in more violent weather, but this is not seen. I speculate that the observable effects of greenhouse gasses may be higher radiative emissivity from the top of the atmosphere near the equator which means less driving force for meridional circulation which is what really causes violent “weather.” Also, there is probably some elevation of minimum temperatures at high latitudes where the air is very dry. Beneficial effects, on balance.
Thank you for your persistent advocacy of the IPCC position on climate. If you didn’t do that, we’d have nothing to discuss.
pochas says:
Whether the “hot spot” is present does not really have any bearing on whether the amplifying effect of water vapor is occurring. The most direct effect of the missing “hot spot”, were it real, would be that the assumptions that go into the lapse rate feedback, a negative feedback in the climate models are wrong, and hence that feedback is incorrectly included…So, the models would be underestimating the climate sensitivity. Admittedly, a lot of the same physics controls this lapse rate feedback and the water vapor feedback, so one might say that the water vapor feedback would be reduced too, but as Isaac Held has pointed out, the water vapor feedback can be divided into two pieces: (1) The feedback that would occur if the atmosphere warmed uniformly with altitude (and a constant relative humidity were maintained). (2) The additional feedback that occurs if the tropical troposphere warms faster than at the surface, the so-called hot spot (and again a constant relative humidity is maintained). It turns out that, although the entire water vapor feedback is larger in magnitude than the lapse rate feedback, just the second part of the water vapor feedback is smaller in magnitude than the lapse rate feedback. This means that the net effect of the missing hot spot would seem to be an underestimate, not overestimate, of the amplification of the warming by these feedbacks.
Your statement here seems to betray some confusion about the theoretical considerations that give you the “hot spot” (i.e., amplification of warming as you go up in altitude in the tropical troposphere). In fact, it is exactly the fact that the lapse rate is expected to be pegged to the moist adiabatic lapse rate that leads to the prediction of the “hot spot” (as Richard Lindzen has in fact noted, although it is not hard to come up with the basic argument oneself). So, your argument that the “lapse rate is in control of the atmospheric temperature profile” is basically just restating the accepted science.
I thought maybe you were trying to make some distinction about which adiabatic lapse rate is important (dry or moist), but I don’t see any way to read what you wrote as saying this…and don’t understand the argument you would be making on this basis at any rate.
@joeldshore
Sorry, my connection has been down and I’ve been unable to engage in this discussion (which I find quite interesting).
Perhaps this might be continued another time.
Regards,
Kohl
joeldshore says:
July 9, 2012 at 8:08 pm
” So, your argument that the “lapse rate is in control of the atmospheric temperature profile” is basically just restating the accepted science.”
Indeed! This is a good place to stop.
Joel Shore:”Admittedly, a lot of the same physics controls this lapse rate feedback and the water vapor feedback, so one might say that the water vapor feedback would be reduced too,”
There is, of course, a third piece of the water vapor feedbacks as well IMO. That is the effect of condensation on the climate system as separate from the release of latent heat that would be captured in the lapse rate feedback. For there to be lapse rate feedback, there must be more condensation and generally more condensation has a cooling effect (in the formation of clouds and in increased precipitation efficiency).
As I said above, however, assuming a more or less constant RH implies, by the Clausius-Clapeyron relationship, that condensation will increase with temperature so you are left with three types of WV feedback -the positive WV GH effect, and the negative lapse rate and condensation effects.
Cheers, 🙂
Shawnhet says:
July 10, 2012 at 12:50 pm
“As I said above, however, assuming a more or less constant RH implies,…”
I am arguing that this constant RH assumption is wrong because the atmospheric temperature profile, and hence water vapor pressure and water vapor concentration is set by gravity and the gas law. A better assumption is constant absolute humidity.
Hi pochas,
I don’t really see how constant humidity can be made to match the historical record. It seems clear to me that the humidity must be less during an ice age for instance and I believe that there are many periods that have been greener than present(which tends to suggest more WV).
In any case, my point to Joel was that it doesn’t make any sense to assert on the one hand that there will be lapse rate feedback at the same time as reduced cloudiness. For lapse rate feedback to be taking place more WV must be condensing. Since condensing water vapor is one of the building blocks of clouds, it does not make sense to argue that cloudiness will go down at the same time as condensation goes up.
It is possible that there is another process going that might lead to this combination but you can’t just assert the process’ complexity as a reason to ignore the apparent contradiction (as Joel does above).
Cheers, 🙂
pochas says:
Not if you actually do things like look at the empirical data. (And, just as a note: Constant RH is not an assumption in the climate models but something that ends up as an approximate prediction of the models. (In reality, the models don’t predict it to rigidly hold true but to hold true approximately at the global scale.)
Shawnhet says:
Frankly, I don’t see any reason why the relationship between the lapse rate feedback and cloudiness has to be as simple as you seem to think it has to be. But, hey, if you want to argue that the lapse rate feedback isn’t there, that means that the models are UNDERestimating climate sensitivity in that respect (although probably not by all that much).
joel shore says:
“…look at the empirical data. (And, just as a note: Constant RH is not an assumption in the climate models but something that ends up as an approximate prediction of the models.”
A ‘prediction of the models’, heh. They program GIGO – Garbage In, Gospel Out – so no wonder they can’t predict their way out of a wet paper bag.
The anthropogenic globaloney warming conjecture says that relative humidity will increase due to warming. Makes sense.. until you look at the empirical evidence. Maybe the temperature record isn’t quite as accurate as claimed, eh?
Smokey says:
That is false (they predict that absolute, not relative, humidity will increase) and furthermore your empirical evidence consists of cherrypicking one particular reanalysis using radiosonde data while ignoring all of the other re-[analyses and the satellite data that contradict it (i.e., that show a fairly steady or slight drop in relative humidity, which is what the models actually predict).
Reanalyses rely heavily on models, by the way, so they are not really “empirical evidence” in a strict sense. They are a combination of empirical data with modeling analysis.
Isn’t joel shore cute? He comments on “Constant RH”, and then wanders off into ‘absolute humidity’ because he was proved wrong on R.H. And he calls a chart showing R.H at various altitudes, and going back to 1948, “cherry picking”. As if.
That is ‘cherry picking’ only in the crazed mind of a deluded climate alarmist. And what is “a fairly steady or slight drop in relative humidity”? They are two difthings entirely.
Have another glass of red, joel. And maybe a valium, you need it.
Joel Shore:”Frankly, I don’t see any reason why the relationship between the lapse rate feedback and cloudiness has to be as simple as you seem to think it has to be. But, hey, if you want to argue that the lapse rate feedback isn’t there, that means that the models are UNDERestimating climate sensitivity in that respect (although probably not by all that much).”
I am not arguing agaist lapse rate feedback, I have been quite clear throughout this thread that I believe that a warming atmosphere (with constant RH) will result in more condensation (and, hence, lapse rate feedback).
You seem to have trouble with my logic, so let me lay it out in more detail. 1.Condensing water in the atmosphere is one of the building blocks of clouds. 2.The more water that condenses in the atmosphere the more (and bigger) clouds can form 3. Since a warming world with constant RH will result in increased condensation, the odds of clouds forming will be greater and more clouds on average.
You seem to be arguing for some process in place of 2 that will make cloud formation *decrease* with increased condensation. While this may be *possible*, it is your responsibility to lay this process out whatever it is supposed to be. Simply saying that it is possible that some process could take place that will make cloudiness less likely with increased condensation does not establish that such a process exists. Based on what we know of cloud formation though this seems unlikely and appears to be contradicted by real world evidence. Hot, wet climates(with lots of condensation) tend to be cloudier than cold, dry ones(with only a little).
Cheers, 🙂
Smokey says:
I don’t think you are fooling anyone but yourself here. I wasn’t proven wrong on R.H. I corrected your misperceptions about what models predict about R.H. And, the point is that your chart (which, as usual for you, is simply a graph with no context or data source given) is from one particular re-analysis that conflicts with all of the others (see http://geotest.tamu.edu/userfiles/216/Dessler10.pdf ). That is what the cherrypick is.
Well, that is part of the problem with your graph. Graphing relative humidity without any reference to what the models predict it to do is incomplete, so it is impossible to tell from your graph what if any disagreement exists. You then wrongly claimed what the models predict about R.H. (As it turns out, I believe there is some disagreement because the R.H. in your graph decreases more than the range that the models predict it to, but again that seems to be an artifact of this particular reanalysis.)
Shawnhet says:
A warmer world has more evaporation and condensation but also more precipitation, which takes the condensed water vapor out of the atmosphere. How this ends up affecting cloudiness is not obvious. As I have noted, Richard Lindzen argued that a certain type of cloudiness (high cirrus clouds in the tropics) would decrease in a warmer world. I have seen no evidence in anything that I have read on the cloud feedback (and I have a whole book…conference proceedings…on it) that suggests that one can make such simple arguments as you want to make about what will happen. If you have seen such evidence presented somewhere, I’d love to see it.
In particular, some of the clouds most important to increased albedo are low marine clouds that I believe often form over ocean waters that are cooler than the land areas (see, e.g., http://meteora.ucsd.edu/~iacob/ml_formation.html )
joel shore has a problem responding to graphs and charts that I post, because they upset his world view. A while back, joel shore objected to one of my charts, just as he objects to the chart I posted showing that relative humidity has been declining steadily at all relevant altitudes since at least 1948. That evidence indicates that AGW is far less than claimed. In fact, AGW is too small to measure.
Anyway, shore objected to a chart I had posted, so I posted fifty (50) different charts and graphs, from numerous different sources, many peer reviewed, all of which supported and verified the chart I originally posted.
joel shore’s response? joel shore rejected all fifty of them!! The conclusion is inescapable: joel shore is afflicted with incurable cognitive dissonance. He is a True Believer. The fact that Planet Earth is falsifying his True Belief means nothing to him, because his belief is religious, not scientific.
Joel Shore:”A warmer world has more evaporation and condensation but also more precipitation, which takes the condensed water vapor out of the atmosphere. How this ends up affecting cloudiness is not obvious. As I have noted, Richard Lindzen argued that a certain type of cloudiness (high cirrus clouds in the tropics) would decrease in a warmer world. I have seen no evidence in anything that I have read on the cloud feedback (and I have a whole book…conference proceedings…on it) that suggests that one can make such simple arguments as you want to make about what will happen. If you have seen such evidence presented somewhere, I’d love to see it.”
Yes, precipitation increases but if it takes moisture out of the atmosphere quicker (on average) than currently, there are two options. If RH is constant, this precipitation will be matched by increased condensation in which case, the total WV is unchanged(ie at its higher level in a warmer atmosphere) and a warmer atmosphere will have more WV(cloud building blocks) than a cooler one. Again, it is not my responsibility to explain how more WV will result in less cloudiness, I don’t think that this is what happens. You, apparently, do think that this does take place so you should try and justify this, perhaps by referring to one of your cloud feedbacks in your book.
“In particular, some of the clouds most important to increased albedo are low marine clouds that I believe often form over ocean waters that are cooler than the land areas (see, e.g., http://meteora.ucsd.edu/~iacob/ml_formation.html )”
I don’t see how the fact that cloud formation and condensation will be more likely to take place in high RH than low ones is relevant. The appropriate comparison would be to compare two climates with the same average RH but different average temperatures. I am pretty confident that, for the general case, (without any special air circulation differences), these comparisons will agree with my position and not yours.
IAC, I’m not sure what your point is here but it seems as though your reference does not support the position you are trying to make.
“The formation of these clouds usually begins when wind over the water surface mixes moist surface air upwards. As this air moves up, it expands and cools. The cooling causes the relative humidity to increase and once the relative humidity reaches 100%, condensation of water vapor into liquid water drops takes place and clouds begin form. The depth through which the air mixes is referred to as the mixed layer.
The altitude (or height) that surface air must rise for condensation to start is called the Lifting Condensation Level or LCL for short. So if air near the surface is allowed to mix upwards to the LCL a cloud will form. Under certain conditions air does not mix high enough for clouds to form, that is the top of the mixed layer is beneath the LCL. While no clouds formed, the mixing has increased the relative humidity near the top of the mixed layer and subsequent cooling of this air could increase the relative humidity to 100% and initiate cloud formation.”
From this we can see, either the air is mixed high enough in which case condensation begins cloud formation or it does not and the relative humidity near the top of the mixed level has increased (IOW RH is not constant).
Cheers, 🙂
Oops, from my first paragraph above, I forgot the second of my two options for what could happen if precipitation increased in a warmer wetter world. The second option would be to let moisture leave the atmosphere quicker than it is replaced which would cause the RH to *fall* until the precipitation was matched by the evaporation.
Smokey says:
Yes…It is. The conclusion is that you are a font of misinformation who scours the internet sites of those who are in the same ideological camp as you, finds all of the deceptive or cherrypicked graphs that they produce and reposts them here. And then, when I very patiently and carefully explain what is wrong with them, you can’t defend them, so you just go into these general diatribes.
joel shore,
As usual, you are completely wrong.
I don’t “scour internet sites”, except in your dreams. At least 99% of my time is spent on WUWT. The rest of it is spent checking out the day’s news on http://maggiesfarm.anotherdotcom.com and Drudge. That’s all [unless someone emails me a tip, or I click on a link someone has posted].
Regarding the “deceptive and cherrypicked graphs” you’re always whining about, I get them all from commenters and articles right here on WUWT. All of them. You just don’t like it, because they debunk your belief system.
As I’ve said many times before, if I had a dollar for every time you accuse someone of being “ideological”, I could have a nice dinner for four at a nice expensive restaurant. It is you who is always being ‘ideological’. Your entire world view is ideological. That’s why you are always accusing others youd disagree with of being ‘ideological’. You see everything, including science, through the lens of left-wing ideology.
The conclusion is inescapable: if it were not for your psychological projection and misinformation, you wouldn’t have much to say.☺
Smokey says:
Fine…Change “sites” to “site”, Really, you let other people scour the internet sites, you see what they link to here on WUWT, and then you save the links and bring them out in response. It doesn’t change the basic fact that you know virtually nothing about the graphs that you post and when I or someone else explains to you why they are wrong, cherrypicked, or misleading, you are unable to defend them.
joel shore,
Give it up, loser. If it weren’t for moving the goal posts you wouldn’t have much to say.
I don’t “let” anyone do anything, they post what they find relevant. And you “explain” nothing, you only accuse people you don’t agree with as being “ideologues”. That’s because you cannot refute what I post.
I can defend anything I post, you just don’t like it when I easily deconstruct your globalobney nonsense. All you ever post is baseless opinion that tries to contradict what Planet Earth is telling us: CAGW is complete nonsense.
Run along now to your thinly trafficked RealClimatePropaganda or Pseudo-Skeptical Pseudo-Science blogs. You desperately need some new talking points. The ones you’ve been using are old and busted.
Shawnhet says:
Since you are getting more WV in an atmosphere that can also hold more WV before that WV condenses, it is not obvious how this goes. I am not saying it leads to less cloudiness. I am just saying that things are not so obvious that it leads to more that you can conclude this from simple arguments.
You are basically arguing that you can tell from simple principles what will happen in processes that climate scientists have been discussing for years. You are basically saying that you are so much smarter than them that you can intuitively figure it out while they are struggling to understand how cloudiness changes! I think such a monumental claim puts the responsibility in your court to come up with compelling arguments backed up by data to supportr this.
Joel Shore:”Since you are getting more WV in an atmosphere that can also hold more WV before that WV condenses, it is not obvious how this goes. I am not saying it leads to less cloudiness. I am just saying that things are not so obvious that it leads to more that you can conclude this from simple arguments.
You are basically arguing that you can tell from simple principles what will happen in processes that climate scientists have been discussing for years. You are basically saying that you are so much smarter than them that you can intuitively figure it out while they are struggling to understand how cloudiness changes! I think such a monumental claim puts the responsibility in your court to come up with compelling arguments backed up by data to supportr this.”
I fully understand that my simple model *might be* wrong but just because something is simple is not an argument that it *is* wrong What you fail to recognize is that all the reasons you have raised why it might be wrong *do not hold water*. For instance, you are correct that warmer air will hold more WV but we can go out and observe what the effects of different levels of water vapor and temperatures in the atmosphere are on the overall levels of cloudiness but, by and large, this data will agree with my position. Do you really dispute that, a climate with an average RH of 60% and an average temp of 20C will not be cloudier that one with an RH of 60% and a temperature of 10C? I would say that this is a pretty compelling relationship.
IAC, just to be fair, I believe that it is plausible that cloud feedback might be negative but it would most likely require that RH not be constant. This would involve clouds not lasting as long when there is more WV in the air. The logic would go like this, more WV forms more cloud but because precipitation efficiency is greater they rain themselves out faster and last less long. This would be, as far as I can tell, consistent with the evidence and would involve more that just saying something really complicated and mysterious *might be* going on ;).
Cheers, 🙂