Guest post by Erl Happ
This post was generated in response to the Christopher Monkton thread. It is not a criticism of Christopher Monkton but of our tendency to imagine that artful mathematicians (I am not one) are sufficiently sophisticated to deal with complex problems. Indeed the debate as to the value of feedback processes illustrates the lack of utility of mathematics when unconstrained by observation of the real world. Climate Science is full of it.
As I understand it the proposition goes like this:
Enhanced GG composition, more back radiation, enhanced evaporation, more cloud and IF cloud enhances back radiation, the surface warms. The enhancement of cloud density depending upon the IF supposedly represents the feedback.
But cloud reflects incoming energy. The feedback notion requires that the loss of energy to the surface due to cloud reflection of incoming short wave radiation is outweighed by the increase in energy trapped in the ‘below cloud level system’ due to cloud returning OLR to the surface. That’s the IF factor again.
The IF proviso requires that evaporation from the surface not only keeps pace with the increase in surface temperature. It must exceed it for cloud density to be enhanced as the surface warms.
There is a little logical problem here. If the feedback from long wave radiation exceeded the value of the reflected short wave, the oceans would soon boil. That problem is sidestepped by suggesting that it is only the high ice cloud that is important in the feedback. So, in the end the result depends upon the mix in the categories of clouds that provide net reflection versus those that provide net surface warming and whether the moisture supply to the atmosphere keeps up and somehow tips the balance towards those clouds that are supposed to provide a net warming effect .
This is already too complex and includes unknowns that are unquantifiable.
Now, lets look at the real world. Consider:
A
Do clouds warm the surface? Logically, if clouds had that effect, with more clouds the surface should warm. But near surface clouds arrive in warm tropical air. It’s warm because of its origin. The warmer and wetter it is the more the precipitation. This warm moist tropical air produces cloud and precipitation strictly in proportion to the chilling it receives. Warm that same air and the cloud disappears. (The Foehn effect). Precipitation enhances the supply of moisture at the surface cooling the surface. The air is in constant movement and the system is mind bogglingly dynamic. But one constant is the decline of surface temperature as we move from equator to pole. Satellites show that warm moist tropical air travels all the way but is dried as it moves. Hence the polar latitudes are cold deserts with the air in these regions containing little moisture that remains to be precipitated producing a gradually accumulating mass of ice in perennially sub freezing temperatures. Lesson: The presence of low clouds reflect very recent change in air temperature and is unrelated to the supply of moisture to the atmosphere from the surface. The presence of these clouds depends upon the supply of energy to the tropical ocean and the direction of the wind.
B
In mid latitudes the atmosphere between 600hpa and 100hpa (where the ice cloud called cirrus and stratus is located) responds in terms of its cloud cover to a moisture supply from places remote to the point of observation. (tropical convection, polar frontal action). Supply is relatively invariable and as a result cloud comes and goes according to flux in the temperature of the upper troposphere. Temperature in this zone is a function of ozone content and depends upon stratospheric processes. In the mid latitudes the troposphere above 300hPa contains appreciable ozone and peaks in temperature in mid winter when outgoing radiation peaks. At this time the surface reaches its seasonal minimum temperature. Radiation peaks in winter due to the enhancement of the high pressure cells of descending warming air in the winter hemisphere. The temperature of the cloud bearing layer does not relate at all to change in surface temperature. If radiation increases the presence of ozone ensures that the air warms and the cloud disappears.
C
For cloud to increase as the atmosphere warms it requires that evaporation is enhanced as the surface warms so as to enhance relative humidity promoting enhanced cloud cover. This proposition is tested once a year in the northern hemisphere. Because of the preponderance of land which is opaque to short wave radiation (unlike the sea) near surface air temperature increases strongly. In effect the surface returns warmth to the atmosphere by conduction and radiation. The convective process of heat loss via decompression (that we see in the tropics) is inoperable because of an insufficiency of moisture supply to the atmosphere. Transfer by conduction and radiation is therefore enhanced and the entire troposphere warms.
We see here that vvaporation fails to promote the addition of sufficient moisture to the atmosphere to maintain cloud cover. So, cloud falls away and global air temperature peaks in July in conformity with this strong seasonal influence driven by the accident of geography which is the northern hemisphere. A potential runaway feedback system that is the exact opposite of that posited above (warming surface more cloud) is curtailed by the passage of the Earth around the sun while it spins on its tilted axis.
In January, when the suns irradiance is 7% stronger due to orbital considerations global near surface air temperature reaches its minimum because global cloud cover peaks. Taken in its entirety, cool the Earth’s atmosphere and cloud increases. The surface cools. It will cool in the face of enhanced radiation.
Summarizing: Does the presence of cloud result in surface warming? No. In January, global cloud cover is 3% greater than July. Irradiance 7% greater. Surface temperature 4° cooler. Will a warmer sun heat the Earth? Not necessarily. It depends upon what happens to the cloud. If there were less land and more sea the ocean would gradually warm.
D
The proposition that cloud is enhanced as the near surface atmosphere warms is also testable by looking at historical data for precipitable water as the globe has warmed. Reanalysis tells us that it actually falls away.
E
The Earth system also demonstrates what happens when additional greenhouse gas is added to the troposphere. This happens in the coupled circulation over Antarctica. The system waxes and wanes according to the activity of the night jet in modulating the ozone content and temperature of the upper stratosphere. The convection that results involves warmer ozone rich air (10ppm) ascending. Relatively ozone poor stratospheric air (say 7ppm) descends into the troposphere (naturally containing ozone at the ppb level) that in consequence becomes ozone rich. The consequence is gross warming of the troposphere on the margins of Antarctica and the generation of the lowest surface atmospheric pressures on the planet. The flux in pressure in this zone depends simply upon the rate of ozone churn into the troposphere. Ozone is carried towards the equator by the counter westerlies destroying cloud as it moves by virtue of its greenhouse gas property. It absorbs at 9.6 micrometers.
As this greenhouse gas is added to the troposphere cloud cover falls away. The surface temperature feedback is due to enhanced shortwave radiation, not longwave retention. This too is a potentially disastrous feedback scenario that is limited by the fact that the ozone content of the stratosphere varies within limits and the Earth’s surface is mainly water which soaks up energy without adding a lot of moisture to the atmsophere. Given enough time, the feed rate of ozone peaks and shortly after atmospheric moisture and cloud cover recovers.
F
The prime source of long wave radiation emanating from the Earth system is the high pressure cells of the winter hemisphere where the air warms by compression as it descends, a cloud free zone promoting surface warming when it is most needed…………..despite the abundant long wave radiation streaming out to space.
Conclusion : Cloud cools.
Oh boy, this topic makes my head hurt, but I guess I’m a sadist.
I have more questions than theories, and my first question has two parts:
1-a) Which is more efficient at moving energy from the surface to space; convection or radiation. I am under the impression that convection is much more powerfull, but it’s a function of available water vapor, so it varies by location.
1-b) So, comparing the ratio of efficiency to the ratio of geographical areas which favor one versus the other, which dominates globally? My gutt tells me that the tropics, which receive the most energy from the sun, favor convective energy transfer and dominate the energy budget of the planet by a large margin.
I’m a big fan of the 80-20 rule, so if the margin is anywhere near that ratio, then the tropics are the key. Are there numbers available to support or rebutt my assumptions? I’m sure someone here can help illuminate on that.
My second question is in regard to clouds versus uncondensed water vapor. Is there a large difference, in the LWIR absorbtion when the same amount of water is present, but in one instance it is condensed and in the second instance it is uncondensed?
I wonder about that because maybe in the higher altitudes and higher lattitudes, the question should be more in regard to absolute atmospheric water content, rather than cloud versus no cloud. If physical transport of water vapor provides a strong transport mechanism for eneregy, then maybe it is important whether the condensation happens or not. My gutt feeling in this case is that it is important, since the condensation releases the energy to be radiated into space. Even if the cloud then destroys itself, it must draw the energy for evaporation of the cloud droplets from somewhere. Even in daylight, it would have to be from below because the sun doesn’t emit much LW radiation, does it?
Sorry to double post, but I didn’t complete my question in the last paragraph.
I know that I contradicted myself in that paragraph, and that was my point. I was intending to share some of the pain that this topic causes in my brain and therefore satisify my sadistic nature. muahahah.
Sorry for my apparent inattention. It’s the day job getting in the way.
Bob Tisdale says: September 28, 2011 at 10:54 am
And
TomRude says: September 28, 2011 at 2:46 pm
Re the ‘Fatal Flaw’ that disqualifies the entire post. And whether I, like Groucho, have a set of principles to suit the moment. Your language is quite aggressive gents. It seems that you are out to do damage.
I presented graphs with the souces of the data and the time span identified, and you reply with maps of a January and a July–or are they a collection of Januarys and Julys? Please plot the annual variations in the data per hemisphere as I had in my graphs and identify your source.
on a hemispheric basis, when surface temperature rises and falls, cloud amount rises and falls.
So far as the latter is concerned: Agreed
Apologies for the lack of a reference, the maps come from the JRA-25 Atlas at: ttp://ds.data.jma.go.jp/gmd/jra/atlas/eng/atlas-tope.htm They represent recent climatology.
Bob I will take your word that your graphs are accurate. I don’t need to reproduce them.
The massive drop in southern hemisphere cloud cover in mid year that seen here http://i56.tinypic.com/23iw8c0.jpg is unrelated to the very moderate decline in sea surface temperature that we see in the southern hemisphere seen here: http://i56.tinypic.com/2d1we2t.jpg
That cloud loss in the southern hemisphere in mid winter is not a product of reduced evaporation from a cooling ocean but increased downdraft and the expansion of high pressure cells to take in more of the continents including Australia. This shows up on the maps. It indicates that the hemispheres are interactive. The loss of cloud in the southern hemisphere in July is forced from the northern hemisphere. Equally the gain in cloud in January has a lot to do with the cooling of the atmosphere in January that is associated with the strong decline in surface temperature over land in the northern hemisphere.
The cloud maps I have referenced should be compared with maps of top of atmosphere radiation to see where the energy is coming from. There is a disproportionate amount of energy emitted from the winter hemisphere in the regions occupied by subtropical high pressure cells. It is plainly not coming from the surface but the atmosphere. It’s the Foehn effect on an inter-hemispheric scale.
Hemispheric data is fine, but in this case we need both a narrower and a broader focus because the behavior of the whole is much influenced by the strange behavior of the parts, and to work that out we need a sub-hemispheric focus.
As Bob’s graph at http://i54.tinypic.com/mbn7eo.jpg shows global cloud cover is greatest in January when land plus sea surface temperature is least. So the globe as a whole behaves differently to what we see in the individual hemispheres. Did you not notice that contradiction and is that observation not equally relevant? The behavior of the whole is not dictated by the ‘apparent’ behavior of the parts.
Bob, your argument is flawed, because while it adequately describes the behavior of the parts it does not apply to the whole. Is it fatally flawed? No, just a bit short of being the whole story.
Could you model this with linear equations? Only if you really understood it in all its regional and seasonal complexity and that is the point of the post. And I think we have just illustrated that point anew. So, no, the post is not fatally flawed.
.
Huub Bakker says: September 28, 2011 at 11:00 am Yes, Monckton. I stand corrected, not once but twice.
George E. Smith says: September 28, 2011 at 12:25 pm
So winds whisking the newly evaporated H2O molecules away from the surface is essential to rapid evaporation; but it is only the liquid surface Temperature that determines IF evaporation will occur.
So please stop talking about these entirely peripheral minutiae, like where and how clouds form and what time of the year that happens. If EVAPORATION occurs “somewhere”, you can bet your life savings that both CLOUDS and PRECIPITATION will occur somewhere else.
If I can add something to your valuable exposition? I observe that the coupled circulation in Antarctica produces a zone of very low surface pressure on the margins of Antarctica that has deepened over the last sixty years. The episodic loss of pressure is accompanied by a smart increase in sea surface temperature that is related to a simultaneous increase in the strength of the westerly winds. But the response in the northern hemisphere to a pressure loss due to the northern coupled circulation is much greater. It is greater because the wind acceleration is much less in the northern hemisphere. It’s what I am talking about in point E above.
As to whether increased insolation at the surface promotes a commensurate increase in evaporation wherever it occurs that is another matter. Extra watts per meter on water at 6°C versus the same stimulus to water at 28°C. Two different situations. Geography does matter.
morbidangel says: September 28, 2011 at 1:06 pm
Ummm… Doesn’t the Foehn Effect have to do with mountains? And does it not say, that since the cloud has disappeared (on the leeward side of the mountain), the air warms and not the other way around.
So Erl has no idea what a Foehn wind is?
As I understand it compressive warming on the lee side raises the temperature of the air, Relative Humidity drops, cloud evaporates. The same thing happens on a planetary scale in the winter hemisphere and that’s why I mentioned it.
Perhaps the former of these two comments posed a question, but the nature of the question was obscure to me.
George E. Smith says: September 28, 2011 at 5:11 pm
Does it make ANY rational sense at all (with no physics knowledge needed) to believe that the higher a cloud layer is, containing LESS AIR, and LESS MOISTURE and LOWER TEMPERATURE, and LOWER PRESSURE; the more back radiated energy it sends back to the surface.
By that rationale, it must be those stratospheric Noctilucent clouds; that are pretty much super cold near vaccuums that are most responsible for heating the earth. If those clouds moved oput to the moon would they warm us even more.
Reductio ad absurdum
I like it.
Gary Swift says: September 28, 2011 at 10:15 pm
A great series of questions and for the moment I am going to stay right out of it.
Septic Matthew says: September 28, 2011 at 10:10 am
Very interesting if we want to describe atmospheric behavior in a narrow band of latitude about the equator. Is it representative of the globe? No. In climate ‘geography’ is vital. The dynamics vary around and up and down the entire globe.
Paul Vaughan says: September 28, 2011 at 8:41 pm
Good to see some acknowledgement of the year in the discussion.
Details please. If you do not provide details all you are saying is that most of the people commenting here are idiots.
why are cloudy nights warmer than clear nights?
Because the air containing cloud is warm having come from a warm place.Its a gloriously diverse world that we live in and the air is in constant movement.
Erl, I’m surprised someone from Western Australia would say this.
It’s quite common here in WA to get cloud from subtropical lows in southern WA.
A couple of years ago there was total cloud cover for 3 or 4 days in the Goldfields (500 Ks from the coast) in January, usually cloud free and hot. The cloud came from the north ie subtropics. Daytime temperatures were reduced from the usual high 30s to less than 20C. 16C on a couple of days as I recall.
Even in winter, here in Perth cloudy days are cold days (although warmer nights) irrespective of the direction the clouds come from.
The reason why N America is as cold as it is in winter, is because air masses from the north originate over land and frozen sea and are dry with few clouds.
Erl Happ says: “Bob I will take your word that your graphs are accurate. I don’t need to reproduce them.”
I didn’t ask you to reproduce them. I asked you to present the data you are basing your claims on and to present them in the same format. Is your post based on speculation from your visual analysis of the JMA maps or is the post based on your analysis of data? If it’s data, please present it. If you can’t, we’ll assume you’re speculating from your visual analysis of the maps.
Erl Happ says: “Bob I will take your word that your graphs are accurate. I don’t need to reproduce them.
The massive drop in southern hemisphere cloud cover in mid year that seen here http://i56.tinypic.com/23iw8c0.jpg is unrelated to the very moderate decline in sea surface temperature that we see in the southern hemisphere seen here: http://i56.tinypic.com/2d1we2t.jpg”
You have provided nothing to support this.
The KNMI Climate Explorer does not have land and ocean masks for the ISCCP Cloud Amount data. Does your source of data? If so, please provide a link so that I can confirm your claims.
And you continued in the next paragraph, “That cloud loss in the southern hemisphere in mid winter is not a product of reduced evaporation from a cooling ocean but increased downdraft and the expansion of high pressure cells to take in more of the continents including Australia. This shows up on the maps. It indicates that the hemispheres are interactive. The loss of cloud in the southern hemisphere in July is forced from the northern hemisphere. Equally the gain in cloud in January has a lot to do with the cooling of the atmosphere in January that is associated with the strong decline in surface temperature over land in the northern hemisphere.”
Do you have data to support your multiple hypotheses contained in that paragraph? Papers maybe? Or is this also speculation?
Erl Happ says: “The cloud maps I have referenced should be compared with maps of top of atmosphere radiation to see where the energy is coming from.”
I find little value in map comparisons without data comparisons. Please provide data that support your claims.
Erl Happ says: “As Bob’s graph at http://i54.tinypic.com/mbn7eo.jpg shows global cloud cover is greatest in January when land plus sea surface temperature is least.”
The graph you linked is Land+Sea Surface Temperature data only. It is not a comparison of Global Cloud Amount and Global Land+Sea Surface Temperature. Also, had you inspected that graph a little closer, you would have noted that the Global Cloud Amount peaks in December, not January, and that there is a secondary peak in Global Cloud Amount in March. See what you miss by looking at maps and not data:
http://i52.tinypic.com/if5vs7.jpg
For your reference, here’s a comparison graph of the annual cycle in Global Cloud Amount and Global Land+Sea Surface Temperature:
http://i54.tinypic.com/iy2xx3.jpg
Now, in an earlier comment, I asked why the Southern Hemisphere Cloud Amount and its variability was so much greater than the Northern Hemisphere. Was it based on the significantly greater ocean area in the Southern Hemisphere? Ocean surface area is 4 times greater than the land surface area in the Southern Hemisphere. But I was also noting that the Southern Hemisphere SST and Cloud Amount data both peak in February and March, while Southern Hemisphere Land Surface Temperature peaks in January.
http://i55.tinypic.com/30ct0n4.jpg
And for reference, here’s a similar comparison with Northern Hemisphere SST, LST and Cloud Amount:
http://i56.tinypic.com/2ccsbo7.jpg
You continued, “So the globe as a whole behaves differently to what we see in the individual hemispheres. Did you not notice that contradiction and is that observation not equally relevant? The behavior of the whole is not dictated by the ‘apparent’ behavior of the parts.”
What? The behavior of the globe has to be dictated by the behavior of the hemispheres. It can’t be anything else. Global data is the sum of the hemispheric data. Do you think that the average of the Northern and Southern Hemisphere Cloud Amount data will be different the Global Cloud Amount data?
http://i56.tinypic.com/23iw8c0.jpg
It is the same:
http://i54.tinypic.com/v7trah.jpg
You continued, “Bob, your argument is flawed, because while it adequately describes the behavior of the parts it does not apply to the whole. Is it fatally flawed? No, just a bit short of being the whole story.”
My argument was that you were once again speculating based on an incomplete analysis. There’s nothing flawed in my argument there. Look at the title of your post: Cloud Cools. You’ve provided nothing in your post that supports this—just speculation. I’ve illustrated why your post is misleading because you are using global Cloud Cover and Global Surface Temperature as the bases for your claims. There’s nothing flawed with that portion of my argument either.
You asked, “Could you model this with linear equations?
I have no interest in it and no need to bother.
You wrote, “Only if you really understood it in all its regional and seasonal complexity and that is the point of the post. And I think we have just illustrated that point anew. So, no, the post is not fatally flawed.”
The point you attempted to make (that I quoted and discussed in my first comment on this thread) was that the seasonal cycle in global cloud amount was inversely related to the seasonal cycle in global temperatures and therefore clouds provide cooling. Your point and conclusion are misleading at minimum. I have illustrated this in numerous ways. I’ll tell you what. Why don’t I write a post about the misleading and misrepresentative graphs and descriptions in your posts per our discussions on this thread and our discussions on the thread of your last post? We’ll let the readers decide if your analyses/posts are misleading.
erl happ (September 29, 2011 at 12:44 am) requested:
“Details please.”
Erl, a communications strategy sensibly addressing the details you crave demands decades, not days. Expectation of instant gratification is grossly impractical. The audience doesn’t even have the base fundamentals needed to construct a sound conceptual framework. This is neither about physics nor “mysterious” physics; it’s about the spatiotemporal sampling framework from which terrestrial signals are aliased & integrated. It will literally take years (probably decades) to educate. Best Regards (…and that’s all for now).
Gary Swift says: September 28, 2011 at 10:15 pm
1-a) Which is more efficient at moving energy from the surface to space; convection or radiation. I am under the impression that convection is much more powerfull, but it’s a function of available water vapor, so it varies by location.
You have some good teachers here:
Cementafriend points to the different types of heat transfer
George E. Smith says: September 28, 2011 at 12:25 pm points out some home truths about the importance of water vapour.
Bob Tisdale is a master at extracting and presenting data from lots of sources
How to evaluate ‘efficient’…….They all work but the only one that actually gets it out of the system and into space is radiation. And generally speaking the radiation that comes from the atmosphere is confined to a particular place on the Earth’s surface.
One question that might be posed and that is which surface most quickly transfers energy to space and which tends to traps it in the Earth system.
Dry, dark vegetation free ground or rock heats quickly and radiates fast becoming cold overnight.
Water traps and holds energy and it does that better in still air but only to the extent that it doesn’t evaporate.
Heavily vegetated land in the tropics offers the fastest rate of evaporation due to leaf surface area very effectively cooling the surface in a high humidity, low wind velocity environment.
The daily precipitation cycle results in convection and de-compressive cooling. So, little radiation from here. A massive amount of work is done on a daily basis. But it doesn’t really get the energy out of the Earth system.
1-b) So, comparing the ratio of efficiency to the ratio of geographical areas which favor one versus the other, which dominates globally? My gutt tells me that the tropics, which receive the most energy from the sun, favor convective energy transfer and dominate the energy budget of the planet by a large margin.
From surface to top of atmosphere the near equatorial latitudes rely upon convection and de-compressive cooling. Very little radiation is emitted from the top of atmosphere here. This is an environment where energy is used to evaporate water, drive convection, cool by decompression but the energy is not eliminated to space. The elimination only occurs where that same air descends in high pressure cells between 10-40° of latitude. Here air warms in compression and gives off copious amounts of radiation in a dry air environment with little water vapour or cloud (at low levels) and a band of cirrus and stratus in the high troposphere that doesn’t really participate in the circulation. In fact the air tends to move equator-ward. It’s the light grey stuff you see in satellite photos here: http://www.intelliweather.com/imagesuite_specialty.htm
So, if your question is where does the energy actually get out of the system the answer is here: http://ds.data.jma.go.jp/gmd/jra/atlas/eng/atlas-tope.htm
Look at the maps showing radiation. Ultimately, the only way that energy leaves the Earth system is by radiation. Anachronistically the winter hemisphere is the more important hemisphere for radiation from the atmosphere. If we are talking radiation from land the important parts are the hot and cold deserts and the waters that are too cool to evaporate. Of course the hot deserts radiate most strongly in the summer hemisphere.
Philip Bradley says: September 29, 2011 at 4:04 am
Erl, I’m surprised someone from Western Australia would say this.
Philip, that is a mysterious comment. I say what I say because I am familiar with the distribution of warm wet air and precipitation: Like here http://policlimate.com/weather/current/gfs_precip.html#picture
Wet air comes from the tropics and the stuff that gets to WA often does a big sweep over the Indian Ocean, varying with the season of course. There is no place like the ‘Maritime Continent’ i.e SE Asia for delivering water to the atmosphere.
Ryan Maue has a great collection of maps on his website at http://policlimate.com/weather/index.html and one had an animation of global precipitable moisture but just now I cannot see it.
Bob Tisdale says: September 29, 2011 at 6:12 am
Bob, check your data:
SH cloud increases with surface temperature
NH cloud increases with surface temperature
Global Cloud cover varies inversely with surface temperature
Are we on the same page with these three statements?
Is your post based on speculation from your visual analysis of the JMA maps
Yes indeed, and my understanding of the way in which the atmosphere receives energy in one place and gets rid of it in another. It is based upon an understanding of the geography of process in the atmosphere in three planes including the vertical. It is based upon observation of cloud patterns in satellite photography. It is based on an understanding or the coupled circulation at the poles and its effect on wind and sea surface temperature.
In the end our understandings are all speculative. It’s not a rude word in my book. There are many paths to learning about atmospheric processes and maps establish the geography of process.
In your explorations in relation to southern hemisphere cloud, it might be useful to look separately at air temperature in the low cloud and the high cloud zone. Say below 700hPa and above 300hPa. And perhaps break it up by latitude a bit. And check out the historical trends in absolute humidity, relative humidity and precipitable water by latitude. Have a look at when the annual minima and maxima in air temperature occur between 0-40°south latitude at each level through to the middle stratosphere.
Write a post criticizing me if you wish but I don’t guarantee to get involved in the back and forth. I like to think carefully and deliberately about what I say and more haste often means less speed.
Bob, it occurs to me that it might be enlightening to split the Southern hemisphere at say 35° south for analytical purposes in looking at the relationship between surface temperature and percentage cloud over the annual cycle. Where can I access the cloud data?
Erl Happ says: “Bob, check your data:
SH cloud increases with surface temperature
NH cloud increases with surface temperature
Global Cloud cover varies inversely with surface temperature
Are we on the same page with these three statements.”
There’s no problem with the data, Erl. I explained the reason for this relationship. The annual variations in Northern Hemisphere Surface Temperature greatly outweigh those of the Southern Hemisphere, making the Northern Hemisphere annual “cycle” dominant. Hence, the annual cycle of the Global Surface Temperature reflects the additional variation in the Northern Hemisphere surface temperature. But with the Total Cloud Amount data, the opposite holds true. The annual variations in Southern Hemisphere Total Cloud Amount greatly outweigh those of the Northern Hemisphere, making the Southern Hemisphere annual “cycle” dominant. And, therefore, the annual cycle in Global Total Cloud Amount reflects the additional variability of the Southern Hemisphere Total Cloud Amount.
You quoted me, “Is your post based on speculation from your visual analysis of the JMA maps,” but failed to quote me fully. Your reply was, “Yes indeed, and my understanding of the way in which the atmosphere receives energy in one place and gets rid of it in another…”
The complete question that I asked you was, “Is your post based on speculation from your visual analysis of the JMA maps or is the post based on your analysis of data?”
I gather this means you have not analyzed cloud cover data or its intricacies or its relationship with surface temperature (which makes sense since you’re questioning the data I’ve presented). So we can conclude from this that your post was conjecture on your part with no basis in data, and, basically, with little to no basis in reality. That’s not a good thing, Erl.
Bob Tisdale says: September 29, 2011 at 9:32 am
The annual variations in Northern Hemisphere Surface Temperature greatly outweigh those of the Southern Hemisphere, making the Northern Hemisphere annual “cycle” dominant. Hence, the annual cycle of the Global Surface Temperature reflects the additional variation in the Northern Hemisphere surface temperature. But with the Total Cloud Amount data, the opposite holds true. The annual variations in Southern Hemisphere Total Cloud Amount greatly outweigh those of the Northern Hemisphere, making the Southern Hemisphere annual “cycle” dominant. And, therefore, the annual cycle in Global Total Cloud Amount reflects the additional variability of the Southern Hemisphere Total Cloud Amount.
I agree with this and I agree that the data you have provided is accurate.I don’t need to analyze it on a numerical basis.
What you need to do is to account for the marked reduction in southern hemisphere cloud cover in mid year rather than to simply say “it happens”. I provide a reason and a description of the process behind that loss of cloud cover. You don’t, other than to suggest that cloud loss relates to surface temperature and evaporation processes and the size of the ocean in the southern hemisphere. The problem is, there is very large reduction in cloud cover in relation to a relatively small reduction in the surface temperature in the southern hemisphere. The southern ocean does not shrink in winter. Your explanation is unphysical.
It so happens (and you won’t learn this by looking at total cloud data) that:
1. the high pressure cells of the southern hemisphere represent descending air warming due to compression giving up copious amounts of long wave radiation.This process is enhanced in winter as the JAL maps of cloud cover and OLR show.
2. The upper troposphere in the region of these high pressure cells contain appreciable ozone.
3.The presence of ozone and the additional radiation in winter results in a mid year increase in air temperature above 300hPa in a zone that contains copious amounts of relatively thin high altitude ice cloud traveling west and north from an origin in the southern mid latitudes. Any increase in the temperature of the upper troposphere from any source affects this cloud. The upper troposphere in this zone peaks in temperature in winter while the lower troposphere peaks in summer.Hence the marked loss of cloud in this region in winter.
4 It can be shown that the temperature of the upper troposphere in this region is affected by stratospheric processes and in particular the QBO with its biennial increase in ozone content and temperature in close equatorial latitudes. This tends to be reflected in sea surface temperatures so we know that this cloud impacts the amount of short wave radiation that reaches the surface.In fact, if you look at satellite photography you will see that this high altitude cloud is the most widely distributed and the characteristic type of cloud in the region.
The really important factor to bear in mind from a study of cloud cover is that globally it peaks in January.The variability in global temperature is greatest between November and March. It is change in cloud cover that is likely responsible. Accounting for inter-annual variation in global temperature requires that we work out why cloud cover varies so much at this time. This is also the time when the variations in ENSO tend to play out. Have you a suggestion as to why this might be so?
Erl Happ says:
“Your point is well made. I failed to elaborate on the changed humidity relations. And since changed absolute humidity per-se is postulated to be the source of amplification (as well as high altitude cirrus cloud) one needs to be sure that humidity actually increases as the CO2 content of the air increases. The evidence from reanalysis data shows that total precipitable water increases with sea surface temperature but the increase in atmospheric moisture failed to keep pace with SST in successive El Nino episodes between 1978 and 1998. So, relative to the temperature of the sea, precipitable water lagged and one would suggest, with it, cloud cover. However, over the last seven or eight years, as CO2 has continued to increase, precipitable moisture has staged a remarkable recovery.”
If my point was well made, then that was purely accidental.
In fact, to criticize my original point, considering only the ocean, then direct sunlight or back radiation cannot warm the air adjacent to the surface, to increase evaporation by lowering the relative humidity. Radiation can only affect the ocean. As you hinted out later in your post, the reason the air is a few degrees warmer than the ocean is that air warms as it descends in high pressure cells. This strongly suggests to me that cloud cover percentage is a fixed function of the geometry of the convective weather patterns much more so than any minor modifications of the back radiation.
Erl Happ says: “What you need to do is to account for the marked reduction in southern hemisphere cloud cover in mid year rather than to simply say ‘it happens’…”
I believe you miss the point of my comments on this thread: I’ve illustrated how and why your post is misleading. And that’s as far as I need to carry this.
On that note, I’m finished on this thread, Erl.
Erl Happ says: “The southern ocean does not shrink in winter. Your explanation is unphysical.”
Oops, I forgot this portion of your last comment. I never provided the explanation you are describing. Do Not Put Words In My Mouth. I have illustrated and described the data. If your explanations do not agree with the data, one might conclude your explanations are incorrect.
Sad, Bob, we need both of you.
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Two of the ten with the most holistic understanding of the system and you have to squabble like this. We have another senseless squabble between lucia and his high and mightiness.
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Kim, its all good. It is vital that ideas and presentations are challenged. I have learned from the exchanges that Bob and I have had on this thread and my next post will be better for it. Nobody gets everything right all the time. Sometimes you may arrive at the right conclusion without having all the ducks properly lined up along the way. Sometimes the ducks appear to line up and the conclusion is wrong.
Practice ploughing the furrow and time and again. As ones skill improves it gets straighter and deeper.
kim says: @ur momisugly September 30, 2011 at 6:50 am
Two of the ten with the most holistic understanding of the system and you have to squabble like this…..
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This is not sad Kim, this is how science is advanced. By discussion, clarifications and the butting of heads.
Bob, I want to make one constructive comment on your climatology graphs:
The interval 12-1 is missing on your graphs. It can be tagged on either end (as 0 or 13 to fool Excel). Your graphs currently represent only 11 of the 12 month-long intervals of the year. You’re representing 12 nodes, but only 11 connectors – (count them). I made the exact same mistake when I first started looking at this stuff and I regretted it because I had to go back & reformat a lot of multi-panel color-contour graphs that I had gone to a lot of tedious trouble to produce. I ended up deciding it’s very helpful to extend each end of the climatology by a 1/4-cycle (to ease interpretation near arbitrary temporal cycle boundaries). I wish map producers would do the same thing with world maps (to dramatically ease interpretation near spatial cycle boundaries). Best Regards.
Erl, the average annual low-cloud cycle is COMPLEXLY related to the annually shifting bands of ABSOLUTE temperature, pressure, wind, & zonal topography. It’s GREAT that you’re getting people looking at annual cycles, but I want to suggest that you’re pushing too far with your process abstraction oversimplification attempts.
There’s clearly a ripe opportunity for someone (with a bit of free time) to start a series of posts highlighting animations of the JRA-25 climatologies. A long, slow education campaign (at a pace the average reader can handle) is needed to correct the misconceptions which have accumulated unchecked from excesses of anomaly-based summaries.
Regards.
Yes, Gail, I’ve calmed down a bit and can see the silver lining that you and Erl both point out. I wish the two could co-operate better, instead of coagulate.
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AnimPolarWind200hPa
http://i52.tinypic.com/cuqyt.png
AnimWind200hPa
http://i52.tinypic.com/zoamog.png
AnimWindZonal
http://i51.tinypic.com/34xouhx.png
Please – anyone with a free second – let me know if these work or do not work for you from whatever browser you’re using. If they work for most people, I’ll put up a few more for discussion in future threads.
Great work Paul. You are onto it.
Paul, and its Firefox, the latest version.
Paul. You might like to put this one aside for an animation:
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ENSO/regressions/
Not interested in chasing interannual ghosts Erl.
Let’s stick to real cycles.
AnimMSLP
http://i54.tinypic.com/swg11c.png