Guest Post by Willis Eschenbach
I have theorized that the reflective nature of the tropical clouds, in particular those of the inter-tropical convergence zone (ITCZ) just above the equator, functions as the “throttle” on the global climate engine. We’re all familiar with what a throttle does, because the gas pedal on your car controls the throttle. The throttle on any heat engine controls the running conditions by limiting (throttling) the amount of incoming energy.
Similarly, in the climate heat engine, the throttle is the tropical albedo (reflectivity). The tropical albedo controls how much incoming solar energy is rejected back to space at the hot end of the heat engine. In other words, the albedo throttles the incoming energy to control the entire system.
I have further said that the tropical albedo is a threshold-based and extremely non-linear function of the temperature. So I thought I’d use the CERES satellite data to take a look at how strong this climate throttle is in watts per square metre (W/m2), and exactly where the throttle is located. If such a throttle exists, one of its characteristic features would be that the amount of solar energy reflected must increase with increasing temperature. Figure 1 shows the results of that analysis.
Figure 1. Average change in reflected solar from a 1° increase in surface temperature. Red areas show greater reflection with increasing temperature. The change in reflected energy is calculated on a per-gridcell basis as the change in albedo per 1° temperature increase for that gridcell, times the average solar radiation for that gridcell. Gray line shows zero change in albedo with temperature. Dotted lines show the tropics (23.45°N/S) and the Arctic/Antarctic circles (66.55°N/S).
Clearly, then, such a throttle mechanism exists. It is also where we would expect to find it, located near the Equator where the maximum energy is entering the system. On average, the throttle operates in the areas enclosed by the gray line. I was surprised by the strength of the mechanism, however. There are large areas (red) where a one degree C warming in temperature increases the solar reflection by 10 W/m2 or more. Obviously, this thermostatically controlled throttle would be a factor in explaining the observations of a hard upper open ocean temperature of about 30°C.
The throttle mechanism is operating over much of the tropical oceans and even some parts of the tropical land. It is strongest in the ITCZ, which runs below the Equator in the Indian Ocean and over Africa, and above the Equator in the Pacific and Atlantic.
Next, it is worth noting that overall the effect of temperature on solar reflections is about zero (global area-weighted average is -1.5 W/m2 per degree, which is smaller than the uncertainty in the data). In addition, large areas of both the land and the ocean in the extra-tropics are quite similar, in that they are all just slightly negative (light orange). This is another indication that we have a thermoregulatory system at work. Since over much of the planetary surface the albedo is relatively insensitive to changes in temperature, small changes in temperature in the tropics can have a large effect on the amount of energy that is entering the system. Figure 2 shows the relationship (land only) between absolute temperature in °C, and the change in reflected energy per degree of warming.
Figure 2. Change in reflected solar (W/m2 per °C) versus absolute surface temperature (°C) over the land. Note that where the annual temperature averages below freezing (0°C), there is little variation in surface reflection with temperature. From freezing to about 20°C, the amount reflected is generally dropping as temperatures increase. Above about 20°C, there are two kinds of responses—sizeable increases or sizeable decreases in reflected solar with temperature.
Next, over the oceans the areas near the poles show the reverse of the behavior in the tropics. While the tropical albedo changes cool the tropics, near the poles as the surface warms, the albedo and the reflected sunshine decreases with increasing temperatures.
Figure 3. Change in reflected solar (W/m2 per °C) versus absolute surface temperature (°C) over the ocean, annual averages. Where the annual temperature averages near freezing, there is strong negative variation in surface reflection with temperature. From freezing to about 20°C, the variation is stable and slightly negative. Above about 20°C, there are two kinds of responses—sizeable increases or sizeable decreases in reflected solar with temperature, up to the hard limit at 30°C
What this means is that in addition to limiting overall energy input to the entire system, the temperature-related albedo-mediated changes in reflected sunlight tend to make the tropics cooler, and the poles warmer, than they would be otherwise. Clearly this would tend to limit the overall temperature swings of the planet.
Finally, the use of monthly averages obscures an important point, which is that the changes in tropical albedo occur on the time scale of minutes, not months. And on a daily scale, there is no overall 10 W/m2 per degree of temperature change. Instead, up to a certain time of day there are no clouds, and the full energy of the sun is entering the system. During that time, there is basically no change in tropical albedo with increasing temperature.
Then, on average around 11 am, within a half hour or so the albedo takes a huge jump as the cumulus clouds emerge and form a fully-developed cumulus regime. This makes a step change in the albedo, and can even drive the temperature down despite increasing solar forcing, as I showed here, here, here, here, and here
From this we see that the thermal regulation of tropical albedo is occurring via changes in the time of the daily onset and the strength of the cumulus/cumulonimbus regime. The hotter the surface on that day, the earlier the cumulus and cumulonimbus clouds will form, and the more of them there will be. This reduces the amount of energy entering the system by hundreds of watts per square metre. And on the other hand, during cooler days, cumulus form later in the day, cumulonimbus may not form at all, and there are fewer clouds. This increases the energy entering the system by hundreds of W/m2.
I bring this up to emphasize that the system is not applying an average throttle of e.g. 10 W/m2 over the average area where the throttle operates.
Instead, it is applying a much larger throttle, of a couple hundred watts/square metre, but it is only applying the throttle as and where it is needed in order to cool down local hot-spots, or to warm up local cold spots. As a result, the averages are misleading.
The final reason that it is important to understand that the albedo changes are HOURLY changes, not monthly average changes, is that what rules the system are instantaneous conditions controlling cloud emergence, not average conditions. Clouds do not form based on how much forcing there is, whether the forcing is from solar or CO2 or volcanoes. They form only when the temperatures are high enough.
And this means that things won’t change much if the forcing changes … because the cloud emergence thresholds are temperature-based, and not forcing-based.
I hold that this immediate response is the main reason that it is so hard to find e.g. a solar signal in the temperature record—because the thermoregulation is temperature based, not forcing based, and thus operates regardless of changes in forcing.
This is also the reason that volcanoes make so little difference in the global temperature—because the system responds immediately to cooling temperatures by reducing albedo, opening the thermostatically controlled-throttle to allow the entry of hundreds of extra W/m2 to counteract the drop in temperature.
There is plenty more to mine from the CERES dataset, and although I’ve mined some of it, I still haven’t done lots of things with it—an analysis of the efficiency of the climate heat engine, for example. However, I think this clear demonstration of the existence of a temperature-regulated throttle controlling the amount of energy entering the climate system is important enough to merit a post on its own.
Best regards to all on a sunny December day,
w.
TimTheToolMan says:
December 31, 2013 at 3:15 am
Willis writes “Then, on average around 11 am, within a half hour or so the albedo takes a huge jump as the cumulus clouds emerge and form a fully-developed cumulus regime.”
Had you thought about looking for a trend in the times of onset? There may not be enough satellite data for that though…
++++++++
If I recall, Willis has done A LOT of research into the times of onset. His studies on this subject are fascinatingly brilliant, and are in the WUWT archives.
Gerald Kelleher says:
December 31, 2013 at 3:30 am
Scott Bennett
You got it backwards
+++++++++
Gerald, respectfully, your equator fetish is getting a bit nasty. If you were spot on, I’d not respond here. But Scott Bennett got nothing backwards. Again, you read into what he wrote and saw a reason to attack him needlessly. Check again, there’s more the equator than you understand. If you could only see the equator through your fetish you’d probably have a lot to offer to the conversations. There are seasons in many equatorial regions which range from dry to wet regardless of what you think you know.
Mario
Respectfully,there is nothing nicer than to look at an actual town on the Earth’s Equator and affirm that there is ,in terms of seasonal fluctuations in daylight/darkness, only one season or no seasons if you prefer,you can see this in the astronomical almanac on this website –
http://www.wunderground.com/cgi-bin/findweather/hdfForecast?query=Pontianak
At the poles there is only 6 months of daylight and 6 months of darkness due to a separate cause and this too you can read from the same almanac –
http://www.wunderground.com/cgi-bin/findweather/getForecast?query=Amundsen%E2%80%93Scott%20South%20Pole%20Station
The cause of the two day/night cycles are dynamically different but it is not often people actually dwell on the North/South pole day/night cycle and the necessary separation from daily rotation and the more familiar day/night cycle at our latitudes.
The only way out of the ‘global warming’ mess is to raise the standard for climate research rather than demean the opposition and there I take my stand.
Gerald Kelleher says:
December 31, 2013 at 4:06 am
Mario
Respectfully,there is nothing nicer than to look at an actual town on the Earth’s Equator and affirm that there is ,in terms of seasonal fluctuations in daylight/darkness, only one season or no seasons if you prefer,you can see this in the astronomical almanac on this website –
http://www.wunderground.com/cgi-bin/findweather/hdfForecast?query=Pontianak
At the poles there is only 6 months of daylight and 6 months of darkness due to a separate cause and this too you can read from the same almanac –
http://www.wunderground.com/cgi-bin/findweather/getForecast?query=Amundsen%E2%80%93Scott%20South%20Pole%20Station
The cause of the two day/night cycles are dynamically different but it is not often people actually dwell on the North/South pole day/night cycle and the necessary separation from daily rotation and the more familiar day/night cycle at our latitudes.
The only way out of the ‘global warming’ mess is to raise the standard for climate research rather than demean the opposition and there I take my stand.
+++++++++++
Please focus. I correctly stated to you: “But Scott Bennett got nothing backwards… There are seasons in many equatorial regions which range from dry to wet…” You’re not addressing anything he said. And your conclusion is not right.
Your last sentence says it clearly to me that your stand should be based on facts of the argument. However, your facts led you to quite an incorrect conclusion. You toss in something about the equator and fail to understand that your guesses are wrong. That does not help the cause –being blatantly wrong. If you would spend more time thinking about what was being said, you’d not jump to incorrect conclusions.
I try to counter the global warming mess with fact and truth. We have that on our side regarding the alarmists untruthful meme.
Mario writes “If I recall, Willis has done A LOT of research into the times of onset. ”
Well I’m reasonably familiar with Willis’ work over the years but I don’t recall him ever quantifying the onset times using the CERES data.
Still… I’m on an awkward tablet with poor internet right now and can’t be bothered doing searches so I’m sure he’ll link if he has.
Gerald Kelleher says:
“Respectfully,there is nothing nicer than to look at an actual town on the Earth’s Equator and affirm that there is ,in terms of seasonal fluctuations in daylight/darkness, only one season or no seasons if you prefer..”
Equatorial locations have two warm seasons, at both equinoxes, that’s when the Sun is directly overhead at midday.
The nature of the thread focus on astronomical inputs using the characteristics of the Earth’s motions which coral climate observations into fluctuations caused by those motions.For me this is just working language and if people have not yet become familiar with the language then they can hardly be hostile when I point out easy to understand examples such as the conditions set at the region of the Equator where daylight/darkness asymmetries are minimal whereas the polar day/night cycle is extreme and from a different dynamical cause.
I am even big enough to admit that perhaps I am not the man for the job of describing these motions but they are there and they completely alter how we look at the seasons and what causes the temperatures to go up and down across an orbital circuit.
This business of the ‘sun being overhead ‘ each day is from a different era,the Equinox in dynamical terms are when the polar latitudes turn through the circle of illumination and the respective poles descend into orbital darkness or emerge as orbital dawn,one of the great astronomical events of the year.The Earth doesn’t tilt sideways to the Sun at the Equinox no more than it tilts towards or away from the Sun at the Solstices,it has a magnificent surface rotation emerging from its orbital behavior and I would like people to take account of this 100% observational certainty –
http://londonastronomer.files.wordpress.com/2013/01/uranus_2001-2007.jpg
At the solstices,Uranus receives the maximum solar radiation along the plane of its ecliptic motion and not at its Equator hence it has a polar climate,were Uranus or the Earth to have zero inclination and the rotational Equator and the ecliptic Equator were coincident,all areas on the surface would experience Equatorial conditions hence an Equatorial climate.
It has little to do with hot/cold or wet/dry,just generalized rules set down by two surface rotations to the central Sun and there for people to work with.
My dear Mario
The maximum energy entering the Earth’s surface in terms of solar radiation would be from a line drawn at right angles to the North/South line you see running parallel with the circle of illumination and that energy remains constant along that line even if the Earth does increase or decrease its distance from the Sun –
http://www.msss.com/mars_images/moc/2003/05/22/earth_americas250.jpg
The Lat/Long system imposed on the daily rotational characteristics of the Earth turn through that maximum energy input over the course of a year but it takes a fine sense of judgment to mark the changes.It is much easier to look at what happens with Uranus first and then return to the Earth a lot wiser.
The New Year always brings a new hope and I wouldn’t stand in the way of a new explanation for the seasons or why natural noon cycles vary from the same dynamical mechanisms.With all creative and productive insights it goes to help those who cannot help themselves and need assistance in understanding the relationship between dynamics and terrestrial effects rather than trying to impress people. Some people may surprise themselves by getting a glimpse of the main points and congratulations to them as my descriptions and my proofreading skills are terrible.This is due to a natural situation where people are either naturally talented at interpretation/intuition while others are not,much like what Pascal noted –
“The reason, therefore, that some intuitive minds are not mathematical is that they cannot at all turn their attention to the principles of mathematics. But the reason that mathematicians are not intuitive is that they do not see what is before them, and that, accustomed to the exact and plain principles of mathematics, and not reasoning till they have well inspected and arranged their principles, they are lost in matters of intuition where the principles do not allow of such arrangement. They are scarcely seen; they are felt rather than seen; there is the greatest difficulty in making them felt by those who do not of themselves perceive them. These principles are so fine and so numerous that a very delicate and very clear sense is needed to perceive them, and to judge rightly and justly when they are perceived, without for the most part being able to demonstrate them in order as in mathematics, because the principles are not known to us in the same way, and because it would be an endless matter to undertake it. We must see the matter at once, at one glance, and not by a process of reasoning, at least to a certain degree. And thus it is rare that mathematicians are intuitive and that men of intuition are mathematicians, because mathematicians wish to treat matters of intuition mathematically and make themselves ridiculous, wishing to begin with definitions and then with axioms, which is not the way to proceed in this kind of reasoning. Not that the mind does not do so, but it does it tacitly, naturally, and without technical rules; for the expression of it is beyond all men, and only a few can feel it.” Pascal
The mathematical modelers tend to ignore physical considerations and that is why there is such a clash of cultures in this thread and why they wouldn’t be able to understand that Pascal uses the word ‘intuitive’ in the sense of interpretative talents rather than ‘guesswork’ as mathematicians imagine.
Over and out.
Gerald Kelleher says:
“For me this is just working language and if people have not yet become familiar with the language then they can hardly be hostile when I point out easy to understand examples such as the conditions set at the region of the Equator where daylight/darkness asymmetries are minimal..”
It’s always close to a 12 hour day at the equator, but at the solstices the Sun is 23.5° away from the zenith at midday, so it does a lower arc through the sky.
“””””……Gerald Kelleher says:
December 31, 2013 at 1:11 am
George Smith
Want to teach students how this works then take a broom handle to represent the constant axial orientation of the Earth as it travels around the Sun and any object to represent the Sun……”””””
Well Gerald, the exact path of the sun across the earth surface is, I am sure, an interesting subject, but as I see it, slightly more than one half of the earth surface is in sunlight continuously (or izzat continually). There is never less than half the earth exposed to sunlight at any time. Sure the amount of sunlight varies slightly over the course of a year, but averaged over a year orbit of the sun, the total solar energy that impinges on the earth does not change perceptibly, and from day to day, the total energy received changes very little. Exactly where it reaches the surface may change slowly over the year, which will affect the weather, I suppose the very slight non-sphericity of the earth will cause the exact solar flux intercepted to change as the earth rotates daily; but I have never seen any graph that shows how much it changes throughout the day and throughout the year. And I don’t see how the axis tilt alters the fact that about half the surface is continually in daylight, every day of the year.
“””””……Willis Eschenbach says:
December 30, 2013 at 11:48 pm
george e. smith says:
December 30, 2013 at 11:35 pm
So Willis, if I tilt my head over at 23 1/2 degrees, a near sphere will look different ?? Dang ! They always look the same to me. Maybe Gerald has discovered something new.
Thanks, george. What I said was that if you tilt your head over at 23 1/2 degrees, the crown of your head will be pointing either towards or away from the sun … but I said nothing about whether a “near sphere will look different”, whatever that might mean…….”””””
Well I guess I didn’t make myself clear. As seen from the sun, earth looks like a near sphere, that changes in apparent angular size from day to day, but the sun has no knowledge of the axial tilt of earth’s rotation axis, so it just goes on illuminating slightly more than half the earth surface area all the time, regardless of any axis tilt, and delivering the same solar energy supply rate adjusted for earth orbital radius change throughout the year.
Gerald Kelleher says:
December 31, 2013 at 8:17 am
My dear Mario
+++++++
Gerald: I’m not going to get distracted commenting about your off-subject interests, or read a diatribe on equator material on this post.
You argue with points that are not being made; make assertions which are patently false, and then shift to talking about the equator.
Perhaps you have lots of good information, but your conclusions start out with the wrong answer, and then you spiral down some path off in the weeds.
George Smith
When I see an attempt to explain the polar day/night cycle where a person standing on the South pole once to the Sun each year then I know people are serious about climate.The maximum radiation entering the system is always orthogonal to the circle of illumination hence it would be nice to encounter the North/South ecliptic axis around which the entire planet turns to the central Sun –
http://www.msss.com/mars_images/moc/2003/05/22/earth_americas250.jpg
Without the orbital component and the proper explanation for the seasons you are all wasting your time and annoying the public in the process with the nonsense that is passed off as climate today.
My dear Mario
The maximum energy entering the Earth’s atmosphere at any given time is dictated by the orientation of half the surface to solar radiation from a line drawn North to South and running with the circle of illumination so that the latitudinal temperature fluctuations known as the seasons are heavily dependent on how where the Earth is in its orbit,and more importantly,where the rotational poles are position in respect to the circle of illumination.
The so-called global warming controversy has all the hallmarks of an older scientific controversy and is taking the exact same route in how it plays out.The climategate affair told you that not even when it is demonstrated conclusively that convictions were driven by variable hypothesis and rigging observations to suit unwarranted conclusions,the driving force was not science but politics and it remains so to this day. The politics, in this case, is modeling itself and these guys would still believe in ‘global warming’ and all its contrived notions were the ice sheets to extend to New York or Sydney rather than giving up modeling for genuine interpretation.
You guys are so wound up with the opposition that you may miss out on what is actually before you when it comes to explaining both daily and annual temperature fluctuations and that the present explanations are simply not good enough or dysfunctional. So,when properly understood,you wake up in 2014 to two individual surfaces rotations of the Earth to the central Sun in order to make sense of why the temperatures are the way they are on the surface at specific orbital points for the heat budget through the year is constant but because of the relationship between daily and orbital components,different latitudes experience that expenditure in different ways.
I may have oversold the issue already and that blame I take upon myself,all the same,it is new and raises lovely issues brought up by ancient Solstice alignments,the history of navigation and timekeeping,the aggressive modeling in the late 17th century that caused the present difficulties and so many other topics that widen the perspective and make climate research an exciting and adventurous affair rather than the sullen,dreary and mean-spirited entity it has become.
George
You are spot on.An observer on the Sun sees the full face of the Earth and no orbital shadow where the Arctic pole is located 23 1/2 degrees South of the circle of radiation which divides daylight from orbital darkness –
http://www.msss.com/mars_images/moc/2003/05/22/earth_americas250.jpg
The hypothetical observer on the Sun would see the rotational pole turn and disappear into the orbital shadow at the Equinox and simultaneously watch the opposite pole which is 23 1/3 degrees North of the Southern face turn into solar radiation.
From a rotational point of view,the entire planet would appear to gyrate over the course of an entire 365 degree circuit for even at the Equator where daylight and darkness lengths are equal,the Sun rises and sets at different points on the horizon as the entire Lat/Long system is carried around in a circle to the central Sun. Applying that principle to the image above will give a graphic description of your statement.
I would just like to necro for a moment and point out that Gravity has final say in all temperature matters on the planet. Just as you cannot “terraform” another body without giving it an earthlike mass, you cannot change the temperature range of a given atmosphere without a MAJOR change in its chemical makeup or a change in the mass of the planet beneath.
Gerald, here’s my problem.
You keep saying that the maximum solar radiation occurs directly under the sun. Of course, you can’t say it that simply. You say it is on the “line of the ecliptic” and “orthogonal to the circle of illumination” … which means directly under the sun.
To which I have replied, and reply again … so what? I mean that seriously. If I accept every single one of your premises, what difference will it make to my description and analysis of the thermostatic throttle above?
w.