Guest Post by Willis Eschenbach
I had the great pleasure of being invited to give a presentation at the Doctors for Disaster Preparedness (DDP) conference this weekend in Knoxville, Tennessee. It was a very interesting and professionally run conference, and I offer my thanks to Dr. Jane Orient 
for her invitation, and to her team for the doing endless logistic work that such a conference entails in a most efficient and nearly invisible manner.
The conference featured a host of fascinating speakers, and the city itself was most pleasant and interesting. I came with a stack of Powerpoint slides and a presentation on climate science. But then I thought “Wait a minute, these are doctors, not climate scientists”, and I ended up putting them aside and speaking for an hour with the main theme being the ancient medical admonition, “First do no harm”.
One of the first people I met carried around a portable CO2 meter. We were indoors at the reception dinner in a large banquet hall, and here is the CO2 concentration:
About 800 ppmv … it gave me a better understanding of why ground level CO2 is not necessarily a good measure of the background levels.
One of the best parts for me of such conferences is that I get a chance to meet my heroes. When I began studying climate science I soon identified the scientists that I thought were doing interesting and outstanding work … but I never imagined that I would meet them, much less get a chance to speak at a conference with them. Dr. Fred Singer, the dean of skeptics, was at the conference, and paid me the compliment of quoting some of my scientific results in his speech. I’ve met him several times before, he’ll be 90 this year, still sharp, still funny. I also got a chance to share a meal with Dr. Art Robinson, the originator of the Oregon Petition. He turns out to be a most interesting man, a PhD biochemist who is doing fascinating research on the diagnosis of the state of a persons health by using mass spectrometry to analyze the trace molecules in their urine. He was most complimentary, and said that my presentation was “absolutely perfect”. I felt quite honored.
It was a very eclectic collection of speakers, including a man whose work is the identification of the various types of ebola viruses, and the kinds of precautions necessary for dealing with the disease. He showed slides of him in Africa in a full moon suit, and spoke of how the hospitals often deal with the ebola patients without even gloves, because the hospitals are too poor to buy them and their stocks have run out in the current medical emergency. Given the recent and continuing ebola outbreak in Africa, it was most timely.
And unlike the ICCC9 conference where I spoke a few weeks ago and the talks were limited to twelve minutes (and unavoidably so given the number of noted speakers), we each got an hour to talk about our subject, which was a great boon.
I ended up speaking on how increases in the cost of energy for any reason are the most regressive tax imaginable. If you make very little money, for example, you pay no income tax. But the poorer you are, the larger a percentage of your expenses goes to energy costs (primarily heating, cooling, and transportation), and there is no exemption for those at the bottom of the heap. My message was, if you think CO2 is a problem, fine, but when you fight it first do no harm … and while increasing the price of energy is an inconvenience for many people, for the poorest of the poor it can mean impoverishment, sickness and death. So fight CO2 if you must, but if you increase energy prices to do it, you are actively harming the poor. I’ve requested the video of the speech, I’ll post it up on youtube when I get it. My speech stole shamelessly from my writings, and it’s nothing I haven’t said before, but it was the first time I’d put it into a one-hour speech. It was very well received.
In between sessions, I wandered around downtown Knoxville. It’s an old city, with a marvelous “Market Square”. Ironically, the huge building across the street is the offices of the TVA, the “Tennessee Valley Authority” which did so much to relieve poverty in the area by providing cheap electricity for the local people. The TVA building, fittingly, has a long lovely fountain symbolic of the renewable hydropower that the Authority provides …
There is also a display of old machinery in the foyer of the TVA building which you can see from outside. It’s all from the time when such machines were works of art. One that caught my eye was a “flyball governor”, first invented by James Watt of steam engine fame. As someone who holds that the climate is regulated not by feedback but by a governor system, it was of great interest, and is a stunning example of the genre:
When the pulley-driven wheel turns, the vertical shaft with the four steel balls (one unseen behind) suspended on flexible spring steel blades spins as well, and the balls are driven outwards by centripetal centrifugal force. This pulls the upper brass ring downwards against the adjustable tension of the spring at the upper right, and controls a valve which regulates the amount of energy entering the system … a most elegant version of an ancient design.
The Market Center is the showpiece and heart of the city. It’s a long open space, and every time I went there it was full of people and something was going on—jugglers, Shakespeare plays in an outdoor theatre …
.. a magician, people break dancing, newspaper sellers, a variety of street musicians, it went on and on. Outdoor cafes ring the Market Square, and the people of Knoxville have turned the outdoor cafe into an art form … now that’s outdoor eating in comfort.
There is only one statue in the square, and contrary to my expectation when I saw it from a distance, that it would be something honoring Civil War heroes, to my surprise it honors heroes of an entirely different kind:
One of the inscriptions on the pedestal was particularly moving …
” … the monstrous injustice of including educated women with felons and lunatics as persons denied the right of suffrage”, indeed. We forget the cost it took to purchase the rights and freedoms we take for granted.
Knowing that if you build a fountain kids will want to play in it, the Market Square also has a fountain specifically designed for kids, with benches nearby for the parents to watch the joy …
There is a museum on the corner of the square, featuring a complete reproduction of an apothecary shop, with reminders of how far medicine has advanced in the last 150 years.
The maids in the hotel who came in to clean my room were great. One was a very large black woman. When I told her I was there to give a speech, she said proudly “I just gave my very first speech myself”. I asked for the details, and she said it was at the drug rehab center where she used to live. I asked her what she’d told them. She said “I told them you can’t just sit around for the rest of your lives drawing government money and using it to buy drugs. You have to get up and stand up and make something out of your lives” … words to live by. She said the management of the rehab center wanted her to go speak to other groups, and I applauded her resolution to do so.
The next day another maid told me she’d been upset when she saw the word “Climate” on some paperwork in another guest’s room, she was all upset about the idea of a climate conference … but then she read a bit more and realized it was skeptics, not alarmists, and after that everything was fine again. So I guess the word is getting out.
One of the best parts of the conference was after it was all over. Everyone was eating dinner, when a loud buzzing went off all around the room, including on my hip. I looked at my phone … tornado alert, take shelter now. I’ve never lived in tornado country, so I followed the example of the locals in the hotel who did … well … nothing. It started pouring down rain, a torrential downpour, lots of wind. When that cleared, I went outside to look for the tornado. I walked up on the hill behind the hotel to get a good view. It’s part of a long ridge, and a sign said that during the war the Union troops (locally called “Federal troops”, I noted) erected ten forts with batteries of artillery during the siege of the town. I could see why, it overlooks the whole city. The sky was chaotic …
… but no sign of a tornado. As soon as I got back to the hotel, the rain and wind started up again, and in a half an hour it was dark, and the sky was full of lightning. I watched the storm from my 11th floor hotel window, I could see the window glass flexing in and out with the force of the gusts. And the lightning was everywhere, cloud to cloud, cloud to ground …
From the news tonight:
Tornadoes were also reported in Tennessee and West Virginia Sunday afternoon and evening. Just north of Knoxville, Tenn., near the Kentucky border, the Claiborne County emergency manager reported that 10 homes had been “completely destroyed.”
A most fitting end to a most diverse and interesting conference. Lightning and wind have picked up again as I write this, here’s the radar from my phone. Knoxville is the blue ball in the middle, the storm is moving southwards, and the lighting is getting amazing again.
Anyhow, that was my weekend. My thanks again to the DDP for putting on a good show. After three hours sleep I’ll fly out tomorrow at 4:35 AM, home for one day to see the good lady, and then off again Wednesday to Vancouver Island, where I’m signed on as first mate on a fishing boat delivery to southern Oregon.
My best to all, keep up the struggle, I’ll post when and as I can.
w.
Willis says: “Now, recall that this is Greg’s distinction, one with which I publicly agreed. A governor is not feedback. It is a specialized system which controls the amount of feedback, in Greg’s terminology a “feedback controller”, which provides either negative or positive feedback as needed. ”
I commented on how that last phrase was not what is meant in engineering and science by feedback and you reiterate it. So perhaps that’s where the problem lies.
In control system a feedback is a proportion of an error signal that is applied back to the input. In a natural system, that I will assume has not been ‘designed’ it is a deviation in some physical parameter that produces a knock-on effect that in turn has an effect on the cause of that change.
A negative feedback is one which opposes the change in the output or “control” variable.
A positive feedback is one which acts to exaggerate the deviation or error.
The former leads to stable, controlled systems, the latter (if unbounded) is inherently unstable and will lead to catastrophic change.
So a control system will NOT apply “either negative or positive feedback as needed. ” It will always apply a negative feedback. The negative feedback will be a positive or negative correction, but it is always a negative feedback if it opposes the error signal.
It seems that Willis’ governor is no different than anyone else’s governor which is a feedback control system. Apparently we are all agreed on that.
The difference is that Willis uses the term feedback to refer to the actual instantaneous correction ( instantly positive or negative as needed ) rather than the conventional sense of a feedback: a linear or non-linear function of the error signal, which is a generalised property of the system, independent of any instantaneous values.
So when Willis says he is “someone who holds that the climate is regulated not by feedback but by a governor system” it is simply that he is using those terms differently.
He means that climate is controlled by what most people in engineering, science and climate modelling would call being controlled by a feedback.
Tropical storms are “NOT a feedback” because what Willis calls a feedback is “either negative or positive feedback as needed” and is different from what most other people in engineering, science and climate modelling mean by the term.
In conventional usage of the term, tropical storms provide a negative feedback that acts like a governor to stabilise tropical SST..
Phew, it’s taken about two years to get there but at least we got there in the end.
Now we’ve got that out of the way, perhaps we can concentrate on whether its effect on a regional scale is linear or non-linear and what this implies about sensitivity.
I think it can be approximated as a strong linear negative feedback or possibly more accurately a non-linear negative feedback. The idea of a PID controller would be worth investigating in view of the apparent stability of the degree.days cumulative integral.
@Greg, let’s just say, from my limited understanding, that when Willis says that it is not feedback, he means that it is something more complex than ordinary feedback. It is a kind of feedback that you cannot express with a simple ecuation or a simple factor. To describe it, you would actually need to describe it using different ecuations, that correspond to different “modes” of operation, the correct mode depending on the value of the signal, yes, but not in a linear, nor polinomial, nor logarithmic or exponential way, but perhaps in any of them depending on the circumstances. No matter the circumstance, there is always feedback, which is why I didn’t understand in the beginning Willis’ claim of it not being feedback. But the way the feedback operates, actually changes, and there are lots of thresholds affecting the “mode of operation” of the feedback. It is not one single feedback to apply to the signal no matter what. You cannot describe the feedback with one number or one expression as the IPCC tries to do. It is quite more complicated than that. This is what makes it a governor. The governor is made of the elements in the system that decide in which mode the feedback will operate at any one time.
I hope Willis agrees with this descritpion, otherwise it would mean that I still have not understood the issue ;D
@Willis, thank you very much for your kind words. it is for me a big honor coming from you. I see your point, but I still think that there was some kind of overreaction. As for a suggestion about how to respond to what one perceives as attacks, if anything, I would tell you to look at the way Leif Svalgaard deals with it, for an example. You will agree with me that he gets far worse attacks here than you do, his opinions are not exactly well received by the broad spectrum of the skeptics’ side of the debate. Yet, he seems totally unaffected by those attacks. All he will normally answer is something like “and you are still totally wrong”.
Nylo says:
July 30, 2014 at 6:10 am
Nylo, I do appreciate your most sage advice, along with your lucid explanation of my view on governors. I’ll study the manner of my good friend Leif as you suggest, he does have a manner about him. However, the idea that Leif gets attacked “far worse” that I do? I haven’t seen that. I get attacked for stuff I did a half century ago, I get attacked for my views on a host of non-scientific subjects … haven’t seen Leif subjected to that, although I could have missed it.
Finally, I see Greg going on again just above about how a governor is simply a feedback … so if he is right, why is James Watts “flyball governor” not called a “flyball feedback”? Surely we have two names because they are not the same thing as Greg continues to insist, viz:
Greg was 100% correct, in my view, when he called a governor a “feedback controller”. A governor is a system which controls the feedback, and as such it is NOT the feedback itself. But now Greg appears to be disowning his own definition, and is giving us a new one, claiming that a governor IS a feedback, and what I call “controlled by a governor” should properly be called “controlled by a feedback” … James Watt would laugh to think that the governor controlling the speed of his steam engine actually wasn’t controlling it at all, it was “controlled by a feedback”.
That propensity to move the goalposts is one reason why discussing science with Greg is generally somewhat less useful than discussing it with my cat …
Best regards, and thanks for your comments, always interesting.
w.
Greg you are being a pedantic ass. The conversational use of many esoteric terms is looser than we might use in our engineering notes where ambiguity is not allowed. I don’t think anyone is confused by Willis’ choice of words, including you, and your putting a fine line on things is not improving the conversation. Not to mention you are being quite loose with your daffynitions. It simplifies to error detection and correction. It applies to the most sophicated inertial nav system and to the simplest meat-based system where the loop includes a teen-age driver on their first outing. That is what Willis correctly implies even if he leaves out the boring details.
Nylo says : “But the way the feedback operates, actually changes, and there are lots of thresholds affecting the “mode of operation” of the feedback.”
Thanks Nylo. Modelling individual storms from first principals would probably be near impossible with the current level of understanding. In particular cloud formation and precipitation are very poorly understood.
What may be possible is a more accurate model of their effects en masse.
If Willis is correct, timing is an important factor. This should be a function of SST and the geographic variability of STT ( hotspots large enough and hot enough to trigger a storm. ).
There are several ways in which TS apply a negative f/b to SST: evaporation, convection and blocking incoming solar.
Willis has suggested timing of onset as a key factor. I think spacial density is also important. It may be possible to find some datasets that could inform on those aspects. Willis did a fairly convincing proof of concept using satellite photographs of equatorial cloud formation about 2y ago IIRC.
dp says:
“Greg you are being a pedantic ass. The conversational use of many esoteric terms is looser than we might use in our engineering notes where ambiguity is not allowed. I don’t think anyone is confused by Willis’ choice of words, including you”
Well if Willis wants to stand up and say in a fairly loud voice that climate modellers are missing some fundamental point about the effects of tropical storms ( which may very well be the case ) then I think it is rather important to clearly state in well-defined terms what he means.
Willis seems pretty strong on “schooling ” everyone else , especially Phds and professional scientists but objects vehemently when someone dares to question what he is saying.
I’m sorry but you have to be pedantic in science. Using “feedback” and “governor” colloquially so that no one knows what he actually means is not going to get anything except laughs and instant dismissal. That is why I have been trying to get to the bottom of what Willis means by all this.
At one stage Willis was complaining that he did not accept that is was a _linear_ feedback per IPCC because TS were non linear emergent phenomena. Now it’s that a governor is not a feedback but a system which uses a feedback, but what “feedback” means seems to have become rather unclear.
Perhaps part of the problem is using English to describe it. Maybe a few equations would make it explicit what he is proposing.
“Greg was 100% correct, in my view, when he called a governor a “feedback controller”. A governor is a system which controls the feedback”
Just saying TS is NOT a feedback , its’ a “system” using a feedback does not seem to add anything useful to the discussion nor does it increase understanding nor indicate what is wrong that should be done otherwise and what that may look like.
What is it that you see as being wrong and how would that be changed by calling it a governor?
Another example of natural emerging phenomena (it is all around us in varying forms) can be seen in any river with a natural bed. In a flood the river will carve a new path which changes the length of the river. River length is not an accident, and the river will immediately begin carving meanders to restore the length to a natural state. Meanders are a natural emergent phenomena to control rate of flow for a given grade. Another is seen in various life forms converging on Fibonacci’s number. Not all emergent phenomena become components in a feedback loop outside the evolutionary path those life forms follow.
The problem is you are both describing certain components (and not necessarily the same components) of the system and not the complete system and so the entire conversation is incomplete. Accept that as best effort in a constrained conversational venue and move on.
@dp
>Another example of natural emerging phenomena (it is all around us in varying forms) can be seen in any river with a natural bed.
I recall reading about the physics of that in the 60’s IIRC. The energy needed to straighten and maintain straight a serpentine path comes from the fall of the water.
My mathematician friend the late David R Garcia told me that when something looks chaotic and or unpredictable, it may reveal itself to be, upon close inspection, simply following a ‘lower level of order’. The (I think premature) conclusion that El Nino’s and La Ninas are basically unpredictable seems to be based on the fact no one can demonstrate a cycle in them, nor a causal (coincidental) mechanism that holds up for extended periods of time.
Using FFT or SFT cannot, in principle, find a Max Tan Delta unless you first a) suspect there is one and b) look for it in a way that is able to find it. It is not by testing various frequencies against the feedback or cause. It is by testing a single input frequencies, one at a time, against the outcome and separating things according to temperature because the manifestation of the effect (Max Tan Delta) only occurs at unique Temp/Freq combinations. I was surprised to learn that materials that will be used at room temperature can be tested at -80 C and the effect predicted for a different temperature, with an accurate frequency given (at a temperature super position). That didn’t make intuitive sense as I am aware that materials change a lot when cooled that much. Anyway, that is what they do with DMA’s.
If the atmosphere as a whole (in combination with the oceans) is operating in a viscoelastic manner, using one Temp/Freq combination (and a description of the effect) one can predict other temperatures and frequencies at which it will also emerge. Solar input varies over a range of frequencies, and because there is a general claim made repeatedly that ‘it’s the sun wot dunnit’ it is a strong candidate to examine first for a sign of a VMTD. There are hints throughout the literature that tend to support such a leap.
“That propensity to move the goalposts is one reason why discussing science with Greg is generally somewhat less useful than discussing it with my cat …”
That must make you cat a perfect peer review recommendation for you hypothesis.
Funny you should mention goal-posts. Perhaps you should look back at the various morphs of ‘its not a feedback it’s a governor” has gone through.
http://wattsupwiththat.com/2013/04/21/dehumidifying-the-tropics/
“Clouds are not just simple feedback, they act as governors, applying both positive and negative feedback in response to different situations. ”
Seems the misunderstanding of what feedback means goes way back. I did not notice before.
“And other research of mine has shown that in general clouds cool the earth in the summer and warm it in the winter. ” Yes, Wiilis, that is what is called a negative feedback. One that opposes the change whichever direction it takes.
“Again, the clouds are not a feedback but act as a governor, tending towards a homeostatic state.” Yes Willis, that is what happens in the presence of a negative feedback. -ve f/b can go up as well as down depending upon the direction of the change that is causing them.
http://wattsupwiththat.com/2013/03/28/tao-rain-sea-and-air-data/
• This ability to drive the surface temperature well below the normal temperature is the sign that the thunderstorms function as a governor, rather than as a feedback.
Here it is the overshoot that is claimed to prove it’s not a feedback but a governor. So this is different from the current claim that a governor is a “system” that controls a feedback. There go the goalposts again.
To which I remarked:
March 28, 2013 at 2:10 am
More interesting finds Willis. Nice digging.
“thunderstorms function as a governor, rather than as a feedback.”
You may or may not be right about this but in order to have any meaningful discussion or for that conclusion to mean anything and be useful you need to define what you mean by both terms.
To which Willis replied:
“Interesting point, thank, Greg. Yeah, I have a post half written on this question.
….
With simple linear negative feedback, a system can never be driven past its starting point. ….With a governor, the system can be driven past its starting point. To control a lagged system like a house or the climate, where things take time to heat up or cool down, such “overshoot” is necessary.”
So now it’s the overshoot and the non linearity that defines the difference. Not that a governor is a “system controlling a feedback”.
My concluding comment at that time was:
“So in conclusion, I think Willis is correct with his tropical air-con governor as far as tropics are concerned. On the face of it I don’t see this as being incompatible with that mechanism being a simpler negative feedback on a global scale.”
That did not solicit any further comment and seems to be the last time we had a civil exchange on the subject.
The governor got its name from how it was used. One was instructed to adjust the governor as needed because it was the obvious device to govern the speed error of a steam engine (the course speed being set by the throttle position, steam pressure, and load and then the governor flyballs being set to about mid-range). One did not speak of adjusting the loop gain and phase angle because they didn’t think in those terms. The result of adjusting the governor is not different than adjusting the loop gain. Railroad engines actually had a control to adjust the steam valve timing relative to the piston which was a form of optimizing the phase of the feedback loop. It compensated for standing waves and friction in the steam path. The governor compensated for changing speed about a point caused by e.g. varying load (grade) and steam pressure (low water, fireman falling asleep, blowing the whistle).
On steam ships and particularly side and stern wheel vessels the governor would govern engine speed when the wheels were tormented by storm-tossed seas. On airplanes they are used in pitch control systems for the propellers. Other feedback systems keep propellers in synch to eliminate the engines throbbing out of synch. There was a time when speed controllers in cars had a sensitivity control as well as a speed control. The sensitivity control allowed the system to keep a light foot on the throttle on twisty roads or to dial up the gain to hold perfect speed on long flat stretches of road. That is equivalent to adjusting the ball height in a flyball governor.
In electronic devices the governor et al is known as automatic volume control, or automatic frequency control and are not far removed mathematically from Willis’ handsome flyball governor. In audio it would be a mic compressor and in single-sideband radio transmitters it would be AGC, or automatic gain control. All so named by usage and not by what comprises them. It is said marriage has a taming effect on men causing them to live longer than their single counterparts. That is a domestic closed loop system.
They all work the same. There is input, there is output, there is a reference, and there is an error signal. There is a variable gain component, and there is a phase relationship. In domestic closed loop systems be cautious of relationships regards loop stability. Pragmatically, there is also dynamic range beyond which control is lost. Don’t be too hung up on terms.
@dp, in climate, in the “thunderstorms acting like a governor”, the signals are the incoming solar radiation and the temperature, but the feedback of the system (which acts by affecting both of them, the incoming radiation by the creation of clouds, and the temperature by the evaporation rate) depends on several other things as well, like wind speed, or the integral of the temperature (how much time it has been having a temperature over some range, i.e. for how much time clouds have been growing).
I’ve never liked the comparison of this governor with the speed control of modern cars. This speed control is IMO not worth calling a governor, the feedback is a simple function of just one parameter, the speed: more speed, less gas, and less speed, more gas. Simple negative feedback. I prefer to compare it more to the gear control in automatic cars. The car will select the gear not based only on your speed, but also on how strong you put your foot on the gas pedal (i.e. how much power the central unit thinks that you want to have), whether you are going uphill or downhill, and even if you are not touching the gas pedal, it will use one gear or another based on whether you have recently used the brakes or not. There are lots of conditions that affect the output, the power delivered and/or the wheels retention by the engine, through gear selection.
Sorry, sent the message too early, let me continue.
My point is that if you tried to guess how much power I have had delivered by my car’s engine based solely on what was the average speed that I kept, you would not be able to. It depends on many more things. Using one driving style or another, I can get quite different mileages per gallon of fuel from my car for the same average speed. It can change up to 20%, I repeat, for the SAME AVERAGE SPEED and the same circuit. So making up a parameter that supposedly tells me how much mileage my car will get in the future based on its speed, is absurd. The feedback is more complex than that. And in a similar way, trying to get at a parameter that tells me how many clouds there will be in the future blocking sunlight based on average temperatures is equally nonsense. For roughly the same average temperature, you can have totally different cloud covers.
I have questioned the energy budget of Willis’ emergent phenomena but that is an entirely different question vs his usage of terms discussed here. That issue brings us back to closed loop system analysis where accidents don’t happen, and where absolute numbers matter. I don’t recall from reading Willis’ paper any supporting data so I accepted his paper as being a notion of what may be at work and not a claim of what is at work. It is a valid concept that needs a proper energy analysis. I’ve lived in the tropics and I know about the weather cycle. I’m even willing to accept it is plausible that cloud generation can limit insolation at the surface because I’ve experienced it. A tropical downpour can be damn cole. Whether or not that affects albedo enough to not just negate but reverse insolation heating I can’t say.
Your statement above has put the cart adjacent to the horse. We don’t design closed loop systems first and then use their performance metrics to calculate the drivers. It isn’t impossible to solve your power riddle by going backward in design evolution from a successful design, but it is necessary to have more information than you offer and it is unnecessarily ugly to do so. In fact designing forward requires knowing more than you offer. Your point is invalid.
dp
Your comment provides the appropriate analogy.
“It isn’t impossible to solve your power riddle by going backward in design evolution from a successful design, but it is necessary to have more information than you offer and it is unnecessarily ugly to do so”
In a car the automatic transmission controller uses not only the foot throttle position, but its rate of change in order to interpret how and when to kick back a gear to increase acceleration. Pushing it incrementally gives a different response compared with pushing it suddenly half-way to the floor – at least it does in cars with computer-controlled drive-by-wire systems. In other words, the engineers ‘thought of that’.
If you were trying to work out how the computer controlled the transmission by examining the input-response curve, you would not get the whole picture by pressing it slowly and watching the response for the simple reason that the rate of input change is a parameter that affects the result.
This is getting easier to explain as the conversation continues. A high rate of change (for example) from a forcing (from any source) can drive emergent phenomena that will not appear at a low rate of change.
Another example is trying to inflate a tire loosely on a rim with a hand pump. After watching someone huff an puff, an observer might conclude that the tire is not inflatable. But if the tire is inflated rapidly, it inflates a little and then self-seals to the rim and thereafter will inflate fully with a small hand pump. An impact of sufficient force and rapidity (frequency) will break the seal and the tire will return to its former deflated condition. These are two step changes that are not always apparent by examining at and even testing the system under controlled conditions.
@dp, it is necessary to have more information than you offer and it is unnecessarily ugly to do so. In fact designing forward requires knowing more than you offer. Your point is invalid.
DP, you have used a long post to explain how you cannot solve my power riddle, and then say that my point is invalid. How can it be invalid, when what I have said is precisely that the power riddle cannot be solved? Of course I know that you cannot simplify the way it works as if it were through some feedback parameter which is a function of some data in particular (temperature in the case of climate, or avg speed for my example), because the feedback depends on more parameters and in a more complex way. There was no riddle, I wasn’t trying to compel anyone to solve a difficult problem, I was asserting that it is not possible to resolve it. That’s what the analogy pretended to reflect, that you cannot “solve” the climate feedback as a function of the average temperature alone either.
If that was your point regards climate then I missed it. I’ll re-read it again. I would limit my agreement with that to it being highly improbable that the climate problem can be exactly solved rather than saying it is impossible to solve. We don’t know (yet) the unknown unknowns. That may change and in any case the answer will be a probability though a more refined probability than anything we have today.
willis: If you’re coming via the inside passage, and aren’t yet South of the 49th, wave as you pass by Salt Spring Island. Please have a safe trip! Enjoy!
John West says:
July 28, 2014 at 12:53 pm
Wes Spiers says:
“there is no centrifugal force”
Tell that to a coffee cup sitting on a dash when a curve is taken a little too fast.
The cup is trying to continue in a straight line. You and your car are trying to change its vector. Is inertia centrifugal?
“Inertia” is a rather old-fashioned term that has no place in the analysis of Newtonian motion. It is not a force, nor an acceleration. So it is neither centrifugal nor centripetal. It is really only a one-word statement of Newton’s first law viz: “a body continues in a state of rest or uniform motion in a straight line unless acted on by an external force.” Or poetically: “A body’s inclined to rest all the time, or travel with uniform motion, ’til due to a force of external source, it’s given a different notion”
The first part i.e. a body stays at rest unless acted on by a force, seems obvious. Why else would it move?
The second part, however, was a stroke of genius. Nowhere on Earth had anyone ever witnessed a body continuing to move at a steady speed without eventually slowing down and stopping. It took Newton to realize, that if it were not for the invisible force of friction, it would never stop.
This discussion is making me relive the years I spent trying to teach students how to solve dynamics problems. I thought I was retired!
Read your textbook!
Knoxville, like East Tennessee generally, was pro-Union during the Late Unpleasantness, as was East Kentucky, NE Alabama, of course West Virginia and Appalachia overall. As such, it would be less likely to feature Civil War (a misnomer) heroes on its square. Andrew Johnson, Lincoln’s second Veep, on the pro-Union fusion ticket, was the only Southern senator to remain loyal to the Union, hailed from Greeneville, where a convention was held to form the state of East Tennessee and secede from the CSA.