tag:blogger.com,1999:blog-7729093380675162051.post1312113707286092959..comments2024-03-28T13:56:47.604+11:00Comments on moyhu: Climate feedbacks and circuits Nick Stokeshttp://www.blogger.com/profile/06377413236983002873noreply@blogger.comBlogger29125tag:blogger.com,1999:blog-7729093380675162051.post-4412873704269646642016-09-12T02:17:25.044+10:002016-09-12T02:17:25.044+10:00regarding a butterfly flapping its wings:
Most pe...regarding a butterfly flapping its wings:<br /><br />Most people don't understand the distinction between initial conditions and boundary conditions. In fact boundary conditions can act much like a recurring set of initial conditions, where the boundary condition acts like a guide to synchronize a behavioral state over time. A good example of a boundary condition is the daily cycle and the seasonal cycle.<br /><br />What causes the problem is that people immediately think a boundary condition can only have something to do with spatial dimensions, which is understandable since a boundary is typically considered a physical location.<br /><br />A good example is the ocean tide, which is primarily set by boundary conditions. Tides will never go out of sync with the moon and the sun since they will forever nudge the response of the ocean to keep in sync with the defined orbit. However, they also behave following spatial boundary conditions, especially noticed in certain geophysical locations where the tides are most pronounced.<br /><br />A huge instability such as a tsunami will have no impact on the tide, and it will readjust and keep going where it left off after the tsunami subsided.<br /><br />Now think about how that applies to ENSO and QBO. Nothing about either of these two phenomena suggests that they are primarily driven by initial conditions. External forces are obviously maintaining a stationary behavior for each of them.<br /><br />What is interesting is that there is a current flurry of media activity surrounding a measured perturbation of the QBO. There is speculation that this perturbation signals a change in the behavior of the QBO -- some say possibly due to AGW or a strong ENSO effect. Now, all we have to do is watch the QBO in the next few years and find out whether is synchronizes back to the behavior it has exhibited over the last 60 years.<br /><br />Of course no one really understands QBO, since it is based on a half-backed theory of the crank Richard Lindzen, but say that that it is stimulated by lunar tidal forces, it should re-align with that cycle within the next few years. That will demonstrate a solid boundary condition.<br /><br />A forcing caused by a growing CO2 imbalance is also a boundary condition, just that this is a boundary condition that is not stable over time. That's what makes it a bit more tricky.<br /><br /><br /><br /><br /><br /><br /><br /><br /><br />@whuthttps://www.blogger.com/profile/18297101284358849575noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-74128832082868419122016-09-09T07:49:41.709+10:002016-09-09T07:49:41.709+10:00"any noise - a butterfly flapping its wings -...<i>"any noise - a butterfly flapping its wings - *could* cause severe instability."</i><br />That's what I'm trying to say by showing that combining feedbacks is like adding a set of conductances, positive and negative. Instability is where the total is no longer positive. The butterfly would have to offer a lot of conductance to tip the balance. But it also says that there is nothing special about having positive feedback in the mix. All that really matters is the after feedback gain.<br />Nick Stokeshttps://www.blogger.com/profile/06377413236983002873noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-15154204772701053122016-09-09T07:03:38.354+10:002016-09-09T07:03:38.354+10:00This is why this guy belongs in the Trump camp of ...This is why this guy belongs in the Trump camp of clowns:<br /><i>"... or deprive the developing world to the cheap energy required to raise their standard of living to that we enjoy."</i><br /><br />Evidently doesn't understand that fossil fuels are a finite & non-renewable resource and that we should be moving toward alternative energy schemes independent of future AGW effects.<br /><br />Can't stand people like Jeff Patterson cause all they do is regurgitate the talking points that they absorb from slobs like Ailes. They aren't here to add any value, but to push their agenda.<br />@whuthttps://www.blogger.com/profile/18297101284358849575noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-37738555693816601362016-09-09T06:21:51.699+10:002016-09-09T06:21:51.699+10:00When considering gyroscopes, solving the non-spinn...When considering gyroscopes, solving the non-spinning equations gives you no clue what will happen when you pull the string. Same for a synchronous AC motor, using a DC power source won't provide useful work (just lots of magic smoke).<br /><br />The fact that a DC circuit can be stable with positive feedback says absolutely nothing about what happens in the real world. Its not just that the energy from the Sun fluctuates, but any noise - a butterfly flapping its wings - *could* cause severe instability. That is why negative feedback rules in the great majority of *stable* systems.Robert Clemenzihttp://mc-computing.com/Science_Facts/RadiationBalance/LTspice/First_Look.htmlnoreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-32673550608447485842016-09-09T05:11:12.566+10:002016-09-09T05:11:12.566+10:00For the record I have never tried to "disprov...For the record I have never tried to "disprove AWG". My view is that CO2 emissions contribute to global warming but that the climate sensitivity to such emissions is very near the low end of the accepted range of estimations. We are about a decade away from having enough high quality data to determine the question once and for all so that the wisest policy decision is to do nothing that would disrupt the global economy or deprive the developing world to the cheap energy required to raise their standard of living to that we enjoy.<br /><br />Your other rude comments are equal inane. I've never attempted a Bode analysis of the climate. I have speculated in the past that some of the natural variation exhibited in the GMST records may be due to systemic response to some external event. That analysis was LaPlacian which are just differential equations in the frequency domain. Do you have trouble with differential equations?Anonymoushttps://www.blogger.com/profile/05024509207922856291noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-6429724552522030232016-09-09T05:11:06.968+10:002016-09-09T05:11:06.968+10:00The point Nick is making with this circuit analogy...The point Nick is making with this circuit analogy that like the climate system, the net feedback is always negative but that a small amount of positive feedback can reduce the amount of negative feedback and thus increase the gain. It's a point well made in language EE can relate to. Evidently you have some disagreement with the analogy so perhaps you should try stating your objection clearly instead of showing all who care to look how an asshat behaves. Anonymoushttps://www.blogger.com/profile/05024509207922856291noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-14483863597007153702016-09-09T04:31:16.963+10:002016-09-09T04:31:16.963+10:00"Why don't you crawl back to your Trump h...<i>"Why don't you crawl back to your Trump hole and leave this place for scientific discussion?"</i><br />Maybe Jeff has said things elsewhere that you object to, but his comments here do not seem unscientific.Nick Stokeshttps://www.blogger.com/profile/06377413236983002873noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-20900683884035269142016-09-09T01:25:13.740+10:002016-09-09T01:25:13.740+10:00Forget the electronics analogies, this is how you ...Forget the electronics analogies, this is how you figure out sensitivity with the outgassing feedback that we know occurs:<br /><br /><a href="http://theoilconundrum.blogspot.com/2013/03/climate-sensitivity-and-33c-discrepancy.html" rel="nofollow">http://theOilConunDrum.blogspot.com/2013/03/climate-sensitivity-and-33c-discrepancy.html</a><br /><br />I am not going to reproduce this here, because the commenting markup is the crudest and ugliest that I have ever seen. <br /><br /><br /><br />@whuthttps://www.blogger.com/profile/18297101284358849575noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-81822875588570738792016-09-09T01:10:29.646+10:002016-09-09T01:10:29.646+10:00Jeff Patterson said:
"... how an asshat behav...Jeff Patterson said:<br /><i>"... how an asshat behaves."</i><br /><br />Why don't you crawl back to your Trump hole and leave this place for scientific discussion?<br /><br />@whuthttps://www.blogger.com/profile/18297101284358849575noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-3539844765459351442016-09-09T00:05:14.157+10:002016-09-09T00:05:14.157+10:00The point Nick is making with this circuit analogy...The point Nick is making with this circuit analogy that like the climate system, the net feedback is always negative but that a small amount of positive feedback can reduce the amount of negative feedback and thus increase the gain. It's a point well made in language EE can relate to. Evidently you have some disagreement with the analogy so perhaps you should try stating your objection clearly instead of showing all who care to look how an asshat behaves. Anonymoushttps://www.blogger.com/profile/05024509207922856291noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-72340102896708215042016-09-08T23:52:22.811+10:002016-09-08T23:52:22.811+10:00For the record I have never tried to "disprov...For the record I have never tried to "disprove AWG". My view is that CO2 emissions contribute to global warming but that the climate sensitivity to such emissions is very near the low end of the accepted range of estimations. We are about a decade away from having enough high quality data to determine the question once and for all so that the wisest policy decision is to do nothing that would disrupt the global economy or deprive the developing world to the cheap energy required to raise their standard of living to that we enjoy.<br /><br />Your other rude comments are equal inane. I've never attempted a Bode analysis of the climate. I have speculated in the past that some of the natural variation exhibited in the GMST records may be due to systemic response to some external event. That analysis was LaPlacian which are just differential equations in the frequency domain. Do you have trouble with differential equations?Anonymoushttps://www.blogger.com/profile/05024509207922856291noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-46046245189194897602016-09-08T22:40:53.067+10:002016-09-08T22:40:53.067+10:00Jaff Patterson said:
"The analogy to climate ...Jaff Patterson said:<br /><i>"The analogy to climate is straight forward. "</i><br /><br />Bwaha! The problem with these EEs is that they think that the climate can be reduced to circuit diagrams, not realizing that the underlying differential equations don't match those of electronics.<br /><br />Jeff Patterson has probably never solved a Mathieu equation or a Storm-Liouville equation and probably couldn't because he thinks the solution to any problem is a Bode plot, ha ha.<br /><br />@whuthttps://www.blogger.com/profile/18297101284358849575noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-59577743158076715242016-09-08T21:31:33.790+10:002016-09-08T21:31:33.790+10:00Robert C,
Well, I think that would be an analogue ...Robert C,<br />Well, I think that would be an analogue GCM 😒. The main problem being that we're struggling to get the DC values.<br /><br />But I do think it could be useful to put in a capacitor for ocean, which would shift to the next time scale down. There is a definition of effective CS which basically does that. For EffCS you adjust for the supposed known flux into oceans, to try to get an ECS estimate before the long ocean stage is done.<br />Nick Stokeshttps://www.blogger.com/profile/06377413236983002873noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-53172037562559149692016-09-08T19:21:18.938+10:002016-09-08T19:21:18.938+10:00Nice. But to simulate the climate you need to add ...Nice. But to simulate the climate you need to add a lot of capacitors - ocean, land, atmosphere, clouds - they should each be modeled as a resister in series with a capacitor. Then the input current must not be DC - day/night and seasons must be considered. Under those conditions the system becomes much more complex and positive feedback stability may be loss.Robert Clemenzihttp://mc-computing.com/Science_Facts/RadiationBalance/LTspice/First_Look.htmlnoreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-44889307905583957792016-09-08T16:04:40.521+10:002016-09-08T16:04:40.521+10:00There are two inversions so the feedback from ther...There are two inversions so the feedback from there is positive. It sums with the negative from the first stage. If the sum total is positive it will oscillate. It not it will be less negative. The analogy to climate is straight forward. Anonymoushttps://www.blogger.com/profile/05024509207922856291noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-60223910117565941152016-09-08T15:59:01.800+10:002016-09-08T15:59:01.800+10:00Brilliant Nick. The mistake many make is not appre...Brilliant Nick. The mistake many make is not appreciating the unit conversion issue which you point out. When the gains aren't unitless many are led astray. Anonymoushttps://www.blogger.com/profile/05024509207922856291noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-65033849870901784902016-09-08T15:07:32.215+10:002016-09-08T15:07:32.215+10:00Bernie Evans, who wrote about the circuit, did bui...Bernie Evans, who wrote about the circuit, did build it. It did not oscillate. The measured voltages are marked in green.Nick Stokeshttps://www.blogger.com/profile/06377413236983002873noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-83887798294361192572016-09-08T15:04:41.703+10:002016-09-08T15:04:41.703+10:00My bad on the last comment. There is positive feed...My bad on the last comment. There is positive feedback in that circuit. Build it on breadboard and see it oscillate.Alexhttps://www.blogger.com/profile/09928340319762651127noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-43612303244664074952016-09-08T15:01:47.916+10:002016-09-08T15:01:47.916+10:00I'd like to point out that Fig 6 shows absolut...I'd like to point out that Fig 6 shows absolutely no positive feedback. You have positive _GAIN_, not positive feedback. If you had any positive feedback the output would oscillate or "stick" to one of the rails.<br /><br />A comparator is stable only in the sense that its output is constrained by the supply rails. An ideal comparator with an infinite supply voltage would output an infinite voltage, whereas an opamp with negative feedback and an infinite supply would output a finite voltage related to its input and the gain.Alexhttps://www.blogger.com/profile/09928340319762651127noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-43757986990211008452016-09-06T02:51:43.470+10:002016-09-06T02:51:43.470+10:00Oscillations! Likely all the oscillations that we...Oscillations! Likely all the oscillations that we see in the climate system are externally forced. The obvious ones are daily and seasonal, but then we have the behaviors such as QBO, which are likely forced by lunar gravitational cycles. The fact that consensus science views QBO as an emergent resonant behavior is troubling. Geoffrey Vallis is also questioning the complicated models we are using and that without a solid foundation of geophysical models "the edifice will come tumbling down".<br /><br />Discussion here:<br /><a href="http://contextearth.com/2016/09/03/geophysical-fluid-dynamics-first-and-then-cfd/" rel="nofollow">http://contextearth.com/2016/09/03/geophysical-fluid-dynamics-first-and-then-cfd/<br /></a><br /><br /><br />@whuthttps://www.blogger.com/profile/18297101284358849575noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-38017005121688520222016-09-06T02:20:25.613+10:002016-09-06T02:20:25.613+10:00Oh yeah, for what it's worth ECS circuits woul...Oh yeah, for what it's worth ECS circuits would require a critically damped delay between input and output. Doable with op amps but hard to eliminate oscillations.EliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-29111404421167236362016-09-02T05:20:04.958+10:002016-09-02T05:20:04.958+10:00Phil,
Thanks. Yes, I mentioned at WUWT that I spen...Phil,<br />Thanks. Yes, I mentioned at WUWT that I spent a lot of time as a student messing with circuits to make music. That's probably why I related to Bernie Hutchins commentary - he's from the world of Moog, who was a hero of the times. Astable multivibrators, which did that switching between states, were our staple circuit.<br /><br />Nick Stokeshttps://www.blogger.com/profile/06377413236983002873noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-57528590721527326872016-09-02T03:29:57.496+10:002016-09-02T03:29:57.496+10:00A "Schmitt trigger is a comparator circuit wi...A "Schmitt trigger is a comparator circuit with hysteresis", according to Wikipedia. Might be more correct to say that a comparator circuit is a Schmitt trigger with or without hysteresis.<br /><br />And yes, a warm smile in memory of Otto Schmitt. Thanks.Philhttps://www.blogger.com/profile/07567197089095711546noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-73917936639893313802016-09-02T02:57:24.279+10:002016-09-02T02:57:24.279+10:00Or a Schmitt trigger, which is a type of comparato...Or a Schmitt trigger, which is a type of comparator. Its inventor, Otto Schmitt, was still an emeritus professor when I was going to the U of Minnesota. He was the lone occupant of the old Music Education building. The guy was nuts but many an engineering student would spend time listening to his stories and ideas. He would always carry two watches and was researching telekinesis at the end. http://www.ee.umn.edu/users/schmitt/bulletin.html<br /><br />This feedback discussion is misguided. What you have to do is look at each case uniquely. The GHG warming via water vapor is a positive feedback system since as things heat up, more water vapor will go into the air. Yet the Arrhenius factor on outgassing has an interesting characteristic in that it won't spiral out of control. Set up the equations and you can estimate the setpoint that it will reach for a given initial forcing. <br /><br />And of course, these don't have anything to do with classical electrical feedback circuits, except if you're an EE you have intuition on how the math works. <br /><br />Some ideas are good and some ideas are bad. <br /><br />@whuthttps://www.blogger.com/profile/18297101284358849575noreply@blogger.comtag:blogger.com,1999:blog-7729093380675162051.post-90437545942531634262016-09-01T23:29:10.906+10:002016-09-01T23:29:10.906+10:00Nice.
As an EE, I've one minor point.
A phys...Nice.<br /><br />As an EE, I've one minor point.<br /><br />A physically realizable op amp with only positive feed back is a comparator with hysteresis. Yes, there are subtly different parts sold as comparators ( http://www.ti.com/lit/ds/symlink/lm311.pdf ), but real op amps can work as comparators.<br /><br />An input above the threshold will produce an output at the positive limit. An input below the threshold will produce an output at the negative limit. This is stable, as long as there is positive feedback.<br /><br />"It is a standard procedure to use hysteresis (positive feedback) around a comparator, to prevent oscillation, and to avoid excessive noise on the output because the comparator is a good amplifier for its own noise. "<br /><br />http://www.ti.com/lit/an/snoa860/snoa860.pdf<br />Philhttps://www.blogger.com/profile/07567197089095711546noreply@blogger.com