tag:blogger.com,1999:blog-16612221.post6310948867350396891..comments2024-03-19T03:14:04.172-04:00Comments on Rabett Run: Why the Green Plate Effect Has Had an EffectEliRabetthttp://www.blogger.com/profile/07957002964638398767noreply@blogger.comBlogger54125tag:blogger.com,1999:blog-16612221.post-16336674865758115362017-11-27T15:31:27.831-05:002017-11-27T15:31:27.831-05:00Here is secret answer #2....
A=S/2, B=A/2 from Ro...Here is secret answer #2....<br /><br />A=S/2, B=A/2 from Robert's law<br />For the system S=A+B from first law<br />The blue plate is S+B=2A<br /><br /><br />So a little algebra gets you S+A/2=2A,<br />And then simply A=2S/3<br /><br />That means B=S/3<br /><br />So blue plate is spewing 2S/3 to space.<br />Green plate is spewing S/3 to space. System is in balance, blue plate is in balance, green plate is in balance.<br /><br />And BTW blue plate 4S/3 energy out where it only had S without the other plate present.<br /><br />Solution requires nothing more than 1st law and 1st year algebra. You never have to go down a temperature rat hole. Temperature is a silly thing to dwell on. It's all about energyPaul Bahlinhttps://www.blogger.com/profile/00094198357070229421noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-86054309009152492402017-11-27T15:08:58.671-05:002017-11-27T15:08:58.671-05:00If you agree with Robert's law let's add a...If you agree with Robert's law let's add another plate to the system in proximity to the first and aligned so that they share a perpendicular center line.<br /><br />Plate 1, let's call it blue, is to the left of plate 2, we'll call it green.<br /><br />Let's define a system boundary around the whole thing and feed an energy S to blue. Blue has two outputs that obey Robert's law. We can call them A. The A on the right strikes green and it has two outputs that also obey Robert's law. We'll call them B.<br /><br />Write a system of equations that describe this system....Paul Bahlinhttps://www.blogger.com/profile/00094198357070229421noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-57609126028874548092017-11-27T14:57:36.753-05:002017-11-27T14:57:36.753-05:00Give up? Here is the secret answer...
A=S/2, B=S...Give up? Here is the secret answer...<br /><br />A=S/2, B=S/2. And the corollary is of course... A=B<br /><br />Let's call it Robert's law and it States that a very thin equlibrated plate with input energy S has two output energies equal and opposite each other normal to the plate's plane.Paul Bahlinhttps://www.blogger.com/profile/00094198357070229421noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-40734458453143677892017-11-27T13:59:10.175-05:002017-11-27T13:59:10.175-05:00Every time I run across this topic I see the same ...Every time I run across this topic I see the same process....<br /><br />A fundamental simple model is proposed and before 3 commments have been made the thread is off to the races with ice cubes and wooden blocks, Plancks, Boltzmans, etc. Pretty soon the snark kicks off followed by name calling and mind numbing math when all that is called for is profoundly simple logic built on agreement with some basic principles before diving into the weeds. I propose a trivial exercise and if we can't get every single person here to agree to the concept we don't proceed so here goes (this is mostly aimed at Betty but YMCV).....<br /><br />Define a system boundary around a blue plate being heated with a constant of S Joules/sec. The plate is very thin so ignore edge effects. When the plate equilibrates it will radiate energy from its two sides. The boundary then has one input, S and two outputs, A and B.<br /><br />Write an equation for A and B in terms of SPaul Bahlinhttps://www.blogger.com/profile/00094198357070229421noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-88486001052577458982017-10-29T11:15:18.425-04:002017-10-29T11:15:18.425-04:00izen discusses and provides animated gifs of a rel...izen discusses and provides animated gifs of a related version of the blue- green plate example here: <br /><br />https://izenmeme.wordpress.com/2017/10/29/back-radiation-and-the-2nd-law-of-thermodynamics/<br /><br />Not that deniers will accept it. The will to deny is strong in some.jgnfldhttps://www.blogger.com/profile/18345702872292499039noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-41583495679705395572017-10-28T11:41:18.923-04:002017-10-28T11:41:18.923-04:00I had a thought that might help some people -- bas...I had a thought that might help some people -- basically turn the problem around and calculate how much you have to actively heat or cool the two plates to achieve a specific goal. I say this because I *think* everyone agrees that a flat blackbody surface radiating to space emits <br /><i>P/A = sigma T^4</i>, <br />and that the power from a hot flat blackbody to a nearby cold flat blackbody is <br /><i>P/A = sigma (T(h)^4 - T(c)^4)</i><br /><br />So assume two flat blackbody plates that are each 1m x 1m (called "Blue" and "Green"). Assume you want to actively keep Green at 220K when blue is actively held at various temperatures. <br /><br /><b>Hold Blue @ 0K</b><br />Actively heat Green @ 267W so it can radiate 133W to space (from its right side) and radiate 133W to Blue (from its left side)<br />Actively refrigerate Blue @ 133W so it can absorb 133W from Green (from its right side) and radiate 0W to space (from its left side)<br /><br /><b>Hold Blue @ 220K</b><br />Actively heat Green @ 133W so it can radiate 133W to space and 0W to Blue<br />Actively heat Blue @ 133W so it can absorb 0W from Green and radiate 133W to space.<br /><br /><b>Hold Blue @ 244K</b><br />Actively heat Green @ 67W so it can radiate 133W to space and absorb 67W from Blue<br />Actively heat Blue @ 267W so it can radiate 67W to Green and radiate 200W to space.<br /><br /><b>Hold Blue @ 262K</b><br />Actively heat Green @ 0W so it can radiate 133W to space and absorb 133W from Blue<br />Actively heat Blue @ 400W so it can radiate 133W to Green and radiate 267W to space.<br /><br /><b>Hold Blue @ 290K</b><br />Actively refrigerate Green @ 133W so it can radiate 133W to space and absorb 267W from Blue<br />Actively heat Blue @ 667W so it can radiate 267W to Green and radiate 400W to space.<br /><br />It is easy to confirm that all these <br />1) agree with simply SB power calculations <br />2) conserve energy.<br /><br />Also, it is also intuitive that if blue is cold, energy with flow from Green to Blue and Green will need an active heater to stay at 220K. Conversely, if Blue is quite hot, energy will flow from Blue to Green and Green will need active cooling to stay at 220K. Thus there must be a sweet spot where green requires neither heating nor cooling to stay @ 220K, and that happens to be when Blue is 262 K (ie when blue is getting 400W input power). <br /><br /><br /><br />Timothy Folkertshttps://www.blogger.com/profile/03388644695220684246noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-76284082736271790622017-10-27T17:16:20.875-04:002017-10-27T17:16:20.875-04:00I hear we may be in for a spell of the Apocalypt...I hear we may be in for<a href="https://vvattsupwiththat.blogspot.com/2017/10/where-is-godzilla-now-that-we-need-him.html" rel="nofollow"> a spell of the Apocalyptocene </a>THE CLIMATE WARShttps://www.blogger.com/profile/02578106673226403151noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-23088750315257942212017-10-27T05:54:16.352-04:002017-10-27T05:54:16.352-04:00Those interested in a deeper intellectual exercise...Those interested in a deeper intellectual exercise about climate may wish to discuss <br />http://bravenewclimate.proboards.com/thread/561/back-future<br />on whether we are headed for the climate of the mid-Pliocene. David B. Bensonhttps://www.blogger.com/profile/15914145623997712113noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-10926904384894019252017-10-26T17:17:21.814-04:002017-10-26T17:17:21.814-04:00"You believe the sun prevents equilibrium on ..."You believe the sun prevents equilibrium on objects it shines on perpetually. "<br /><br />Betty, It's not the sun's fault if people paint white objects black, or darken atmospheres with infrared inks like CH4 or CO2.THE CLIMATE WARShttps://www.blogger.com/profile/02578106673226403151noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-10116256889504504672017-10-26T02:09:26.091-04:002017-10-26T02:09:26.091-04:00Yep but there are many out there trying to sow con...Yep but there are many out there trying to sow confusion and simple examples are needed to deal with them. <br /><br />Part of the value of the GPE is the obvious thrashing it gas inspired at rr Dr roys and elsewhere makes the point of how empty the confusioinsts arguments are.<br /><br />One of the things those of us on the other side need to learn is to keep things simple.<br /><br />Wrt blankets there is a long history of objection that they only cut off convection, that they cannot warm a hotter thing etc. Even there the GPE has value bcs it shows how a source of constant heat energy plays an important roleEli Rabrtthttps://www.blogger.com/profile/13793489993164786719noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-67823850721230369382017-10-25T17:58:00.705-04:002017-10-25T17:58:00.705-04:00Jeez this is getting complicated. I am a retired L...Jeez this is getting complicated. I am a retired Landscape Architect, so no scientist but exposed to a little. I totally understand that something hot (the sun) can heat something smaller and cooler (the earth) and that that cooler thing can conserve its heat by having a thermal radiative blanket (the atmosphere) until it reaches equilibrium. When the thermal blanket is made more effective (more CO2 (see old science)) the equilibrium must increase the temperature on the cooler thing. Suwannee Davehttps://www.blogger.com/profile/08920710561840672218noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-74205793094311190692017-10-25T13:02:20.105-04:002017-10-25T13:02:20.105-04:00Tom,
While what you say is true, glass is a prett...Tom,<br /><br />While what you say is true, glass is a pretty good insulator and wrapping the bulb w. tinfoil pretty much kills convection between the glass envelope and the bulb. Convection btw the outside should be the same for glass or Al wrapped glass. Same with the IR coating on the halogen lamps.<br /><br />The multiple layers, of course, make a difference in the numbers, but not the principle of a single plate. Multiple layer atmospheric models are pretty much what GCMs use (~20 ??)EliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-24407124683248586702017-10-25T12:23:35.694-04:002017-10-25T12:23:35.694-04:00Eli, unlike your foil-wrapped light bulb example, ...Eli, unlike your foil-wrapped light bulb example, the multiple layers around spacecraft do not touch each other and are separated by vacuum. So conduction and convection don't operate. I assume Gator's vacuum container similarly has vacuum between its layers.Tom Daytonhttps://www.blogger.com/profile/14033524810322903771noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-40661411180844652942017-10-25T11:41:15.908-04:002017-10-25T11:41:15.908-04:00Eli -- maybe, but the layers will equilibrate to a...Eli -- maybe, but the layers will equilibrate to an intermediate temperature and radiate. The main thing is that the layers should not be transparent. I guess the main thing is that this is a real world, very practical example of the engineering of radiative heat transfer. It works.Gatorhttps://www.blogger.com/profile/13974079614971006038noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-30809440404635611922017-10-25T11:39:15.096-04:002017-10-25T11:39:15.096-04:00
So soon you forget
http://rabett.blogspot.com/20...<br />So soon you forget<br /><br />http://rabett.blogspot.com/2008/09/light-dawns-there-are-styles-in-science.html<br /><br />Also reflective IR coatings on halogen lamps<br /><br />http://www.smithmillermoore.com/Pdfs/technicalarticles/3-6-13_DSI_LTB_The_Rebirth_of_theIncandescentLightBulb.pdfEliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-18747211240721189632017-10-25T11:17:32.361-04:002017-10-25T11:17:32.361-04:00Yes, Eli, but the key to Gator's note's re...Yes, Eli, but the key to Gator's note's relevance is the "multilayer" part. We use multiple layers to insulate spacecraft. IR reflection as you responded is a contributor, but the multiple layers are important contributors as well. https://en.wikipedia.org/wiki/Multi-layer_insulation Tom Daytonhttps://www.blogger.com/profile/14033524810322903771noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-55294224884262516762017-10-25T03:34:41.574-04:002017-10-25T03:34:41.574-04:00Gator: Not quite, because the aluminized mylar re...Gator: Not quite, because the aluminized mylar reflects the IR rather than absorbing it and then re-emitting thermal radiation.EliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-29369950556777061152017-10-25T01:57:40.236-04:002017-10-25T01:57:40.236-04:00I believe your green plate effect is a simplificat...I believe your green plate effect is a simplification of what we called "superinsulation" back in my cryogenics days. The insulation around a dewar is basically vacuum + layers of aluminized mylar. The vaccum to prevent heat transfer by conduction, the many layers of mylar to prevent heat transfer by radiation.Gatorhttps://www.blogger.com/profile/13974079614971006038noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-30536115595040160422017-10-24T20:32:19.322-04:002017-10-24T20:32:19.322-04:00You believe the sun prevents equilibrium on object...<i>You believe the sun prevents equilibrium on objects it shines on perpetually.</i><br /><br />Thermal equilibrium is when temperature is uniform across a system/s, right?<br /><br />I believe that polar orbiting satellites or heliocentric orbit satellites (constantly in the sun) are not the same temperature as the sun.barryhttps://www.blogger.com/profile/12419101193566520809noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-37591019086644903362017-10-24T18:02:23.301-04:002017-10-24T18:02:23.301-04:00I'm confused by all of the pointless mystifica...I'm confused by all of the pointless mystification going on. Eli's original post seemed perfectly clear and correct, although there seems to be a tacit assumption that 100% of the radiation incident on a plate is absorbed. It's just a case of equilibrium energy balance, and I can't see why anyone needs to drag in the 2nd law. With regard to Timothy's comment, why not just say that the blue plate emits a fraction n/(n+1) of the incident radiation to both left and right, and absorbs a fraction (n-1)/(n+1) emitted by the plate immediately to the right. In general, with n plates, the i'th plate emits a fraction (n + 1 - i)/(n + 1) on both sides, and absorbs the radiation emitted from the plates to its left and right.winstonhttps://www.blogger.com/profile/14425489734425086756noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-79493010866709426492017-10-24T06:14:59.709-04:002017-10-24T06:14:59.709-04:00When the Sun and the plate are at equilibrium, the...When the Sun and the plate are at equilibrium, they will be at the same temps, true. However, this state is also known as the heat death of at least the Solar System and probably the universe as well!<br /><br />Talk about misstating the problem!jgnfldhttps://www.blogger.com/profile/18345702872292499039noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-32576619509087147012017-10-24T02:13:33.484-04:002017-10-24T02:13:33.484-04:00You can't state the problem correctly. You can...You can't state the problem correctly. You can't calculate correctly. You believe the sun prevents equilibrium on objects it shines on perpetually. Eli didn't prove the GH effect. He actually disproved it.Betty Poundhttps://www.blogger.com/profile/08770072864644204965noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-47649111335547761362017-10-23T22:40:36.479-04:002017-10-23T22:40:36.479-04:00Re. alpha Ori, etc.: I've often wondered why g...Re. alpha Ori, etc.: I've often wondered why greenhouse effect deniers don't realize that were they correct the greater of astronomical knowledge beyond the Solar System gained since the 19th century would be immediately falsified as well. The fundamental spectroscopic underpinnings involved in taking stellar spectra and inferring anything from them involve the very same underlying math and physical laws--in particular, the Stefan-Boltzmann Law.jgnfldhttps://www.blogger.com/profile/18345702872292499039noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-21656201737780805522017-10-23T19:33:14.369-04:002017-10-23T19:33:14.369-04:00Hey Timothy,
I assume you meant "energy per ...Hey Timothy,<br /><br /><i>I assume you meant "energy per second per unit AREA".</i><br /><br />Yes I did.<br /><br />I've been using the mirror idea, too.<br /><br /><i>The two ideas are related but not the same. When people say "heats up " it blurs the distinction.</i><br /><br />Maybe if I'm talking to a physics grad, but I see what you mean. Either term gives skeptics conniptions.<br /><br /><i>No matter what the (cross-sectional) surface area, it is emitting at 200 w/m2 from each side (with no Green). The TOTAL power absorbed and emitted will change in proportion to A, but not the intensity (flux density) = P/A.</i><br /><br />Understood. I came across this interesting tidbit while looking things up.<br /><br /><i>The Sun has a higher surface temperature, so it must radiate more energy per unit surface area than alpha Ori. In spite of this, alpha Ori has a far greater luminosity than the Sun! There is only one way that alpha Ori could radiate more total energy it must have a larger total surface area.</i><br /><br />http://astronomy.nmsu.edu/geas/lectures/lecture23/slide02.htmlbarryhttps://www.blogger.com/profile/12419101193566520809noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-73382442540520073732017-10-23T16:32:51.766-04:002017-10-23T16:32:51.766-04:00Timothy,
you are of course right about the serie...Timothy, <br /><br />you are of course right about the series. Chris A.https://www.blogger.com/profile/18367529816136236930noreply@blogger.com