Monday, December 12, 2005
Sunday, December 04, 2005
with folk from a really big research university. The question is what do you do when the rabett hole goes down to Australia. Life is indeed different on both ends. Eli does all the budgeting, processing and begging at the research administration office himself with a boost from an occasional passing Co-PI. The guys on the other side have resource specialists, grant administrators, paperwork runners and more. They need it. Their F&A (AKA indirect cost) rules are so complex that you need a CPA to get it right.
Don't bring in the dollars there and you get a stall in the restroom for a lab and a space next to the washbasin for your office. At Eli's NRHU (non-research habituated university) getting a grant means more work rather than less. Eli, besides being a rabett, is a good gerbil. As Ms. Rabett points out Eli is a silly rabett.
Posted by EliRabett at 12:04 PM
|Well this blog does not have a topic, occasionally themes, but is a place for the bunny muse.|
Occasionally Eli ventures into the realm of economics. Recently there was a debate on the Wall Street Journal site between Max Sawicky (in the red trunks) and Tyler Cowan (in the brown) on tax policy. A lot of Steve Forbes friends came out to cheer, mostly for the Flat Tax, getting rid of tax on business (e.g. on them), etc. Eli is not much amused by this attempt to shrink government income until it can be drowned in a bathtub. Katrina shows that the tub can be your city or town and there is a fair amount of collateral damage. I posted this in the comments section, but since the topic arises as the living dead from time to time, I thought I would put it here in order to have something to refer to on occasion.
"To stop taxing business is an invitation for those who operate small businesses to evade and cheat on their taxes even more than they currently do. And they do. It is well known that the greatest intensity of tax cheating occurs among small business proprietors. Even without outright cheating the opportunities of shifting expenses which have a personal benefit to business expenses (e.g. auto purchase or rental) are endless and used. Eliminating business taxation would be just another invitation to the ball.For those of you who doubt Eli, ask anyone you know who operates a business, or is pretty high up in one, who owns or pays for the auto they drive. All of the one's that I know drive business owned autos.
Posted by EliRabett at 11:52 AM
Sunday, November 20, 2005
(Quite long, but quite amusing:)
As part of our on-going obsession with Essex and McKitrick's Taken by Storm we return to their briefing. Not that we have made no progress friends, we now know that by temperature, they do not mean something read by your average garden thermometer holding concrete figure, but something much more amusing and a lot less useful. Having confused us, their mother-in-laws and definitely McKitrick, they then choose to cast aspersions on global temperature measurements, calling it the king of temperatures, "T-Rex". As we will see old friend T is not adverse to taking a bite out of their butts. This is fair because E&M have sown a lot of confusion in their jeremiad
First, two definitions: An extensive parameter depends on the size of the system, an intensive one does not. Volume and energy are extensive, temperature and pressure are intensive. We can boil Essex and McKitrick down to two statements. By the end of this post, mom will be able to tell you why both are wrong. The first is:
...the physical equations involving temperature assign no meaning to a sum of temperatures on their own, only in conjugate pairs with extensive variables. So here is a question: if the mean is the “total T”, divided by the number of observations n, and “total T” (i.e. the sum of some temperature numbers) does not have a physical significance, what does the mean mean?
and the second is
If the physical context does not imply one type of average then mathematics steps in with an infinity of ad hoc possibilities. It includes an infinite variety of weights, exponents, algebraic formulas, functions and other mathematical cookware, all chosen to reduce a list of numbers to a single value. When any one of these cookware rules is used, it is normally presumed wishfully that the number produced is “representative.” But in reality an averaging rule can be found to rationalize any value in the list from the largest to the smallest as the “representative. Only in the case of a particular physical context can we select one from this range that has a specific physical meaning. Everything else is just statistics. Everything else is ad hoc. But no such physical rules are prescribed for intensive variables on their own. In the absence of physical guidance, any rule for averaging temperature is as good as any other.
But there is a physical context that implies the arithmetic average is the proper one for temperatures in a homogeneous medium like the atmosphere, and there are several types of averages which are idiotic for averaging temperatures if you use the wrong scales as Essex and McKitrick do. Tim Lambert has pretty well taken apart Figure 2 and 3 in the Taken by Storm briefing, showing the fine touch of Essex and McKitrick with averages.
Unfortunately, either Essex or McKitrick or both do not understand zero and negative numbers. You know where my money is. Let us look at the various types of averages.
For a set of n measurements (a1, a2, a3, a4.....) the arithmetic mean is the sum divided by n. For an arithmetic average, it does not matter where the zero of the scale is, e.g. whether you use Celcius or Kelvin (no ethical scientist uses Fahrenheit or Rankine. Engineers OTOH.......).
The geometric mean is the nth root of the product of all the measurements. IF one of the measurements is zero, then the geometric mean is zero no matter what the other values are. If n is even should you pick the even or odd root? If there is an odd number of negative measurements the root is imaginary, and so on. Clearly there is a real danger in using the geometric mean if you are using a temperature scale where the possibility of zero or negative measurements exists.
To calculate the harmonic mean you find the average of the inverses (1/ai) and then take the average of that. Clearly, if one of the ai is zero, the harmonic mean blows up, and you would be a lot better off.
The root-mean-square average is the square root of the average of the squared measurements (ai^2). Let us see how that does on a couple of simple cases: The RMS average of (+2,+2) is +2, so is the RMS average of (+2,-2) is +2....Hmmm.
But let us not bother with such trivialities. Let us look at the first example that Essex and McKitrick propose.
Consider a system consisting of a cup of coffee, at 33 degrees C, and a cup of ice water at 2C. What is the “one” temperature that describes both these liquids, at this moment, as they stand? Clearly there isn’t one temperature, there are two. The physics does not say in any way that there is a single temperature for the whole. But if you are interested in climate you might say that there is one temperature anyway, if your thinking has been clouded by the T-Rex obsession. To such a person combining the temperatures of the ice water and coffee into one number would be no different than combining the temperatures of the poles and equator into one number. Of course you can do it. You have an infinity of choices, but the physics doesn’t say which one to use. Fine then: pick an averaging rule. Better yet, pick four out of the infinity of choices. Then ask whether this system is “warming” or “cooling” as the liquids relax to room temperature. As is conventional, cooling will mean our average is declining, while warming will mean the average is rising.They then calculate the various averages for the coffee and the ice water warming separately up to a room temperature of 20 C. They claim to plot the predictions of the arithmetic average, the harmonic, the RMS and what they call radiation (proportional to T^4 following the Stefan-Boltzmann law). The only one they get right is the arithmetic average (see below). The figure to the left shows what they calculated. I have added the lines showing the temperatures of the coffee and the ice water
Essex and McKitrick then riff about how the radiation curve is higher than the RMS, and the arithmetic average, and the harmonic is lower (yr. hmble. hare added the geometric average for the heck of it)
So, let us ask is there anything that sets the arithmetic average apart? Why yes, happy that you asked. How about if you had first equilibrated the ice water and the coffee, and then let them warm up to room temperature. You would get the blue dots which overlay the arithmetic average. That seems to me a fine physical reason for preferring the arithmetic average.
But wait, what hath McKitrick wrought? He calculated the "Radiation" curve using Celcius. Any General Chemistry student knows you have to use absolute temperatures when dealing with thermo, maybe even Essex knows that when he is not hunting T Rex, but McKitrick? Hmmm. When you use Kelvin, you get the dashed brown line, which is pretty close to the arithmetic average. Tell you what, let us use Kelvin for all of the averages.
That looks a bit different does it. If you excuse the bad graphics (still learning, advice sought), and blow the image up a bit you will see that the ONLY average that did not change is the arithmetic average.
Seems to me another pretty good reason for using the arithmetic average to characterize temperature. What is more, a lot of the blather about how different the averages are, well, has gone poof.
But wait, we have more! E&M spent a long time pointing out that to "properly" average an intensive quantity, you have to multiply it by an extensive property and you then average the extensive product. Energy appears to fit that bill, remember that for something homogeneous, E = Cv T, where Cv is the specific heat per mole, or m^3, or whatever, and T is in Kelvin. Another good reason to use Kelvin and not that effete Celcius. Now there can be problems if Cv is a function of temperature, but for the atmosphere, it is not the case, or more accurately put, not significantly so.
Posted by EliRabett at 11:42 PM
Thursday, November 17, 2005
Dean Baker thinks that textbooks are longing to be free and what we need is the ability to copy texts off the net. Other than the fact that Eli has done this and finds it a bad investment of time and money (them cartridges cost), he also knows that the textbook publishers make their books available at less than half the price outside of the US (does this perhaps remind you of drugs...., perhaps grandma should pick up your books on her trip to Canada).
Anyhow, a bit of googling showed that a popular chemistry text, "General Chemistry" by Ebbing and Gammon, costs $145 in the US and L34.95 in the UK (about $60) in the UK.
We invite everyone to find the most outrageous difference between textbook prices from the US and Europe or Japan. Prices are to be quoted from Amazon. Use www.tinyurl.com to compress any urls. Prizes to be determined later (probably a textbook).
Posted by EliRabett at 11:33 PM
Friday, November 11, 2005
Dean Baker of the Center for Economic and Policy Research has a paper Are Copyrights A Textbook Scam? Alternatives to Financing Textbook Production in the 21st Century. He argues that
The reason that textbooks are costly is that the government grants textbook publishers copyright monopolies. Copyright monopolies allow the publishers to prevent anyone from competing with them in the market. They are the only ones that can sell a copyrighted textbook in whole or in part. This prevents individuals from freely reproducing a textbook or making it available over the Internet.He is wrong. You could have all the copyright protection you wanted, but if the textbooks were sold into a competitive market, rather than being specified by professors and bought by students, prices would fall, inexpensive paperback versions would appear and the little cute tricks like new editions every other year would be held in check. For details see our earlier post, Who ordered that?
If you think that I am wrong, ask yourself why high school texts, which are both specified and bought by Boards of Education are really cheap.
The good news is that people are starting to wake up. Baker nails it when he says:
Textbook costs have consistently outpaced the overall rate of inflation, presenting a large and rapidly growing burden to millions of college students. According to the Government Accountability Office (GAO), textbook prices have been rising about 6 percent annually, or twice as fast as the overall rate of inflation, since the 1987/1988 academic year. The GAO estimates that the average first-year student at a four-year public university spent $898 on textbooks and supplies in the 2003/2004 academic year.1 This means that a student working at a minimum wage job would have to put in nearly 170 hours of work each year, just to pay for her textbooks.
Posted by EliRabett at 9:29 PM
Monday, November 07, 2005
Wm. at Stoat is explaining GCMs. With all the too and fro about butterflies and momentum, we somehow have missed the point about how momentum is transferred from the Earth to the atmosphere as it rotates. Inquiring minds wish to know how do GCMs handle that?
Update: Wm.'s answer is here
Posted by EliRabett at 8:20 PM
Sunday, November 06, 2005
Reading the several versions of Essex and McKitrick anyone familiar with thermodynamics (heat engines, blackbodies, chemical reactions, etc.) will start to scratch their heads. One peculiar statement after another appears dealing with temperature and other basic stuff. It turns out that Essex is using a rather special definition of temperature for a non-equilibrium radiation field. If you want to read about it look up "How hot is radiation", C. Essex, D.C. Kennedy and R.S. Berry, Am. J. Phys. 71 (2003) 969 . It really is a nice paper for a field known for impenetrability and crypticisms of all sorts.
As is standard in equilibrium thermodynamics, temperature is defined as (dU/dS)p (that should be the partial derivative of the system internal energy with respect to entropy at constant pressure, but hey, Blogger has a lousy equation editor). The energy and entropy of the ensemble are then obtained from the Hermetian density operator and the Hamiltonian of the radiation field.
In the equilibrium limit, the radiation emitted by a black body has the same temperature as the body, and the non-equilibrium temperature collapses to that from a black body. However, as Essex, Kennedy and Berry point out, while their definition is "relatively" simple for a radiation field, it is not so simple to define a non-equilibrium temperature for (radiation field + matter). They say:
"The Gibbs-Duhem relation for radiation, SdT-Vdp = 0 implies that the two intensive thermodynamic parameters, pressure, P (conjugate to volume) and temperature T (conjugate to energy), reduce to one independent intensive parameter, which is usually identified as T. This feature of radiation thermodynamics, like the photon's zero mass and lack of rest frame, makes radiation thermodynamics much simpler than that of matter, which has conserved particle numbers and nonzero chemical potentials. It also makes generalizing intensive thermodynamic parameters out of equilibrium much easier. Thus radiation is a natural context in which to introduce non-equilibrium temperature."
So, pretty clearly Essex is talking about non-equilibrium thermodynamics, and probably playing telephone with McKitrick. BUT, then they are clearly treating the atmosphere as a non-equilibrium system, and that reminds me of the jokes about for all practical purposes:
A mathematician and a physicist agree to a psychological experiment. The (hungry) mathematician is put in a chair in a large empty room and his favorite meal, perfectly prepared, is placed at the other end of the room. The psychologist explains, "You are to remain in your chair. Every minute, I will move your chair to a position halfway between its current location and the meal." The mathematician looks at the psychologist in disgust. "What? I'm not going to go through this. You know I'll never reach the food!" And he gets up and storms out. The psychologist ushers the physicist in. He explains the situation, and the physicist's eyes light up and he starts drooling. The psychologist is a bit confused. "Don't you realize that you'll never reach the food?" The physicist smiles and replies: "Of course! But I'll get close enough for all practical purposes!You may prefer these versions:
http://www.badpets.net/Humor/Tech/EngineerJokes.html Third one down
Posted by EliRabett at 10:49 PM
Thursday, November 03, 2005
Saturday, October 29, 2005
has spread from Roger Pielke Senior's blog to Stoat and James' Empty Blog and sci.environment and who knows where else. Along the way, we discover that RPS (just lazy, not disrespectful, I save that for RPJ), believes that momentum is not conserved in the atmosphere. Mr. Rabett stuck his oar in briefly, saying that #22
"Dissipative forces exist on a macroscopic level, but then again, so do infinite heat baths. On the other hand, they result not only in the loss of conservation of momentum, but also of conservation of energy. However, as soon as you start looking at the bath in microscopic detail, dissipative forces disappear and you regain the conservation laws.a position that I maintain, and sensible people agree with. Within the atmosphere, momentum IS diffused to larger and larger volumes so that any particular molecule has an infinitely small share, but it IS conserved. Along the way, Eric Swanson in sci.environment raised the point that radiative emission might dissipate momentum. Certainly greenhouse gases in the atmosphere emit photons.
To the extent that a model treats part of the system as an infinite bath for energy or momentum, you can beat the conservation laws but you have to be careful in the analysis lest you push the assumption too far. It appears to me that the surface of the earth is such an energy bath for atmospheric dynamics models, as the surface of a pipe is for fluid flow. However, as long as the perturbation stays away from the wall it will not dissipate. Since the surface is in all climate models, and since the models show that small perturbations in the atmosphere propagate, for the purposes of this discussion, the butterfly flaps."
Eli Rabett has intensively consulted with the techno-bunny elite on this point. Along the way, we came up with some wrong answers, drafted a few papers for the journal of last resort, and finally found an answer which was so pleasing that we went out for a few beers to celebrate. My colleagues have designated me to provide the answer to a world waiting with baited breath (have you ever kissed someone who spent the day swallowing worms??).
Momentum is clearly conserved on emission of a photon, it is merely partitioned between the molecule and the photon. De Broglie came up with the idea that photons have momentum, and this is certainly shown by the Compton effect. So what happens in the atmosphere? As usual, there are three cases.
IF the photon is absorbed by another molecule in the atmosphere, momentum is conserved, merely transferred from one molecule to the other. This is boring
IF the photon is absorbed by the surface or in the ocean then momentum is conserved, but since roughly the same number of photons strike the earth going north or south, or east or west, there is no net change in the momentum of the earth and it may be treated as an infinite dissipative sink for momentum. This is uninteresting**
IF the photon is emitted to space, then momentum is transferred from the atmosphere to an infinite sink which is REALLY dissipative. This is both surprising and pleasing (to me, but then again I blog Saturday night, so my standards may not reach yours).
**This is not the case for energy transferred from the atmosphere to the earth by radiation. This is not uninteresting.
Posted by EliRabett at 11:27 PM
"Consider that an ordinary laser pointer, powered by small flashlight batteries, generates peak temperatures of about 10^11 Kelvin. Yet you can shine it on your hand and not feel any warmth! This can happen because temperature represents the distribution of energy across physical states, and the fewer the states the higher the peak temperature, even at low energies.
The laser distributes a small amount of energy across very few states, which allows the temperature peak to get very large, despite not being perceptible by touch. Lasers are idealized in thermodynamics as having infinite temperature because ideally the laser radiation would have all of its energy in one quantum state."
How do you think Essex is defining temperature? Does it have much to do with a temperature measured in the atmosphere? If you are an expert in non-equilibrium thermodynamics, you may have a clue. For extra credit, why is this definition of what useful, and can you think of an interesting counter-example. The answer can be googled.
As for me, I have papers to mark.
Posted by EliRabett at 10:15 PM
Thursday, October 27, 2005
I think I may take up Essex and McKitrick, or at least share it with Tim Lambert. I should say at the beginning that I have a very different point of view than Tim, more physically based for one, but Essex and McKitrick sticks in my craw, and keeps on coming up, so I need a place to point to rather than posting the same comments a zillion different times.
Chris Essex and Ross McKitrick have written a book entitled "TAKEN BY STORM
The Troubled Science, Policy and Politics Of Global Warming" in it they make a large number of troubled claims.
The book itself is not on line, but a briefing pamphlet is at http://www.takenbystorm.info/TBSbriefing.pdf. They should know better. The briefing alone is an invitation to a fisking, with so many dubious claims that one hardly knows where to begin. For example, starting at the bottom of page 6 they say:
"Temperature is not energy. It is a thermodynamic variable with some special properties that make it far more interesting than it usually gets credit for."
True enough, but then they start going off the rails
"Consider that an ordinary laser pointer, powered by small flashlight batteries, generates peak temperatures of about 10^11 Kelvin. Yet you can shine it on your hand and not feel any warmth! This can happen because temperature represents the distribution of energy across physical states, and the fewer the states the higher the peak temperature, even at low energies."
Which is absolute garbage. A system with any number of states can have any temperature. You would think Essex would know better. What matters is the distribution of population in the various states. The simplest example is the two level system, which is described at any number of web sites. The temperature is determined by the relative populations in the two states, or alternatively the temperature determines what the relative population in each state is. Chicken/egg.
Here is a neat little applet that lets you play around with a two level system http://physchem.ox.ac.uk/~rkt/tutorials/heatcap/heatcap.html. The energy slider changes the separation between the two states, the temperature slider increases the temperature of the system.
The degeneracy slider is a bit more complicated. If the degeneracy is greater than one, the upper state rather than being composed of a single state, is built out of two or more states with equal energy. Leave that at one for now.
The relative populations in each state are shown by the green bars on top of each level. The blue arrow indicates how much population is shifted into the upper level if the temperature is increased 1 K (same as a 1 C change).
If Essex and McKitrick are right, how come the population of the system can be cooled to ~ 0K if most of the population is in the lower state.
The paragraph above is really a twofer. The statement about the laser temperature is another goody. More about that next time. As homework, go look up what the temperature describing the distribution of energy across states in a system which lases is.
Posted by EliRabett at 11:48 PM
Tuesday, October 18, 2005
Ms. Rabett is a teabag. She never saw a nice cup of tea she did not crave, but the retailers of the world want to sell her flavored excretia that only people who hate tea like. Did you ever notice at Starbucks or wherever that the black tea (in the rare cases they have it) is always sold out, but the strange teas which no sane person drinks are there a plenty. Same thing in restaurants, they bring out this fancy tea case with cyanide flavor aplenty, but no black tea. Oh, they say, no more of that left.
They could reorder and make some money, but that would not be the capitalist way. I say, bring back the Tea Board so we can get some real leaves.
Posted by EliRabett at 10:57 PM
Wednesday, October 12, 2005
. . .will tell you that in a greenhouse, the glass windows cut off heat flow caused by air exchange between the inside and the outside of the car. They will also tell you that cutting off the air flow is not what happens in the greenhouse effect. This is the default statement.
What happens in a greenhouse is the same mechanism that heats a car up when you close the windows. The sun’s light (radiation) shines through the glass. The light energy checks in, but it can’t get out because both air flow (most important) and conduction are closed off. The fancy name for air flow is convection. We might fall into the habit of using that below.
That leaves radiation. The wavelength of radiation emitted from a surface depends on the temperature of the surface according to a formula first derived by Max Planck. It turns out that the emission from the sun is peaked in the green which can pass through the glass windows, but the radiation from surfaces at 300 C is peaked at much longer wavelengths in the infrared (IR), which is absorbed by the glass.
The IR radiation inside the car can heat the air inside the car, but, because it is adsorbed by the glass windows and the metal, it cannot get out. OTOH, the surface of the car and the glass is heated from the inside by radiation, conduction and convection.
The surface, in turn, can radiate heat away, but, because the glass has an inside and an outside, half of what is radiated goes back into the car and half out into the air. In short, for cars with closed windows and greenhouses, at first, the rate of radiation into the car exceeds the rate of radiation out of the car and other heat transfer processes are pretty much cut off.
There is another radiation law called the Stefan-Boltzmann law, which says that the rate of emission for radiation from a hot surface is proportional to T^4 , (which is T*T*T*T, T being the temperature in Kelvin) so if you heat something up a little, the total amount of energy emitted goes up a lot.
The sun pumps energy into the car at a constant rate. The temperature of the car increases until the surface is hot enough that the energy radiated from the surface per second exactly equals the energy pumped in by the sun. You get one hot car.
With all that in mind, let us talk about the atmosphere.
Again, the sun is the only real source of energy. Heating from the core of the earth is very small by comparison, but that is another story. The emission rate of radiation to space has to equal the rate at which the sun’s radiation reaches the earth. This is called radiation balance. If radiation balance did not exist, the earth would heat up until the surface was hot enough to emit enough energy to restore the balance.
If there was no greenhouse effect, the emitted IR light from the surface would all escape to space. The temperature of the surface necessary to emit enough energy so that the earth would be in radiation balance under those conditions is about 256 K or ~ -17 C. However, some of the light emitted from the surface is absorbed in the atmosphere by the greenhouse gases or clouds. That heats the atmosphere, but it also means that the molecules in the atmosphere will radiate. At the lowest level of approximation, which is good enough for this argument, half of the radiation from the atmosphere escapes upward to space and half is emitted downward to heat the surface. If you want more details google radiation balance.
Since not all of the radiation from the surface escapes to space when there are greenhouse gases, the surface has to emit more energy so that the amount of energy escaping to space per second equals that striking the earth's surface from the sun. In order to emit more energy the surface of the earth has to heat up. That is the greenhouse effect. And that is why the greenhouse effect both is and is not similar to a greenhouse. The atmosphere is not like a blanket, but it is like the glass in the greenhouse, or in your car.
Posted by EliRabett at 10:32 PM
Sunday, October 02, 2005
Shopping in the US requires an affinity card, or whatever those annoying things that they ask for at the checkout to give you the discounts they advertise are. We know they are selling the information along with the data they gather on our shopping habits. Lucky for us, when you sign up for the things they don't ask for ID, so Eli Rabett has a full compliment of supermarket/drug store discount cards. Sign your sock puppet up today. The only downside is that you have to pay cash when you use the card so they can't back track.
Posted by EliRabett at 5:14 PM
Saturday, October 01, 2005
has been a hard thing to do, so don't expect miracles folks. Conventional wisdom, CW says, that it is simple to explain what the greenhouse effect is not, the thing that keeps greenhouses warm and heats up your car in the in the summer. The CW for those two cases is that you cut off convection, exchange of atmospheric gases between the inside and the outside, and as a result the inside of the greenhouse and the car warms as solar energy pours in through the windows. OTOH, says the CW, that ain't the greenhouse effect, the thing that keeps the surface of the earth mostly toasty, or at least about 25 C toastier then it would be without.
I am going to show that what happens in the greenhouse and your car is much like what happens in the earth's atmosphere, and the CW misses something important. This posting will grow and hopefully change under the influence of comments. Eventually we might port it elsewhere, like Wikipedia but I don't want to throw this into that scrum without some preliminary doodling.
Let us start by discussing your car in the summer sun. You have to balance the flow of energy in with a flow of energy out. Assuming the sun is constant, any physicist will tell you that there are only three ways to ditch energy: Conduction, convection, and radiation. A chemist will throw in exothermic phase changes and reactions.
If your car is sitting in the sun with all the windows open, energy from the sun's radiation flows into the car and either is reflected out (off the white seats) or absorbed (off the black ones). For the sake of this thought experiment, assume that the car was sitting in a garage with the garage door opened and had reached an equilibrium temperature with the air around it.
Pull it out of the garage. As seats absorb energy from the sun, they will become warmer and heat the air next to them. The air inside is now a bit hotter than the air outside. The flow of energy into the car is balanced by flows of energy out of the car both from exchange of air and radiation through the open window but also the air inside heats the windows and surface of the car which then radiate faster. For the purpose of this argument we will make the usual spherical elephant assumption and postulate an all glass auto. On net the air in the car will be a bit warmer than that outside in order to maintain the balance.
As the sun's radiation pours in this process heats the windows and body of the car. The wavelength region that the warm seats and the body of the car radiate in is the infrared which cannot pass through the glass, but the glass can radiate back into the car and, on the other side, into the air.
Now close the windows. The rate at which energy flows into the car decreases as convection is cut off. The immediate rate of energy flow out by radiation stays the same, therefore the rate of energy flow into the car exceeds the rate of energy flow out of the car, and....the air in the car warms. As the air in the car warms, the interface between the atmosphere and the car, the glass also warms, as things warm, the rate of radiation increases as the fourth power of the temperature, so the hotter glass radiates at a faster rate. The air in the car stops heating when the temperature is high enough that the energy radiated from the glass surface out into the air (half goes back into the car) exactly balances the energy radiated into the car from the sun.
If you want a hydraulic analogy, imagine a pipe with water flowing through it. Now narrow one part of the pipe. The flow out of the pipe will decrease, but if the flow into the pipe remains constant, the pressure in the pipe will increase until the balance between the flow in and the flow out is restored.
Does anyone see where I am going??
Posted by EliRabett at 8:15 PM
Saturday, September 17, 2005
There are a lot of research adverse universities trying to move up and grab more of those F&A costs (overhead in industry speak)
The only occasionally successful way of upgrading research at a non-research habituated place is to shove the old guard to the side, grab their lab space, and push them into attic offices slightly smaller then a cell at Gitmo and about as well air conditioned. Then the Dean waits for time to take its toll. In the meantime you open the alumni purse for a few real stars, let them talent spot some young stars and hire bodyguards so that the old folk don't do fancy knife work. It does not always work.
With the abolition of forced retirement, this can be quite expensive. It also might be wasteful because no one really knows what the old guard could have done with real support. Probably they are more optimistic than everyone else, but the truth is they never have had a chance.
Thus we come to the Rabett solution: Any member of the old guard can get as much in set up funds as a new assistant prof, if they give up tenure and go on a rolling contract, like your local football coach. Renewal conditions are negotiated, for example x publications per year, y dollars of grant funds, z students supported. The length of the renewal period might be between 3 and 6 years.
Posted by EliRabett at 5:18 PM
Sunday, September 11, 2005
If it is a college textbook, the professor. Textbook prices have more than doubled in the past 15 years but few professors care, or have even noticed. The US has a North Korean textbook market: those who order the things (the professors) get them free, and the ones who buy them (the students) are captive.
The GAO (I simply cannot bring myself to call the Government Accounting Office by its new newspeak moniker) has a report on the college textbook market requested by David Wu (R) Representative from Oregon. Three cheers for him!!! A worthwhile read for faculty and those sent to the poorhouse after buying books.
Still, they fail at the bottom line. Textbooks cost a whole lot less elsewhere because in the US textbooks are specified by the instructor. I can get any chemistry textbook hand delivered complete with slobbering publishers rep the next day at no cost. They will cheerfully pile the supplementary material they carefully designed to kill the used book market (more on that in a later post. GAO has nailed that issue) up to my ceiling.
I exaggerate, but if the General Chem program at Really Large State U, can get slobbering reps and more. The economics are simple. At RLSU the GChem course might have ~5000 students or more. At $140 for the book (more if the students are offered the "package") that is ~ 0.7M$, about 75% of which goes to the publisher and the rest to the bookstore. At our smaller place we are down by an order of magnitude, but the business is steady enough that we can get a decent lunch brought in every couple of years when we consider new texts and all the free copies we want. English and math are the 1000 pound gorillas in the textbook business, but chem ain't bad.
As you might suspect I am a trice uncomfortable about this. The situation is negatively affecting higher education in the US as students seek to escape economic thrall by not buying books, and selling them back as soon as they can. When I graduated I had a library built up across many fields which even today stands me in good stead. To assuage my conscience I don't accept desk copies. If a publisher sends one to me, I call them up and tell them to take it back. If they don't come within a couple of weeks I give it to a student. More later, but you might ask your favorite US academic bloggers what they do about desk copies.
Posted by EliRabett at 7:54 PM
that feels like an oral presentation on an obscure topic in a small hot room at a not very well attended conference during lunchtime.
That pretty much sums up the direction of Rabett Run. Eli Rabett is a not quite failed professorial techno-bunny, a couple of chair elections from retirement, at a wanna be research university that has a lot to be proud of but has swallowed the Kool-Aid. The students are naive but great and the administrators vary day-to-day between homicidal and delusional. His colleagues are for the most part merely fey but not harmless. This is not to say that they are not smart, they are, but that they have a curious inability to see the holes that they for dig themselves. Prof. Rabett is thankful that they occasionally heed his pointing out the implications of the various enthusiasms that rattle around the department and school. Ms. Rabett is thankful that Prof. Rabett occasionally heeds her pointing out that he is nuts. There are no little Rabetts, so you will not be hearing about the doings of Jessica the Wonder Child. As he grows older, Eli has learned that it is less important what is done, than that it be done well and consistently.
Eli has published a fair amount of research in a wide variety of engineering/physical science areas and is almost competitive. He does know most of the people who do research for a living and some of them might respect him, if they knew who he was. Some of what he knows is relevant to climate studies, although he is not a climate scientist as such, and he has commented on other blogs on climate, as well as chemistry and physics.
As someone who has floated between chemistry, physics and engineering Dr. Rabett is a mile wide and an inch deep. But he is also familiar with the lack of understanding the inch wide and mile deep folk have about most things and the curious implications of this among what are probably the brightest group of people on the earth.
So hello, I must be going.
Posted by EliRabett at 11:52 AM