Guest post by Bill DiPuccio, Science Teacher
Let’s face it, high school science videos can be boring and ineffective. I like my science with a twist of comic exaggeration. So I decided to produce a video with enough humor to keep the students awake, and enough depth to challenge them intellectually.
This 30 minute video on the Greenhouse Effect is the prototype for a possible new series: “Bill Scientific” (I gave it a personal imprint to infuse some warmth and presence). Unlike introductory videos which attempt to cover a broad field of knowledge in a short time, the goal of this prospective series is to drill down into specific, but pivotal, topics in the physical and earth sciences.
Rather than just spooning out information, each program would be designed around experiments (the simpler the better) that can be used to illuminate and verify crucial scientific principles. Students will see science in action and gain a better grasp of the empirical basis for scientific theories.
Of course, future programs will depend on the response from students, educators, and scientists, as well as securing funding. The “Greenhouse Effect” was shot and produced on amateur equipment and software. Despite these limitations, I believe the final product faithfully conveys the intent of series.
P.S. If you like the video, pass it on!
tjfolkerts,
That is a bunch of total crap.
What the heck, let’s try one more ….
lrshultis says: April 27, 2012 at 8:41 pm
“Why not try to show the spectral intensity graphs to their correct proportions. A lower temperature spectral intensity graphs lies completely under a higher temperature spectral intensity graph.”
Once again, this is true as far as it goes. The other point that need to be made is the geometry. The sunlight is indeed more intense at all wavelengths. However the sun only covers about 0.001% of the sky. The other 99.999% is the earth’s atmosphere.
Roughly speaking, the sun is 100,000 times “brighter” than the atmosphere, but covers 1/100,000 as much area, so both provide similar amounts of energy. So drawing the graphs with similar areas is completely legit.
Smokey says “That is a bunch of total crap.”
And as is much too common, Smokey is once again all smoke and no fire.
What SPECIFICALLY do you disagree with? What SPECIFICALLY do you propose as a better answer?
Definitely a ‘don’t try this at home’ moment.
Exhaust fumes from petrol engines contain 1000 to 2000ppm CO and just 667ppm can cause coma, seizure and fatality. CO2 is 14% but it is the ability of CO to bind to haemoglobin in red blood cells and persist, that deprives the victim of oxygen, and could kill.
Not a good example, Bill.
tjfolkerts
1. The “. . . common answer . . .” is wrong. CO2 no more “warms the Earth” than your gloves “warm your hands”. I love a bad analogy combined with an appeal to consensus.
Nobody seems to be able to calculate an “average temperature” for the Earth’s surface which stands up to scrutiny. I have to admit, neither can I. But thanks for the vote of confidence.
I hope I don’t offend you by asking you to measure the temperature of your fingers inside the gloves. Your fingers don’t receive heat from the gloves, they receive heat transferred by the blood stream from cells oxidising carbon. The reason your fingers get cold on the surface is that the heat transfer process cannot keep up with the heat loss occasioned when the temperature differential between the skin surface and the surroundings exceeds the body’s ability to replenish the lost heat.
If you place your glove on the hand of a corpse, the hand will not become warmer. Neither will the Earth by surrounding it with anything at all.
2. I imply nothing. I am stating that the Sun cannot provide sufficient energy to maintain the Earth’s surface temperature at a higher level than exists now. Otherwise, the Earth’s surface temperature would be higher than it is. I trust you agree. Whatever the current surface temperature is, it is – depending on your definition of the “surface”. I assume the Earth will continue to cool until the Earth emits precisely as much EMR as it receives from the Sun.
3. There is no “scientifically based” greenhouse effect that depends on CO2 or any other substance transmitting the total EMR spectrum more efficiently in one arbitrary direction than another. Perpetual motion and infinite free energy are then practical. Unfortunately, there exist plans for perpetual motion or “free” energy generators depending on the application of the principles you appear to believe in. They are nonsense too.
As to insulation, build your houses. Don’t turn on your internal heat generator – that provides, like your fingers, an internal heat source. Which house is warmer? The answer of course, is that they are both the same temperature. If you must use analogies (which I generally see as a device to obfuscate, rather than educate,) then use appropriate analogies. Blankets, insulation etc. do not provide warmth – no ifs, buts, or maybes. Find one that does, and free energy is at your command.
Finally, the maximum radiative transfer of energy is reduced, rather than enhanced, by placing GHGs in the radiation path. So, still no “global warming.”
For a bit of fun, think about why the water in the abyssal ocean depths is around a few degrees C. Interestingly, descending into the ocean results in falling temperatures, while descending into the lithosphere towards the centre of the Earth results in rising temperatures. After you have considered this for a moment or two, you may come to the conclusion that the Earth is still cooling, yourself.
In the meantime,
Live well and prosper.
Mike Flynn.
Keith Minto,
Not meaning to stir the pot, but at CO2 levels above around 7%, the stuff becomes poisonous. I notice a brief look at Wikipedia shows some contradictions. The British Navy was losing divers due to CO2 buildup in the inspired air in rebreathing equipment, even though there was plenty of O2.
Interesting. You probably don’t get the option of deciding whether you will die of suffocation or poisoning, or whether the CO gets you first.
Live well and prosper,
Mike Flynn.
Spartacus says:> almost everything in the atmosphere is more concentrated near the surface, including CO2.
Ah, this rather depends what you mean. If you’re measuring atmospheric constituents as parts-per-million, then no: CO2 (or other minor constituents like Argon) have constant concentration with altitude. If you’re measuring by molecules-per-m3 then yes: everything gets rarified as you go upwards. Your phrasing would normally have the former meaning (and so be incorrect) which is why people misunderstood you.
Mooloo: one of my heroes is Richard Feynman who preferred to teach by conceptual models. You have asked me to ‘write equations’. I could do so and fill papers with them but that does not make the science right. The equation you need is the last one plus whatever working to prove it!
A touching faith in equations is a crutch for people who do not understand physics. The only correct measure of radiative heat transfer in the atmosphere is to have two radiometers with 2 pi viewing angle back to back and use the difference signal.
It is set by S-B1 – S-B2 where 1 is hotter than 2. 1 is normally a composite emitter of the earth’s surface and the air path to the lower detector. 2 is defined by the average temperature of the air in 2 pi angle and its emissivity. The S-B2 ‘back radiation’ is a measure of IR impedance to space, not evidence of an energy source. The use of pyrgeometers is a dead end because they measure atmosphere temperature convolved with average emissivity in the view angle. It is not a measure of energy flow.
You prove this by looking at how the Bedouin make ice. They dig a pit in the desert with water at its base. Overnight it freezes because the pit tends to a black body and the restriction of the view angle reduces the emissivity of the air it sees. So S-B1 – S-B2 increases. Bad physicists and meteorologist [who aren’t taught proper physics] imagine the ‘back radiation’ is lower but this is wrong.
For clouds, the emissivity is much higher than clear air [~0.2], up to ~0.9, and they behave as a grey body. Meteorologists imagine ‘back radiation’ is higher. This is not the case. In reality S-B2 is higher because emissivity is greater. S-B2 is still a measure of IR impedance to space!
Everything would still be fine were it not for the Aarhenius’ claim in the Trenberth cartoon that IR from the Earth’s surface is the S-B level for a B-B in a vacuum. Aarhenius was a bad physicist. In chaos theory this defines an ‘attractor’, a calibration point, which is fundamentally wrong because it converts mostly convective hear transport in the atmosphere to mostly radiative.
The 2-5 times greater prediction of AGW assuming most recent warming has been AGW has to be backed off by making unrealistic estimates of cloud albedo. It would be better to correct the physics back to Manabe, in which case there might be a chance with much lower radiative transport near the earth’s surface of getting the right result. But then you wouldn’t have the scare story. Another issue is the failure to put the real attractor into the models which is the upper ocean temperature of 29 °C.
In short, the physics in the IPCC climate models is appalling and it’s time the discipline stopped fooling itself. It’s the end game.
Some of the objections to the ‘Greenhouse’ effect are semantic. Some people are objecting to ascribing an active action to a passive object. They insist that an object only warms or makes something warmer if it has an internal source of energy.
This despite the colloquial use in common English of phrases like ‘wearing a coat to keep warm’.
The confusion disappears if the actual flows of energy are identified and measured. Expressed as numerical functions the semantic problem vanishes.
Of course empirically we all know that a cloudy night is warmer than a clear night.
Slight mistake above; each IR detector has pi radians viewing angle.
Bill
I think your appoach to teaching young people the ‘Greenhouse Effect’ is probably appropriate for the modern generation. The emphasis given to water vapour as the major greenhouse gas is an often neglected but important aspect for youngsters to be made aware of . The relatively small contribution of CO2 as a greenhouse gas and the even smaller contribution of anthropogenic CO2 from the burning of fossil fuels is also important and is well made. I also liked the points made on the effects of cloud variation.
What I would like to see introduced to the video would be some mention of other sources of CO2. In particular that produced by human and animal respiration. I find that many people young and old do not appreciate that they themselves create CO2 by the mere act of breathing. I saw recently a very good example statement which went something like:-
“The air we inhale contains around 400ppm of CO2. When we breath out it contains 40,000ppm of CO2 i.e. ten times as much”. (I’m not sure of the validity of 40,000ppm but that can be checked). Multiply that by the world population and add to it that created by the breathing of other animals will help your students develop a greater understanding of what CO2 really is.
I don’t think the car exhaust demonstration is useful but if retained you need to explain the difference between the innocuous CO2 and the poisonous CO.
I support your intentions and wish you well
Correction to my post April 28, 2012 at 3:50 am
Third para second line should be ….. CO2 i.e a hundred times as much
fredj: 40,000/400 = 100
tjfolkerts says:
April 27, 2012 at 6:42 pm
You might want to rethink your example, unless you either 1) do not mind claiming that the two resister readings are different with an 8% confidence level or 2) are really just providing the best argument against using anomalies for judging temperature changes.
The fact that there is a non-zero difference in means does not imply that that the difference is statistically distinguishable from zero. The uncertainty in each measurement plays a critical role in determining whether such a difference is meaningful. To a first approximation, we can just propagate the error upon subtraction, which would tell us that resister two is 0.5 +/- 7 Ohms greater than the first. Although the value obtained from subtracting the two means is non-zero, any freshman level science student would readily conclude the two resisters are nevertheless indistinguishable. The source of the non-zero difference is solely due to experimental error. We can apply higher level statistical hypothesis testing to provide us with the exact same answer, unless we are willing to reduce our confidence level from the standard 95% to a paultry 8% level at best.
Fredj says: “What I would like to see introduced to the video would be some mention of other sources of CO2.”
Thanks Fred. That is a very good idea. While I would be inclined to save the details for a video on Global Warming, a brief breakdown of the sources of CO2 (part of the carbon cycle) would have improved the accuracy of the video and removed any mystery surrounding CO2.
Mike says: “If you place your glove on the hand of a corpse, the hand will not become warmer. “
Exactly! So if you shut off the sun, then the atmosphere would cease to warm the surface (after a very short time). But as long as the sun keeps shining, the atmosphere can keep elevating the surface temperature (above what it would be with no atmosphere).
“Don’t turn on your internal heat generator – that provides, like your fingers, an internal heat source.”
Let me say once again, we DO have an “internal generator” generating thermal energy. The sunlight penetrates to the “interior of the atmosphere” (ie the surface) and heats the atmosphere “from the inside” (like the furnace heats the house “from the inside”). You are missing this critical idea, and it then throws off the rest of your thinking. (And no, this is not a perpetual motion machine that violates any laws of thermodynamics).
I assume the Earth will continue to cool until the Earth emits precisely as much EMR as it receives from the Sun.
I don’t think we are really disagreeing here. I acknowledge that the earth is indeed still cooling. My point is that estimates I have seen put the geothermal energy flux at ~ 0.1 W/m^2. So yes, the geothermal energy is helping to warm the surface. And yes, the interior is slowly cooling. But these energies are tiny compared to other energy fluxes and can (for the most part) be ignored.
Finally, I agree that measures of “average temperature” are challenging and problematic. The records have changing coverage and changing instruments and changing times of data collection and changing surroundings. Then there is the whole question of how meaningful “average temperature even is, or whether some sort of “average energy” or average “T^4” would be a more physical thing to calculate. But however you think about it, if there is an upward trend at any given temperature station, then that station has experienced warming. If most stations show increasing temperatures, then there is “global warming”.
Thanks for the discussion. It helps me continue to refine my ideas and explanations.
Tim
PS. Sorry, Bill. We all seem to have hijacked your thread about your video.
W Connelly says:> Ah, this rather depends what you mean. If you’re measuring atmospheric constituents as parts-per-million, then no: CO2 (or other minor constituents like Argon) have constant concentration with altitude. If you’re measuring by molecules-per-m3 then yes: everything gets rarified as you go upwards. Your phrasing would normally have the former meaning (and so be incorrect) which is why people misunderstood you.
Even with my poor English, you know perfectly what I meant and there’s no possible confusion. CO2 is more concentrated near surface as well as any other gas and this is valid in mass concentration or Kg of a compound/ m3 of atmosphere (volume). In simple terms, the number of molecules of CO2 in a m3 of atmosphere declines with the altitude. You can twist, distort, flip it upside down but this is an undeniable truth – There’s more CO2 near the surface, as well as any other gases. The possible GH effect, due to the possible action of GHG, is more intense near the surface because of this bigger density and not because it radiates from above to the surface (or back to the surface as you say). This is a nonsense and it’s in Trenberth’s classic draw. Usually, versions of this Trenberth’s concept drawing, have a small and grayed out layer of greenhouse gases (simulating a imaginary blanket) and, by magic, radiation that comes from earth’s surface is reemitted again, with a perfect reflection angle, towards the earth’s surface. This is a highly misleading scheme and should be corrected. There are comments from other people above that identify correctly what happens at a molecular scale. Almost every wikipedia article about this is misleading and you should learn this effect perfectly and do your wikiedition with honesty.
Even Trenberth should correct his old scheme correcting that fictional “back radiation” because in term of atmospheric physics (even considering that this is only a scheme) it’s almost hilarious. There are other thing to correct in this scheme but this is the most comical one to say the least.
http://iedro.com/blog/wp-content/uploads/2012/04/RBRWuG0086_Trenberth_Radiative_Balance_BAMS_2008.gif
Cheers
Spartacus,
Connolley says: “…CO2 (or other minor constituents like Argon)…”
The amount of the trace gas agron is huge compared with the minuscule trace gas CO2. Argon comprises 1% of the atmosphere, while CO2 comprises less than 0.0004.
Spartacus: the major problem with the Trenberth cartoon is the claim that heat transfer from the Earth’s surface to the atmosphere is [17+80+396=493 W/m^2] when in reality it’s [17+80+63=160 W/m^2], or an exaggeration by a factor of 3.08.
If we include the 78 W/m^2 directly absorbed by the atmosphere, the exaggeration of the total heating is a factor of 2.4. Taking the IR alone, the exaggeration is by a factor of 356/23=15.5.
This is a ‘Perpetual Motion Machine of the Second Kind’ to give it it’s formal thermodynamic definition. it cannot exist because ‘back radiation’ is an artefact of the measurement procedure, as described above. What this false assumption does is the magnify the radiative part of the heat transfer in the atmosphere out of all proportion to reality.
if you want to, you can prove it very simply. On a warm, humid, cloudy night put your hand out, palm down. The back of the hand is a fairly good IR radiation detector and 333 W/m^2, about twice the average SW from the Sun, is about what you get 1/3 m from a 2 kW kitchen heater/ If it exists, you’ll easily feel it. I can’t and neither can anyone else……
Correction 1 and 1/3 m from a 2 kW heater, just over 4 feet.
ZP says: “To a first approximation, we can just propagate the error upon subtraction, which would tell us that resister two is 0.5 +/- 7 Ohms greater than the first. Although the value obtained from subtracting the two means is non-zero, any freshman level science student would readily conclude the two resisters are nevertheless indistinguishable. “
Apparently I expect above-average freshman-level students. 🙂
Let me make it more direct. I hook up a resistor to a poor quality DMM with a 5% uncertainly that reads 100.0 Ohms. I then warm that resistor, and the reading slowly creeps up to 100.5 Ohms. I am 100% sure that the second reading is higher than the first, even though I am not at all sure whether the second resistance is truly above or below 100 Ohms. In fact, I am pretty sure the second reading is 0.5 +/- 0.1 Ohms higher than before. Linearity is a different question than absolute accuracy. If that resistor was being used as a thermometer, I would know the second condition was warmer, even if I didn’t know the calibration curve. I would not be ~ 10% sure that the second one was warmer!
If I measured two resistors with two different poor quality meters, then your conclusions would have been appropriate. And that is precisely why such care must be taken whenever different instruments are compared.
Thank you. Let’s remove “back radiation” from our collective lexicon, shall we? There is no “back radiation”; only radiation. Which, as the person who wrote the above blockquoted bit points out, occurs from any body whose temperature is above 0K. The fact that such radiation may balance out in a bidirectional exchange is irrelevant.
Hi Slarti: I have refined my proof that ‘back radiation’ is an artefact of the measurement process and not as Meteorology imagines, ‘downwelling IR’ from an energy source.
Put two radiometers back to back with no temperature gradient and the difference signal is zero. Take one radiometer away and the shielding at the back of the detector stops the Prevost Exchange signal from the other direction nullifying its signal.
So, poor climate modelling saps only imagine there is a real energy source in the sky – the ‘Sky Dragon’. All the climate models need to be reconstructed – sorry folks but that’s science for you! The net result is that the IPCC has exaggerated AGW by at least an order of magnitude.
Mydogsgotnonose says:
“Spartacus: the major problem with the Trenberth cartoon is the claim that heat transfer from the Earth’s surface to the atmosphere is [17+80+396=493 W/m^2] when in reality it’s [17+80+63=160 W/m^2], or an exaggeration by a factor of 3.08.
I just looked at the paper, and they are rather careful to use the correct term “energy flux”. There is indeed an energy flux of ~ 396 W/m^2 of upward IR, along with the ~ 333 W/m^2 of downward IR, which agrees with their claims. The net IR flux is indeed ~ 63 W/m^2 as you state, but this is a different issue than the individual fluxes that Trenberth is carefully describing.
So you are each right in your own way (but your claim about their claim regarding “heat transfer” is not strictly correct).
“This is a ‘Perpetual Motion Machine of the Second Kind’ to give it it’s formal thermodynamic definition. “
No, sorry, it is not. According to wikipedia (which agrees with other sources):
Where is there mechanical work that was created? Which one heat reservoir do you think we have? Where do we have a system without a cold reservoir to absorb heat?
It is not even any other sort of violation of the laws of thermodynamics. If you think it is, show the calculations of energy and/or entropy that show a specific violation.
Mydogsgotnonose says: ” .. stops the Prevost Exchange signal.. “
I don’t know what you mean by “Prevost exchange signal” or “Prevost exchange energy”. Please give an equation for calculating both of these quantities.