Greenhouse Gas Experiment June 20, 2007
Posted by physics309 in Global Warming, McKinney, Science.trackback
I received a copy last week of a paper I wrote that was accepted by a peer-reviewed journal. Since I’m a liberal arts teacher, getting a paper accepted is always good news. I like to average about one per year, whereas a research scientist needs to average several per year. This particular paper has an interesting story behind it and is relevant to the topic of global warming, something I’ve followed for over twenty years now.
The story began at a Lunar and Planetary Sciences Conference I was attending in the early 1990s. This is an annual conference hosted by the Lunar and Planetary Institute and held at the Johnson Space Center in Houston, Texas. This is a great conference and I really enjoy going to it. There are several rooms with scientists giving lectures on their research all day for about five days straight. For me, it’s worse than being in a candy store. Which one do you go to? There’s a series of lectures on Venus in room A, but there’s some really interesting lectures on Mars in room B, while the latest results from a particular mission are being shown in room C, not to mention what’s going on in room D. You follow the schedule and move from room to room to catch the ones most interesting to you. The wealth of scientific discovery being revealed is exciting! In fact, there is so much to present they can’t schedule it all. As a complement to the lectures they have poster sessions, displaying hundreds more presentations. Of course, not all lectures and posters are equal. Some are enlightening and tremendous fun. Others are of interest to only a few select people. Then, there are the ones that make you wonder how they ever got in the door.
I was at one of the poster sessions and was following my routine of walking along, getting a quick view of each, and stopping at certain ones that caught my interest. There was one in particular that caught my eye simply because I thought the topic was so preposterous I felt there must be a mistake. This individual was claiming the greenhouse effect doesn’t exist. He wasn’t saying that global warming doesn’t exist (something that was in much greater debate in the scientific community at the time), he was claiming that the actual effect of warming a planet with an atmosphere doesn’t exist and all of the scientific literature on the topic was in error. I stopped just long enough to clarify that, in deed, this was what he was claiming and intended to move on but, as they say, those that hesitate are lost. This gave the author time to corner me and launch into his rationale for his claim. I certainly didn’t want to get into an argument or to encourage him, so I politely listened to everything he had to say and moved on when I got the chance, thinking there must be a way to prove this guy wrong.
His premise was that, ignoring heat coming from a planet’s interior, the total amount of heat coming in from the Sun and then being radiated out from a planet must be equal. Therefore, there can’t be any warming because this would require an imbalance in the heat flux. An interesting concept, but one that is wrong. His problem was that he did not take account the time rate of change of the heat flux. Add a layer of insulation and for a period of time, more heat will be coming in than going out, resulting in a higher temperature. Eventually, the amount of heat leaving will again equal the amount of heat coming in, but the temperature will be higher than it was before.
Imagine you are a planet and your constant body hear represents the constant heat from the Sun. Now, imagine you’re laying on a bed on a chilly evening. This would be a planet with no atmosphere; your body heat is escaping almost immediately into space (the air, in this case). To keep warm, you pull a sheet over you. Now, the sheet keeps some of the heat in and you’re warmer, but still chilly. Next, you pull a blanket over you. Now, more of your body heat is retained and you’re even warmer than before. You continue to pile blankets on top of you and you get warmer and warmer, eventually reaching the point where you become hot.
Hey! Wait a minute here! Didn’t we establish that your body temperature is constant? How is it, then, that you keep getting hotter and hotter? It sounds like something’s going on here.
In fact, if we were to take some instruments in and measure the amount of heat going into the air, we would find that, over a period of time, you are emitting the same amount of heat energy when you had nothing over you as when you had just a sheet, and as much as when you had a single blanket, and as much as when you had a pile of blankets. Given enough time, the amount of energy leaving your body is constant and it will eventually get radiated into the air. The trick is the phrase, ‘enough time’. The amount of time needed when you had nothing on you is much shorter than the amount of time when you had a pile of blankets. That’s what insulation does for you, it doesn’t stop you from losing heat, it just stretches out the amount of time it takes for it to happen. As you added blankets, we would find that, for a while, the amount of heat being emitted into the air was less than the amount of heat emitted by your body. But, everything has to balance over time, so when you get up in the morning and remove your source of heat, the blankets will continue to emit heat until they are the same temperature as the surrounding air. This shows that if you add a layer of insulation, there will be a period of time when less heat is emitted out than is supplied, and if you remove the insulation, there will be a period of time when more heat is emitted than is supplied.
That’s how global warming works. By increasing the amount of greenhouse gases in our atmosphere we have increased the amount of insulation – we’ve put some blankets on the Earth. This insulation will store heat for a while and will eventually get back into equilibrium where the amount of energy being radiated back into space is equal to the amount of energy coming in from the Sun. But, since we’ve slowed down the rate that the energy is lost, the temperature will be higher. Just like with the blankets.
So, this guy with the poster was saying none of that really happened and I decided there had to be a way to prove him wrong. I ended up designing a very simple experiment that I’ve used in my astronomy labs since then. Using two 2-liter bottles and a couple of cans of Coca-Cola, I create two environments in the bottles. In one bottle, I pour the Coke in and agitate it within the bottle. In the other case, I agitate the Coke and remove the carbonation before pouring it in. This creates two environments that are identical with the exception that one has nitrogen-oxygen atmosphere, and the other has a carbon-dioxide atmosphere. Then, you stopper them and put the two bottles in the sunlight with a thermometer in the stopper to measure the rise in temperature. My classes have consistently obtained results that show the carbon dioxide atmosphere goes up a couple of degrees higher than the nitrogen-oxygen atmosphere. Clearly, the guy with the poster was wrong.
Now, this experiment will be published and available for anyone to use.
Coming up, I will share my observations concerning global warming.
One way to make this experiment more fair would be to place baloons over the tops of the bottles.
In the bottle with the carbonated cola, the soda will release CO2 into the bottle gradually and eventually there will be a significantly higher pressure in that bottle due to the closed cap and the “extra” CO2 released by the cola.
According to the ideal gas law, PV = nRT, the increased pressure will contribute to an increase in the temperature in the bottle.
Global warming is based on the fact that greenhouse gases absorb some of the incident solar radiation; the increase in the energy of those gas molecules is dispesed to the atmosphere by collisions with other gas molecules. Higher levels of greenhouse gases lead to more heat introduced to the atmosphere by this mechanism, and a gradual heating occurs. As you correctly stated, a constant level of green house gases would eventually reach a steady state, where the flux of energy to the earth would be equal to the flux leaving the earth – but after a period of time where the atmospheric average temperature had risen by amount.
The seal around the thermometer is usually not tight enough to allow pressure to build, keeping the pressure in the two bottles equal, but you’re point is well made. Thanks for pointing that out.
Chris
Any chance you could send me a preprint of the paper?
On its way. Let me know if you didn’t get it.
Chris
Wow that’s quick. Thanks.
Have you ever tried this experiment at night? I suspect that the results would be the same, except that the CO2 atmosphere at night would decrease in temperature slower than the N2/O2 atmosphere similar to when the bottles were placed on the snow. It might also be interesting to see how the temperature varied over an entire diurnal cycle, if the leakage from the bottles could be contained that long.
That is an interesting idea. You’re right, it should be similar to the snow experience and the CO2 atmosphere should decrease in temperature more slowly than the N2O2 one. I don’t think leakage would be that much of a problem. The CO2 is heavy and sits inside the container pretty well. Shrinkage of the atmosphere would occur, but any gases leaking in would sit on the top of the CO2.
[...] an excellent, simple, and cheap experiment to verify the greenhouse effect from Tales From The Travels. So, this guy with the poster was saying none of that really happened and I decided there had to be [...]
Have you insulating the 3/4 of the bottles surface through which
heat escapes.
You will get a very different result.
I’m not sure what you mean. Heat escapes through 100% of the surface. It also comes in through 100% of the surface. So, if you insulate any part of it, you’ll be reducing the amount of solar radiation that can get in. This will certainly give very different results.
Rubbish
Heat comes in on the exposed side and goes out through the unexposed areas.
That is plain common sense.
If the unexposed areas are insulated the temperature differential
disappears.
Heat is always entering and leaving all surfaces, it is never a one-way affair. I should point out that energy is entering the system in the form of light, not thermal energy, and is entering through one-half of the surface, the surface facing the Sun. The thermal energy is escaping equally through all of the sides of the bottle. It is also escaping through the top and bottom, but these are not equal in all respects to the sides, so the heat flux will be different.
The goal of this experiment is to demonstrate to students that greenhouse gases really do store heat and it demonstrates that point very effectively. This is part of the education for students that are aware of, but not necessarily knowledgeable about, the issues concerning global warming and the effects of greenhouse gases on our environment, which is certain to be one of the most important issues of their lives. The experiment is not designed to be a rigorous scientific experiment to measure exact effects on the atmospheric system caused by greenhouse gases.
Yes, changing the conditions of the experiment will produce different results, but it is also a different experiment that tests something different. If there are other points that you wish to test or demonstrate, it is only logical that a different experiment would be needed.
I am very interested in your experiment. My daughter and I have been researching how a large scale housing development and golf course, replacing a forest, could effect the carbon dioxide in the environment for her science fair project. Her hypothesis is that cutting down the trees and adding more households with cars is a bad carbon trade off and will increase the greenhouse gas effect. We would like to try your experiment in support of this.
Your daughter is correct. But, its even worse than she thinks. By cutting down the trees you will also be releasing the carbon that is stored within their wood as they decay. This will create carbon dioxide and methane.
There’s no doubt that CO2 is a greenhouse gas, but your experiment doesn’t take the concentration of CO2 into account. What is the difference in temperature rise when CO2 iss 280ppm vs. 380ppm, etc.
The Earth’s atmosphere isn’t contained in a bottle, either. The Earth is essentially a living organism that we still are trying to figure out. We’ve had periods in our history where temps have gone up for several hundred years and gone down for several hundred years. A century of weather is just a blip in the history of weather, and even when scientists go back 140,000 years using proxy data, they don’t include the margin of error and they don’t mention that the sample rate is 3-6000 years. There is a very good chance that many centuries comparable to ours could exist within those periods of missing data.
Your argument is a false one. The purpose of the experiment was to demonstrate that CO2 is a greenhouse gas and will store heat better than an N2O2 atmosphere and it does that quite well. This experiment was not meant to model the Earth’s atmosphere, nor was it intended to address the history of climate change. The arguments you present have all been shown to be invalid arguments concerning climate change, but climate change was not the point of this experiment anyway.
You’re correct, the idiot claiming that the greenhouse effect doesn’t exist was wrong.
Please enlighten me about how my arguments have been shown to be wrong. Are you saying that the Vostok ice core data samples aren’t 3000 to 6000 years apart? The little ice age and medieval warm period didn’t exist?
Anyway, back to the experiment. The experiment is invalid since the quantities of gas are different. Did the class measure the pressure of the gas in the bottles? As we know, PV = nRT. V should be the same in both bottles if the same amount of liquid is added, n is constant, but not equal between both bottles. It’s likely that the pressure is higher in the CO2 bottle (hiss of gas when uncapping vs no hiss when uncapping) Higher pressure, higher temperature. Plus the bottle with the CO2 atmosphere also has N202 along with it. So you have equal quantities of N202 atmosphere and then additional CO2 in the CO2 bottle. Having more molecules in one bottle over the other could cause the bottle to retain more heat.
The pressure in both bottles is the same because they are open to the air. While the top is tight enough to prevent the hot gases from escaping, it is also loose enough to prevent pressure from building up. This actually works against the greenhouse gases because they are more likely to heat up and create a pressure that will allow some to escape. However, capping the bottles tightly has not shown any difference in observed results at this level of measurement.
The CO2 fills the bottles to the top and forces the N2O2 out of the bottle. We proved this by inserting burning wood splints and seeing them go out as soon as they entered the CO2 bottle, but continued to burn when inserted in the N2O2 bottle.
While the number of CO2 molecules may be different than the number of O2 and N2 molecules in the other bottle, the difference is not going to be significant enough to cause the observed differences in temperature rise.
The ‘Little Ice Age’ is a misnomer. What was observed was a regional drop in temperatures, not a global one. There were also large regions that experienced temperature rises during this same period. And, none of this has anything to do with the experiment, which was designed simply to demonstrate that the greenhouse effect is real.
Does the global atmosphere expand when it heats up?
Does the global atmospheric pressure increase?
How does equilibrium vapor pressure of oceans come into play?
Is infrared light and heat the same thing?
Does CO2 reflect heat or does it absorb and re-radiate it?
How much of the heat that encounters a CO2 molecule comes back to the earth’s surface?
Does the rate of heat transfer depend on the temperature difference between two objects?
Wouldn’t a higher global temperature increase the rate of heat transfer to space?
Can you predict when the stock market will go up? It’s a much less complicated system than the climate and we are going to need a lot of dough to pay for all the proposed remedies to climate change. How are we going to get termites to pay their fair share of the cost? Economics, science, and religion are killing my buzz! Face it — In the long run we’ll all be dead.
The atmospheric greenhouse effect assumes that in daytime, a cool atmosphere “back radiates” to a warmer earth surface. While all bodies radiate, the nett effect can only be heat passing from warm bodies to cooler bodies – 2nd Law of Thermodynamics.
This NASA diagram shows no greenhouse :
http://eosweb.larc.nasa.gov/EDDOCS/images/Erb/components2.gif
My view is that the atmosphere acts like a radiation shield on an automotive exhaust. One or more sheets of metal between the hot exhaust and cool surroundings, reduce radiation from the hot exhaust. The shield(s) adopt intermediate temperatures. There is no “greehouse effect” between the shield and the cool surroundings.
The result is that absorption of sunlight by gases in the atmosphere, moderates daytime temperatures. Similarly it increases nightime temperatures.
It would be interesting to see a trend of the difference between global average max and min temperatures over the past 150 years. If GHGs are increasing, one would expect a falling trend. This trend would be less susceptible to urban heat island effect. Is this data available ? (It is obviously stored in order to calculate global average temps).
You’re wrong when you say the diagram does not show any greenhouse effect. There is an arrow labled ‘Radiation Absorbed By Atmosphere 15%’. Atmospheric absorption is what the greenhouse effect is all about, and what this experiment is all about. The experiment shows that a CO2 atmosphere absorbs more energy than a N2O2 one.
As for the day/night difference, that is an interesting question. You could be correct on this, although I have some thoughts about it. It would depend on the relationship of energy escape rate at night versus energy storage rate during the day. I don’t know where to find that data, but I agree with you that it should be somewhere.
Correct … the diagram does show heat from sunlight being absorbed. I have no argument about the atmosphere absorbing incoming solar radiation. However, it does not show greenhouse “back radiation” (that is, a cool atmosphere radiating heat to a warmer earth) as most of these heat/energy “greenhouse” diagrams do.
I suspect that there is a general confusion about heat / wavelength / temperature. The 2nd Law doesn’t care what the wavelength of the energy is. The idea that a cool atmosphere can absorb long wavelength radiation from the earth and then “back radiate” this to a warm earth violates the 2nd Law.
As you and the diagram suggest, all the atmosphere does during daytime, is to absorb some incoming solar radiation.
Your statements about greenhouse effect and the 2nd law are both incorrect.
The 2nd law of thermodynamics says, in various forms, that entropy always increases. Heat can, and does, move from a cool body to a warm body, as long as there is an increase in entropy somewhere else to compensate.
But, that isn’t what the greenhouse effect is all about. What the greenhouse effect says is that the atmosphere is trapping heat, like a blanket on a bed, and keeping the overall temperature higher than it otherwise would be. By adding more greenhouse gases to the atmosphere, the atmosphere becomes more efficient at trapping heat. Individual molecules will trap heat, then reradiate them. But, there is not a preferred direction to this radiation. Energy will be radiated by the molecules in all directions. Some of this radiation will be reabsorbed by the ground, some will be reabsorbed by other molecules in the atmosphere, and some will radiate into space.
There is certainly no violation of the laws of thermodynamics there.
Yes, the general expression of the 2nd Law is that there is always a tendency to an increase in total entropy. In a simple system such as this, assuming constant pressure, perhaps you can give an example of heat flowing from a cold body to a hot body without the input of work ?
Have you discovered a source of perpetual energy ?
If the greenhouse effect acts “like a blanket on a bed, and keeping the overall temperature higher than it otherwise would be” as you suggest, we would expect temperatures to be lower in daytime if there was less GH gases. This is exactly the situation over deserts, with low levels of water vapour in the atmosphere … but deserts are hot in the day, not cool. The only NETT effect that GH gases have is to absorb incoming solar radiation, as shown in the NASA diagram. There can be no NETT back radiation from a cool atmosphere to a warmer earth.
Again, you are wrong on several counts.
First, there is work being done on the Earth by the Sun, a huge amount, in fact.
Second, the Earth’s environment is certainly not a simple system. There is nothing that is simple about it. If it was, things like weather forecasting would have been perfected long ago.
Third, being a desert does not mean it is hot. Antarctica is considered the driest desert in the world. A desert such as the Sahara is hot because of the intense solar radiation during the day is absorbed by the ground and not by ground cover. Plant life converts much of this radiation into chemical products through photosynthesis. More energy is used up in evaporation. Without ground cover and without the evaporation that would be found in a wetter climate, the ground absorbs all of the heat and then reradiates it. After sunset, the ground is no longer receiving solar radiation and cools rapidly. This daily cycle has nothing to do with the greenhouse effect or global warming. What you would need to do is to check the long-term average temperature in a desert to see if there is any change. The data shows that, yes, even the desert areas are getting hotter.
Also, the atmosphere is typically only cooler than the ground during the daytime, but warmer during the night.
As for the net effect, your statement is correct, but misleading. It is true that eventually, all energy coming into the atmosphere will leave it. But, this could take thousands of years, or even millions. If energy is trapped in the atmosphere at a rate greater than what it radiates back out into space, then the temperature must rise.
By the way, referring to your comments about radiating from a cool system to a hot one, you must take into consideration the atmosphere. The upper levels of the atmosphere are much hotter than the lower ones. Temperature drops as you go up in altitude, but then rises again to temperatures in the 100s and even 1000s of degrees. By your argument, we could never radiate any heat into space at all because it would first have to radiate through this much hotter layer of the atmosphere.
If you think that global warming is false, then I suggest you check into my $1000 Global Warming Skeptic Challenge. If you can prove, via the scientific method, that global warming does not exist, I’ll pay you $1000.
Are you now suggesting that the work done by the sun on the earth is responsible for heat travelling from a cold bodies to hot bodies ?
You did not answer my question:
… assuming constant pressure, perhaps you can give an example of heat flowing from a cold body to a hot body without the input of work ?
I have no argument that the earth’s atmosphere and climate is complex. The discussion here relates to the claimed “greenhouse effect” … that is, the daytime “back-radiation” from so called GHGs.
Once again you have sidestepped … your greenhouse theory would suggest that the daytime Sahara temperatures should be cool rather than hot, because of low levels of the major GHG, water vapour. Low GHG’s mean what you call your “blanket” is missing.
“As for the net effect, your statement is correct” … we are making progress !
Do you disagree with this NASA diagram showing no “back radiation”, no greenhouse effect, and no what you refer to as “a blanket” ? :
http://eosweb.larc.nasa.gov/EDDOCS/images/Erb/components2.gif
The atmosphere is not opaque as you imply. Warm parts of the atmosphere will show a nett radiation to cooler parts. However the atmosphere does not absorb all radiation passing through it. It is partially transparent … that’s why even in very polluted areas we can see the sun.
Your $1000 is very “old hat” and looks very silly compared to the $500,000 offered here :
http://www.ultimateglobalwarmingchallenge.com/
… if you can prove global warming is true.
I’ve decided to use your submissions as the second entry in my Global Warming Skeptic Challenge. Check my blog in the next few days for my review of your argument.
I should add that the sign of a good scientist is that he is a skeptic about just about everything. History is full of examples of great scientists who have stood against the tide of popular opinion. Galilleo is a good example, although he waited till his death bed before standing for the truth. Bruno was a little more bold and was burnt to death as a result. John Nash didn’t want to be “contaminated” by ideas of others, so he derived everything himself from first principles.
Most scientists probably had similar experiences to mine years ago when I first heard about CO2. I’d learnt 350ppm in school and now it was higher … at first glance it seemed there might be a connection with global temperatures. However it didn’t take a great deal of investigation to start to see the flaws in the hypothesis. Until a couple of weeks ago, I’d taken greenhouse for granted, as I’m sure 99% of other scientists do. I may have made similar statements as the blogger here. On questioning greenhouse in detail, it is clearly built on just as poor grounds as the theory about man’s CO2 causing global warming.
Your arguments have a number of fatal flaws. I hope to be able to get to your posts soon and detail where you are making your errors.
Waiting with bated breath for your fatal response.
You can see my reply here.