Home/BlogPERSONAL NOTE: I’ve been unavailable for a while…my oldest daughter was in a bad car accident, will be OK eventually, but won’t walk for about 3 months. So, I might not be answering queries.
The global average lower tropospheric temperature anomaly for January, 2012 took a precipitous plunge, not totally unexpected for a La Nina January (click on the image for the full-size version):
The 3rd order polynomial fit to the data (courtesy of Excel) is for entertainment purposes only, and should not be construed as having any predictive value whatsoever.
Here are the monthly stats:
YR MON GLOBAL NH SH TROPICS
2011 1 -0.010 -0.055 +0.036 -0.372
2011 2 -0.020 -0.042 +0.002 -0.348
2011 3 -0.101 -0.073 -0.128 -0.342
2011 4 +0.117 +0.195 +0.039 -0.229
2011 5 +0.133 +0.145 +0.121 -0.043
2011 6 +0.315 +0.379 +0.250 +0.233
2011 7 +0.374 +0.344 +0.404 +0.204
2011 8 +0.327 +0.321 +0.332 +0.155
2011 9 +0.289 +0.304 +0.274 +0.178
2011 10 +0.116 +0.169 +0.062 -0.054
2011 11 +0.123 +0.075 +0.170 +0.024
2011 12 +0.126 +0.197 +0.055 +0.041
2012 01 -0.093 -0.059 -0.127 -0.138
Progress continues on Version 6 of our global temperature dataset. You can anticipate a little cooler anomalies than recently reported, maybe by a few hundredths of a degree, due to a small warming drift we have identified in one of the satellites carrying the AMSU instruments.
Hi Dr Spencer,
Thanks for the update.
Wishing your daughter a speedy and full recovery.
Best wishes as well.
Best wishes to you and your family.
Thanks for the update, and keep up the great work.
Best wishes for a speedy and full recovery of your daughter.
God Bless you and your family Dr. Spencer! I’ll keep your daughter in my prayers.
Look at the Figure 3 at http://www.skepticalscience.com/media_v_reality.html (http://www.webcitation.org/659tLf4XU) and how they claim that skeptics “You need to look at all of the data rather than ignoring” … Who is ignoring data?
I wish you and your family well for the future and thank you for continuing your work.
Best wishes for you and yours. Keep up the good work.
Prayers going out your daughter’s way, Roy…
Best wishes for your daughter.
Dr Roy,
Sorry to hear about your daughter’s accident.
Family comes before global warming or ice ages, so my sincerest wishes for her full recovery; and my best to your family.
No answer from you permitted; you have more important issues.
George
Dr Spencer,
My best wishes to your daughter, and I hope her recovery progresses well.
Nikolai,
I think that the increasing sarcasm from such people is a sign of panic.
Wishing your daughter well for a speedy and complete recovery.
We are experiencing intense cold in parts of Europe, and the attendant death toll is a sad reflection on societies inability to understand and do something about the risk. Let’s all hope for a speedy end to the current spell of La Nina cooling.
Our prayers are with you and your daughter.
I wish your daughter a speedy recovery. Not going to pray, since that has shown to have zero effect.
What caused the steep uptick in temps in the last week of the month? That was a pretty big recovery from the low temps in the middle of the month.
Temporary warmings and coolings of a few weeks duration are usually caused by fluctuations in the average rate of transfer of heat from the ocean to atmosphere, called intraseasonal oscillations.
My thoughts and prayers are with your daughter, you and your family. She’s indefinitely more important than some global atmospheric temperature anomalies. Please take good care of her and your family!
When I read about your daughter I thought I’d add a human dimension by wishing her well, and the family well. Then I read the feedback and was touched by the fact that so many of your supporters value the human perspective and are more concerned for her, and your family, than for the ongoing debate. For several years I’ve had the highest admiration of your respect for the scientific method. My best wishes to your daughter.
Dear Roy,
May God look after you and your daughter and provide the best for both of you.
Bardzo ciekawy tekst jak i ca?y blog, polecam go tak?e wszystkim znajomym. Keep it coming on and on!
Dr. Spencer, best wishes for a speedy recovery for your daughter.
Kevin
I wish a speedy and complete recovery for your daughter.
Given what I’ve noticed comparing UAH with RSS data, I expect the revised UAH monthly data to show more than a mere few hundredths of a degree downward revision. I expect closer to minus 0.070.
Dr.Spencer, I don’t post on your blog, but I am an avid reader. You offer a fair balanced approach to the subject of climate science, and have taught me a great deal.
On a personal level, I felt compelled to write on your blog this evening, and wish you’re daughter a very speedy recovery. Godspeed.
Our prayers for the speedy recovery of your daughter.
I’m sorry to hear about your daughter. Our best wishes for her recovery.
Roy,
I have a question: Is it possible to estimate the “no-volcano” TLT history? i.e. What would your TLT history (and trend since 1991) look like if we had not had the Mt Pinatubo event and the subsequent temporary cooling?
It struck me that had the Mt Pinatubo eruption _not_ occurred, we should have seen an “even flatter” TLT trend since the early 1990s, as the associated cooling depresses the early part of the series you show in the chart above.
Best wishes for your daughter’s speedy recovery.
yes, you are correct. John Christy has done this, I’ll ask him about it.
Sorry, I should have added the El Chichón event into my question as well, for completeness.
It seems to me that both of these volcanic cooling events might contribute a significant amount to any warming trend observed, merely by depressing the early of the series…
Best wishes for a full recovery by your daughter. Family comes first.
Hope your daughter makes a full and speedy recovery. Best wishes from Down Under.
Simon
Australian Climate Madness
Q,
“What caused the steep uptick in temps in the last week of the month? That was a pretty big recovery from the low temps in the middle of the month.”
An equally relevant question might be, what caused the steep fall in temps during the first 22 days of the month?
If both were the result of “intraseasonal oscillations”, what causes those oscillations? That is, why should the rate of heat transfer between the ocean and the atmosphere change so rapidly?
The changes in oceanic heat flux required to cause these oscillations is, as I recall, about 1%. They might look dramatic, but they represent very small changes in the atmospheric heat budget terms (convective transport from the surface, IR cooling, etc.)
FYI – On a larger scale, equatorial ocean temps (-/+ 5 degrees of the equator, tend to give a glimpse of future global air temps. This link would indicate we’re in for another drop in atmospheric temps.
http://nomad3.ncep.noaa.gov/cgi-bin/pdisp_sst.sh?ctlfile=monoiv2.ctl&ptype=ts&var=ssta&level=1&op1=14tave&op2=none&month=nov&year=1981&fmonth=jan&fyear=2012&lat0=-5&lat1=5&lon0=-180&lon1=180&plotsize=800×600&title=Equitorial+-5+to+%2B5+SSTA+Monthly+13Mo+Avg&dir=
Best wishes to Dr Spencer, his daughter and the whole family.
Anybody checked if SkS has published a blog already showing car accidents increase due to AGW?
Best wishes to you and the rest of the Spencer family and a speedy full recovery for your daughter.
Thanks to everyone for their concern and prayers.
-Roy
Roy,
Sorry to hear about your daughter, and I wish her a speedy recovery.
Here are some paragraphs that I first read some time ago, and are still relevant today. Anyone care to guess the date and source?
“This process is called the greenhouse effect, although this is partially a misnomer in that the glass on a greenhouse prevents convection and wind cooling as well as reradiation.”
“… an increase in mean global temperature … from the increased CO2 levels … but it is not clear whether these changes are at least partially offset by increased evaporation rates which would produce more water vapour and hence cloud cover. Additional cloud would reflect incoming solar radiation and tend to lower temperature. This type of effect is called negative feedback, …”
“much of the difficulty in assessing the impact of co2 pollution is concerned with estimating the relative magnitudes of the different positive and negative feedback processes”
It seems to me that these questions are still unresolved, and perhaps not receiving the attention they deserve. The comments certainly provide a more balanced description than we usually see today.
Obviously no one else is interested, but these comments were originally published in 1980 in a book called “Environmental Chemistry”.
After 32 years and billions in research grants, these basic questions are still unanswered.
But you don’t get grant money when you research these questions. Only research that prints to fit will get funded.
I’m very sorry to hear about your daughter and the pain those who love her must be feeling right now. You have my sincerest condolences and best wishes for a full recovery. God bless all of you.
I think it’s interesting to note that the tropics anomaly is much less negative than during last year’s La Niña, yet the global anomaly is very close to what it was in the coldest month last year (March)! It would be interesting to see a plot of the global anomaly minus the tropics for the satellite period – or even just minus the tropic Pacific.
I’m sorry to hear about your daughter’s accident and wish you and your family all the best!
Dr. Spencer, best wishes for a speedy recovery for your daughter.
It is really cold now in Europe. For some weeks it has been cold in the north part of India and in Nepal, too.
Im wondering if anybody has got good explanations, why it is happening.
hv writes “Im wondering if anybody has got good explanations, why it is happening.”
Sarc on. CAGW of course!!! Dont you know by now, that EVERY unususal weather condition is caused by CAGW. Sarc off.
Anyone seen a study that proves that the current cold spell in Europe has been caused by “global warming”. I would be delighted to see a reference.
So sorry about your news. Hope things work out OK.
Best wishes for a speedy and full recovery for your daughter!
And thanks, Roy, for your continued efforts to restore world leaders to reality.
Today society suffers because power obscured reality: “Power tends to corrupt, and absolute power corrupts absolutely. Great men are almost always bad men.” – Lord Acton
Society is in collapse worldwide and we are all trapped – together with our blinded leaders – like rats on a sinking ship, . . . unless we find a way to work together with those we have criticized.
Thanks to the efforts of brave scientists like you, world leaders know that they were wrong – but cannot admit it.
Again, Roy, thanks and best wishes for your daughter.
I would venture to say that throughout history society often looked like it was “in collapse” — during the Crusades, the Black Death, the French Revolution, the revolutions of 1848, the Civil War, the Great Depression, WW2, and so on. Though people often like to think their times are special and especially difficult, we’re doing quite well compared to them, and if anything these times will be remembered for 9/11 (maybe), the Arab revolutions, the ascendancy of China, and, in the long run, the large slug of carbon we transferred to the atmosphere.
Our present problems will resolve. New ones will take their place. Babies will be born, grow up, do good work, mess up, love, laugh, cry, suffer illness, and die. So it goes. Try to stay brave.
Thank you very much Dr. Spencer.
I’m wishing a prompt and complete recovery for your daughter.
I hope your page at http://www.drroyspencer.com/latest-global-temperatures/ will be updated soon.
I have updated my pages containing your graph.
Best regards
My thoughts and best wishes are with you and your family. Best wishes for your daughter’s speedy recovery.
socialism and freedom eventually become mutually exclusive.
why ?
because socialism combined with freedom allows for the weak to reproduce at high rates. the ratio of weak to strong therefore increases until socialism is no longer self sustainable.
therefore we either get rid of socialism or get rid of right to reproduce ( freedom ).
This is a hideous promotion for social Darwinism. In any case, there are several democratic socialist countries who are doing quite well, and those aspects of the U.S. that are socialist aren’t doing so badly either.
If the temperature and the CO2 level of the planet rises, won’t this lead to more plant life (algae blooms, etc.) which would mitigate the global warming effect? Do researchers include this in their models?
Yes, and yes. Start reading here:
http://en.wikipedia.org/wiki/Dynamic_global_vegetation_model
Dr Spencer, best wishes to you and your daughter for a speedy recovery.
Roy, please let me know if I can help in any way regarding your daughters’s recovery. I tend to look on the bright side of events, being thankful that they were not worse and benefitting from lessons learned. Happy to hear she will recover in time. If she needs an ipad and doesn’t have one, please let me furnish one for her, or anything else needed when movement is limited.
Regards, Harley
A speedy recovery to your daughter and prayers for your family as she recovers. Thanks for your great site!
Roy…sorry to hear about your daughter. Hope she has a full recovery, both physically and mentally. Had a pretty scary accident myself a couple of years ago, although injuries were minor. The emotional impact can be deep, however.
Roy,
So sorry to hear about your daughter.
Happy to hear she will eventually be okay.
Best wishes for a speedy recovery.
Dr Roy,
My best wishes go out to your daughter, I hope she will have a fast recovery.
I’m writing to discuss your polynomial curve fit. I did a sine / trend / offset / acceleration fit just to see what the various factors are. If you assume there is a cyclical component, then the underlying trend is much less than the least squares regression would indicate since we are not looking at a full cycle. My analysis indicates an underlying trend of 0.51°C per century, with an incomplete sine wave riding on it, resulting in a curve much like your polynomial…
Mine is also for entertainment (or I will invite endless questions on the significance of each variable)…
I also threw in a projection since I seem to almost always get the answer of cooling until 2028 (or thereabouts) no matter which dataset I use.
Have a look… Comments welcome. Thanks, Mike S.
http://naturalclimate.wordpress.com/2012/02/03/uah-global-temperature-deconstruction-as-of-jan-2012/
Dr.Spencer,best wishes for your daughter.
Michael D Smith,
“I also threw in a projection since I seem to almost always get the answer of cooling until 2028 (or thereabouts) no matter which dataset I use.”
I get similar results from calculating the rolling 50 year linear trend from HadCRUT3.
There appears to be a pattern which closely correlates to a sine wave pattern, which peaks approximately every 60 years and which is currently approaching a peak, which suggests that the 50 year trend will decline over the next 30 years.
This does NOT imply actual cooling for 30 years but some cooling over the next 10-15 years.
The 10 year trend seems likely to remain negative until about 2014 and the 20 year trend will become negative by 2020.
This is a bit late, but here it is.
Another respected authority on thermodynamics saying that in an isolated column of gas in a vertical gravitational field, at thermodynamic equilibrium, although the pressure at the bottom will be greater than the pressure at the top, the temperature will be uniform throughout. The experts this time are Dilip Kondepudi and Ilya Prigogine, on pages 257 and 258 in ‘Modern Thermodynamics. From Heat Engines to Dissipative Structures’, Wiley, ISBN 0 471 97394 7. Prigogine won a Nobel Prize for his work in thermodynamics.
Dr. Spencer,
I’m very sad to read about your daughter.
Having been in a very bad car accident in the past and for that knowing the pain of stay immobilized for months in a bed,
I wish your daughter a fast and full recovery.
Best wishes,
Massimo.
Dr. Spencer,
Best wishes for your daughter!
Matteo
Bless your daughter and you and all your family. I know it is hard on all of you.
Best wishes to your daughter !
I received your Fundanomics – great fun.
Thanks for all – VF
I hope your daughter gets well soon. take care
Dear Roy, I hpe your daughter is recovering well. Thanks for all your excellent work.
Charlie
I hope your daughter’s recovery goes smoothly.
Dr Spencer,
I will keep your daughter and your family in my prayers.
I hope she has a full recovery.
Here’s some fun facts to lighten up the mood; which I hope everybody can appreciate.
I know weather is not to be confused with climate and I know December and January were, especially in Northern Europe and Northen Siberia much above the long-term average temperatures. For example, Sweden was on average 3-5C warmer than “normal” (hmmm, what is normal btw???) in January : http://www.smhi.se/nyhetsarkiv/januari-2012-vintern-kom-till-slut-1.19822?search=yes&month=2&year=2012 (for those of you who can read Swedish, otherwise use a translation program in your web browser)
I also know that most you are aware of the extreme cold that rules in entire Europe right now (from Spain to deep into Siberia). Since I mentioned Sweden, it’s interesting to note that in Kvikkjokk-Årrenjarka in Lappland -42,7C was measured, which is the lowest temperature since measurements started in 1888: 25C below the long term average! http://www.smhi.se/nyhetsarkiv/mycket-kallare-an-normalt-i-hela-sverige-1.19879.
Moral of this little story: monthly numbers don’t mean much. (As you all know of course, but I thought I’d point this out in this fun-fact way as both January and February can be used by “both sides” to argue in favor of their own case: warming vs. cooling).
Another interesting little correlation-fun-fact is that the Dutch 200km long 11-city ice-skating tour will most likely be held again this year on February 15. The last time it was held was in 1997. Note that the tour has only been held 15 times since it’s first time in 1909, with 12 of the 15 tours prior to 1963. I thought this possible 15-year hiatus, as well as the race’s year-record appears to coincidentally coincide with the global temperature trend since 1900 and especially also over the lack of trend over the last 15 years. ps: note that ice-thickness-requirements are now more strict (thicker ice is needed; at least 9″) than previously due to the huge increase in actual participants and spectators, which the ice needs to be able to support.
Roy,
Sorry to read about your daughter. I hope she makes a speedy and full recovery.
Christopher…re your comment on a vertical column of air having a uniform temperature throughout. Your point is not clear to me. What do you mean by uniform, are your authors implying a constant temperature throughout?
If so, your authors might try walking to the top of Mount Everest in T-shirts. I’ll allow them oxygen to compensate for the altitude.
Down in the valleys below Everest, they could definitely walk about with T-shirts, and they might get away with it on certain days at base camp, which is roughly 18,000 feet. I have read many accounts of Everest summiters and I have never read of any who were not bundled up against the extreme cold at 29,000 feet.
Mind you, a lot of the cooling up there comes from the jet stream winds which can cool the Everest south col dramatically with 100 MPH winds. That’s why you don’t find ideal vertical columns of air in reality.
It has taken me a long time in my life to understand that you cannot take text books verbatim. In the world of programming, I read more than a dozen books on C++, all with different and very abstract definitions of a ‘class’. It was not till I read Stroustrup, the inventor of C++, that I found out that a class is an undefined type, which I could have understood immediately had any other author said that. Stroustrup simply said, “A class is an undefined type”.
Thermodynamics is a field made far more complex by mathematicians, and the introduction of abstractions like entropy. The concepts are complex enough as it is without authors inferring that the relationship between P,V and T don’t hold in the atmosphere.
Climate scientists have made it even more complex by misinterpreting the early work of Planck. He made it clear, if you read him, that his equation on radiation only applies when the surface dimensions on which radiation impinges is much larger than the wave length of the radiation. Climate scientists have completely ignored that when they applied Planck and Boltzman to atmospheric CO2 molecules, as Gerlich and Tscheushner succinctly pointed out in their treatise on falsifying the greenhouse effect.
a few more fun facts about the european cold: this is the 33rd official cold wave in Holland, as measured since 1901. The last one was in 1997 (when the last 11-city tour was held! đŸ™‚ ). This year’s is the 3rd coldest (-18.9C = lowest temperature at station de Bilt, which is used in NASA GISS, measured during this cold wave). The lowest was in 1942 and the 2nd lowest in 1956; -24.8C and -21.6C, respectively.
All data can be found here: http://www.knmi.nl/klimatologie/lijsten/koudegolven.html. The first column is the cold wave’s start date, the 2nd column the end date, the 3rd column the total length of the cold wave in days (defined by KNMI as at least 5 days constantly below 0.0C, and 3 of those 5 with minimum temperatures below -10.0C). The fourth column is the number od days with temperatures below -10.0C and the last column shows the lowest temperature.
Given the current weather forecast, one could expect the 2012 cold wave to last another 2-3 days and the number of days with temperatures below -10.0C to be 1-2. Today clocked another -12 to -14C in de bilt which hasn’t been recorded in the list yet. That will make this cold wave certainly colder than usual and a little longer and more intense.
Note that the 1900’s, ’30s, ’50s, ’70s, and ’90s all experienced only 2 cold waves per decade each, and the ’10s only 1 and the ’20s 3 cold waves. Only the 40s, 60s, and 80s produced 5 or more. Given this alternating pattern, let’s see if the 2010s produce 2 (or more)?
Dr. Spencer
Very sorry to hear about your daughter. I hope she makes a full recovery.
regards
Richard Baldwin
Dr. Spencer
Thanks for all your great work.
And my best wishes for your daughters hopefully speedy and full recovery.
Speedy recovery for your daughter, Dr. Roy!
Dr. Spencer: Recently Steve Goddard said,”Earth is nearly a steady state system – which means that the energy balance is conserved.” Would you comment on this interpretation of the laws of thermodynamics?
After spending three months helping a friend recover from his auto accident, I understand completely where your priority is. She will need and receive all the help necessary. I pray that your daughter makes a full recovery.
Roy, I am sorry to hear about your daughter and wish her a full recovery.
I note that you have not had time to respond to my post on the thread about atmospheric pressure in which I pointed out that the -18 deg.C figure is meaningless because the Earth’s surface is not insulated and thus does not act like a blackbody. It loses thermal energy (perhaps more than 50%) by diffusion, conduction, convection, evaporation and chemical processes and so there is far less energy left for radiation than was inserted in the S-B equation to obtain that figure.
But secondly, I join with Prof Claes Johnson in saying that backradiation cannot be converted to thermal energy in a warmer surface. Now I know you say you are just considering net radiation, but there is no physical way in which an approaching “ray” of radiation can somehow reduce or cancel out a part of an exiting ray which would usually be at a different angle anyway.
The only way you could get any cancelling effect, thus slowing the rate of cooling for example, would be if the radiated energy is first converted to thermal energy within the surface. Only thermal energy can be added to, or subtracted from, other thermal energy to get a net effect.
Johnson is saying that radiation below the cut-off frequency (ie, basically radiation from a cooler source) will be merely reflected, transmitted or scattered without ever being converted to thermal energy.
Now you would agree that reflection could not cause a greenhouse effect, but he is saying that the end result (energy-wise) is exactly the same. Scattering is the same as reflection except that the angles are different.
Now, over the years, relative humidity has been decreasing while temperatures have been rising. I say that decreasing relative humidity causes the adiabatic lapse rate to increase because it is drier. That in turn means emission is taking place at lower temperatures and is thus reduced in intensity, so there is a net positive radiative balance as a result. The only way the extra thermal energy left in the atmosphere gets back to the surface is due to the precipitation being warmer, or less cold – less snow and warmer rain.
So there you have it. There is no greenhouse effect due to carbon dioxide or any backradiation. Only water vapour affects the radiative balance because of its unique capacity to affect the lapse rate (due to release of latent heat) and to carry the thermal energy to the surface via precipitation.
Responding to the post of Gordon Robertson of February 6, 2012 at 7:56 PM.
He writes: “Christopher…re your comment on a vertical column of air having a uniform temperature throughout. Your point is not clear to me. What do you mean by uniform, are your authors implying a constant temperature throughout?”
Christopher replies: Kondepudi & Prigogine 1998 are explicitly saying that the temperature is constant throughout; I cited them as referring to an isolated column of gas. Your argument about the cold on Mount Everest shows that you do not understand the notion of an isolated column of gas. Mount Everest is not remotely connected with an isolated column of gas.
Let me state my respect for your rightly sceptical viewpoint, which I share with you. But:
You write further comments about thermodynamics and the abstraction of entropy and about Planck. I do not like to say things that you would not like to think, but you seem to be asking for it. Without entropy, thermodynamics does not work. As for your comments on Planck and molecules, I suggest you need to read Planck again much more thoroughly. I am a keen student of Planck.
The other authors to whom I referred include Maxwell, Boltzmann, and Gibbs. If their thermodynamics is not good for you, then I would infer you are not in touch with the subject. Kondepudi & Prigogine 1998 is a good introductory text, with a fairly up-to-date viewpoint, and right in most points.
Responding to the post of Doug Cotton of February 8, 2012 at 7:29 AM.
Dear Doug Cotton, your thinking on this subject is seriously muddled. So muddled that it would not make sense for me to try to criticize it line by line. You are using one-liners that would make a television newsman blush. You need to consult a good textbook on radiative tranfer.
DR Spencer,
I’m late on your bolg this month so I’m sorry to learn about your daughter accident.
My best wishes for her and for your family.
And thanks for this post, here in EUrope it is pretty cold and I heard the Vice President of IECC say on my radio this evening that this is certainly not an effect of global warming, this is a first, usualy all climate phenomena those last yerars where caused by GW, what a change !
I think that the rising co2 in the atmosphere has happened because of some natural warming. That warming was probably because of the abnormal high solar radiance of the past 100 years or so. From now on both the solar radiance and co2 staying in the atmosphere will go down. co2 will stay more in the oceans than it did during the past 100 years…
hv: Then why is the recent change in CO2, per degree of warming, 10 times larger than during the warming after an ice age?
http://en.wikipedia.org/wiki/File:Carbon_Dioxide_400kyr.png
Christopher Game…in Planck’s book of 1914, Page 2, The Theory of Heat Radiation he says:
“We are therefore obliged to introduce right at the start a certain restriction with respect to the size of the parts of space to be considered. Throughout the following discussion it will be assumed that the linear dimensions of all parts of space considered, as well as the radii of curvature of all surfaces under consideration, are large compared with the wave lengths of the rays considered”.
In their paper related to this, Falsification Of The Atmospheric CO2 Greenhouse Eff ects Within The Frame Of Physics ( http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf ), the German physicists Gerlich and Tsceuschner, make a similar claim on page 12:
“For instance in many calculations climatologists perform calculations where idealized black surfaces e.g. representing a CO2 layer and the ground, respectively, radiate against each other. In reality, we must consider a bulk problem, in which at concentrations of 300 ppmv at normal state still N ~ 8.10e6 CO2 molecules are distributed within a cube V with edge length 10 [microns], a typical wavelength of the relevant infrared radiation. In this context an application of the formulas of cavity radiation is sheer nonsense”.
That is obviously based on the restriction imposed by Planck, that radiation calculations do not apply at the dimensions of CO2 molecules. Nor do any blackbody calculations.
If you read G&T, who have expertise in thermodynamics, as well as physicist/meteorologist, Craig Bohren, you begin to realize that the highly simplified notion of greenhouse warming, as well as AGW, is based on some kind of science fiction.
Gordon, why is it obvious that radiation calculations do not apply to atmospheric CO2 molecules?
The C-O bond length of CO2 is 1.16 Angstroms.
The absorption wavelengths of CO2 are 4.26 microns and 15.0 microns, both over 3 million times larger.
The density of dry air at Earth’s surface is 1.2 kg/m3, so the number density is 3e22/m3 so the average distance between particles is about 35,000 pm.
So I don’t see what the problem is.
Dear Gordon Robertson, thank you for your careful reply. I do not wish to antagonize you, but it seems reasonable to say that you illustrate the saying that a little learning is a dangerous thing.
I think that you misunderstand G&T because you lack background knowledge of physics and thermodynamics.
If you read Planck a little deeper than page 2, you will come to the part where he tells about his famous oscillators that emit and absorb radiation. These are not actual physical objects, but are theoretical probes. Nevertheless they are very numerous and Planck considers them in the light of Boltzmann’s 1878 statistical theory for molecules of gas. Over the quarter century after Planck discovered his law it came to be understood that the real physical entities that did the job of Planck’s oscillators were occasional processes of transition of particles such as electrons, from one quantum state of binding to another. The oscillators are not persisting material objects, but are transient excitations of molecules or other more or less atomic objects.
The atmosphere below about 70 km in altitude is mostly in what is known as local thermodynamic equilibrium, a concept you will find explained on pages 333-335 of Kondepudi and Prigogine 1998 that I recommended to you. States of gas in local thermodynamic equilibrium exhibit radiative emission and absorption are that can be described by an emissivity (a relative radiative efficacy for a given temperature for each molecular species) and by a source function, that tells of the nature of heat at that given temperature. The source function for local thermodynamic equilibrium has the Planck distribution.
Occasionally I have reason to look at Bohren and Clothiaux’ 2006 text. If you are interested, Chapter 1, ‘Emission: The Birth of Photons’, of that text will tell you in more detail about what I just mentioned in the foregoing paragraph. You can buy it on the internet for a few dollars. They give due credit to Planck for his pioneering work in that account. I am not saying that I think that text is the best, but it may be one that you will have confidence in.
I suggest you give G&T a rest. They are not a good pedagogical guide.
I am not at all supporting the AGW story in writing this. Rather, I am keen that our attacks on the AGW story be well reasoned. If you really want to make a reasoned attack on the AGW story, I say more strength to your arm. But you need to read some basic physics before you embark on a physical argument.
Spencer, Lindzen and others have yet to come to grips with the fact that the Second Law of Thermodynamics also applies to radiation, meaning there can be no radiative forcing by any GH effect. Hence, at night for example, the cooling of the surface cannot be slowed by any radiation from the cooler atmosphere. (In fact Prof Nahle’s experiment in Sept 11 proved the lower atmosphere cools faster than the surface at night, as I also found in my backyard.)
In order to slow the rate of cooling of the surface the radiation would have to add thermal energy, just as it would if it were to increase the rate of warming in the morning.
It cannot do this without heat transfer from cold to hot, which is against the Second Law. Johnson merely showed how and why the Second Law applies to radiation. I don’t ask you to accept any more than that simple statement which is also made by these German physicists in a peer-reviewed published paper over 100 pages in length which knocks the AGW conjecture for six.
http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf
“Unfortunately, there is no source in the literature, where the greenhouse effect is introduced in harmony with the scientific standards of theoretical physics.”
Sunspots influence low-level clouds which then influence climate. A wider lower solar cycle can have the same influence on climate as a narrow high one. The sunspot time-integral (properly reduced by the energy radiated from the planet) exploits this. Google ‘sunspot “time integral”‘ and follow the links to find an analysis that resulted in a simple equation that calculates average global temperatures since 1895 with 88% accuracy and accurately (std dev less than 0.1C) predicts temperatures since 1990.
Dan Pangburn: Since you’re trying to sell your equation everywhere, it seems… can you please explain to us why sea-surface temperatures can be modeled as a sawtooth function with a set-period?
And why you assume that the amplitude of this function is constant in time?
Response to the post of Doug Cotton of February 11, 2012 at 2:55 AM.
Doug Cotton’s post is hard to respond to because it is vague and merely allusive, and this makes it hard to know exactly what he means.
But it seems that he is ignoring the well-known and regularly occurring phenomenon of polar inversion events, in which the lowest kilometer or so of the atmosphere near the ice surface are at higher temperatures than the very lowest that is practically touching the ice. In those events, the atmosphere is indeed radiatively exchanging energy with the ice, with net effect of transfer of heat from atmosphere to ice.
Besides being vague and merely allusive, Doug Cotton’s post is also careless. The second law of thermodynamics allows transfer from cold to hot; it just requires that when that happens there must be some other transfer so that the net effect is of global increase in entropy. I suppose Doug Cotton has a refrigerator in his home that works like that.
If his aim is to attack the AGW story, Doug Cotton would do better to stick with Drs Spencer and Lindzen rather than the rather muddled and inconclusive chatter of the G&T unrefereed paper that he links to. And take more care with his attempts to present physical arguments.
Christopher Game says:
February 11, 2012 at 12:14 PM
“Doug Cotton’s post is hard to respond to because it is vague and merely allusive, and this makes it hard to know exactly what he means.”
Here is my understanding of what he means. (Doug can of course correct me if I am wrong.) Suppose the air temperature is 20 C and the ground is 10 C. In that case, a photon from an excited CO2 molecule that hits the earth will cause the earth to warm up. However if the air temperature is 20 C but the ground is 30 C, a photon from an excited CO2 molecule that hits the earth will more or less get reflected away without causing any warming at all. True or false?
Werner Brozek says:
>>Suppose the air temperature is 20 C and the ground is 10 C. In that case, a photon from an excited CO2 molecule that hits the earth will cause the earth to warm up. However if the air temperature is 20 C but the ground is 30 C, a photon from an excited CO2 molecule that hits the earth will more or less get reflected away without causing any warming at all. True or false?<<
Werner: particle interactions happen in a very small, local space. Particles do not somehow sense what the temperature is around them before deciding to interact or not.
Responding to the post of Werner Brozek of February 11, 2012 at 10:17 PM.
Doug Cotton’s post might intend to mean that, but it doesn’t say so. The nearest is comes it seems is: “there can be no radiative forcing by any GH effect. Hence, at night for example, the cooling of the surface cannot be slowed by any radiation from the cooler atmosphere.” Nocturnal inversions are not as marked as polar inversions, but they occur commonly. Doug’s comment seems to deny that.
Werner Brozek writes: “However if the air temperature is 20 C but the ground is 30 C, a photon from an excited CO2 molecule that hits the earth will more or less get reflected away without causing any warming at all. True or false?”
Christopher answers: A photon from an excited CO2 molecule that hits the earth will most likely (about 97% probably) be absorbed by the earth. For example, the probability over snow that it will be absorbed is usually more than 99%. The phrase “more or less reflected” is vague. True, when the ground is at 30 °C and the air at 20 °C, the radiation exchange will have the effect that radiatively, the ground heats the air. That follows from what some would call the zeroth law of thermodynamics. For radiation this idea was pioneered by Prevost in 1791, with some later help thrown in.
I am trying to make the point that if we are to out-argue the AGW people, we need to present our arguments properly stated, not throw around vague and merely allusive half-truths that have no definite physical meaning. It doesn’t help our case to make slip-shod statements.
Christopher, you wrote, “A photon from an excited CO2 molecule that hits the earth will most likely (about 97% probably) be absorbed by the earth.”
Why?
What I’ve seen is that, of the 198 W/m2 of solar radiation that makes it through the atmosphere, an average of 30 W/m2 are reflected away, or about 15%:
http://home.iprimus.com.au/nielsens/solrad.html
So where do you get your number of 3%?
Responding to the post of David Appell of February 11, 2012 at 11:58 PM.
The sunlight has wavelength different from that of atmospheric thermal radiation from CO2 molecules.
As a rough global average for the absorption of such CO2 radiation by the land-sea surface, textbooks such as Paltridge and Platt 1976 observe that the fraction varies widely depending on the diversity of character of the surface, citing papers such as Beuttner, Kern (1965). My estimate of the average from there was roughly 97%. That figure is quite different from that for sunlight, which is reflected significantly more, as you say. Kiehl & Trenberth 1997 citing Briegleb 1992 do not bother with the difference from 100% considering the general level of accuracy in the estimates and the nearness of the amounts of emitted and absorbed thermal radiation between atmosphere and land-sea body for non-window wavelengths. The textbook of Wallace & Hobbs 2006 on page 420 put the long-wavelength number between 92% and 97%. Perhaps 95% might be a better estimate of the average than my 97%.
Dr. Spencer,
I was wondering if you think this has any merit. Nine year lag? Looks interesting.
http://wattsupwiththat.com/2012/02/13/do-latest-solar-studies-confirm-upcoming-global-cooling/#more-56469
David Appell,
For the same reason that the PDO can be.
I should add that I took a quick look at the solar a index and compared it to La nino/nina trends.
As the sun starts to quiet down again (solar flux nearing 100)my confidence is going up, that indeed the prolong solar minimum is intact,and this decade will be one of global cooling,more climatic extremes, and increased geological activity.
At this very moment in time, solar cycle 24 is now showing less activity ,then very weak sunspot solar cycle 5, way back in year 1798.
As Joe Bastardi ,has said and I agree, we have the triple crown for global cooling in place. That being weak solar activity, PDO now in it’s cold phase, and a very likely overall increase in volcanic activity, which along with low solar activity, will serve to keep the AO more negative then it would be otherwise.
La Nina, will be more common, and that does tend to offset a more -AO , but that will be couteracted by the prolong solar minimum and an increase in volcanic activity in my opinion.
Just look at what has taken place in climatic extrems so far this decade compared to the previous 3 or 4 decades, I say there is no comparisome, and the WORST, is yet to come.
Just look at Eastern Europe , as an example for the winter of 2011-2012.
Global warming,due to CO2 increase will be proven wrong, well before this decade ends.
THE LAYMAN SUNSPOT SITE HAS GREAT ARTICLE AS TO WHY THE CLIMATE REALLY CHANGES,AND THEY ARE 100% CORRECT.
CO2 equals a joke, when it comes to climate change. Ridiculous!!!
Does anyone ever bother to check how Joe Bastardi’s predictions turn out? Let’s look at his post here last April 5. The March temperature was just posted with a large drop and Joe said.
“That drop in the tropics is astounding since last year (1C). The implications as to the ENERGY budget of the ocean-atmosphere system, which I feel is the real measuring stick here, not global temps ( warm moist air has much more energy than cold dry air, and a reduction of a smaller amount where air is warm and moist more than offsets a large rise in temp in cold dry air, if we are talking energy considerations which is what has to be quantified to solve this problem). This is like turning down the thermostat, and borders on alarming to me in that this could be even more of a “crash” than even I previously thought ( 2011 returns to near normal in the 30 year running mean)”
Global temperatures turned back steeply upward right after this “prediction” and 2011 was not below normal or even close. So much for his “crash”.
YR MON GLOBAL NH SH TROPICS
2011 1 -0.010 -0.055 +0.036 -0.372
2011 2 -0.020 -0.042 +0.002 -0.348
2011 3 -0.101 -0.073 -0.128 -0.342
2011 4 +0.117 +0.195 +0.039 -0.229
2011 5 +0.133 +0.145 +0.121 -0.043
2011 6 +0.315 +0.379 +0.250 +0.233
2011 7 +0.374 +0.344 +0.404 +0.204
2011 8 +0.327 +0.321 +0.332 +0.155
2011 9 +0.289 +0.304 +0.274 +0.178
David Appell says:
hv: Then why is the recent change in CO2, per degree of warming, 10 times larger than during the warming after an ice age?
—
I think that the big problem is that we don’t have temperature measurements, which would be accurate enough to say anything about the change rate of co2 per degree of warming… We don’t know what the global temperature was in year 1900 for example. I mean, if it was 14,5 C or 14,7 C for example. I think that satellite measurements are accurate, but we have got them only from 1970’ies.
Hindcast,
After 30 years of warming, the global average temperature is now negative. That’s sort of the definition of a “crash” isn’t it?
He also wrote:
“In May, I forecasted the global temperatures to fall to -0.15C in one of the months – Jan, Feb or Mar this year, and perhaps as low as levels we saw in the 2008 La Nina. A rapid free fall has begun. Dr. Ryan Maue at his site (http://policlimate.com/weather/) maintains a plethora of useful forecast information including GFS global temp projections over the next 16 days.”
http://wattsupwiththat.com/2012/01/19/global-temps-in-a-crash-as-agw-proponents-crash-the-economy/
Although you should keep in mind that the only group Bastardi represents is himself. This in the same sense that every time James Hansen makes yet another failed short term climate prediction, this doesn’t “disprove” AGW either.
David Appell:
My main idea was to point out that we don’t know why there is more co2 in the atmosphere now than some time ago. It might be because humans make it more. It might be because for some reason it doesn’t stay in the oceans as much as before, for example because of ‘global’ temperatures have gone a bit up, or maybe because of changed water circulations of oceans, changed wind patterns, cutting of forests, or…
The second thing is that we don’t know if ‘global’ temperatures have gone up 0,6 Celsius degrees during the last 100 years or so. It might have gone up even 1,0 Celsius degrees or only 0,2 degrees. Or even not at all. Our knowledge about the past temperatures is not accurate enough.
The third thing is that we don’t know if the the amount of co2 in the atmosphere has any measurable effect on ‘global’ temperatures.
If one reviews what has happened to the earth’s climate in the past during prolong solar minimum events, one will see each and everytime, the temperatures have declined, geological activity has increased, and climatic extreme events, have become more common.
There is a lag time for the temp. decreases, due to prolong solar minimum conditions, of from 4 to 8 years. This current prolong solar minimum started Oct.2005, so we are now in that zone. In contrast to atmospheric circulation responses, and geological activity responses, being much quicker, to respond to changes in solar activity.
As was demonstrated during the last half of 2010,and first half of year 2011, when solar activity was very low and had been for quite sometime, with only occasional spurts of activity ,which is however, needed within the prolong solar minimum, to achieve the increase in geological activity,in my opinion, and thus have a maximum impact on the climate.
This time should be no different. In the past when ever the angular momentum exerted by the planets on the sun ,has been like it is now, the sun has always had a prolong solar minimum event. Each time that has happened, the global temperatures ,as I said above have declined.
Just reivew what transpired during th Maunder Minimum, and Dalton Minimum ,the two most recent solar minimum events.
If it turns out this small increase in solar activity which took place from Aug. 2011 to early Jan. 2012 ,is the maximum for sunspot cycle 24, which is lookng more likely ,we are going to be in for quite a decade of wild climate, in my opinion.
ONE RULE OF THUMB, IS QUITE SUN = ACTIVE EARTH.
ACTIVE SUN= QUIET EARTH.
salvatore del prete says:
“In the past when ever the angular momentum exerted by the planets on the sun, has been like it is now, the sun has always had a prolong solar minimum event. Each time that has happened, the global temperatures, as I said above have declined.”
I agree with you. Let’s see what will happen now.
salvatore del prete:
“This time should be no different. In the past when ever the angular momentum exerted by the planets on the sun ,has been like it is now, the sun has always had a prolong solar minimum event. Each time that has happened, the global temperatures ,as I said above have declined.”
I’ll probably regret asking this, but what do you mean by “angular momentum exerted by the planets on the sun”?
It is the gravitational force the planets exert on the sun, due to their relative postions to the sun, as they orbit about the sun.
If you go to the LAYMAN SUNSPOT SITE, and look and scroll under the summaries given for solar activity each day, the site has a comprehensive article about climate/solar interactions, and explains angular momentum and how that relates to prolong solar minimum conditions.
Ray:
Please read the original article:
New Little Ice Age
Instead of Global Warming?
by Dr. Theodor Landscheidt
To understand what salvatore del prete says.
Model comparisons are irrelevant, because physics proves the conjectures underlying the models are wrong.
When solar radiation (UV, visible and IR etc) travels through space we do not know what its end effect will be until it strikes something. We will observe its effect and say – there’s some light from the Sun – but it may be more light if it hits a white surface than a dark surface, as a camera exposure meter will confirm. It may generate thermal energy (more or less depending on what it strikes) or it may appear as light as it starts to penetrate the oceans, but end up as thermal energy in the deeper depths. Of course some will be reflected or scattered and strike another target sooner or later, and another etc.
My point is, “heat” is the transfer of thermal energy, but thermal energy is not a fixed amount of energy travelling along with radiation. The energy in the radiation has to go through a physical process of being converted to thermal energy. This happens only for those frequencies in the radiation which are above the natural frequencies that can be emitted by the target, because the target cannot re-emit those frequencies. (The hotter the source of spontaneous radiation, the higher will be the peak frequency.) So solar radiation can be converted to thermal energy in the Earth’s surface, but radiation emitted from a cooler atmosphere cannot be converted to thermal energy in a warmer surface. “Heat” only appears to be transferred (and only from hot to cold) because only radiation from hot to cold will be converted to extra thermal energy in the target.
It does not matter whether you are increasing the rate of warming in the morning or decreasing the rate of cooling later in the day, you still need extra thermal energy to do this. You cannot get this extra thermal energy from a cooler atmosphere, morning or evening. You cannot say the Second Law is not broken because of the direction of net radiation or net heat flow. All that matters is, what actually happens between any two points – one point on the surface and one point in a cooler atmosphere. What goes on between other “points” – a point on the Sun and another point on the surface is irrelevant. The Second Law must apply between any two points.
So the whole conjecture about backradiation slowing the rate of cooling, and about the greenhouse effect, is all based on incorrect assumptions which involve a violation of the Second Law of Thermodynamics. That law could not function anywhere and everywhere if radiation from cold to hot could transfer thermal energy.
Responding to the post of Doug Cotton of February 15, 2012 at 8:15 PM.
Doug Cotton is writing loosely, for example of “extra thermal energy”, and writes ambiguous half-truths, but does not look closely at the detailed physics, apparently because he has not studied it closely. So his reasoning is unreliable. In making the kind of dogmatic pronunciamento that he does in that post just above, instead of helping us fight the AGW monster, Doug Cotton plays into the hands of the AGW people and helps them by letting them say, with some justification, “Oh, look at the nonsense one reads from sceptics and deniers.” Careful study of some textbooks would probably help Doug Cotton mend his ways. Paltridge & Platt 1976 would be a good start.
I completely agree with Doug Cottons point on the 2nd law.
Here another Issue: The whole basis of AGW is the greenhouse effect as we would probably all agree. Now if one closely examines the physical assumptions this effect is based on (as has be done very well by Postma http://www.tech-know.eu/uploads/The_Model_Atmosphere.pdf), it is very easy to realize that it can’t model actual physics in its current form.
I urge anyone interested in this subject to read about this effect and form their own opinion. This is the CORE issue of the whole AGW debate, which should be clearly examined.
Additionally I find it very questionable why personal attacks are justified to discredit scientific work. If correct calculations and mathematical proof is provided by an author why should anyone care if he is established in climate science or an unrelated field.
Finally I put forward to you one simple question which challenges the current model. If a radiation balance is assumed for the earth/sun system, the model shows a black body radiation temperature of -18C without the GHE. Why would you assume this to be a earth SURFACE temperature if your system is both the earths surface and the atmosphere?
Those who think I am “writing loosely” or perhaps haven’t learnt any physics in my 50 years studying and teaching such might like to give their own explanation …
(1) Of the point I often make (and which Dave explains above) about why the -18 deg.C is assumed to apply to the surface – which radiates nothing at all like a blackbody.
(2) Let me hear your thinking on this. Remember the Second Law must apply from any point to any other point. It is not “averaged” over the whole Earth over 24 hours for example.
If your bath tub is filling as fast as it can with the hot tap turned on fully it will indeed fill faster if you also turn the cold tap on.
If the Earth’s surface is filling with thermal energy (ie it is warming) as fast as it can on a sunny morning with the Sun shining fully it will indeed fill (warm) faster if you also radiate extra thermal energy from a colder atmosphere if and only if you violate the Second Law of Thermodynamics.
One more question for Chtristopher Game et al …
Suppose you pass radiation from a slightly cooler object (surface area 5 sq.m, 300 K) through a reflective funnel which concentrates the radiation onto a slightly warmer object (310 K) with the same emissivity of, say, 0.9 but surface area only 0.5 sq.m.
Please explain with suitable calculations how the Second Law of Thermodynamics would actually apply to ensure thermal energy only transferred from the warmer to the cooler object.
I will also post this on several other forums to see if anyone has a correct solution other than mine, which you should know by now if you’ve read my posts.
Maybe it all needs more explanation for some of you.
Only radiation from hot to cold has any effect because it contains frequencies (in the upper extremes of its spectrum) which are above those that can resonate with the target when the target is cooler. The energy in radiation with these frequencies is thus retained and must be converted to thermal energy.
In contrast, radiation from a cooler source always contains frequencies which can resonate with a warmer target and thus be scattered without any energy left behind to be converted to thermal energy. So it does not warm anything which is warmer than its source.
The above is easily seen from the first plot here http://scienceworld.wolfram.com/physics/WiensDisplacementLaw.html
As you can envisage from this plot, as the temperatures approach each other the amount of overlap increases and so the rate of heat transfer decreases until it ceases when the temperatures match.
I know that you may get similar results making calculations with two-way radiation, but situations can be hypothesised which would lead to invalid results.
Consider my funnel experiment concentrating radiation from, say, a large but cooler surface of 5 sq.m onto a smaller but slightly warmer surface of 0.5 sq.m. Even when temperatures become equal you would then have 10 times as much radiation in one direction, or a net of 9 times – all without warming because, if it did warm, the Second Law would be broken..
Thus only the passage of radiation from hot to cold is relevant and it fully explains all that happens in regard to heat flow and temperature changes. More importantly, it explains how and why the Second Law is valid for radiation.
You simply cannot refute this example – equal temperatures and yet net radiation in one direction. Why no further warming?
It is little wonder that Claes Johnson was able to prove this computationally
Response to the posts of Dave of February 16, 2012 at 3:35 AM.
It is good to see that you are on the right side of the argument. But not good to see that you are supporting Doug Cotton’s poor quality muddle-headed posting, which is more likely to weaken our cause than help it.
Response to the posts of Doug Cotton of February 16, 2012 at 9:40 PM, of February 17, 2012 at 12:09 AM, and at 4:05 AM.
Dear Doug Cotton, you would do better to try to compose one well constructed and physically valid post than to post three shouting and hand-waving muddle-headed ones as you have done above. Such posts are well intentioned but will not actually help our cause. When it is pointed out that his argumentation is of poor quality, a teacher should do better than merely raise his voice and wave his hands.
You say that the land and sea surface of the earth “radiates nothing at all like a black body”. That is an inaccurate statement and tells a lot about the accuracy of your views on the relevant physics. I suggest, as I did above, that you try reading a relevant textbook if you really want to help our cause.
Solar Flux 103 getting lower!!!
I say if solar flux levels go to 90 or lower and stay that way for the balance of the decade (as they have been thus far),that the temperature trend will be down. If temp. trend were to remian neutral or worse rise, with that solar condition, I would admit to being wrong.
It will be a test of time to see who is right ,who is wrong, if the sun cooperates. Past history suggest it will.
Dr. Spencer,
This is kind of a stupid question, but why do you use a 13-month moving average? I do my own graphs on temperature and I use a 12-month average and I wonder if that is important? Here is a link to my graph.
http://www.anupchurchchrestomathy.com/2012/02/comparing-giss-hadcru-rss-and-uah.html
It would be informative, would it not, if the statistical and systematic errors associated with each data point in the time series were shown on the plot and listed in the table.
Joel Upchurch says:
“This is kind of a stupid question, but why do you use a 13-month moving average? I do my own graphs on temperature and I use a 12-month average and I wonder if that is important? Here is a link to my graph.”
Joel, my apologies for not using the reply option but it doesnt’ work for me for some reason. This question crops up every now and again and since nobody has answered you, I will have a go. I hope that you will see my reply.
I think it is because it is traditional to centre a moving average on a mid-point, especially if the average is “filtered”, i.e. given different weightings depending on the distance from the mid-point.
Since a 12 month average doesn’t have a defined mid month, i.e. do you use the 6th or 7th month, so a 13 month average is used instead, with the 7th month is used instead.
There is also a convention that the average is plotted at the mid-point of the data used, not the end point, as I think you have done in your graph.
Personally I prefer to use a 12 month average, since there are no seasonal implications. Otherwise, the average never coincides with a calendar year. I only think a 13 month average (or any odd no.) is justified if there is a weighted filter involved. I also prefer to plot the average at the end of the period, since I feel that plotting in the centre causes more confusion than it prevents and makes the average look out of date. The question of the “out of date” average also sometimes arises in the case of the UAH graph. This is recognised by bodies such as the U.K.M.O., to the extent that in order to avoid the filtered average looking out of date, they assume that the data after the last known point are the same as the last know point, which inevitably loads the average in favour of the last data point.
I think that the convention of plotting the average at the centre point originated in pre-computer days, when it may have made some sense. However, try to get Excel to plot a moving average at the mid-point. I haven’t found a way to do that yet.
The above is mostly my own personal opinion, and I have no doubt that there will be some who strongly disagree.
Ray, Thank you very much for your response. I agree that getting Excel to compute a moving average of a mid-point. My personal problem with Excel is that there is no easy way to display two different y access on the same graph.
Joel,
Just to clarify about Excel and the mid-point.
I was referring to the automatic calculation of the moving average, using the “add trendlines” option.
Regarding the addition of a second y axis, I think you can do this by right clicking on a data series and selecting “format data series” and the “plot series on secondary axis” button. You can then adjust the axis range as required. Otherwise, you have to add the data to the chart first, then change the axis. I hope that is what you were referring to.
Joel,
Sorry, I meant to say after the second sentence that if you calculate the moving average in the actual spreadsheet, you can, of course, put the mid point where you like.
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