| Previous :: Next Topic |
| Author |
Message |
RodF
Member
Joined: 01 Sep 2007
Posts: 2593 | TRs | Pics
Location: Sequim WA |
|
RodF
Member
|
 Mon Apr 07, 2008 4:26 pm |
|
|
I have no argument with the contents of your last posting (except your claim "it was never my intent to goad anyone" is simply laughable). And this continues to obscure your fundamental confusion over this simple equation, and over what emissivity is. I'll address these in separate postings.
In the last several pages of postings, you made a series of extravagant claims for this equation; claims which you still have neither justified nor retracted.
| Mtn Dog wrote: | | You've made a correlation between rising CO2 and rising temperature as if one is automatically causing the other. All I'm asking is for you to tell this story with numbers. How does CO2 cause a rise in temperature and by what amount for a given change in concentration? I've already done most of the homework for you. |
| Mtn Dog wrote: | | This equation suggests that earth's temperature is highly volatile... |
| Mtn Dog wrote: | | The 4 W/m2 stems from calculating the heating that would result from doubling CO2 and is reflected in ε. |
Apply your claimed standard to your own claims:
| Mtn Dog wrote: | | In the future please recognize that specific claims must be refuted with specific details |
"of all the paths you take in life, make sure a few of them are dirt" - John Muir
"the wild is not the opposite of cultivated. It is the opposite of the captivated” - Vandana Shiva
"of all the paths you take in life, make sure a few of them are dirt" - John Muir
"the wild is not the opposite of cultivated. It is the opposite of the captivated” - Vandana Shiva
|
| Back to top |
  
|
|
Mtn Dog
Technohiker
Joined: 01 Aug 2004
Posts: 3336 | TRs | Pics
Location: Bellevue, WA |
|
Mtn Dog
Technohiker
|
Mon Apr 07, 2008 5:35 pm |
|
|
RodF:
OK, I confess to being at least a little "tongue in cheek" about the equation for earth's energy equilibrium in response to Joker claiming it was too complicated for him to understand so he's only going to rely on secondhand "experts" instead.
You are mixing two completely different things together, however. I never intended for the Energy Balance Equation to be used to determine the increase in radiative heating resulting from the rise in atmospheric CO2 concentration. I provided that separately on page 63 of this thread.
| Mtn Dog wrote: | | Also, the change in radiative forcing as a result of changes in CO2 concentration is provided by the IPCC in this formula: ΔF = αln(C / Co). This is where the 4 W/m2 comes from for a doubling of CO2 in the atmosphere. |
This assumes that CO2 will double to 600 ppm. It's 3.7 W/m2 if you use 560 ppm instead. I also pointed out that any real dispute in regard to Global Warming at this point boils down to the temperature change that would result from this ~4 W/m2 increase in radiative heating should the day eventually come that CO2 concentrations double from pre-industrial levels. The AGW side is using computer modeling to extrapolate their results while other climatologists are trying to point out where the models fall short and are also trying to gain a better understanding of the ways in which Earth's primary Greenhouse Gas, Water Vapor, regulates the planet's temperature. Your link to James Hansen's work figures it will be 2.8°C but that's based on modeling that is still being tweaked. I've heard the number is much closer to 1.0°C once you properly account for negative feedbacks (and with a 100 ppm rise in CO2 so far the earth's temp is nearly .6°C higher at this point). The earth has kept its temperature relatively steady over hundreds of thousands of years. This includes previous ice ages, interglacials, and CO2 concentrations that were 15 times higher than the projected level may rise to in 2100. It's also difficult to attribute ALL of this century's warming to human causes. Your link to Hansen shows they are also including changes in solar radiance and the effects of CFC's to help calibrate the model of the recent historical record. Great work! But I'm sure there's still a lot more involved before climatologists come to terms with a definitive number.
Footprints on the sands of time will never be made sitting down.
Footprints on the sands of time will never be made sitting down.
|
| Back to top |
|
|
RodF
Member
Joined: 01 Sep 2007
Posts: 2593 | TRs | Pics
Location: Sequim WA |
|
RodF
Member
|
Mon Apr 07, 2008 6:11 pm Emissivity
|
|
|
| Mtn Dog wrote: | | No, RodF, the Greenhouse Effect is reflected in ε. If ε were'nt included in the equation then the right side would reflect earth's energy output without an atmosphere (the left side is of course earth's energy input). |
This appears to reflect a fundamental misunderstanding of what emissivity is. The emissivity ε of a material is the ratio of energy radiated by the material to energy radiated by a black body at the same temperature. A black body is a perfectly opaque object; it does not have an atmosphere; it does not have a greenhouse effect.
Emissivity is a measureable physical property (not a mere fudge factor that can be fit at will!). Here are infrared emissivities measured in the laboratory, in the field, and by satellite [1] [2]
fresh water 0.985 - 0.99
seawater 0.98-0.99
ice 0.97 - 0.99
snow 0.99
leaves 0.95 - 0.99
mixed forest 0.95 - 0.96
boreal forest 0.92 - 0.97
grass 0.96
grasslands 0.93 - 0.97
soil 0.93 - 0.97
barren land 0.93 - 0.96
United States 0.96
sand 0.9 - 0.99
Sahara 0.90 - 0.93
Australia 0.90 - 0.96
fresh basalt 0.9
Venus 0.9 +-10%
Summary: (1) Emissivity is a measured physical property, not an adjustable parameter. (2) The infrared emissivity averaged over Earth's surface is ~0.98, approximately 1.
"Effective emissivity" is a distinct concept, and must not be confused with actual emissivity. The term arises in two ways:
(1) optically thin layer: Water has a true emissivity of essentially 1, whether it is in the ocean or in cloud droplets. Fog may be 90% transparent to infrared, and only 10% absorbing and emitting in the infrared. It then has an "effective emissivity" of 10%, even though we know the true emissivity of the droplets is 1.
(2) cold objects: Cold objects emit much less radiated energy than warm ones (varies with T^4) and they emit it on average at longer wavelengths (varies linearly in T). To a crude first approximation, the first effect dominates: a cool object with true emissivity of 1 looks like a warm object with low "effective" emissivity. For example, if we view a cold object (high cloud) against a warm background (Earth's surface), it appears dark in the infrared. Its apparent or "effectivity" emissivity is low, even though we know the true emissivity of the droplets is 1.
The distinction between true and "effective" emissivity is often not made explicit, because it is assumed to be obvious to readers. But this assumption has not held true in this thread.
"of all the paths you take in life, make sure a few of them are dirt" - John Muir
"the wild is not the opposite of cultivated. It is the opposite of the captivated” - Vandana Shiva
"of all the paths you take in life, make sure a few of them are dirt" - John Muir
"the wild is not the opposite of cultivated. It is the opposite of the captivated” - Vandana Shiva
|
| Back to top |
|
|
RodF
Member
Joined: 01 Sep 2007
Posts: 2593 | TRs | Pics
Location: Sequim WA |
|
RodF
Member
|
Mon Apr 07, 2008 6:14 pm |
|
|
| Mtn Dog wrote: | | Here's all you need:
S/4 (1 - A) = ε σ Te^4
If you learned how to multiply and divide you can figure out how much energy affects the earth via the sun and the greenhouse effect. |
It is important to realize that this equation represents only three objects: the Sun, the surface of the Earth, and cold space. The Earth represented in this equation is assumed to be a blackbody with no internal structure (oceans, continents, atmosphere, etc). So this equation obviously CAN NOT tell us anything about the internal structure of this blackbody, e.g. the properties of the greenhouse effect.
Confusion has arisen about how to apply this equation, and between effective and true temperature and emissivity. To clarify this, let's rearrange it into two separate equations:
Equation 1: given true emissivity, solve for effective temperature.
Te = (S/ (4 ε σ (1 - A)))^1/4
Equation 2: given true temperature, solve for effective emissivity.
εe = S / (4 σ (1 - A) T^4)
Equation 1 gives:
Venus: ε = 0.9 gives Te = 236 K = -37 C
Earth: ε = 1 gives Te = 256 K = -17 C = 1 F
Equation 2 gives:
Venus: T = 743 K gives εe = 0.0091
Earth: T = 288 K gives εe = 0.61
Summary:
Given the true emissivity, this equation gives the incorrect temperature.
Given the true temperature, this equation gives the incorrect emissivity.
This is especially apparent for Venus; it is NOT colder than Earth, and no known material object has an actual emissivity as low as 0.0091.
Restated:
The "effective" temperature calculated from this equation differs significantly from the true temperature, or the "effective" emissivity differs significantly from the true emissivity.
The difference is the greenhouse effect. The only purpose this simple equation serves is to show that Earth, and even more so Venus, are not naked blackbodies: they do have a significant greenhouse effect. However, this equation cannot tell us anything about the internal properties of this greenhouse effect, which this equation assumes doesn't exist!
"of all the paths you take in life, make sure a few of them are dirt" - John Muir
"the wild is not the opposite of cultivated. It is the opposite of the captivated” - Vandana Shiva
"of all the paths you take in life, make sure a few of them are dirt" - John Muir
"the wild is not the opposite of cultivated. It is the opposite of the captivated” - Vandana Shiva
|
| Back to top |
|
|
RodF
Member
Joined: 01 Sep 2007
Posts: 2593 | TRs | Pics
Location: Sequim WA |
|
RodF
Member
|
Mon Apr 07, 2008 7:22 pm |
|
|
| Mtn Dog wrote: | | The earth has kept its temperature relatively steady over hundreds of thousands of years. This includes previous ice ages, interglacials, and CO2 concentrations that were 15 times higher than the projected level may rise to in 2100. |
Of all the absurd obfuscations in your posting, that takes the cake. Our local climate here has been relatively stable, in that you'd recognize the place if you set foot in it, for only the last ~4000 years. In the early Holocene, it was much warmer and drier: where we have Doug fir around the Puget lowland now, we had Gerry oak; where we now have coastal Sitka spruce, we had Doug fir. And only ~12,000 years ago, the site where your house now stands was buried beneath 3000 feet of solid ice!
Are the Ice Ages "relatively steady"? You missed Hansen's Figure 3 and 4, in which measured CO2 levels are plotted against measured temperatures (from O-18 isotope record in the Vostok Antarctic ice core) for the last 425,000 years. This is experimental verification (completely independent of global climate modelling that you so distrust) that CO2 climate sensitivity is ~3.2C for a doubling of CO2, a solidly established value which has stood for 30 years now! And that today's CO2 level is higher than anything during the last 425,000 years and rising: we are now venturing into uncharted territory.
The rate at which we are increasing CO2 is ~>10,000 times faster than Mother Nature has ever done it. At the current rate of +2 ppm/yr, we will more than double the pre-industrial level of CO2 by the end of this century. The last time the Earth saw that level of CO2, 35 MY ago, the entire Antarctic ice sheet almost disappeared, and sea level rose almost 300 feet.
Is all this what you mean by "relatively steady"? I say again: of all the absurd obfuscations in your posting, that takes the cake.
| Mtn Dog wrote: | | OK, I confess to being at least a little "tongue in cheek" about the equation for earth's energy equilibrium in response to Joker claiming it was too complicated for him to understand so he's only going to rely on secondhand "experts" instead. |
Readers may compare for themselves this obtuse retraction with your prior disclamations of "subterfuge and end-arounds".
| Mtn Dog wrote: | | I also pointed out that any real dispute in regard to Global Warming at this point boils down to the temperature change that would result from this ~4 W/m2 increase in radiative heating should the day eventually come that CO2 concentrations double from pre-industrial levels. |
In that case, your 3-page harangue with the "here's all you need to know" radiative balance equation was irrelevant game intended only to puff yourself up. Frankly, you've been acting like a real jerk: grow up.
| Mtn Dog wrote: | | The AGW side is using computer modeling to extrapolate their results while other climatologists are trying to point out where the models fall short and are also trying to gain a better understanding of the ways in which Earth's primary Greenhouse Gas, Water Vapor, regulates the planet's temperature. Your link to James Hansen's work figures it will be 2.8°C but that's based on modeling that is still being tweaked. I've heard the number is much closer to 1.0°C once you properly account for negative feedbacks (and with a 100 ppm rise in CO2 so far the earth's temp is nearly .6°C higher at this point). |
Alright, buddy: if it's such an active "scientific debate", give us a link to just one published scientific paper that you're willing to stand behind which reaches that conclusion, out of the thousands which are published in climate science each year.
For that matter, show us just one climate textbook out of the dozens published each year which is actually used in public school or university courses (not just some "Of Pandas and People" scribe, but is actually used) that reaches that conclusion.
"of all the paths you take in life, make sure a few of them are dirt" - John Muir
"the wild is not the opposite of cultivated. It is the opposite of the captivated” - Vandana Shiva
"of all the paths you take in life, make sure a few of them are dirt" - John Muir
"the wild is not the opposite of cultivated. It is the opposite of the captivated” - Vandana Shiva
|
| Back to top |
|
|
Mtn Dog
Technohiker
Joined: 01 Aug 2004
Posts: 3336 | TRs | Pics
Location: Bellevue, WA |
|
Mtn Dog
Technohiker
|
Mon Apr 07, 2008 10:00 pm |
|
|
RodF: First, thank you for providing a better explanation of emissivity. When Stephan sought to determine the actual temperature of the sun and the earth he treated them both as theoretical black-bodies. I shared the equation for several reasons, not the least of which was to show the relationship between incoming and outgoing radiation on earth as well as the effect of reflectivity and effective emissivity through the "blanketing" greenhouse gases absorbing and reemitting infrared heat. Earth's energy balance, or budget is interesting in that the earth receives 342 W/m2 from the sun and the current change in CO2 amounts to maybe 1.6 W/m2.
I'm being a jerk? You are the one that took my post completely out of context and then went on for three pages about how wrong I was for what you mistakenly thought you heard me say. The equilibrium equation and associated energy budget chart are important for people to realize the parameters by which this discussion is framed. But the 4 W/m2 is really at the heart of the issue so I thank you for conceding that at least this part of the discussion is finally settled. What I meant by earth's temperature remaining relatively constant is that in the last 8,500 years global temperature hasn't varied by more than 2.5°C and the trend hasn't varied by even 1°C.
As for the temperature change that will result from doubling CO2 concentration, a great resource is the natural experiments conducted by Sherwood Idso. He derived surface air temperature sensitivity factors over land and water based on empirical measurements. He was published in Climate Research in 1998. His results show a global average λ=.1°C/W/m2 which would result in a change of .4°C. CO2 induced global warming
You can also work it out from Kiehl and Trenberth's Global Mean Energy Budget. They show the downward heating from the greenhouse effect as being 324 W/m2 and I believe that the greenhouse effect has a net warming of 32 or 33 °C above the otherwise cool earth with no atmosphere. If you divide the temperature by the heating you get 32.5/324 or .1°C/W/m2. For 4 W/m2 that results in .4°C. Earth's Annual Mean Energy Budget
Footprints on the sands of time will never be made sitting down.
Footprints on the sands of time will never be made sitting down.
|
| Back to top |
|
|
joker
seeker
Joined: 12 Aug 2006
Posts: 7953 | TRs | Pics
Location: state of confusion |
|
joker
seeker
|
Fri Apr 25, 2008 10:05 am |
|
|
Geez - this thread was about to bubble off page one of Stewardship! 
I watched a very interesting Frontline show a few nights ago - Hot Politics. It provided a nice recap of the political machinations around Global Warming. They include some great interviews from folks on various sides of the issue. Gore-bashers will be pleased to know Gore and Clinton don't come off a whole lot better than Bush in this show.
Not sure when it will be rebroadcast (these sorts of shows are always shown multiple times), but you can find a "watch online" link at the bottom of the page I linked to above.
The show's web site also includes links to supplemental materials, inclduding some fascinating documents, e.g. a seminal energy industry memo outlining tactics to derail the Kyoto Protocol (the show goes into how some of the players behind those tactics have since flipped to the other side of the debate as they've become convinced of the science, which of course is not a logical proof of anything  ), and a report on climate change impacts on the US produced and then supressed by the Bush administration (good detailed breakdown of predicted impacts that gets well beyond the caricatures often trotted out on both sides of the debate).
Disclaimer: I'm posting this not to make any sort of case regarding the science itself, but simply as a good information resource for folks who are interested in how our political system has reacted to this issue.
|
| Back to top |
|
|
Mtn Dog
Technohiker
Joined: 01 Aug 2004
Posts: 3336 | TRs | Pics
Location: Bellevue, WA |
|
Mtn Dog
Technohiker
|
Sat Apr 26, 2008 10:17 am |
|
|
The politics surrounding this issue, including your reference to the conspiracy theory that global warming doomsayers are somehow being suppressed, have long since left real science by the wayside. And sadly, the proper scientific method has taken a back seat to politics, environmental agendas, and hysteria. This century has brought a disturbing trend in it suddenly not being OK to offer dissent to new scientific theories when historically, science has always thrived and advanced itself on the dissent and falsification of newly emerging theories.
Here's a link to all the things that have so far been blamed on global warming: The Global Warming Hype List Crazy, isn't it?
Footprints on the sands of time will never be made sitting down.
Footprints on the sands of time will never be made sitting down.
|
| Back to top |
|
|
Guiran
Member
Joined: 03 Mar 2004
Posts: 621 | TRs | Pics
Location: University of Washington |
|
Guiran
Member
|
Sat Apr 26, 2008 11:14 am |
|
|
| Quote: | | He was published in Climate Research in 1998. |
Any comparable work in the past decade as our understanding of these issues has improved?
|
| Back to top |
|
|
Mtn Dog
Technohiker
Joined: 01 Aug 2004
Posts: 3336 | TRs | Pics
Location: Bellevue, WA |
|
Mtn Dog
Technohiker
|
Sun Apr 27, 2008 8:54 am |
|
|
Guiran:
Be careful you don't head into the territory of a fallacy in an Appeal to Novelty. Just because new things have come along in the last ten years doesn't mean the science of climate sensitivity is now invalid or obsolete. Sherwood Idso has also more recently done research on various plants and how they respond to higher CO2 concentrations, much like in a greenhouse. He doesn't consider CO2 to be a pollutant gas and neither do I.
This "memo" doesn't provide a date or explain who even wrote it but I don't see anything wrong with it anyway. I think it's perfectly reasonable for groups to make attempts to offset the hype and hysteria in the media on the pro-AGW side of the issue; especially since Hansen and the IPCC have so wildly exaggerated the results in the name of computer modeling. Besides, who are "some of the players" and what exactly is the "science" they became convinced of?
Footprints on the sands of time will never be made sitting down.
Footprints on the sands of time will never be made sitting down.
|
| Back to top |
|
|
joker
seeker
Joined: 12 Aug 2006
Posts: 7953 | TRs | Pics
Location: state of confusion |
|
joker
seeker
|
Sun Apr 27, 2008 10:29 am |
|
|
Watch the show and read more on the PBS site if you truly want answers to your questions, as you'll get much more context than I can efficiently provide here (it is a tightly edited one hour program), and frankly I'm not interested in a tit-tat back-and-forth on the details - I simply wanted to share a good info resource and point to a few samples of the info here (and you're right - nothing wrong for folks who have a certain belief to strategize on how to convince others of it - that's one of the things I liked about this show - it layed out a range of history on the politics w/o demonstrating flagrant bias, inluding letting all the willing players speak for themselves, and putting good original source material on the web site). No harm in exploring more info on the topic, eh?
|
| Back to top |
|
|
Mtn Dog
Technohiker
Joined: 01 Aug 2004
Posts: 3336 | TRs | Pics
Location: Bellevue, WA |
|
Mtn Dog
Technohiker
|
Sun Apr 27, 2008 9:17 pm |
|
|
No, you're right Joker, there isn't much harm in exploring more info. on the topic. However there is a limit and with some of these programs I've almost become repulsed by them insofar as they have insulted my intelligence. The link you provide for Frontline (which by the way, won't be on KCTS again during the next two weeks according to their schedule) automatically works from the false premise that AGW is real, humans are pretty much fully responsible for it, and immediate action now will curb the looming catastrophic effects of it if we only act while there is still time. Give me a break! I'm so sick of hearing this nonsense now that I know definitively what the details are behind the issue and how it breaks down scientifically (and I didn't need a computer model to figure it out either, how about that?). Yes, the earth is getting warmer and yes, humans have a role in it but that role is pretty much negligible - which is what we should expect when we increase the concentration of a TRACE greenhouse gas.
Footprints on the sands of time will never be made sitting down.
Footprints on the sands of time will never be made sitting down.
|
| Back to top |
|
|
Echo
not a voice
Joined: 26 Apr 2004
Posts: 244 | TRs | Pics
Location: Bouncing around |
|
Echo
not a voice
|
Mon Apr 28, 2008 8:13 am |
|
|
Mtn Dog said | Quote: | | Yes, the earth is getting warmer and yes, humans have a role in it but that role is pretty much negligible- which is what we should expect when we increase the concentration of a TRACE greenhouse gas. |
MD, after seven months and 65 pages, and after all your "studying", if you can still make that statement, you haven't learned anything. 
Sweetest Echo, sweetest nymph, that liv'st unseen Within thy airy shell,
by slow Meander's margent green, And in the violet-embroidered vale.
Sweetest Echo, sweetest nymph, that liv'st unseen Within thy airy shell,
by slow Meander's margent green, And in the violet-embroidered vale.
|
| Back to top |
|
|
kleet
meat tornado
Joined: 06 Feb 2002
Posts: 5303 | TRs | Pics
Location: O no they dih ent |
|
kleet
meat tornado
|
Mon Apr 28, 2008 8:14 am |
|
|
| Mtn Dog wrote: | | This "memo" doesn't provide a date or explain who even wrote it but I don't see anything wrong with it anyway. |
Are you talking about the one that looks to be authored by Joe Walker, Michelle Ross and Susan Moya, with the date April 3, 1998 on it?
I thought there were a couple of interesting lines in that memo:
| Quote: | | Yet if we can show that science does not support the Kyoto treaty - which most true climate scientists believe to be the case - this puts the United States in a stronger moral position {snip} |
| Quote: | | Convince one of the major news national TV journalists (e.g., John Stossel) to produce a report examining the scientific underpinnings of the Kyoto protocol. |
A fuxk, why do I not give one?
A fuxk, why do I not give one?
|
| Back to top |
|
|
BeyondLost
Crazy Bob
Joined: 07 Jul 2007
Posts: 3601 | TRs | Pics
Location: Whidbey Island, WA |
| Mtn Dog wrote: | | I'm so sick of hearing this nonsense now that I know definitively what the details are behind the issue and how it breaks down scientifically (and I didn't need a computer model to figure it out either, how about that?). |
Wow! That's such a relief. Mtn Dog has the definitive answers and nobody has to study this nonsense anymore. 
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Disclosure: As an Amazon Associate NWHikers.net earns from qualifying purchases when you use our link(s). |
