Tuesday, September 09, 2008

Survival Blanket

An outbreak of the "the greenhouse effect is not like a blanket" has recently been spotted in several locations. This consists of saying that blankets don't work by cutting off radiative transfer, but only convection. There is a neat little item that the bunnies huddle under when caught out in the cold, called a survival blanket. First developed by NASA, it is in the emergency kit of an half-wit or above who ventures out into the wild. Basically a thin, light silvered film that you can wrap about yourself and your loved one (us bunnies are very warm), which both cuts off convection and reflects back thermal radiation from your body and keeps you toasty and alive.

Invite a denialist of your acquaintance to huddle under one of these.

Comments below

41 comments:

Atmoz said...

Do Greenhouse Gases Act as Blankets? (regular blankets, not the nifty tin-foil ones Teh Bunny has a picture of in this post. Also, Comment on IPCC Explains the Greenhouse Effect.

Anonymous said...

MarkeyMouse quotes William Kininmonth: "The IPCC, in its most recent (2007) report has the statement (Frequently Asked Question 1.1):

“The reason that the Earth’s surface is this warm (14oC) is the presence of greenhouse gases, which act as a partial blanket for the longwave radiation coming from the surface. This blanketing is known as the natural greenhouse effect.

There are two problems with this statement. Firstly, a blanket acts as an inhibitor of conduction and not radiation; oxygen and nitrogen are equally as good insulators as water vapour and carbon dioxide and adding greenhouse gases does not materially affect the conducting properties of the atmosphere. Secondly, net upward longwave radiation increases with altitude (according to the IPCC global average data, from 66 Wm-2 at the surface to

235 Wm-2 at the top of the atmosphere); the increase is due to the greenhouse gases and can hardly be described as inhibiting (ie, blanketing) radiation loss to space!

In an attempt to clarify the situation, the IPCC has an additional explanation (Frequently Asked Question 1.3):

“Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth. This is called the greenhouse effect.”

As the IPCC’s global average data clearly show, there is more longwave radiation emitted from the Earth’s surface than is emitted by the atmosphere back to the surface. The net effect of longwave radiation is to cool the Earth’s surface, not to warm it.

The above two explanations from the IPCC are quite different and neither accord with the data presented on the global average Earth energy budget. As you will appreciate, the greenhouse effect is the underpinning science for the hypothesis of dangerous global warming from increasing atmospheric carbon dioxide caused by human activities. If we cannot get the underpinning science as a clear and logical construct then the edifice is no more than a house of cards! Also, if it is not possible to explain how the Earth’s greenhouse effect is sustained then how can we be confident that the computer models used to project global warming are adequately representing the greenhouse effect?

As FASTS claims that the physical principles of the greenhouse effect are well understood I presume FASTS has a different explanation than what IPCC has presented. I would be grateful for a summary of the FASTS principles of the greenhouse effect.
" http://jennifermarohasy.com/blog/2008/09/bill-kininmonth-requests-explanation-of-the-greenhouse-effect/

EliRabett said...

Ah Atmoz, thermal radiation shields (which you can think of as blankets) keep things cool too, ask your friendly cryostat owner and operator.

(Atmoz wrapped a blanket around some ice cubes and saw that they melted more slowly. He was probably the first blogger to watch ice melt, a current sport amongst us. However, the point is not that blankets keep things warmer or colder as such, but that they do so by slowing down the rate of heat flow by convection and radiation into and out of a system.)

Arthur said...

Markey (or Kininmouth/Marohasy) seems to ignore the rather obvious point that the low net radiative flux in the lower atmosphere is exactly the reason why the ghgs are acting like a blanket! Without ghgs there would be no back-radiation and net radiative flux would be about 6 times higher - well at least until earth froze over! How can somebody be so close to the essence of the issue and yet miss the point so utterly???

Atmoz said...

Eli,
I'm not saying thermal radiation shields don't act as insulators. Just that some people don't usually think of them as "blankets". The use of the term blankets in an FAQ aimed at non-scientists is misleading.

Anonymous said...

How can somebody be so close to the essence of the issue and yet miss the point so utterly???

That looks like a rhetorical question, but I'll answer to clarify if nothing else:


There are two likely possibilities:

1) they actually understand the issue and are purposely (ie, dishonestly) clouding it.

2) they are simply parroting the talking points of someone who actually understands the issue and is purposely (ie, dishonestly) clouding it.

Flavius Collium said...

It depends on the abstraction level. If you don't care about the difference of conduction/convection/radiation, the blanket analogy works very well.

I mean, if those people claim that the radiative greenhouse effect violates the second law of thermodynamics, then the conductive and convective greenhouse effects violate the second law of thermodynamics as well.

Is it more accurate to say that the Earth is flat or that the Earth is spherical? You can nit forever that there is no evidence of Earth being *perfectly* spherical (which hasn't been claimed in a long time anyway) or theories linking quantum mechanics and gravity in a comprehensive way (and what about dark matter?), hence that answer is wrong and you can go on spouting nonsense about flat earth (to spell it out clearly, this is an analogy of the situation where some claim there is no such thing as greenhouse effect.)

So make up your mind.

Anonymous said...

I think the real problem is that there is no really good commonplace analogy for the atmospheric greenhouse effect -- not even the common everyday greenhouse!

Scientists simply can not win in this case.

If you try to explain it in terms that a layman can understand, other scientists (and political hacks) criticize you for being scientifically inaccurate.

On the other hand, if you explain it in scientific terms involving IR absorption, kirchoff's laws and the like, well, the political hacks accuse you of evading the issue with fancy scientific terms and equations (and throw in the "it violates the second law of thermodynamics argument to sound as if they know what they are talking about).

To say nothing of the fact that the average person does not understand a word you say if you try to be scientifically accurate.

Anonymous said...

Interesting philosophical point, concerning "that the average person does not understand a word you say if you try to be scientifically accurate".

By definition the "average person" must be neither thick -- sorry, scientifically illiterate -- nor scientifically literate. It's an impossible situation to resolve satisfactorily for the occupants of either set.

"Ah, but ..." I hear you say, "... what measure of average are you using?"

Anyway, as we all know (especially in physics), analogy is always imperfect.

Anonymous said...

And I should have signed that message.

Cymraeg llygoden

Dano said...

Invite a denialist of your acquaintance to huddle under one of these.

o First of all, who the heck actually talks to denialists? Are you out of your mind?!?

o Second of all, denialists don't actually go out of their basements, do they? I mean, let alone into nature where the microclimate cannot be controlled.

Come now. You've been reading too many comment boards without your [killfile] or DotEarth Defender thus your brain is addled..

Best,

D

bi -- International Journal of Inactivism said...

In other news, it looks as if Malarkey Mouse has lost his ability to express any thoughts in his own words. Has he been Taken™ by the Phantom Soviet Empire™ just like in his worst fears, or is it some sort of side effect arising from his overuse of the tinfoil hat?

Anonymous said...

By definition the "average person" must be neither thick -- sorry, scientifically illiterate -- nor scientifically literate.

That is only strictly true with regard to scientific literacy.

It is certainly not generally true with regard to IQ, for example. Most people (in the US, at least) with an IQ of 100 are basically scientifically illiterate.

And i was being conservative/kind when I referred to the "average person". There are lots of otherwise very smart people (ie, with IQ well above the average) who are totally clueless when it come to science. I know from firsthand experience. I have many of the latter in my immediate family (a Harvard MBA and a Columbia MBA).

So allow me to modify my previous statement, if you please:

the vast majority of people (in the US, at least) do not understand a word you say if you try to be scientifically accurate.

Now that is a scientifically testable statement (and, I believe quite accurate)

EliRabett said...

Atmoz said:

"I'm not saying thermal radiation shields don't act as insulators. Just that some people don't usually think of them as "blankets". The use of the term blankets in an FAQ aimed at non-scientists is misleading."

Eli said:

What is the bunny, chopped liver? Nope that's the other guy:)

Anonymous said...

Repeated from the dead thread (with a typo correction):

jae to Herr Hare and harettes:

LOL. The bunny must be desperately looking for something to chew on, lately. I don't know WHO besides you mentioned survival blankets, which are a very special type of "blanket." Another Hare-brained tangent. As the bunny probably knows, open air is one of the absolutely worst insulators on the planet, due to convection (which is another reason the CO2/AGW idea is so silly). But air is, alas, a poor conductor, also. So, if you take a material with low mass (to minimize conduction)and use it to surround billions of very tiny air bubbles(to minimize convection), you get the best type of insulation known, other than a vacuum, where there is no convection. It's called foam insulation.

Anonymous said...

jae adds:

Oh, yeah, and you CAN add the shiny foil to the foam insulation and retard radiation, too. You can buy these things at Home Depot.

Anonymous said...

jae says if you take a material with low mass (to minimize conduction)and use it to surround billions of very tiny air bubbles(to minimize convection), you get the best type of insulation known, other than a vacuum,

Actually, though I'll grant you the part about the air bubbles minimizing convection, its not "low mass" that minimizes conduction of heat by a material.

The fact of the matter is, mass does not even enter into the equation of heat conduction.

H = k * A * delta_T / x

where k is thermal conductivity of the material, A is area, X is thickness of the material and delta_T is the temperature difference from one side of the material to the other (ie, across the material, perpendicular to the area)


It's not "low mass", but "low thermal conductivity" minimizes heat conduction.

And the "best type of insulation known, other than a vacuum," is actually "silica aerogel", which I suppose one might term "foam insulation" (though it ain't the kind of foam insulation you get at Home Depot)

BTW, jae, How about those smart photons?

You know, the ones that are emitted by a colder body and know to avoid a warmer one (like the plague).

Anonymous said...

jae,

jae: if you take a material with low mass (to minimize conduction)

You don't really have a PhD in chemistry, do you?

Please tell me you don't.

or at least tell me you got it through a correspondence course from the University of Outer Mongolia so I don't stay awake late at night worrying about the dismal state of science education in this country.

Anonymous said...

You are right Eli. The thing people who criticize the blanket analogy forget is that a blanket impedes both convective and radiative transfer of heat.

It's not an either/or situation. And what one is really concerned about conveying to public , at any rate is that both the blanket and the atmospheric greenhouse effect reduce energy loss.

By and large, the person on the street does not understand the difference between radiative heat loss and convective heat loss (or conductive heat loss, for that matter), so arguing that the blanket is not a good analogy really misses the main point.

It's interesting that Ray Pierrehumbert, who knows far more about the physics of the greenhouse effect than most ( certainly more than most bloggers, with the possible exception of a a few others who post at Real Climate [and Eli, of course]), actually uses the blanket analogy in his textbook (linked to by Eli)

Pierrhumbert says:

"As shown in Figure 3.5, a greenhouse gas acts like
an insulating blanket, reducing the rate of energy loss to space at any given surface temperature."

//end quote

Hey, if it's good enough for him, it should be good enough for the rest of us.

That's one problem with blogs. Everyone and his sister tries to tell the scientists what to do and say, even the best way to describe physical effects to the public.

Anonymous said...

jae to one of the anonomice:

"The fact of the matter is, mass does not even enter into the equation of heat conduction.

H = k * A * delta_T / x"

I stand corrected. Mea culpa. A detail is wrong, but the concept is correct.

Anonymous said...

Incidentally, to those who would challenge the claim that "even an ordinary blanket (not "space/survival blanket") impedes radiative transfer of heat", I would pose this question:

How many black blankets (or quilts) do you have in your house?

I don't believe I have ever even seen one, at least not the kind intended to be put on a bed to keep you warm at night.

But then again, maybe one can only find black (and presumably designer "doily") blankets (and matching lawn-giere?) at the high end Madison Ave stores.

Me, I shop at Target.

Anonymous said...

For your information, that's hardly a detail, jae.

For a chemistry PhD, or at least one who claims to be (I have my serious doubts) that's an MFU.

Your statement that "if you take a material with low mass (to minimize conduction)"

indicates that you are not the least bit familiar with the conductive heat transfer equation -- something that is in EVERY freshman level physics book that I have ever seen (and I have seen a lot of them over the years).

We're not talking advanced engineering heat transfer books here, we're talking very basic physics (which, by the way, has something to do with chemistry, at least last time I checked)

Not only that, your statement about "low mass (to minimize conduction)" is really rather vacuous .

What does that mean? "Low mass" compared to what? To say nothing of the fact that the mass of something depends on the thickness, the area and the density of the material.

so in the context of conductive heat transfer, it makes absolutely no sense to talk about mass by itself.


Finally, I would just note that there is a real irony in your statement about "low mass(to minimize conduction)":

I can have two "plates" of the very same area and the very same thickness, one made of lead and the other made of aluminum, and the plate with lesser mass of the two -- aluminum - (roughly 1/4 the mass of the lead plate) is actually a much better conductor of heat (nearly 7x as good) than the plate with the greater mass (lead), which is actually exactly opposite to your above goofy claim
"low mass (to minimize conduction)

Jae, in all seriousness, I would really suggest that you crack a physics book (or two) because (notwithstanding what your Chemistry PhD adviser apparently told you once) physics is relevant to chemistry (just a teensy eeensy weentsy bit)

Anonymous said...

jae to all:

Well, the discussions of insulation demonstrate well that, by far, the dominant heat transfer mechanism in the atmosphere is convection. That's one of the reasons the AGW "greenhouse warming" theory and the radiation cartoons are so silly.

Anonymous said...

Janet and John Do a Primary School Science Project is probably a better book to crack open first.

Cymraeg llygoden

Anonymous said...

well, the discussions of insulation demonstrate well that, by far, the dominant BS transfer mechanism on Eli's blog (if not the entire blogosphere) is jae


and
Here's an additional required reading list for jae (and other PhD chemists who believe in photons with little feelers out front to sense hot objects and little photonic brains to decide whether or not to avoid said object based on its temperature)

Mr. Tompkins in Wonderland (1940)
and Mr. Tompkins Explores the Atom (1945) , by George Gamow,

Actually, I recommend those books only partly in jest. Those books are quite good -- and better than many introductory textbooks from the standpoint of teaching physical concepts.

Anonymous said...

jae to the anonomice who have nothing substantive (only insults) to add:

The energy of a photon is related to it's wavelength by the Planck formulae. Thus, a photon in the visible range is MUCH more powerful than one in the IR region. So, you "experts" can maybe visualize that photons are NOT all created equal.

From Wicki:

Although Planck's formula predicts that a black body will radiate energy at all frequencies, the formula is only practically applicable when many photons are being measured. For example, a black body at room temperature (300 kelvin) with one square meter of surface area will emit a photon in the visible range once about every thousand years or so, meaning that for most practical purposes, a black body at room temperature does not emit in the visible range.

Go back to your fairy tales, which you can (maybe) comprehend.

Anonymous said...

Ever wondered how an infrared camera images, say, a human body?

The human body radiates infrared at around 10 μm.

Fancy that.

Anonymous said...

Grrr! That were me.

Cymraeg llygoden

Anonymous said...

Jae,
I am very glad to see that you have already taken me up on my suggestion to read some introductory physics.

Wikipedia is OK, but do be careful. Sometimes people make edits about smart photons and the like. I have witnessed such things (not on wiki, but elsewhere)

You just learned about blackbody radiation, I see.

Keep it up and report back to us on your progress in a few years.

With some hard work, you might one day know what the average physics, chemistry or engineering BS does.

By the way, does your statement above that
you "experts" can maybe visualize that photons are NOT all created equal.

mean that some photons are smarter than others?

Anonymous said...

jae to ??:

Good, now maybe I can get some more information from the experts here.

Your average radiation cartoon that purports to show how the "greenhouse effect" works shows a "backradiation" of about 324 watts/m-2. Can someone tell me how that heats us, since that amount of radiation is consistent with a blackbody radiating at only 1 C?

Dano said...

Hence my phrase 'self-marginalizing denialist fringe'.

Best,

D

Tracy P. Hamilton said...

jae:"Your average radiation cartoon that purports to show how the "greenhouse effect" works shows a "backradiation" of about 324 watts/m-2. Can someone tell me how that heats us, since that amount of radiation is consistent with a blackbody radiating at only 1 C?"

Because of the first law of thermodynamics? The IR photons being sent our way are absorbed, but their energy does not disappear.

This is high school level!

Anonymous said...

jae,

I don't know what cartoon's you refer to when you say "Your average radiation cartoon that purports to show how the "greenhouse effect" works"

but I'd certainly be careful about taking numbers from any old "cartoon" obtained from the internet.

Having made that caveat, Fig 7 in this paper by working climate scientists at NCAR is probably pretty reliable.

It shows that the earth's surface actually receives about 390 W/m^2 (equal to the emission of a blackbody at ~288K (15C) )

To get the 390 W/m^2 , you have to add the 168 W/m^2 (solar energy absorbed by earth: direct+ diffused ) to the 324 W/m^2 (longwave back-radiation from atmosphere) and then subtract from that 78 W/m^2 due to evaporation of water (latent heat) and also subtract 24 W/m^2 due to what they term "thermals" ("sensible heat", due to convection and conduction)

390 + 168 - 78 - 24 = 390W/m^2

There may be more accurate estimates that have been made since that paper (1997), but i suspect that the numbers have not changed all that much.

And by the way, jae, it is pretty clear from that diagram that i linked to that your above claim that

"by far, the dominant heat transfer mechanism in the atmosphere is convection"

is simply so much BS.

and by the by the way, jae, I was the one who made the snide remarks above so now you can't say I have not contributed anything substantive (so there, hah!)

In fact, what I have contributed in this one comment is FAR more substantive than anything that you have contributed so far (with your ignorant comments about the greenhouse effect violating the 2nd law of thermodynamics etc)

Simple "denial" ("The greenhouse effect is bunk") is not a particularly valuable contribution .

In fact, from the scientific standpoint, such "arguments" mean nothing.

Anonymous said...

Correction for above

that should have been

324 + 168 - 78 - 24 = 390W/m^2

instead of

390 + 168 - 78 - 24 = 390W/m^2

but it should be clear from what i wrote what was intended, nonethless

Anonymous said...

jae.

One more comment and I'm done with (you are a lost cause)

I also contributed the comments above about heat conduction, and the comments about the greenhouse effect on the other thread that linked to the real climate "learning from a simple model" post.

So you can insert your smart photons where they won't shine (in your blackbody cavity) OK?

Anonymous said...

Isn't it time for the climate bloggers to start sharing a list of the IP numbers used by the inveterately bogus posters?

It's really just spam. Black hole is appropriate

Dano said...

Agreed. jae is simply spam to purposely confuse the discussion - a FUD purveyor.

As another idea in addition to sharing IP addies, rather than trying to correct obvious spam, we should simply ridicule. No corrections, ridicule. Spam is not worth anything but ridicule.

Best,

D

Anonymous said...

"As another idea in addition to sharing IP addies, rather than trying to correct obvious spam, we should simply ridicule. No corrections, ridicule. Spam is not worth anything but ridicule.
"

Wow, what a perfect example of worthless spam!

Anonymous said...

Notice jae was too embarrassed to even post his name on the last comment.

The ridicule ("not all photons are created equal: some are smarter than others") has obviously gotten to him.

Steve Bloom said...

Eli, it might be useful to reference the other common use of reflective blankets by people, i.e. for forest fire survival. It makes for a vivid image.

Anonymous said...

on a normal greenhouse is a solid glass roof - CO2 is only 350ppm, which means that ''the blanket is the size of a postage stemp, CO2 not guilty; http://globalwarmingdenier.wordpress.com/climate/