Jumat, 01 April 2011

The fallacy of the greenhouse effect 2

Part 1 Part 2


In part 2 I rebut some of the claims to an atmospheric greenhouse effect using the concepts introduced in the first part.



Given the Earth's distance from the Sun and the Sun's electromagnetic radiation (EMR) Earth should by conventional calculations be about -18C temperature on average. However Earth's surface temperature is 15C on average -- a difference of 33C. Many have resorted to the notion of a greenhouse effect to explain this difference.



To the various greenhouse claims I have heard:



1. It is a one way valve for EMR.
2. Back radiation will add energy.
3. It reflects energy like a mirror.
4. It reduces the emissivity of Earth.
5. It slows the EMR flux.
6. It is a greenhouse blanket.
7. CO2 is an absorber of infrared energy therefore it must add energy.
8. The air above is cooler therefore capable of absorbing energy from the ground and this adds heat.
9. It shallows the environmental lapse rate (vertical temperature gradient) and therefore slows convection.


I now address each of these points in turn:



1. It is a one way valve for EMR.


Rebuttal:

  • A one way valve for heat requires work. A passive blanket such as the atmosphere does not have its own work.

  • It depends on the relative temperature and the atmosphere happens to be colder than the ground. Heat only flows from hot to cold despite the presence of back radiation.

The greenhouse theory is that light from the Sun falls to the ground warming it up. The Earth then emits at a lower temperature than the Sun at lower frequencies that are absorbed by greenhouse gases.  You then get more warmth than you otherwise would because this adds to the heat content of the Earth.




figure 1


Contrary to the above depiction Earth's atmosphere is a "passive blanket". A passive blanket can only slow fluctuations of temperature such as how the Earth stays warmer at night and cooler during the day than the Moon with its lack of atmosphere.



Earth has better surface temperature regulation than the Moon due to the heat capacity of its atmosphere; the ability to reflect more sunlight back into space; and how the fluids of the air and oceans redistribute heat.  For the greenhouse effect to work it would require Earth's atmosphere to be an active blanket; that is, a powered one.



If the air were to get warmer than the ground, heat could flow from the air to the ground. Yet the air can't get warmer than the ground because the energy to warm the air came from the ground in the first place.



The heat lost from any object can't warm something else up more than itself.  And heat can't turn around back on itself and heat itself up again.  Work would have to be performed for such a thing to happen and greenhouse gases have no energy source of their own.



That the air is colder than the ground is shown in the vertical temperature gradient or environmental lapse.  Moving up in altitude the air temperature cools by an average of 6.5 degrees celsius per kilometre1.



It's an Achilles heel for greenhouse theorists. The air can only be gaining heat from the ground if it is colder than it.  Meanwhile the air can only heat the ground below if it gets warmer than it.  The air can't be both hotter and colder at the same time.  Hence: no heat pump or one way valve effect.



This convention of heat flow is represented in the following diagram:



Figure 2
Object A has the highest temperature. B has the second highest. C has the third highest. D is the coolest -- an infinite heat sink maintained at absolute zero. Despite A and C receiving the same amount of EMR from B only C is heated by B. A is not heated by B.
For the greenhouse effect to be real C could heat B and B could heat A. Contrary to this contention heat only flows in the direction of the black arrows2.


In figure 2 above, B is not heated by C despite its back radiation. And A is not heated by B despite its back radiation.



EMR may convey heat or not depending on the relative temperatures of the objects involved.  It is better to view EMR as an information signal to the Universe which may or may not convey heat depending on the situation in which it is received as well as sent.



Mutual EMR is really about equalising temperature differences throughout the Universe.  It is not about raising the overall temperature from nothing.



In radiative transfer the range of EMR frequencies emitted from a colder object will not be able to on the whole stimulate a warmer object to become warmer still.



And so in the case of the Earth the air won't heat the ground because the atmosphere is colder than it.



2. Back radiation will add energy.


Rebuttal:

  • All objects emit and receive mutual EMR. These mutually exchanged vectors cancel. They do not add.

Every object emits and absorbs EMR at all frequencies to some extent and the amount mutually exchanged cancels. Everything is bathed in a sea of EMR even on the inside of objects. Yet this mutual exchange neither adds to nor subtracts from the total energy.



There's a popular post on Dr Roy Spencer's website from 6 August 2010 called help back radiation has invaded my backyard.



Figure 3

Does back radiation warm you up like a ray gun?  It depends on the relative temperature.


The fact of the matter is back-EMR is not indicative of any greenhouse effect nor of heat trapping of EMR.  It's better to view the back radiation from the sky as merely a measure of its temperature.



The infrared that's emitted by the night sky back to the ground says nothing of how the energy arrived there whether as a result of convection; evaporation and re-condensation of water; or by EMR absorption.





3. It reflects energy like a mirror.


Rebuttal:

  • At equilibrium the internal reflection or emission of EMR makes no difference to the temperature of an object.

Imagine a hollow sphere that has EMR emitting on the inside and out (figure 4a).

Figure 4a



Cross section through hollow sphere emitting EMR.


Let us split this sphere in half to consider the effect of one side upon the other (figure 4b).





Figure 4b


Let the left hemisphere emit to the right hemisphere 50% of its EMR -- 25% of the whole.  Now the right side absorbs this and re-emits 12.5% of the whole back to the right hemisphere as per greenhouse theory.  In such a way energy is added to itself and counted again.


This impossibility is resolved by assuming that the internal flux of EMR in an object is cancelling. The same is true for the upper layers of atmosphere radiating on to the lower levels and the surface of the Earth.



Were this argument not to be true the  law of conservation of energy3 would be wrong and you could get energy for free from nothing from such things as mutual radiation.



The only thing that can make a difference to the temperature of an object involving the exchange of EMR is to change the emissivity.



An example of this is an emergency silver foil blanket where it's low emissivity warms up the inside.  CO2 has a high emissivity.  So it's not like a foil emergency blanket.  CO2 will help the heat loss of the Earth through its high emissivity.



In a Princeton University atmosphere lecture note (page 8/12 here) it says that at some frequencies of infrared clouds and the atmosphere act like a mirror.



If it's reflecting, rather than absorbing and re-emitting EMR, this reflection is an elastic collision and no energy is absorbed by the "mirrors", which in this case are the clouds and the air.



If this form of back radiation could add to the overall temperature the following impossible energy multiplication could occur:







Figure 5


4. It reduces the emissivity of Earth.


Rebuttal:

  • Just as CO2 is a good absorber it is also a good emitter. CO2 increases Earth's emissivity.

  • The process of absorption and emission merely moves the emission point from the warmer surface to the cooler upper atmosphere.

The only way to get increased temperature without the application of work is to have a lowered emissivity.  Being a good absorber of EMR CO2 is equally good an emitter as per Kirchhoff's law4. This increases Earth's emissivity.



Over 99% of the CO2 absorption of infrared light occurs within about 10 metres of the ground.  For example infrared absorption by CO2 at wavenumber 2349 is 99% at 70 centimetres above the surface5.  This will heat the air a little bit if it's cooler (like depicted in figure 15a below) or not at all if the air is at the same temperature. 



Then there is the phenomenon of line broadening of the CO2 absorption -- the so-called wings on the initial absorption line. It's a widening into a trough or valley in the red graphs of figure 6 from what's usually a thinner line (like this) for CO2 absorption.



The broadening occurs through such things as Doppler broadening and it seems to reduce the emissivity of Earth (figure 6).



Figure 6
Four modtran emission temperatures looking down from heights 1, 8, 18 and 80km including absorption of CO2 and other gases.  Red graph is the apparent atmospheric emission temperature at differing wavelengths.
Humidity = 0.  CO2 = 375ppm.
It's better to view this line broadening as just an expansion of the role of CO2 and other greenhouse gases in moving the emission point from the warmer surface to the cooler upper atmosphere.  The bottom of the prominent trough of CO2 absorption in 6b 6c and 6d above centred on wave number 680 is tied to the temperature of the air at that point.



You can compare the emission temperature to the air temperature in this green graph generated at the same modtran simulator:



Figure 7
Temperature graph in green.
The reader may question: if EMR is the only way for Earth to lose heat the fact that Earth emits less must mean that it warms up.  I intend to address this controversy in a follow-up post.  Suffice it to say that there's more to the question of what the Earth's average temperature really is.  Plus there could be other ways energy can be lost or gained in the atmosphere not involving a greenhouse effect.



If adding a high emissivity agent such as CO2 could block the transmission of heat-energy in the form of EMR then the application of a high emissivity coating to an object would be a useless way to enhance an object's energy dissipation because it would block energy from getting to the surface due to the high absorptivity that comes with high emissivity thus cancelling itself out.



High emissivity coatings are used in rockets. It lowers the temperature of the combustion chamber because, while the high emissivity coating does not significantly stop heat conduction within the rocket liner wall where physical heat conduction dominates, it does assist EMR to leave the object.



So too it is for the atmosphere.  CO2 assists the emission of EMR into space. If there was any credibility for an atmospheric greenhouse effect at all there would be a hot spot in the air that's just not there (as publicised by Jo Nova).





5. It slows the EMR flux.


Rebuttal:

  • Yes but irrelevant in light of the huge amount of heat conveyed by evaporation and convection. 

  • As long as the up going EMR is lower than the down going there is no addition of heat to the ground.

  • The Earth emits as much EMR as it receives from the Sun so there is no imbalance.

"Slows the EMR flux" means that the difference between the up going and the down going EMR is lessened.  When you sum the up going and the down going the total EMR emitted through the troposphere is lower so the Earth gets warmer.  That's the idea at least.



However, even though through the process of absorption and re-emission EMR does bend around corners and goes back down to Earth the energy isn't being multiplied.  It can't be counted again.



All molecules of the atmosphere absorb and emit EMR at every wavelength to a certain extent. There is only a slight difference between the magnitude of EMR in the vertical direction -- the downward being slightly less than the upward.



The heat budget diagrams of Prof Kevin Trenberth of the IPCC and Gavin Schmidt of NASA multiply the upward radiation after it is absorbed and re-emitted by the atmosphere by a factor of two (based on this diagram from here).





 figure 8
Kiehl and Trenberth heat budget 19976.


There is something very wrong with the above diagram (many things actually). Shouldn't there be an equal amount of EMR radiated up and down from the sky layer?



In figure 9 the EMR down is 324 W/m2 while the EMR up is  165 + 30 = 195.  How can there be such a discrepancy?  Is this IPCC voodoo magic?



figure 9


 My adjusted version with opposing vectors of EMR cancelled. (NASA has a similar version here.)

 
With the upward and downward EMR vectors cancelled (figure 9) the upward net EMR is 66 W/m2.



And once that infrared EMR is absorbed in the first few metres above the ground it's done all the heating it will do and it creates barely a blip on the vertical temperature gradient (see figure 15a below).



The greenhouse effect says that EMR energy is trapped (figure 10a).





Figure 10a


This is incorrect.  The Earth actually emits as much EMR as it receives from the Sun7.



Figure 10b


Earth emits EMR at an apparent temperature of  -18C mostly from the top of the atmosphere8. The EMR projected upward dissipates heat from the Earth because it goes to a cold heat sink: the Universe. The EMR projected downward toward Earth neither adds to nor subtracts from the temperature.





6. It is a greenhouse blanket.


Rebuttal:

  • Blankets and greenhouse roofs work by blocking convection. This does not exist in an unrestrained gaseous atmosphere.

The gas of the atmosphere acts nothing like a human blanket nor the glass roof of a greenhouse. In both the latter cases the mechanism of warming is reduced heat loss due to the blocking of convection.



Figure 11
The fibres of a blanket blocking convection of air particles.


If you put on too many winter clothes you will experience overheating due to lack of convection.  The human body feels comfortable at air temperatures a few degrees lower than body temperature.



The body prefers to lose a certain amount of the heat generated internally.  If the air temperature goes above this comfort zone the body will sweat to utilise that powerful mover of energy the latent heat of evaporation of water.



The human experience of a blanket is projected onto the atmosphere to visualise a greenhouse effect.  But absorption and re-emission of EMR is not a slower nor a blocker of heat energy.



There's so much heat conduction from convection in the atmosphere that if you get rid of the air immediately above the ground (say 10 metres) the temp will go up to about 70C (based on beer bottle experiment of first part). If you get rid of the atmosphere altogether, with its reflective power, it will become about 107C like the Moon.



Let us consider three main modes of heat transport from the surface to the upper troposphere:



figure 12


Object A represents the Earth.  Let there be three main modes of heat loss from the surface: convection, water evaporation and EMR.
The idea of the greenhouse effect is that one of the three main modes -- EMR -- is "blocked" or slowed down like a tap that you can turn down.  In solids and fluids at Earth temperature EMR is not that significant a conveyor of heat.



Considering the power of water evaporation and convection to pick up the slack, a few degrees C is not going to make much difference in the scheme things such as the vertical temperature gradient.  EMR is not the independent factor greenhouse theorists consider it to be.



Absorption of infrared by CO2 can delay or slow the outgoing heat for a time by converting the faster escaping infrared light into slower moving convection.  But it can't create extra warmth.  It cannot displace the ground temperature to a hotter point as depicted in diagram 15b below.





7. CO2 is a good absorber of infrared energy therefore it must add energy.


Rebuttal:

  • Yes absorption can make an object warmer. But it doesn't then turn the energy around and make the warming object (in this case the surface) warmer than it originally was.

Yes, an object absorbing EMR will warm if the radiating object is warmer than it. The temperature in the sky will be changed. But that doesn't mean that it heats us more than we originally were down here on the surface of the Earth. That's not if you wish to believe in the laws of thermodynamics anyway.



Once EMR leaves the ground and moves upward it is immaterial to the ground temperature whether it is subsequently absorbed on the way out or not.  The magnitude of the heat flow in EMR is irrelevant to the question of the emanating object's starting temperature as long as the direction of heat points away.



Once it warms the air to the higher temperature (close to the ground) its work is done. You don't keep counting every emission and re-absorption from a greenhouse gas molecule.





8. The air above is cooler, therefore capable of absorbing energy from the ground and this adds heat.


Rebuttal:



This version comes from climate sceptic Lubos Motl. I base this contention on a comment he made -- I think it was on comment is free (The Guardian) -- where he said the greenhouse effect exists because the air is cooler than the ground.  I think the reasoning is along the lines of the following sort of observation (figure 13).





Figure 13


It's basically a variation on point 7.  The idea is that the atmosphere is a cooler than the ground just like that gas cloud is and therefore absorbs some heat. This is true.



But in the above diagram putting the cloud there doesn't make the emanating object warmer than it was.





9. It shallows the environmental lapse rate and therefore slows convection.


Rebuttal:

  • Gradients are a result of temperature difference not a cause.

The flow of heat is the result of the difference in temperature from one place to another. It's an effect not a cause.  Heat doesn't back up like cars on a freeway going slower with the cars in front effectively slowing the cars behind.



Heat flows as fast or as slow as the temperature difference requires regardless of any so-called EMR blocking.



If anything CO2 will deepen the vertical temperature gradient due to it displacing a lot more weight in the vertical direction when it rises and hence loses more temperature than main constituents O2 and N2. (This paragraph was edited 10 April 2011).



In the warmth of the day the vertical mixing of the air just goes higher or increases the gradient (figure 14).  The diurnal variations in convection have gradients that tend to meet at a point about 2 km off the ground to where the vertical temperature gradient resumes at a constant gradient and magnitude around the clock.





Figure 14


It is this vertical temperature gradient which dominates over the flow of EMR and which therefore renders any greenhouse effect by absorption meaningless.





Figure 15
Horizontal axis is temperature in kelvin. Vertical axis is altitude.  Blue line represents air temperature without greenhouse effect. Red line is with greenhouse effect.


The above figure 15a depicts the greenhouse warming I would expect. Note that in my graph 15a the temperatures meet at the ground.  In greenhouse theory the air temperature moves the  ground temperature to the right.



Since the ground is the source of the heat diagram 15b is against the laws of physics.  Even the deviation in my depiction in figure 15a above is an exaggeration to the true effect that the greenhouse absorption has.  Being only 390ppm CO2's heating effect is negligible.



At the end of the day any human-made heating whether it be CO2 absorption; or a building; or an asphalt car park even if it's like 2 - 3 C will be nothing in the scheme of things such as the vertical temperature gradient; the dissipation of heat at night; convection; and so on.



References:



1. Environmental lapse rate.

2. The second law of thermodynamics.

3. Conservation of energy.

4. Kirchhoff's Law.

5. Calculation at 2349 wave number per centimetre using an absorbance calculator. Assumes no scattering. Absorption coefficient is 1214. Atmospheric molarity 0.000023 mol per litre.

6. Kiehl and Trenberth, 1997: Earth's Annual Global Mean Energy Budget, Bull. Am. Met. Soc. 78, 197-208. Here and here. Pic only here. (Updated 2008 diagram here.)

7. NASA measurements of EMR flux.

8. Encyclopedia of the Solar System, Second Edition (McFadden, Weissman, Johnson, 2006).



Further Reading:



WattsUpWithThat guest posts by Tom Vonk 1,2.

Jumat, 12 November 2010

Refreshing A Current Affair stories

Tonight I was watching A Current Affair Queensland edition and there were two environment-related stories.  The first was on the fad of banning plastic bags sweeping Australia. 


Tasmania has now joined three other states in banning them.  But, refreshingly and unexpectedly, the article sensibly argued that the so-called green polypropylene bags that replace the usual polyethylene ones take a lot longer to biodegrade.  Plus, they are prone to getting bacteria with multiple use, which the article didn't mention.





"Green" shopping bags: they're more about feeling good than actually helping the environment.


Then there was a story about the changing climate in Queensland.  I've noticed it for about three years now -- the climate is getting cooler, cloudier and rainier.  It's actually quite pleasant for me but it is creating a lot of storms, floods and cyclone activity.





1974 Brisbane flood


For every second of that story I was waiting for them mention "climate change" or "carbon emissions".  But to their credit there was no mention of it at all and instead there was a sensible explanation of it being due to the la Nina in the Pacific.


Furthermore, they honestly reported that this is nothing new for Queensland but a return to the way it was in the 1970's -- floods and rain.  I hope this is a sign the the climate change madness is coming to an end.  Well done ACA.

Minggu, 24 Oktober 2010

The real reason for NBN: censorship




Stephen Conroy: clubbing democracy and freedom to death
Senator Stephen Conroy loves his Chinese-style Internet filter for Australia.  It's also the real reason he supports the government's uneconomical National Broadband Network: to hardwire in the censorship.


From The Australian 25 October 2010:
..if things go according to plan, NBN Co will be Australia's communications gatekeeper, owned and driven by a government that favours internet censorship.

The consequences of this in a democracy raise potentially disturbing issues affecting the free flow of information that go well beyond dollars and cents. In effect, the NBN rollout gives the government the ability to determine what content is suitable for delivery into the home -- a situation not dissimilar from that which operates in China.


Websites like Planetary Vision would be prime targets for Conroy's Internet filter.  Australia already has one of the most controlled, monopolistic media in the world.  Getting a handle on the Internet would starve one of the few routes for unfiltered information to reach the Australian people.  Total information control.  He who controls the information controls the people.


Let's review what's in store for the Australian people:


Smart electricity meters on every house allowing unlimited warrant-less monitoring of people's sleeping hours and usages of electrical devices.  A tracker in every automobile to track your travel under the guise of stopping level-rail crossing accidents.  And a NBN with China-style censorship hardwired in.


What happened to the Australia I knew?  We are in the grip of the New World Order.  Fascist scum like Stephen Conroy need to be removed from office.  They are un-Australian.

Senin, 18 Oktober 2010

The fallacy of the greenhouse effect

Part 1  Part 2



An object can warm through the absorption of electromagnetic radiation (EMR). However, an object passively warmed can't warm the object providing the warmth. Were this to be so energy could be multiplied for no extra input merely by having objects mutually radiate EMR. But there is no such temperature multiplication because the amount mutually exchanged cancels. It does not add as is required by greenhouse theory.


The reason that an object can be heated by EMR on earth by the sun is because the sun is warmer than the earth.  The idea of the greenhouse effect is that the cooler, upper layers of air are able to warm a warmer ground by backradiation. But this can not happen.


Greenhouse theory would even require that the backradiation from the earth to the sun warms the sun by a small (if practically imperceptible) amount. This is impossible too because a cooler object can not warm a warmer one unless work is done.  But greenhouse gas, not having an energy source, can not provide this work nor can the earth provide work to the sun.


200-plus years of thermal study must be thrown out the window if we are to believe that EMR from a colder object can warm a warmer one. If that were the case energy could be made from nothing merely by bringing two objects together mutually radiating EMR (such as the air and ground) such as the following examples show.



Let object A represent a warmer object radiating to an infinite heat sink C maintained at absolute zero.  Object B is introduced into its field of radiation and so is warmed:





Object B comes up to equilibrium temperature.    Now it has its own radiation and object A is subject to more radiation than it was before (which was zero).  If the cooler object B can warm the warmer object A through backradiation then object A will heat to a higher temperature than before for free merely because object B is passively warmed.



Object A and B now radiate more energy to the universe than when A was by itself merely by B's presence. This is clearly not possible.



Now to carry it further let the sphere B be replaced by many such spheres B on one side of A.  They all radiate as much EMR as the original object B. With eight spheres the energy is multiplied eightfold according to greenhouse theory:



Object A is eight times as warmed by backradiation as it was when there was only one sphere B.  In the case of the atmosphere this is the equivalent of putting more greenhouse gas "energy absorbers" in the atmosphere.



Now let the EMR blocking coverage continue from eight spheres B to a hemispherical shell B.  This is a cross-section through B:






Now half the radiation of A is blocked by B.   According to greenhouse theory half of this half will be radiated back to object A thus warming it.  Object A now emits 100% +  25% now re-radiated back by the hemisphere B.  An extra 25% energy gain for free!



Let the hemispherical shell B become a fully enclosing spherical shell B:



According to greenhouse theory as much of the amount emitted outside of shell B will be emitted inside.  But what happens to the amount emitted inside?  Does it add to the energy?  According to greenhouse theory yes, but how can it?  Only the amount emitted to the outside of the system is relevant.



(The outside shell B must radiate a total amount which was equal to A's original output.  Being at a larger radius it will have a lower emission temperature.  Effectively the shell B is a red shifter of the EMR spectrum.  Yet the amount of energy emitted in total will be the same.)



If adding shells as greenhouse blockers could work as an energy multiplier then Willis Eschenbach's steel greenhouse model would work.  Many commenters on that thread in defence of the greenhouse effect objected to its preposterousness but it is not warranted because the model is an accurate representation of the greenhouse effect; it's just that the greenhouse effect is preposterous.



For me the resolution to the paradox is to view heat energy like a stream that only flows downhill, from warmer to cooler, despite the presence of backradiation.



An ordinary, human blanket creates warming by blocking convection not by "backradiation". An emergency aluminium foil blanket warms by a high reflectivity/low emissivity, not by absorption and re-emission.



In the case of the earth the only way that a chemical can alter temperature is by a lowered emissivity.  But greenhouse gases being good absorbers are also good emitters as per Kirchhoff's law.



An empirical example of how a cooler object can not warm a warmer object can be seen in the operation of a vacuum furnace.


Representative vacuum furnace production run: (a) furnace and workload temperatures versus time; (b) power requirement to achieve the temperature profile.
My note:  (The lower black line is a more efficient power supply than the upper red dotted line).
In a vacuum furnace the air is removed, so the only way to convey heat is via EMR.  For the first 2 hours the power input (black line) is made higher at 40% of max power to bring the furnace walls up to temperature.  Then the power is backed off to 20% for a further 26-hour period in which the 7.5 ton load (the product to be heat treated) comes up to the desired temperature.



Notice how the power input stays constant throughout the latter 26-hour heating period despite this massive 7.5 ton load coming up to nearly the same temperature as the oven and backradiating all of that EMR to the furnace walls? 


It's only the amount of heat loss to the outside of the furnace that the power needs to supply.  The reverberation of EMR within a system neither adds nor subtracts from the energy content.  This is empirical evidence against the greenhouse effect.



During the daytime earth's atmosphere provides cooling.  In the daytime sun some water placed in beer bottle with the backside painted black will heat to over 64C in a vacuum sleeve.  The same bottle will without the vacuum will heat to just 41C. 


(Data at Green Power Science here.)



(Also, for reference, the equilibrium temperature of a sphere in the direct sun from ground to space here. From here.)



Without the atmosphere it would be about as hot as the surface of the moon where the daytime temperature is 107C. From 107C to 64C shows the shielding effect of earth's atmosphere.


Convection and thermal inertia (thermal mass) of the atmosphere takes the temperature down even lower than the 64C mentioned above.


CO2 absorbs all its EMR within the first 10 - 25 metres.  (1,2,3) The slight warming that this creates is meaningless by the time you move upward in the atmosphere where the vertical temperature gradient dominates.



You could argue that the slight warming of air above from CO2 absorption causes a shallower temperature gradient and so slows convection.  But observe that regardless of the temperature on or near the ground -- from 50C in a desert to -40C in Antarctica -- when you move up to a certain height the vertical temperature and gradient is the same (depending on latitude).







Moving upward from the ground there is a negative temperature gradient -- the air gets cooler with altitude by about 6.5C per km.





The real mystery to me is what creates this vertical temperature gradient.  It dominates over the slight CO2 warming that occurs with 25 metres of the ground.



Seeing as heat can not flow from a cooler object to a warmer one (even with backradiation) the upper layers of troposphere can't warm the warmer surface. The exception to this is the temperature inversion that occurs below 2km at night and occasionally during the day.




A temperature inversion is the only way there can be a greenhouse effect. Then the air above can warm the ground below. But even then it is a passive slower of heat and, while it might keep it from getting colder at night, it can't make the earth 33C warmer than it otherwise would be. And the occasional daytime temperature inversion is not going to create the 33C warming attributed to the greenhouse effect.


As mentioned above every EMR absorber is equally well an emitter by Kirchhoff's law. Carbon dioxide emits just as much as it absorbs unless it is changing temperature. But it isn't changing temperature that much as being only 380 parts in every million the warming effect is minuscule and can't significantly warm the air compared to the energy delivered by convection and water evaporation.


The following is a graph of EMR taken over the Arctic taken from the SkepticalScience website.  It seems to show a lowered emissivity for the earth due to "energy blockers":




It shows the emission and absorption at CO2 absorbing frequencies centered around a wavelength of 15 µm.   



It  looks like a mirror image in the CO2 absorption zone with energy reflected down. It's really that the atmosphere is optically thick at those frequencies of light and looking up from the ground you see the downward component of a unidirectional emission of CO2 and H2O from the warmer, lower layer.  Looking down from high above you see emission from the cooler, upper troposphere.



What we are really seeing in the above is not energy blocking but the point of emission being moved from the earth's surface where it is warmer to the upper troposphere where it is cooler.  



Yet even this vertical displacement can't make the earth warmer because emission and absorption is not an "energy blocker" like a lowered emissivity could be said to be.



An interesting thing to do with the above graph from SkepticalScience would be to turn the sensor on the ground facing down instead of up and turn the sensor at 20km facing up instead of down to demonstrate how the CO2 is emitting as much as it is absorbing at every altitude. 



This visualisation can be approximated by a handy modtran simulator at the University of Chicago.  With it you can alter CO2, humidity, clouds, ground temperature, etc. 



Enter the webpage above and change nothing in the left pane except the humidity to zero and hit "Submit the Calculation" and you get the following graph:


1. Iout, W / m2 = 345.714

Ground T, K = 299.70

Sensor altitude = 70 km

Looking down, no clouds, rel. humidity = 0, tropical latitude

CO2 375ppm:






In this graph the higher frequencies are on the right.  The divot in the middle centered on 670 wavenumber is the CO2 absorption with "wings" -- a widened absorption area.  H2O absorption also overlaps a bit with this CO2 absorption.



Now in our model let's increase the CO2 to 10,000ppm CO2:
2. Iout, W / m2 = 324.048

Ground T, K = 299.70

Sensor altitude = 70 km

Looking down, no clouds,
rel. humidity = 0, tropical latitude

CO2 10,000ppm:




It says there's 21 less W/m2 emitted into space.  The wings of absorption get greater.  And so, earth should get warmer.  But is emittancy really the only factor that cools the earth?



Back to normal CO2, let us now add 100% relative humidity water vapour to it:

3. Iout, W / m2 = 287.844

Ground T, K = 299.70

Sensor altitude = 70 km

Looking down, no clouds, rel. humidity = 1, tropical latitude

CO2 375ppm:




A 58 W/m2 less emittancy for 0 to 100% humidity compared to a 21 W/m2 difference from 375 to 10,000ppm CO2.  So,  water vapour is much more powerful than CO2.  But while no one is suggesting increases in CO2 to 10,000ppm, changes in relative humidity  from zero to 100%, or parts in between, happen regularly on earth and yet it does not boil up.



Water vapour does change adiabatic cooling rates but not because of the greenhouse effect but the latent heat of condensation.  Charts of adiabatic cooling do not take into account greenhouse gases.



If EMR was the only way that heat was dissipated from the surface then clouds, which block EMR, would cause tremendous warming.


At night clouds keeps us warm through a slightly lowered emissivity/increased reflectivity and by blocking convection but this won't make the planet warmer than it otherwise would be.   During the day clouds make us cooler, not warmer, by reflecting sunlight up. 



At the very periphery of earth's atmosphere EMR is the only heat output.  It is only at the periphery of an object where emissivity can make a difference to the object as a whole.  But the emissivity at the edge says nothing of the heat flow within the material.



Let us explore this with the modtran simulator by adding a thick layer of clouds:
4. Iout, W / m2 = 290.858

Ground T, K = 299.70

Sensor altitude = 70 km

Looking down, cumulus clouds base 0.66km top 2.7km, rel. humidity = 0, tropical latitude

CO2 375ppm


Now the emittancy has gone down by a whopping 55 W/m2 compared to run 1 above.  According to Hansen et al 1 W/m2 = 3/4 of a degree C.  So 55 W/m2 change will cause a 41C temperature increase!?  Ask yourself does this happen when there's thick cloud over a large area, day or night?



So far every modtran graph I have provided has been at the sensor height of 70km looking down over the tropics.  To prove my point that the lowered emittance is due to the height at which the emission takes place we can view the emission spectrum from varying altitudes.



First it's useful to note in the right hand pane along with the emission curve there is another graph underneath with the air temp and the concentration of some gases.

5.  Iout, W / m2 = 395.012

Ground T, K = 299.70

Sensor altitude = 5 km

Looking down, no clouds, no humidity, tropical latitude

CO2 375ppm:






Wavelengths of the window frequencies are affected by atmospheric conditions like clouds and water vapour. Although most of the EMR comes from the ground at window frequencies it still doesn't mean that that EMR is the main mode of transmission through the atmosphere.  For example, the top of the clouds will merely replace the ground as the blackbody radiator.  This is because convection and water evaporation are  valves that offset CO2-global-warming-by-absorption.



Where the absorption valley bottoms out in the graph of greenhouse gas absorption represents the height that the emission takes place.  Even with 10,000ppm of CO2 in the air the temperature line that the valley bottoms out at is the same because there is saturation for CO2 absorption/emission even at 375ppm; the valley just broadens with more greenhouse gas it doesn't deepen.



What you get is the bottom of the valley, no matter the greenhouse gas concentration, follows the temperature gradient for that height of emission (green line above).



5 km looking down:

6.  Iout, W / m2 = 395.012

Ground T, K = 299.70

Sensor altitude = 5 km

Looking down, no clouds, no humidity, tropical latitude

CO2 375ppm:




At 5km the width of the valley is already at what it is at 70 km looking down (test run 1) while the bottom of the absorption valley is near the temperature for 5km altitude.



The knee of the temperature graph is about at 17 km in the modtran model.  This gives the lowest, deepest value for the valley because the air is at its lowest temperature at that height.

7.  Iout, W / m2 = 347.284
Ground T, K = 299.70
Sensor altitude = 17 km
Looking down, no clouds, no humidity, tropical latitude
CO2 375ppm:


Moving up again in altitude raises the bottom of that valley to the temp at the height above 17km:

8.  Iout, W / m2 = 345.4

Ground T, K = 299.70

Sensor altitude = 40 km

Looking down, no clouds, no humidity, tropical latitude

CO2 375ppm:




With the atmosphere thinning out above that height the EMR pretty much stays constant with height after about 35 km.



But it's interesting that above the 17km temperature knee in the modtran model despite the presence of CO2 the emission increases with altitude for about 18 km (from 17 to 35 km altitude).  Thus showing that CO2 is a good emitter.



Above the altitude at which convection and adiabatic cooling dominates (which is the troposphere) CO2 assists the emission of EMR to space.



Over Antarctica on a very cold day (I tweaked it to the record -89C!) you can see that even if the ground gets cold CO2 is still emitting more warmly than the ground:

9.  Iout, W / m2 = 73.036

Ground T, C = -89

Sensor altitude = 70 km

Looking down, no clouds, no humidity, arctic latitude

CO2 375ppm:


Notice how the top of the hill which replaces the valley in previous graphs is near that same yellow 220K blackbody line that the valley bottomed out at even though the ground is at -89C?  The emission temperature of the CO2 is the same regardless of the ground temperature.



(One could argue that I am pushing the limit of the modtran model above with this, although I did find this graph (from here) with a similar emission shape to test run 9.)



And, as well as its increased emissivity, due to the increased adiabatic cooling rate of CO2 compared to O2 and N2 it may offset the slight warming of the lower atmosphere to provide a net cooling effect.  At least one model in agreement with this is here: THE “GREENHOUSE” EFFECT.


With the cooler atmosphere backradiating less longwave radiation than is outbound you could say that heat loss is slowed down by a lower flux of EMR.  The IPCC predicts a modest warming of 1C for a doubling of CO2.  



But  daily fluctuations of 50C or more in some places make no difference to the sign of, or above a certain height the magnitude of, the vertical temperature gradient.  It shows that convection and evaporation of water convey more heat in the troposphere than EMR and therefore neutralise the slight greenhouse warming in the very lower portion.



In conclusion, whatever greenhouse warming there is it still won't make the earth as a whole warmer than it would be otherwise because the greenhouse effect can't can't generate extra energy or a higher temperature like a lowered emissivity can.  Whatever slight warming there is all washes out in the mix compared to daily and seasonal temperatures which vary widely. 



If this negative temperature gradient didn't dominate so over greenhouse warming there would be a hot spot such as explained on the JoNova website.



Energy blocking and reabsorbing is not a mechanism of storing energy nor of increased temperature.  The reason for what creates the negative vertical temperature gradient and the supposed 33C warming is to be explored in a follow-up post.


































Rabu, 11 Agustus 2010

Greenland is not melting

A 20km-wide iceberg broke off a Greenland ice shelf recently.  It has been used by the media as a powerful emblem in their coverage of global warming.  But there's a huge irony here.  Because, if anything, a larger iceberg is indicative of more snowfall and greater ice mass rather than warming temperature -- more snow and ice making for a faster flow and huger ice blocks.  Warmer temperatures would cause the opposite to this, with the ice receding, and hence less ice for breaking off into big chunks. 







(photo via Watts Up With That.)



The iceberg broke off in an inlet of water of the Arctic Sea in the north of Greenland.  It is a piece of ice shelf; a tongue of ice that floats over seawater supplied by the mass of land ice behind it.  It is more melted and dissipated by sea water than by air temperature.  From wiki:
"...Rough mass balance estimates using these scales suggest that about 80% of its mass is lost as basal meltwater..."
Therefore, if it is breaking off huge chunks it's more likely to mean that the ice is moving faster and not having time to melt into the sea.  Please don't be alarmed, though, by the fact that it is "moving faster".  This sort of change is more likely to be caused by more snow accumulation, not "melting" as interpreted by the alarmist media.



The ice shelf normally creeps forward at around 1km per year.  But, this varies and it has been going faster for a number of years.



Government-sponsored science prefers to focus on the slight increase in melting at the edges of Greenland during the warming of the late 20th century:







There are wild claims of ice loss in Greenland.  But these focus on the extra melting caused by warmth and ignore the extra snow accumulation on top.  As I show below there's more snowfall during warmer periods. 



The Greenland ice sheet was gaining mass according to satellite altimetry up to the year 2003:







There is newer satellite data from NASA from 2003 that contradict the older results up to 2003.  Given NASA's tweaking of the ERBE satellite results and GISS's upward tweaking of land temps I wouldn't trust them on these latest Greenland ice loss claims.



As I said above: a bigger iceberg should imply more snowfall, not global warming.  Having said that though, break-offs can be influenced by any number of local conditions such as ocean currents and ocean temperature and wind.



Temperatures are actually cooling the last few years on Greenland (1,2,3) and this will slow the ice melt.



Prior to these last 3 years of cooling, during the warmer period of the 1990's and early 2000's, the Greenland ice sheet was affected by warming temperatures, causing it to lose mass at the edges and gain it in the middle.







This is to be expected for a slight warming: more melting (ablation) around the edges and more precipitation on top in the form of snow.



When it comes to glacier flow it's important to recognize that ice is a thermal insulator.  The bottom layer and all layers on top except for the very top-most layer are immune to air temperatures.



The two main things that can make a glacier flow faster are increased ice mass and geothermal heat.   A minor influence can come from plate tectonics like earthquakes and volcanoes.  It is also possible that with enough liquid precipitation or melting, streams of water can have an influence.



But, Greenland is so cold there isn't much meltwater or rain except in summer and even then not enough to endanger it.  And, in any case Greenland isn't as vulnerable to liquid water streams as, say, equatorial glaciers for reasons explained presently.



There are two types of glacier, warm and cold.  Warm glaciers occur in the tropics and temperate regions.  Mountain glaciers in New Zealand are a good example of a warm glacier.  Warm glaciers move faster and are possibly more affected by liquid rain and meltwater.  This is because the core temperatures in warm glaciers are closer to 0C -- the freezing point of water.   The warmer ice has lower viscosity and the warmer air temperatures can sublimate the ice quicker, so they are more vulnerable to climate change.



By contrast, in cold glaciers like Greenland and Antarctica the ice moves more slowly, has less heat for lubrication, and is less susceptible to the spreading of liquid streams.



(Picture from Daily Mail)



The property of being a warm or cold glacier occurs as it is being formed.  If it is formed under cold conditions, for example, it will still be a cold glacier even if the air temperature outside was to suddenly increase.  This due to the insulating effect of ice.



A glacier is not going to melt from the bottom up even if there is a bit of liquid (in the form of water) conveying heat to parts of it underneath its surface.



AGW scientists claim that the water from the moulins can spread across the bottom of the ice sheet and lubricate its movement.







I'm no glaciologist but I don't see how this sheeting of water at the bottom can occur.  Surely if the water was somehow able to sheet across the bottom it would refreeze under the intense cold and pressure.



Glaciers move forward through viscous flow not by lubrication from water.  (Video here.)





The intense pressure causes the normally solid ice to act viscously like a fluid.  Heat can lubricate this flow by making the solid ice less viscous.  Liquid is not required to lubricate glaciers to make them move.  In any case the liquid water wouldn't lubricate due to the intense pressure from the ice.  Water does not act like a lubricant under these conditions.  (Just on that point, an ice skater doesn't glide over the ice by melting the ice under the blade of the skate but rather, because the solid ice transforms viscously under pressure and allows such movement.)



The glacier is just as frozen on the bottom as it is in the middle (aside from a slight warming due to geothermal heat -- see graph below). And Greenland sits in a basin making the bottom of the ice sheet below sea-level.  Even if you could lubricate the bottom through heat from the atmosphere or water it would still not flow uphill!












So, the scientists' claims of global warming causing a surging in the glacier flow are not true.  It's  mainly extra ice mass from snowfall and other factors that cause the surging.



Coming back to the insulating property of ice, it is such a good insulator that it retains traces of the physical temperature from thousands of years ago.  It takes hundreds or thousands of years for atmospheric temperature changes to be reflected deep down.  A sudden increase will not melt them!



This NASA webpage shows how the physical temperature influence of the air at the time of deposition is retained in the ice for thousands of years in Greenland.  It's not going to melt anytime soon even if air temps go up!









Greenland and Antarctica are secure in their position inside the polar circles.  The large land ice sheets of the last ice age in Canada and Eurasia outside the Arctic Circle melted away thousands of years ago.









The Holocene period has been mostly warmer than today for 12,000 years.  If Greenland and Antarctica were going to melt they would have done so by now.  The Medieval Warm Period would have melted them.  The Roman Thermal Optimum would have melted them. But they didn't.



A Penn State colleague of Michael Mann, Richard Alley, recently testified to the US Congress that a 2 - 7C temp increase could melt Greenland's ice in a matter of decades flooding the world.  This is an unbelievable distortion.



Following is a graph which shows why we need not fear warming melting the polar ice caps.  For warmth has the effect of increasing the precipitation on the ice sheets:







(From webpage here.  By the way, this graph is from the same Richard Alley mentioned above that testified to Congress that a 2 - 7C temp increase would melt Greenland!  Of all people he should know better -- that warmth increases the snow and hence the ice sheet!!)



Greenland and Antarctica basically operate at ice load saturation.  They have as much ice as they will hold with the excess creeping forward and breaking off into the sea, such as we see presently with this Greenland ice calve.



With Greenland and Antarctica safely tucked within their polar circles warmth can only increase the ice mass (due to precipitation), not decrease it as the above graph shows.  With average temperatures in the Arctic and Antarctic well below freezing, a 2C temperature increase is not going to melt all that ice anyway. Greenland creates its own zone of cool temperature that carries through even in the summer months:





Antarctica's ice sheets are secure even if there were to be a few degrees temperature rise in air.







Glaciers are the product of an ever-changing equilibrium between ice loss at the edge and ice gain on top from snow.





As long as the snowfall continues to rise when it gets warm as it has in the past Greenland will not melt and Al Gore won't have to sell his recently acquired California beachfront property!