Guest essay by Jan Kjetil Andersen
As Willis describes in his article on December 21, the atmosphere can be seen as a gigantic heat engine, i.e. a machine which convert thermal energy, namely temperature, into mechanical energy, namely wind.
It may seem a bit strange to view the weather system as a kind of machine and compare it with engineered constructs like an automobile engine, but it is sound physics because all such systems are bound by the same fundamental physical laws and they utilizes the same basic phenomena to create movement from heat.
A heat engine cannot convert heat directly to mechanical energy since that would break the second law of thermodynamics. What are needed are temperature differences. The greater temperature difference the greater effect of the machine. The amount of the energy in the temperature difference that is converted to mechanical energy is called the machines efficiency.
And here we have a very interesting, but less known fact of heat engines; the maximum theoretical efficiency decreases with increasing temperatures. This is interesting because it negates the conventional wisdom and often cited myth that a warmer climate leads to
more storminess, like the claim in the Guardian “a warmer planet has more energy to power stronger storms”, see http://www.theguardian.com/environment/2011/jun/27/climate-change-extreme-weather-2010.
Let us therefore take a look at the theoretical foundation of this effect. This is described by Carnot’s theorem.
Carnot’s Theorem says that the maximum efficiency drawn from a heat engine is the temperature difference between the warmest element and the coldest element divided by the temperature of the highest element.
Expressed as a formula it says: Emax = (Th-Tc)/Th.
Emax is the maximum efficiency
Th is the high temperature element measured in Kelvin
Tc is the cold temperature element measured in Kelvin.
The Carnot cycle is an ideal reversible cyclic process involving the expansion and compression of an ideal gas, which enables us to evaluate the efficiency of an engine utilizing this cycle.
For an interactive demonstration of the Carnot heat engine cycle, courtesy of the University of Virginia, click on the image:
Three important effects can be seen from Carnot’s theorem. The first is that a temperature difference is a necessary condition for converting heat energy to mechanical energy such as wind.
The second effect is that even if we had a perfect heat engine with zero internal friction; it would not achieve anything close to 100% efficiency. The maximum theoretical efficiency for a heat engine operating between 300 K and 600K is for example 50%. The efficiency of a real machine would of cause be considerably lower.
This is why our car engines only operate at about 25% efficiency. The warm element for a car engine is the exploding fuel inside the cylinders and the cold element is the air intake.
The best coal fired power plants have about 40% efficiency and the best gas powered about 55%. The cold elements for those plants are the coolant water, and those with highest efficiency utilize cold seawater as coolant.
Warming gives less efficiency
The third effect is as mentioned above, that, for a given temperature difference between the warm element and the cold element, the efficiency will decrease if both elements heat equally much. On cold days one can see a discernible effect of this in car engines; because the air intake is colder, the engine gives somewhat more power and higher efficiency.
This is also why some turbo charged engines have intercoolers. The turbo gives higher effect, but a non-intentional side effect is that it also increases the temperature in the air intake which will reduce the efficiency. The intercooler reduces the temperature increase introduced by the turbo.
The same effect applies to the wind formations in the atmosphere. Consider the summer temperature in the northern hemisphere; the cold element is the Arctic with a temperature of approximately 0 Celsius and the warm element is in the tropics with approximately 35 Celsius.
The Carnot theorem gives a maximum efficiency in this temperature range of 11.36%. If the temperature increased with 1 Celsius all over the globe, i.e. the difference changed to 1 Celsius in the Arctic and 36 Celsius in the tropic, the maximum efficiency would sink to 11.32%.
This is a minuscule difference, but the point is that it is a decrease, not an increase as the conventional wisdom will have it.
Less temperature differences on the surface
In addition to the effect of higher overall temperatures, the temperature differences will also be smaller. It is quite uncontroversial that the largest effect of global warming is on the cold polar winters and the smallest on the hot tropical summers.
![GFDL_CM2p1_SfcTemp_JJA_DJF_A1B_wht3200x2000[1]](http://wattsupwiththat.files.wordpress.com/2013/12/gfdl_cm2p1_sfctemp_jja_djf_a1b_wht3200x20001.png?quality=75)
However, to be fair, this is not all there is to this. Some climate models tell that the temperature differences in the upper troposphere will increase and this may have larger effect than both the reduced differences on the surface and the higher temperatures.
No settled science there.
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phlogiston says:
December 28, 2013 at 10:23 pm
“The idea that radiative (or any other) cooling is needed to drive air down in Hadley circulation makes no sense.”
——————————————————————————————-
Actually, prior to the inanity of the failed global warming hypothesis, it used to be rather standard meteorology –
“Air convected to the top of the troposphere in the ITCZ has a very high potential temperature, due to latent heat release during ascent in hot towers. Air spreading out at higher levels also tends to have low relative humidity, because of moisture losses by precipitation. As this dry upper air drifts polewards, its potential temperature gradually falls due to longwave radiative losses to space (this is a diabatic process, involving exchanges of energy between the air mass and its environment). Decreasing potential temperature leads to an increase in density, upsetting the hydrostatic balance and initiating subsidence.”
A huge political effort was put into keeping the findings of the first IPCC report ambiguous. After 1990 a great amount of work was put into saving global warming. This included inventing “strongly positive water vapour feed back”, erasing the MWP that disproved it and cooking up radiative-convective circulation models that negated the role of radiative gases in driving vertical tropospheric circulation.
Phlogiston, instead of siding with Kevin E. Trenberth and claiming no role for radiative gases in tropospheric convective circulation, perhaps you should be asking why climate “scientists” were so desperate to trash working meteorology theory.
Mario Lento says:
December 28, 2013 at 7:19 pm
Thank you for the correction and good explanation Mario.
/ Jan
Matt G says:
December 28, 2013 at 4:55 pm
TB says:
December 28, 2013 at 4:23 pm
“No, not always, in jet disruption processes the jet can move E>W under a warm High in an Omega-block as deep cold air is advected west beneath. This is a common cause of the UK’s coldest winter events.”
I agree that some of time little jets may wander E>W, but virtually always W>E.normally.
Even during one of the most severe cold spells in the UK for decades at the time of year..
http://www.wetterzentrale.de/pics/archive/ra/2010/Rrea00120101201.gif
The jet hardly moved E>W.
http://virga.sfsu.edu/archive/jetstream/jetstream_atl/big/1012/10120106_jetstream_atl_anal.gif
The key component along with thermal gradient causing the jet stream, is cold very dry air meeting warm moist air.
The link before gave an example of this especially moisture related, when the cool dry polar air reached the moisture of the Atlantic ocean, but itself not warmer than the land masses to the West or East of it. that didn’t have a jet, but had relatively dry air.
http://virga.sfsu.edu/archive/jetstream/jetstream_atl/big/1307/13070406_jetstream_atl_anal.gif
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Matt:
We are nitpicking here, but the example you link is not a very good one as the High has become filled with colder air – there needs to be more “orange” over Scandinavia A warmer core. And I never said it would be as strong as a 200KT Atlantic jet. I also said a jet forms when air flows from warm to cold aloft. Therefore in any contortion in the flow (cut-off cold air low, say) there will be accentuated flow around the “contortion”.
You talk of another factor when you mention cold dry/very moist. That is warm advection overgliding the cold and releasing LH. It is part of the Omega equation and is a prime drive of development for baroclinic waves.
Konrad says:
December 29, 2013 at 12:16 am
phlogiston says:
December 28, 2013 at 10:23 pm
“The idea that radiative (or any other) cooling is needed to drive air down in Hadley circulation makes no sense.”
——————————————————————————————-
Actually, prior to the inanity of the failed global warming hypothesis, it used to be rather standard meteorology –
“Air convected to the top of the troposphere in the ITCZ has a very high potential temperature, due to latent heat release during ascent in hot towers. Air spreading out at higher levels also tends to have low relative humidity, because of moisture losses by precipitation. As this dry upper air drifts polewards, its potential temperature gradually falls due to longwave radiative losses to space (this is a diabatic process, involving exchanges of energy between the air mass and its environment). Decreasing potential temperature leads to an increase in density, upsetting the hydrostatic balance and initiating subsidence.”
A huge political effort was put into keeping the findings of the first IPCC report ambiguous. After 1990 a great amount of work was put into saving global warming. This included inventing “strongly positive water vapour feed back”, erasing the MWP that disproved it and cooking up radiative-convective circulation models that negated the role of radiative gases in driving vertical tropospheric circulation.
Phlogiston, instead of siding with Kevin E. Trenberth and claiming no role for radiative gases in tropospheric convective circulation, perhaps you should be asking why climate “scientists” were so desperate to trash working meteorology theory.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Konrad:
I have discussed this with you on another thread I believe.
It seems you still do not appreciate the effect of mass air convergence aloft a Hadley Cell.
As air moving N will converge to a westerly Sub-tropical jet and sink as a result. (Err has too!)
Radiative cooling is NOT needed. It happens but that is not the driver.
The radiative cooling will be offset by subsidence warming anyway.
And this: “Actually, prior to the inanity of the failed global warming hypothesis, it used to be rather standard meteorology”
Did not get a mention in my professional training my friend.
As I’ve told you before and provided links to the mathematics of it.
This reminds me of the BBC’s orbit documentary (Which, in later episodes which I did not see, apparently attributes this to AGW). This “engine” does not seem to be driven by CO2.
As for the engine comments, yes cold, denser air makes them run better (volumetric efficiency – nonturbo). That’s why, on a cold, damp morning, a nice twin carb’d 6cyl engine in say a Triumph GT6 runs and sounds GREAT!
norah4you says:
December 28, 2013 at 7:13 pm
Which data? I have only presented a model and some examples.
There are no climate data in my article.
/ Jan
TB’s first comment was quite sciency but contains numerous conceptually errors and I was pleased several people took them on. I don’t have time to address them all but I will note that “storminess’ is not increased by raising the average temperature of the system. The simplest demonstration of this is the terrible and powerful storms that occur on very cold planets within our solar system.
I will take issue in more detail with the version of the Carnot Cycle as a model for the heat engine that is the atmosphere. As I see it, the explanation of an ideal cycle is fine but misleading enough to lead many into blind alleys. There is no point debating how ideal dry gases behave when the atmosphere is full of evaporable and condensible water. Rising currents of damp air harvest moisture out of the air parcels into which they rise and cool. It doesn’t have to be at any particular altitude or temperature.
The speed of rising is determined by the relative temperature of the rising parcel and the stationary air medium. Increasing the system temperature increases the enthalpy but does not increase “the power of the storm” as claimed by the Guardian. People’s homes are not blown flat by enthalpy. The silliness of the Guardian’s position is enduring testimony to the fact their science writers can’t read. Their African version is called “The Mail and Guardian”. It is advertised as ‘Africa’s best read’. Well, it is not Africa’s best write. Given the litany of insults they have hurled against scientists who actually know what they are talking about they are richly deserving of the exposure given them here.
From a physical point of view the Earth is a closed system, for all intents. From an energy point of view it is an open system. The whole planet can cool and die and sometimes it nearly does. As for its upper temperature it is strongly self-regulating with the aforementioned water vapour as the principal factor, as well as ozone and to lesser extents GCR’s and CO2. These control mechanisms easily reach 40 or 50 watts per square metre. A sustained drop of 20 watts reaching the surface initiates an ice age.
Self-regulating heat pumps or heat engines, if you will, occur throughout nature and according to their size they behave in characteristic ways. The speed at which they operate is always optimal meaning at maximum efficiency balanced on the edge of turbulent flow. I think Prof Adrian Bejan, author of dozens of articles and textbooks on convective heat transfer, would be surprised to hear that the efficiency with which the Earth dispenses with heat drops as the temperature rises. The temperature of the cold side is constant. Why all these red herrings?
Wiliis has ably demonstrated the tropical albedo and thunderstorm cooling effects that Bejan pointed to when he stooped to comment on the trivial matter of how the atmospheric heat engine works. It is indeed a Carnot Cycle with un-ideal gases and some chaotic wind thrown in. Doubling the CO2 concentration, which could happen naturally, will not measurably change a thing. At least not with the network of instruments we have now.
TB says:
December 28, 2013 at 9:35 am
I am not saying that the climate is a Carnot engine. No such engine exists because the Carnot engine is only a concept for an ideal heat engine. But the point is that all such mechanisms which convert differences in heat into mechanical energy have to obey the same fundamental physical laws. The Carnot theorem is fundamental because it is a direct consequence of the second law of thermodynamics.
Whether it is two or more sources and sinks does not matter, if it helps one can also imagine that the climate system is modeled by a zillion microscopic heat engines, the concept is the same.
By showing that a Carnot engine has less efficiency when all temperatures are risen equally much, then I will argue that one can assume that a real heat engine working on the same temperature ranges should also have less efficiency if all other data is considered to be unchanged.
You may say that the last assumption will be wrong, and yes, as I have written above, they will not be unchanged; we can assume that the cold areas of the planet will heat more than the warm areas, but that will only reduce the efficiency of the heat engine further.
/ Jan
TB says:
December 29, 2013 at 1:29 am
“Konrad: I have discussed this with you on another thread I believe.”
—————————————————————————————-
Yes TB, I believe you have…
You claimed that vertical tropospheric circulation strong enough to generate the observed lapse rate would exist in the absence of radiative cooling at altitude because –
“A natural lapse rate will develop regardless of atmospheric radiative responses. Due differential latitudinal heating > frictional turbulence > convection > overturning > geopotential height gradient > Coriolis > adiabatic cooling/heating – creating a heat pump and warming the lower layers/cooling aloft. Radiation is NOT needed. Models know this.”
I stand by my response –
“I would suggest that you have left out wizards, unicorns and climate “scientists” frantically waving their hands trying to drive megatonnes of gas in a giant flow from surface to 15Km altitude and back.”
“Out of your depth on a wet pavement” doesn’t really cover it. How about “so far out of your depth the fish have lights on their noses”?
Might I suggest that “pwned” would be an elegant sufficiency…?
chris y says:
December 28, 2013 at 10:54 am
Here you only rise the temperature for the warm element and let the cold temperatures remain unchanged. Of cause the wind will increase then, you need no model to understand that, but no one believe that only the warm parts of the planet will heat up.
This is a more realistic scenario which confirms what the article says.
No, because the Carnot theorem is a fundamental principle, it will always apply when heat differences are converted to mechanical energy. How can you claim that it apply if you change the temperature by 1 C as in your point 1 and 2 above, but not when you change it with 5 C?
/ Jan
Konrad,
You can get an isothermal structure in a tall glass column if vertical circulation is constrained.
You cannot get it for a rough surfaced rotating sphere illuminated from a point source.
It is not necessary for the conduction air to a colder surface to achieve net warming of that surface
All that is necessary is:
i) A surplus of incoming radiation over outgoing radiation where illumination is full on. The disparity being caused by conduction to the air.
ii) A reduction in the rate of outgoing radiation elsewhere to a level lower than would have been the case for a surface with no atmosphere. The disparity being caused by the insulating effect of adiabaically warmed descending air.
The energy engaged does not have to be large because the bulk of energy passing through is undisturbed.
All that is necessary is that there be SOME diversion of energy throughput via conduction to the convective overturning and whatever the amount of that diversion the average global surface temperature will rise proportionately.
On Earth that is about 33 C.
That proportion is determined by mass and not radiative capability.
gbaikie says:
December 28, 2013 at 10:50 pm
This was a really original and funny idea gbaikie, I enjoyed reading it.
Much of what you say is correct, but unfortunately it will not work. However, I think this is an excellent problem for physics or math students, let them try to figure out why this will not work.
Well, the answer is that you will have to accelerate not only the rocket but also the column of water inside the cylinder below the rocket. The mass of that water column will increase with the length of the pipe and will limit the launching speed of the rocket considerably. I have not done the math, but I will guess it will be less than 100 mph.
/ Jan
Col Mosby says:
December 28, 2013 at 9:28 am
Col, you are right, more dense air is also an effect of colder air and this will also give higher effect . But the principles of the Carnot theorem also apply. The source of the work comes from the increased pressure inside the cylinder. The pressure builds up because the temperature increases, and most of the temperature increases is caused by burning fuel inside the cylinder.
You can see from the ideal gas laws that if the temperature starts at a higher level you get lower increase in the pressure for a given increase in the temperature.
Thank you for the comment
/ Jan
Stephen Wilde says:
December 29, 2013 at 3:42 am
“…you can get an isothermal structure in a tall glass column if vertical circulation is constrained”
Glass?!
While I may use silica micro spheres vacuum packed in vacuum metallised mylar in the original experiments, due to inhalation risk I only provide instruction for replication using EPS foam.
AGW believers may be trying to build these things!
Everybody take out a circle of paper and a safety crayon….
Sorry, a typo. Don’t know where it came from.
Konrad, this is what you said and I mistyped.
“In tall gas columns,”
tobyw says:
December 28, 2013 at 5:48 pm
Toby, there are tidal energy heating our planet, but it is negligible compared to the solar heating.
The source of the tidal energy is the earth rotation. Because the earth is not perfectly elastic, some of the gravitational stretching from the moon and sun is converted to heat. This slows the earth rotation.
Since we know that the earth rotation slows very gradually, the tidal energy released each year has to be very small compared to the rotational energy of the earth.
/ Jan
Konrad says: “Coriolis forces are not a driver of atmospheric circulation. Coriolis forces have no influence on air masses at rest within a rotating reference frame.”
Oh, bad call. You would be right if the atmosphere was perfectly homogeneous, but of course it’s full of local variations like changes in pressure, clouds, etc. These inhomogeneities want to travel in great circles over the Earth (what we surface-dwellers would call “straight lines”), but the Earth’s rotation follows a great circle only at the equator — elsewhere, the rotation is seen as having a lateral shear as it follows a small circle. A high-density air mass is pushed to the left in the Northern Hemisphere (to higher-latitude, slower-rotating places), so travel leftwards around the low-pressure cores of hurricanes — so counter-clockwise in the NH. So the Coriolis force is a terrific driver of winds as it “grabs” all the inhomogeneities in the air and forces them into motion.
The atmosphere, absent external energy sources, would become isothermal (the same temperature from top to bottom) despite the density gradient imposed by gravity.
The dry lapse rate of 9.8 C/km is largely created by the thermalization of IR radiation by the greenhouse gases. Increasing the concentration of GHG’s increases the rate at which the 9.8 C/km is arrived at.
The environmental lapse rate of 6.5 C/km is caused by convection (and water vapors phase change) resulting in a warmer atmosphere than one with GHG’s alone (absent water of course ).
The question I have is what temperature would a pure nitrogen (no GHG’s or H2O) atmosphere be, given the ocean surface temperature of 22 C?
noaaprogrammer says:
December 28, 2013 at 5:00 pm
noaaprogrammer
Good question.
Atmospheric tides are regular oscillations in the atmosphere which can result in mechanical energy such as wind.
These tides are a phenomenon with very different sources. Some of the tides are generated by the periodic heating of the atmosphere by the Sun. The atmosphere is heated during the day and not heated at night. This effect is similar to a heat engine as discussed in this article.
However, atmospheric tides are also powered by the gravitational pull of the Moon and the Sun similar to ordinary tides. This is a source for mechanical energy that is not powered by a heat engine. The source is the rotational energy of the earth.
This means that some of the mechanical energy in the weather system is not created by a heat engine, but it is a very small part.
/ Jan
Jan- you say:
“No, because the Carnot theorem is a fundamental principle, it will always apply when heat differences are converted to mechanical energy.”
Agreed 100%.
Jan again- “How can you claim that it apply if you change the temperature by 1 C as in your point 1 and 2 above, but not when you change it with 5 C?”
My third point is that real world cyclones can have 100’s of percent increases in wind speed in response to a sea surface temperature increase (5C for example) that the Carnot model predicts should only give a few percent increase in wind speed. Yet the cyclone expert at MIT uses the Carnot cycle to model a cyclone, even though the results of the analysis are basically worthless.
The Carnot cycle is not a useful model when used to estimate cyclone wind speeds and/or the effects of global warming on cyclone wind speed.
own-gbaikie says:
December 28, 2013 at 10:50 pm
Ah, I wonder if this would apply to what I call a pipelauncher.
This was a really original and funny idea gbaikie, I enjoyed reading it.-
I am glad you found it amusing.
*Much of what you say is correct, but unfortunately it will not work. However, I think this is an excellent problem for physics or math students, let them try to figure out why this will not work.*
Such results I would find extremely interesting.
“Well, the answer is that you will have to accelerate not only the rocket but also the column of water inside the cylinder below the rocket.”
It’s like the scotty quote from star trek.
No the water doesn’t move [assuming acceleration is constant].
So water after one starts some accelerate [say 1 gee] then after this water inside pipe doesn’t move-the pipe moves pass it.
-The mass of that water column will increase with the length of the pipe and will limit the launching speed of the rocket considerably. I have not done the math, but I will guess it will be less than 100 mph.-
It seems it would have limit due to nature of water- things have problems going over speed of sound in water. So near terms I tend to think max speed would be around 300 mph.
As first type of it’s kind probably realistic to shoot for max of about 200 mph.
But I it could over time be developed so one was getting up to speed of sound. But don’t expect
supersonic speeds without running across unexpected problem. And it gets progressive
harder to do such speeds- particularly if gee have to be 1 or less gees of acceleration.
And if going to go as fast as 200 mph, this pipelauncher would leap a distance out of the water, unless one adds some sort of braking featues.
But one think if not in windy conditions, one have bottom of pipe leave the water by somewhere
around say 100 feet or so.
Also if column water pushed down is say 50, as soon bottom of pipe was 50 feet from the surface
one can’t accellerate, so one could decrease acceleration near the top so you not pushing water down to 50- say lower acceleration so it was instead 20 feet [or something like that.
If want to be fancy, you make that water leap up into the air after the rocket. Or you make to column of water accelerate, somewhat Such a “move” could used to help brake the rocket by some amount- [but too much vacuum] and it could crush the pipe- which would be bad.
Many people have said that 100 or 300 mph isn’t not significant for rocket which ulitimately travels 17,000 mph. But there are reason why couple hundred miles hour would significantly improve a rockets proformance. So like add, say 20% to it’s payload.
Crispin in Waterloo says:
December 29, 2013 at 2:52 am
“TB’s first comment was quite sciency but contains numerous conceptually errors and I was pleased several people took them on. I don’t have time to address them all but I will note that “storminess’ is not increased by raising the average temperature of the system. The simplest demonstration of this is the terrible and powerful storms that occur on very cold planets within our solar system.”
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>That, I believe, is because they generate internal heat, as well as having much different chemistry (and density/pressure boundaries as a result) : http://en.wikipedia.org/wiki/Jupiter
“Jupiter still radiates more heat than it receives from the Sun; the amount of heat produced inside the planet is similar to the total solar radiation it receives. This additional heat radiation is generated by the Kelvin–Helmholtz mechanism through contraction. This process results in the planet shrinking by about 2 cm each year.”
“The water clouds can form thunderstorms driven by the heat rising from the interior.”
“The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries.”
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
“The speed of rising is determined by the relative temperature of the rising parcel and the stationary air medium. Increasing the system temperature increases the enthalpy but does not increase “the power of the storm” as claimed by the Guardian. People’s homes are not blown flat by enthalpy. The silliness of the Guardian’s position is enduring testimony to the fact their science writers can’t read. Their African version is called “The Mail and Guardian”. It is advertised as ‘Africa’s best read’. Well, it is not Africa’s best write. Given the litany of insults they have hurled against scientists who actually know what they are talking about they are richly deserving of the exposure given them here.”
It does increase the power of the storm in the way that I described – but will do so again. You talk of moist air, well the strength of rising thermals has another driver – LH. This is where the extra energy will come from. Warmer air simply allows greater evaporation and can physically hold more WV molecules – hence more LH of condensation released aloft in cloud to fuel it’s growth/uplift (or Typhoon/hurricane development ) – all other things equal.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
“From a physical point of view the Earth is a closed system, for all intents. From an energy point of view it is an open system. The whole planet can cool and die and sometimes it nearly does. As for its upper temperature it is strongly self-regulating with the aforementioned water vapour as the principal factor, as well as ozone and to lesser extents GCR’s and CO2. These control mechanisms easily reach 40 or 50 watts per square metre. A sustained drop of 20 watts reaching the surface initiates an ice age.”
GCR’s can’t, that I’m aware of, as they do not in any large number pass into the Trop, they are largely stopped by O3 in the Strat. A paper would be appreciated. Yes, an IA will be initiated via feed-back loop as the Earth’s NH progressively received less summer insolation and snow fields can survive through until the next winter. This increases albedo, lowers absorbed SW and allows CO2 to sink into cooling oceans. WV content additionally lowers with temp to give a triple whammy.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
“Wiliis has ably demonstrated the tropical albedo and thunderstorm cooling effects that Bejan pointed to when he stooped to comment on the trivial matter of how the atmospheric heat engine works. It is indeed a Carnot Cycle with un-ideal gases and some chaotic wind thrown in. Doubling the CO2 concentration, which could happen naturally, will not measurably change a thing. At least not with the network of instruments we have now.”
I beg to differ that Willis demonstrated anything that wasn’t known already and the region he speaks of, though receiving max insolation, isn’t anywhere near large enough to regulate the Earth’s temp. Or he hasn’t quantified it as yet to my knowledge to prove such a case. I have posted links to papers that have concluded that SW reflected is near balanced by IR back-radiated over much of the tropical equator.
CO2 doubling’s effect has been known of via laboratory and empirical demonstration + mathematical theory for ~150 years. And there are spectrometer readings taken from ground-based instruments that indeed do measure it’s effect. As well as satellite measurement showing the radiative imbalance at TOA. More is coming in than leaving.
Max Hugoson says:
December 28, 2013 at 10:49 am
Max, take a look at what happens inside the cylinder if we use the laws of an ideal gas
PH = (TH/TL)*PL
PH = high pressure after the fuel has burnt
PL = pressure before the burning
TH = Temperature in the cylinder after the fuel has burnt
TL=Temperature in the cylinder before the fuel has burnt
Let’s assume that the burning will rise the temperature by 500K
Let’s assume a cold day is TL = 300 K and a warm day it is 350K
On a cold day you then have PH= 800/300*PL = 2.67*PL
On a warm day you have PH = 850/350 * PL = 2.44*PL
That means you get a higher pressure, which gives more effect a cold day. The energy used is the same, in both cases it rise the temperature with 500K, but you get more effect out of it when you start with a colder gas.
/ Jan
A couple of ;nitpicks here…
Though I do like the article from a Mech E point of view…
The first one…
Climate as a heat engine
Posted on December 28, 2013 by Anthony Watts
Guest essay by Jan Kjetil Andersen
As Willis describes in his article on December 21, the atmosphere can be seen as a gigantic heat engine, i.e. a machine which convert thermal energy, namely temperature, into mechanical energy, namely wind.
I will disagree. You are forgetting about water. There is a huge amount energy released into space from the transport of warm water pole ward.
Also –
TB says:
December 28, 2013 at 9:35 am
Jan:
I know what you’re getting at.
But I feel the comparison of the Earth’s climate system with a Carnot engine is inappropriate.
….
To say that the earth will become “stormier” in a warmer world is (Meteorologically) correct. (supposing an unchanging LR). But there are exceptions.
A warmer world will have more evaporated water to release LH and therefore convective cells will have more power available to push up through the atmosphere to counter that LR. ..
The High Plains’ most violent weather occurs when delta t is greatest in the spring. As the atmosphere warms through the summer the severity of the storms decrease. Hence in late August through early October violent storms nearly die out and are replaced by long gentle rains until the atmosphere cools.
Look at a graph of storm intensity v time for a given year – it is two humped.
Also plotting some of the Carnot cycle on a T-S diagram might help some people.