Discussion > GHG Theory step by step
To validate my prediction that a planet with no greenhouse gases would have no troposphere we could really use a planet with an atmosphere, but no greenhouse gases. Offhand I can't think of a body like that in the solar system. Any candidates?
Jul 21, 2017 at 4:03 PM | Unregistered Commenter Entropic man
I thnk the purpose of this thread was to look at problems with Global Warming Theory on Earth.
An over reliance on unverifiable data from outer space does seem to be one of them
golf charlie
Golf Charlie
On the contrary, we are making progress.
We have shown that the lapse rate is mostly a gravity effect and is not directly caused by the greenhouse effect.
We have shown that there is a probable link between the % of greenhouse gases and the thickness ofthe troposphere.
This makes it more likely that one mechanism for global warming is valid ie. that extra greenhouse gases raise the tropopause and the extra thickness of the troposphere raises the equilibrium surface temperature.
Oh yes, if differences in greenhouse gas concentration change the behaviour of the atmosphere then there must BE a greenhouse effect.
Entropic man
Jul 21, 2017 at 6:11 PM | Entropic man
You state twice that "We have shown that ...", followed by ".. probable link..." then add something is " ..more likely..." and conclude with "Oh yes, if differences in greenhouse gas concentration change the behaviour of the atmosphere then there must BE a greenhouse effect."
Some of the physicists here, might want to comment on the assumptions based on presumptions, but I am not sure it answers the query raised in the Real Climate post about lapse rates
"The most favored explanation has been that the “lapse rate,” or decrease in temperature as you go up in the atmosphere, has actually been increasing. This would contradict all of our climate models and would spell trouble for our understanding of the atmosphere, especially in the tropics."
When you use "we", is that a representation of the consensus of Climate Science?
golf charlie
EM "From the numbers I gave earlier it looks like the dominant parameter determining lapse rate is gravity (presumably because it affects the pressure gradient)"
I think you mean magnitude of the LR.
Schrodinger's Cat may be after the current working hypothesis's cause of lapse rate. Andr any other hypothesis on that,
ssat
The pattern is the subject of a paper by Nikolov and Zeller, recently reviewed by Tallbloke on his site.
Schrodinger's Cat
Jul 22, 2017 at 10:40 AM | Schrodinger's Cat
this one?
https://tallbloke.wordpress.com/2017/06/01/foundations-of-greenhouse-theory-challenged-by-new-analysis-of-solar-system-observations/
golf charlie
Radical rodentThe implication being that you do, of course. Your pompous arrogance is showing through, yet again. Exponential can be diminishing as well as expanding, in which case, my extrapolating the data could well be a gross overestimation. (And, no, you cannot say, “Let’s leave it another 20 years, then we will know…” The ONLY way we will know will be in 2100. I’m prepared to wait; are you?)"The greatest shortcoming of the human race is our inability to understand the exponential function." —Albert Bartlett
Radical Rodent
Convection happens around a heat source in my bath, which AFAIK is lacking a tropopause or any GFGs. Convection of gas in an atmosphere will always have a lapse rate.
rhoda
And an atmosphere without a lapse rate will not have convection?
Yes and their working hypothesis stands?
No and it falls?
.ssat
Obviously, Entropic man, you do not read my posts. On the previous page (Jul 20, 2017 at 6:00 PM), I have explained what “lapse rate” is, and the difference between the two basic forms. Lapse rate is utterly independent of the presence or otherwise of greenhouse gases; in an atmosphere, it just IS. This does NOT mean that greenhouse gases, or otherwise, might not affect the value, but they are not the cause of lapse rates.
Radical Rodent
Ssat
"And an atmosphere without a lapse rate will not have convection?
Yes and their working hypothesis stands?
No and it falls?"
An atmosphere with a lapse rate becomes cooler with increasing altitude. A packet of warmer air surrounded by cooler air would be bouyant and rise, hence convection.
An atmosphere which becomes warmer with increasing altitude, such as the stratosphere, will have the opposite to a lapse rate. Convection will damp out because warm rising air will expand and cool. It will quickly reach a region with the same temperature and stop rising.
An atmosphere with no temperature gradient at all would have a constant temperature at all altitudes. Once again
convection would quickly damp out.
Occasionally a temperature inversion forms when a layer of warm air moves over cooler air. Convection is suppressed.
I think your answer is No. The hypothesis fails.
Entropic man
Radical rodent
I read your posts and enjoyed your description of the complex interaction between surface and lower atmosphere in deserts. Golf Charlie will be comforted by the knowledge that the lapse rate can vary with the composition of the atmosphere.
Having established that lapse rate is a measure of the temperature gradient, but not it's cause, the question becomes " Why is there a temperature gradient?"
Entropic man
Jul 23, 2017 at 12:04 AM | Entropic man
I am comforted by any serious attempt to examine evidence. Climate Science still spends too much time and other people'smoney trying to justify its own premature conclusions.
golf charlie
Why is there a temperature gradient?That, one would have thought, is quite simple, and was covered in a later post of mine (Jul 21, 2017 at 11:48 AM): the predominant heating of the atmosphere is by conduction from heated surfaces to adjacent air, and convection to disperse the heat through the atmosphere. (I shall ignore why you, Entropic man, should think that my earlier post was merely about what might be happening in deserts; quite why you should read it like that, I shall keep as a mystery.)
To rephrase that: the atmosphere closer to the surface is heated predominantly by conduction when in contact with the surface. The heated air is less dense, so rises; obeying the gas laws, it cools as the pressure reduces with altitude: however, the cooling is not entirely adiabatic – there will be some loss of energy into the surrounding atmosphere as the air rises, thus dispersing the energy into higher altitude air. Naturally, the rising air causes surrounding air to move laterally to replace it; thus a breeze is caused, and the lower-altitude air now also has this stirring to disperse the heat within that particular parcel. The air rising in a thermal will eventually lose sufficient energy, either to space, or the surrounding atmosphere, and will fall back to Earth again. On Earth, this actually happens in two separate circulatory systems, the thermals of the tropics rising to create the trade winds, of between the latitudes of around 20-30°; the “horse” latitudes around 35° being where the cooled air sinks back to Earth, heating the higher-latitude system as it does so, helping to create the “roaring forties” in the process (there is also the “furious fifties,” for those who have endured Cape Horn, but that is more complex, with the Earth not being a non-spinning, homogenous, smooth ball in space). The polar regions have a different circulatory system.
Thus, it can be seen that a temperature gradient is the result of predominantly solar activity, and the Earth’s gravity; the Earth’s spin will make the mix a lot more complex. There will be many, many other factors involved but these three factors will be the predominant drivers of the weather systems.
Radical Rodent
And an atmosphere without a lapse rate will not have convection?Yes and their working hypothesis stands?
No and it falls?
Jul 22, 2017 at 5:11 PM | Unregistered Commenter.ssat
A shorter answer than RR's, but if the model allows a spherical world similar to reality then the atmosphere will still be stirred because of the thermal difference between equator and poles driving expansion/contraction and thus turbulent transport between such regions, driven purely by surface contact.
(Not even any need to complicate the issue with the phase changes of the water cycle.)
michael hart
Mr Hart. Yes, moving from a world of averages does introduce differential heating and, of course, day/night. However, climate science has declared there is a greenhouse effect without which you would be 33 degrees cooler. For that, there must be a lapse rate. To argue against that there has to be a proof that a non-radiative atmosphere could produce that 33 degree difference.
Or alternatively, show why the Stefan-Boltzmann derived 255 degrees should be 288 degrees.
Not an easy couple of tasks.
.ssat
Radical rodent, Michael hart
I am mostly thinking of the thermodynamics of vertical temperature gradients.
Basic thermodynamics suggests that heat flows from hotter to colder. Thus each stable temperature gradient must have a heat source at the hot end and a heat sink at the cold end.
This is the temperature profile of the atmosphere.
There must be heat sources at the surface, 50 kilometres and120km. There must be heat sinks at 12km and 80km.
Any alternative physics you come up with has to explain this profile.
Particularly it must describe a mechanism which removes energy from the atmosphere at 12km, in your case without involving greenhouse gases.
Entropic man
EM, you are imposing rules which are not justified by the physics to make your case. In a non-radiative atmosphere the only way for heat to escape a sunlit planet is via radiation from the surface. How the gases arrange themselves is a matter for the gas laws, convection and gravity. NO heat sink is required.
rhoda
Entropic man: and you accept a graph that shows the Earth’s atmosphere at 120 km to be approaching 100°C? It also starts with a surface temperature below 0! What part of the surface is this a profile above?
I would moot that at those altitudes, the atmosphere would not only be very thin but also very, very cold. In fact, I DID look it up, quite recently, and the measurements given by the respected body that provided them (I can’t remember who, but I think it was during a discussion with you, so I would have ensured that it was one whom you most likely trust) were very, very low. Rhoda does give a very reasonable reply.
Radical Rodent
@EM:
http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/atmos/atmos.html
Shows a clearer temperature profile of the atmosphere.
You ask where are these other sources and sinks (or virtual ones) that could account changes in the temp profile from the earths surface upwards.
The exploration of ionosphere has been explored extensively, mapped and theorised.
Figure 1 from here:
http://www.sws.bom.gov.au/Educational/1/2/5
shows how electronic density varies with height and solar strength (day night).
Electron density in the air (all of it, not just the ionosphere) is dependent upon photons.
A good write up on this from Standford University is here:
http://nova.stanford.edu/~vlf/IHY_Test/Tutorials/TheIonosphere/IonosphericMorphology.pdf
Gases that cause variation in electron density are known to be: Nitric Oxide (NO), molecular oxygen (O) & atomic Oxygen (O).
We have the sun streaming photons down, we have a warm surface streaming photons upwards.
With the distinct layers and boundaries shown (temp, humidity & electron density). Each significant gas responding differently to these streams of photons depending upon pressure at each height., It is not surprising that the temperature profile is as measured.
It is notable that at extreme altitude, day/night variation in electron density is extremely high.
Ionospheric electron density profiles obtained with the Global Positioning System: Results from the GPS/MET experiment by Hajj, George yr:1998, show measurable free electrons down to 60km, right in the middle of the standard temperature profile plot you show before.
I feel there is a lot more to be explored before we can announce what is determining earths temperature.
Steve Richards
Rhoda
"In a non-radiative atmosphere the only way for heat to escape a sunlit planet is via radiation from the surface. "
YES!
That means that in a non-radiative atmosphere the spectrum of the outgoing longwave radiation should match the emission spectrum of the surface. This averages 288k.
In practice the measured OLR spectrum corresponds to a temperature of 233k, the temperature at 12km.
We have a radiative atmosphere and the tropopause at 12 km is where most of the radiation to space is coming from.
Entropic man
Still using arithmetic averages when dealing with T to the fourth? You can't make a case that way. Ignoring convection?
Relying on the lapse rate to explain the cold troposphere warming the surface? That one doesn't work any better than DWIR did.
rhoda
Radical rodent
Try searching for images of "temperature profile of the atmosphere". You will get many different graphs, all showing a similar pattern.
At ground level high air temperatures and high heat content go together. At 120km you get the temperature but not the heat content.
The thermosphere at 120km is almost a vacuum. It has a very low heat content because there are so few particles.
If I suspended you behind a sunshade at 120 km you would freeze as your body heat radiated away.
The molecules that are present absorb UV and X-rays from the Sun. This accelerates them to high velocities and high kinetic energies. Since temperature is a measure of the average kinetic energy of the molecules the thermosphere has a high temperature.
Entropic man
Rhoda
You comment makes no sense. How am I ignoring convection? How have I neglected the T^4 relationship emerging from the SB equation?
The radiation at 12km creates a heat sink. Heat moves upwards in the troposphere by convection to the heat sink . Heat moves downward to the heat sink by conduction from the stratosphere.
You don't need averages. There are specific set of measurements. Go here and the second graph shows the upward and downward longwave radiation at Point Barrow.
Go here and you will see the actual outward radiation spectrum and comparison with the black body spectrum for different temperatures.
You can see the atmospheric window between 13 micrometre and 8 micrometres. At these wavelengths the atmosphere is transparant to longwave radiation, the satellite measures radiation from the surface and the radiation curve follows a contour corresponding to a typical daytime surface temperature around 295K.
Outside the window the graph follows a contour corresponding to the temperature at the radiating altitude for each wavelength up near the tropopause, a range from 200-270K.
The only exceptions occur greenhouse gases affect he OLR, for example the effect of CO2 around 15micrometres.
Your explaination? Remember it must obey the 1st and 2nd laws of thermodynamics, and everything else we know about heat flow. It must also predict and explain why we see the patterns of upward and downward radiation shown in the graphs.
Entropic man
Seat
I would agree with Dr Spencer's description.
For dry air and PV/T =k , then the change with altitude will be adiabatic and k will be constant for a packet of air rising from surface to tropopause.
For a moist atmosphere k will be constant up to the condensation altitude and lower above that altitude as the water vapour condenses out and the latent heat increases the kinetic energy of the molecules.
From the numbers I gave earlier it looks like the dominant parameter determining lapse rate is gravity ( presumably because it affects the pressure gradient)
Venus and Earth have similar gravity and similar lapse rates. Mars, with much lower gravity, has a much lower lapse rate.
The proportion of greenhouse gases mostly affects the thickness of the troposphere. Venus and Mars both have atmospheres with 95%+ greenhouse gases and have tropospheres more than 45kms thick. Earth with 2% greenhouse gases has a 10km thick troposphere.
To validate my prediction that a planet with no greenhouse gases would have no troposphere we could really use a planet with an atmosphere, but no greenhouse gases. Offhand I can't think of a body like that in the solar system. Any candidates?