Layman struggles with Science

[Scpg02.]

I could tell you where Nasif got his information and try and put you in contact with him but that is the best I can do. The math is over my head as well.

[Richard111]

Thanks for the offer Scpg02. Nasif is a member of this forum. No problem to PM him, just that I wouldn't dare. He wants to get his message to a wide audience which I approve. Also I think it is a problem for him to communicate down to the level of us acolytes. Plenty of comments from him on the forum.
For me to understand anything I have to visualise it pictures, this is a problem for the mathematical types.

[Scpg02.]

(04-12-2011 11:33 PM)Richard111 Wrote:  I have to visualise it pictures, this is a problem for the mathematical types.

I'm not going to go there.

[Richard111]

It gives me headaches.

Derek pm'd me about developments on Jennifer Marohasy's blog and I see there is a new thread: a note from neutrino
More ding dong battles with formulas.

I'm baffled as why gravity gets no mention even though convection gets lots. You can't have convection without gravity.

I'm also fixated on the penetration distance of CO2 specific radiation through the atmosphere. I have read of figures as low as 10 metres and Nasif seems to imply any radiation is limited to 1,700 metres. My own dumb bunny calculations show it is unlikely that 15 micron radiation will get passed all the CO2 molecules in say 2,500 metres. Whatever, it just does not make sense to me that the whole atmospheric column is used for radiative calculations when CO2 specific radiation can only travel a shortish distance through the atmosphere.

[Derek]

(04-13-2011 11:45 AM)Richard111 Wrote:  Whatever, it just does not make sense to me that the whole atmospheric column is used for radiative calculations when
CO2 specific radiation can only travel a shortish distance through the atmosphere.

I second that, well said Richard111.

I think that the peak frequency of liquid water emission is at least partially to blame,
for such nonsense / confusion..

BTW - Richard111 have you seen,
http://www.sciencemag.org/content/early/...5.abstract

[Richard111]

Bit of a rambling post this. Based on the idea that a picture is worth a thousand words when you try to convey a difficult concept to the uninitiated. To wit; this picture originating from the Air Vent:



Apart from appearing on several other sites, here is a
Joe Bastardi video that also put it to good use.

And sadly, as usual, I missed the boat having gone to all the trouble of doing the calculations HERE on the 6th of April LAST YEAR but failed to visualise how it might look. So much for me claiming I tend to think in pictures.

Having read that the greenies are going to enrol students to harass citizens on street corners about "climate change", (so what is spring, summer, autumn and winter then?) I thought I would expand on a post I have made before. The following is intended for those (deleted) students.

If we accept that the level of CO2 in the atmosphere is 400ppmv we can then safely surmise that for every 2,500 cubic metres of air we will have the equivalent of 1 cubic metre of CO2. At STP (standard temperature and pressure) physics tells us that all molecules in a cubic metre of air actually occupy just 0.1% of the volume. Put it another way, 99.9% of the volume of 1 cubic metre of the atmosphere at STP is NOTHING!! The same sort of NOTHING you find between the stars!

Never mind that, just concentrate on our CO2 which we will squish into the minimum space to make a solid of exactly 1 litre in size, a cube just 10 centimetres on a side. This will have a surface area of just 6% of 1 square metre. So for purposes of cooling via radiation and conduction that litre size lump of CO2 ain't going to cool very fast.

What we will do now is roll out our litre of CO2 into a sheet exactly 2 square metres by 1/2 (half) a millimetre thick. Nearly the size of a standard sheet of hardboard from your local DIY shop. This will give us a surface area of a fraction OVER 4 SQUARE METRES! Now for purposes of radiation and conduction those departing joules have a much better platform to work from.

But wait! CO2 is not in solid form, it is a gas at STP, and under these conditions 1 cubic metre will hold 2.5469 x 10^25 molecules. (Okay, you guys in the 6th Form apply Avogadro's number and tell me what is the mass of that CO2, in grams please.) Well, the cube root of that number is 2.9422 x 10^8 (+/-), so we are going to slice our cubic metre of CO2 into 294 million slices of 1 square metre just 1 molecule thick. How will that be NOW for the rate of cooling via radiation and conduction? Certainly more than our piddling 4 square metres above.

But wait, its much worse than that! We are assuming CO2 molecules are side by side. They are not. Every individual CO2 molecule is surrounded by 2,499 other atmospheric molecules, mostly nitrogen (N2) and oxygen (O2) which are not very good at radiating or absorbing IR but are quite happy to take up the heat, if any, by conduction (molecular collisions) with the CO2 molecules.

When air is warmed it rises. It will keep rising until the temperature/density equalises. This process will attempt to keep the temperature gradient steady at 9.8 degrees celcius per vertical kilometre. This known as the dry adiabatic lapse rate. So whatever the temperature of the surface the air above will cool at a rate of about 10C for every kilometre of altitude. This vertical temperature/density change is entirely due to gravity. Nothing whatsoever to do with CO2. Check out the atmosphere of Venus at the altitude where air pressure is 1 bar and you will see the same adiabatic lapse rate continuing upwards.

"But", you say, "CO2 absorbs IR from the surface." It sure does. But only at discrete frequencies such that the total energy absorbed is something under 8% of the radiation leaving the surface. So if the surface is at say 16C it will be radiating some 400 watts per square metre. The CO2 in the air above will be happily absorbing 32 joules per second of that upwelling radiation. So how much is it warming the air? Right, first we need to know how far up the atmosphere the radiation specific to CO2 will penetrate. The longest distance I've found on the internet is 1,700 metres and the shortest is 10 metres. Whatever the distance simply calculate the mass of a 1 square metre column of that air and apply the rate of energy input of 32 joules per second against the heat capacity of the air. However much energy is warming the air it will not effect that adiabatic lapse rate, the warmer it gets, the faster it will rise. Only H2O, water vapour, can change the lapse rate as it RELEASES HEAT into the atmosphere as the vapour condenses. We are not discussing H2O for the moment.The point to bear in mind is that for any small parcel of air warming up, it will expand, reduce density, rise and cool. Descending air will warm. This is a continuous process.

"But", you say, "CO2 will re-radiate half the absorbed IR back to the ground." Umm.. NO! We have just discussed above, that CO2, having warmed by absorption, will cool very quickly by passing heat energy into the air by conduction. That absorbed radiation which warmed the air is lost to the CO2 above the absorbing height. CO2 does radiate, but the question is; is it re-radiation, or radiation as a normal part of the whole atmosphere cooling process, and how much radiation?

We need to look at the Maxwell-Boltzmann energy distribution of molecules in the atmosphere. Look at Post:#129 and Post:#131 above. There you will see M and B provided a statistical analisys of the kinetic energy of all molecules in a given parcel of air at given temperatures. These data are still used in research today to predict reactions of different gas mixtures at temperatures encountered in industry.

We talked about cubic metres of air above but I wonder if such a volume would be temperature stable so lets talk about 1 litre of normal air, one thousandth of a cubic metre. This will now have 2.5469 x 10^22 molecules of which 1.02 x 10^19 molecules will be CO2. If you think that is a lot of molecules, well Avogadro's number is 6.0221414 x 10^23 molecules per mole, so that amounts to a tiny fraction of a gram (about 0.00075grams) of CO2. Be that as it may, lets look at an M-B curve for 273K (zero celcius) which whould equate to an altitude of about 1,600 metres for our litre of air.



What the M-B curve is showing is the kinetic energy distribution of all the molecules in that 1 litre of air which a thermometer would report as having a temperature of 0C. The thermometer responds to the AVERAGE energy of each molecule of air striking the thermometer bulb. We see the peak of the graph at around 400m/s (metres per second), to the left of the peak energy reduces, but to the right of the peak we see energy increases. If we look at the 600m/s point on the X-axis and do a rough check of relative area under the 273K curve by counting the rectangles we get a ratio of 9 : 2, or you could say 18% of all the molecules in our 1 litre parcel of air has a kinetic energy above 600m/s. That also means just 18% of the CO2 in our parcel of air has kinetic energy above 600m/s.

That 600m/s kinetic energy level was mentioned in a report I read that this was the energy level most likely to result in a CO2 molecule firing off a photon if it had recently absorbed a photon OR because of multiple collisions driving the CO2 molecule to an energy level high enough to emit a photon. I have not found any verification of this energy point for CO2 emmission so the following summary may have to change.

As I see it CO2 is only capable of absorbing 8% of the upwelling radiation from the surface. It is then only capable of emitting 18% of that radiation which means 1.44% and then only HALF of that returns to the surface. A grand total of 0.72% of the original radiation might be returning to the surface. 70%, and more, of the surface is water. Long wave IR can't penetrate more than a 100microns anyway.

I believe CO2 has NO IMPACT on global climate.

[Richard111]

In my struggle to understand the relationship between radiation and temperature and reading Joe Postma’s paper LINK where he mentions the average radiative equilibrium temperature of the Earth with the Sun as being -18C or 255K (page 11). I was reminded of one of Patrick J. Tyson’s essays:

SATELLITE DETECTION OF GLOBAL EMISSIVITY

Quote:The wavelengths of emitted photons are also a function of the temperature. In general, for any given temperature, there will be a certain frequency or wavelength that is the most probable. Most of the photons will be emitted at or near this wavelength. Wien’s Law gives this point of maximum intensity as:

λ = 2,898 / T

Here, λ is the wavelength in microns, and T the absolute temperature in degrees Kelvin.

This got me wondering as to just what was the peak emissive wavelength at any given temperature. The above little equation provides the answer.

So just what is the wavelength at 255K (-18C) == 11.3647 microns.
And at 288K (+15C) == 10.0625 microns.

Well that seems to fit nicely so what is the peak temperature at 15 microns, the favourite radiative band for CO2 ? == 193.2K Yikes! As near as dammit -80C!

So it looks like carbon dioxide molecules don’t need any particular excitation from intermolecular collisions to fire off a photon anywhere in the atmosphere below the tropopause, and some bit above.

My assertions about the kinetic energy of CO2 molecules being too low to allow radiation unless excited by collisions with other molecules is unwarranted.

Back to the drawing board and more study. My early thoughts regarding “layers” in the atmosphere, defined by penetration of 15 micron photons before being absorbed, seems the way to go. I must go back to Nasif Nahle’s paper on the subject.

[Derek]

Out of interest Richard111, what about the frequency of emission of water vapour and water droplets ?

Genuinely, I am curious, and well, errrr, not a little interested..

[Climate Realist]

(05-17-2011 05:17 AM)Richard111 Wrote:  In my struggle to understand the relationship between radiation and temperature and reading Joe Postma’s paper LINK where he mentions the average radiative equilibrium temperature of the Earth with the Sun as being -18C or 255K (page 11). I was reminded of one of Patrick J. Tyson’s essays:

SATELLITE DETECTION OF GLOBAL EMISSIVITY

Quote:The wavelengths of emitted photons are also a function of the temperature. In general, for any given temperature, there will be a certain frequency or wavelength that is the most probable. Most of the photons will be emitted at or near this wavelength. Wien’s Law gives this point of maximum intensity as:

λ = 2,898 / T

Here, λ is the wavelength in microns, and T the absolute temperature in degrees Kelvin.

This got me wondering as to just what was the peak emissive wavelength at any given temperature. The above little equation provides the answer.

So just what is the wavelength at 255K (-18C) == 11.3647 microns.
And at 288K (+15C) == 10.0625 microns.

Well that seems to fit nicely so what is the peak temperature at 15 microns, the favourite radiative band for CO2 ? == 193.2K Yikes! As near as dammit -80C!

So it looks like carbon dioxide molecules don’t need any particular excitation from intermolecular collisions to fire off a photon anywhere in the atmosphere below the tropopause, and some bit above.

My assertions about the kinetic energy of CO2 molecules being too low to allow radiation unless excited by collisions with other molecules is unwarranted.

Back to the drawing board and more study. My early thoughts regarding “layers” in the atmosphere, defined by penetration of 15 micron photons before being absorbed, seems the way to go. I must go back to Nasif Nahle’s paper on the subject.

Yes, this (bolded) is right, CO2 molecules are firing off IR all the time. However, the -80C temperature is another clue. The IR radiation they are firing off is incapable of warming anything on the earths surface or atmosphere above -80C! However, even "-80C radiation" will make its way out to space and thus, if anything, CO2 slightly cools the atmosphere. As -80C is still hotter than outer space.

The mistake Climatologists made in making the KT diagram their basis for the greenhouse effect from radiation is that they assume all radiation is equal and that all radiation can warm. It is not and it cannot!

This is another way of explaining my previous thread where I explained why back IR from atmospheric CO2 cannot heat the earths surface and why it cannot heat the lower atmosphere. It is simply too cold.

According to to laws of thermodynamics, heat always moves from hot to cold.

Oddly, CO2 sublimes at -78C. I wonder if that and the "close to -80C" are co-incidental?

[Scpg02.]

Really all this proves is that the focus on CO2 was political not scientific.

[Richard111]

(05-17-2011 10:58 AM)Scpg02. Wrote:  Really all this proves is that the focus on CO2 was political not scientific.

Quite so. That is why I've concentrated on the physics of CO2 and not global temperature or sea level. It's fun quoting FACTS to greenies.

[Richard111]

Learning about the relationship between peak emission wavelength and temperature has scrambled my poor mind. In my post above you see how a simple formula derived from Wien’s Law gives the point of maximum intensity for a given temperature in degrees Kelvin.

I had to re-read Claes Johnson's essay on Computational Blackbody Radiation to try and sort out my mind. I have selected the following text from his essay as I feel these statements encapsulate the area of my confusion.

Quote:A blackbody acts like a transformer of radiation which absorbs high-frequency radiation and emits low-frequency radiation.

The temperature of the blackbody determines a cut-off frequency for the emission, which increases linearly with the temperature:

The warmer the blackbody is, the higher frequencies it can and will emit.

Thus only frequencies below cut-off are emitted, while all frequencies are being absorbed.

These statements seem quite clear and straight forward. I will now attempt to write down my understanding of them using a thought experiment.

Imagine two black bodies, A and B, radiating at each other. Body A is at 288K (+15C) and body B is at 273K (0C). Peak emission from body A will be at 10.0625 microns and body B is at 10.6154 microns. So body B is radiating at at a longer peak wavelength (cooler) than body A. The temperature readings confirm this anyway.

Body A is emitting at the shorter wavelength (higher frequency, higher temperature) but it is intercepting all radiation from body B. Since A is already radiating at all frequencies arriving from B it cannot store that energy as heat.

Body B is receiving frequencies above its peak wavelength so it can store that energy and warm up. But body B can store only that excess energy that is above its own peak emission level. So the warming is real but small.

To summarise: body A is recieving radiation from B but NOT warming. B is seeing radiation from A and being warmed by the slight excess in energy.

Eventually both bodies reach the same temperature and radiation levels. They will have reached equilibrium. They will continue to cool at the same rate, each counteracting any change in the other.

All of the above, as I see it, agrees with Claes Johnson's explanations.

Now for my area of confusion. Both bodies are emitting and absorbing at the longer, cooler, wavelengths without any exchange of energy.

Let us now return to the real world where body A is the earth's surface, well 1 square metre of it will do, and body B is the atmosphere above that 1 square metre. I realise these are not "black" bodies so the emissions will be less. Either way, both bodies will be radiating at each other way above the 15 micron level which equates to a peak temperature of -80C (193K)!

We are reliably informed that CO2 radiates happily at 15 microns but so what? Only in the Antarctic at midwinter will we possibly see temperatures of -80C, the rest of the world is much warmer and will therefore not respond to any 15 micron radiation.

Will anyone please explain to me what AGW is all about? It cannot be about CO2 as that operates in the very cold part of the IR spectrum.

[Derek]

(05-18-2011 11:05 PM)Richard111 Wrote:  Will anyone please explain to me what AGW is all about?

Politics.

[Scpg02.]

(05-18-2011 11:05 PM)Richard111 Wrote:  Will anyone please explain to me what AGW is all about?

as Derek said, politics. I would go deeper though. Read this long post about made during a time of energy crisis in California. Then apply what you learn to AGW.

http://www.freerepublic.com/focus/f-news...page=67#67

Quote:The supply regulation game is at least as old as the Dutch East India Company's manipulation of coffee prices by controlling access to the plants.

[Richard111]

Phew! Long post indeed Scpg02. Will have to go back to it.

I've been looking up Wien's Law and trying to absorb the implications. Found independant confirmation of the so simple little formula in post #149 above at this site:

http://feps.as.arizona.edu/outreach/bbwein.html

I also found a graph derived from Wien's Law:


What grabbed my attention is the 6,000K line which represents the Sun emission level. The left hand intensity scale is in watts per square centimetre!

Now look at the intensity level as it trails across the IR range! It is the sum of that energy arriving at the earth that does the warming. This shows a high proportion of incoming energy from the Sun is in the IR band! I have seen no reference to this in any of the global energy budgets. Also the fact that IR cannot heat water and the Earth is over 70% water and a very large portion of the land surfaces are at the poles. Is there any single correct claim in the AGW catalogue?

[Richard111]

Oooops... I just worked it out! 20,000 angstroms is 2 microns.

But that is what learning is all about.

The area under the IR section of the graph accounts for some 45% of the total incoming energy (not light and not UV). I think my above argument still holds.

[Sunsettommy]

I am not sure where you coming from?

Most INCOMING IR fails to reach the planets surface.

This source shows a very nice chart.That states only two types of solar radiation reaches the in any significant amount.

Visible light and Radio Waves

Solar Energy in Earth's Atmosphere

The chart



A little of the FAR Infrared reaches the surface.

[Climate Realist]

(05-20-2011 08:28 PM)Sunsettommy Wrote:  I am not sure where you coming from?

Most INCOMING IR fails to reach the planets surface.

This source shows a very nice chart.That states only two types of solar radiation reaches the in any significant amount.

Visible light and Radio Waves

Solar Energy in Earth's Atmosphere

The chart



A little of the FAR Infrared reaches the surface.

That is true, but it is the Infra red that is warming our atmosphere by DIRECT sunlight- not IR reflected from the surface and certainly not from "back Radiation (IR)"

Thus the direct radiation from the sun ensures all CO2 molecules are already in a perpetual excited state.

[Richard111]

Nice chart C R. As in my ooops post above, I have only just got the significance of NEAR IR and FAR IR. My assumption was if there was a window out then that is the way in! There is a long way between 2 microns and 10 microns.

Looks like some NEAR IR reaches the ground at the observatory height. I think what I want to find is confirmation that NEAR IR is included in the incoming energy level from the sun. This is not "backradiation".

[Climate Realist]

(05-21-2011 12:23 AM)Richard111 Wrote:  Nice chart C R. As in my ooops post above, I have only just got the significance of NEAR IR and FAR IR. My assumption was if there was a window out then that is the way in! There is a long way between 2 microns and 10 microns.

Looks like some NEAR IR reaches the ground at the observatory height. I think what I want to find is confirmation that NEAR IR is included in the incoming energy level from the sun. This is not "backradiation".

That was Sunsetomy's chart not mine...

The IR windows are where there are no Infra Red Interacting Gasses (IRIGs) to absorb the incoming IR. These windows have no part to play in any alleged "greenhouse effect".