A Note: Global Warming Threads

Discussion in 'Earth Science' started by Tristan, Aug 27, 2004.

  1. Trippy ALEA IACTA EST Staff Member

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    The demonstrably are not the same. By your own scenario, the sphere reflects more light near its edge (the terminator) then the disc does. Their albedo's are different therefore their properties are different, it really is that simple.

    I'm not ignoring the distribution of energy - that's a seprate issue.

    Look, Billy, you're really starting to try my patience here, the position I am taking is the position that's inherent in the calculations based on the Stefan Boltzman equations. A sphere and a disc of the same size, with the same properties intercept the same amount of radiation.

    If I have a sphere of water, and a circular dish of water the same size as the sphere of water, the amount of radiation absorbed by the sphere varies as a function of the zenith angle because that's the way that water behaves, where as the radiation absorbed by the dish does not vary as a function of radial distance. This is your point, I understand all of this and nothing I have said denies any of this - this is root of the discussion between Andre and myself about the latitudinal variations in solar flux and albedo of the earth versus the behaviour of some ideal material. Something which I would like to get back to when you're through with wasting my time.

    Now understand this.

    My point that I have been trying to convey to you is that the only thing this actually proves is that a dish of water is a poor model for a sphere of water, because when using a point source of light, the albedo of the sphere of water varies as a function of position that that the albedo of the dish of water does not they therefore do not have the same properties and so the dish of water is a bad model for a sphere of water. Instead of using a dish of water as a model, we must instead use a disc made of some hypothetical material with an albedo that varies as a function of position in the same way that it does on a sphere of water, thus giving the disc the same properties as the sphere. When we do this, we discover that the disc and the sphere intercept and absorb the same amount of total power.
     
    Last edited: Nov 19, 2013
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  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Well a least we agree on the physic. I don't call the angle at which light is incident on a surface a "property" of the material, or of the surface, but you seem to.

    The only way that two objects can have the same albedo with one having zero angle of incident light on it (In my extreme case of the cone's flat bottom and at 85 degrees on the conical surface , just to make my point very clear) is if the two illuminated OBECTS ARE MADE OF VERY DIFFERENT MATERITALS. (Not what I call "having these same properties"!)

    Perhaps in my extreme example case: a cone of solid dense carbon, with a silver bottom plate, would do what you claim (absorb the same energy per unit of area of the beam cross section falling on the objects) with two equal light beam parallel to the cone axis, one striking flat bottom and the other striking conical surface.

    In your less extreme case of disk and sphere, perhaps a uniform grey paint on the disk and a white paint at the sphere's "light normal" point grading smoothly into black at just illuminated equatorial band, would absorb the same energy as you claimed, but to me saying these very differently painted surfaces have the "same properties" is quite a stretch of the meaning of "same properties."

    But now that the disagreement is not about the physic, but what the words "same properties" mean, I don't intent to reply more.
     
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  5. Trippy ALEA IACTA EST Staff Member

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    I didn't call the incident angle of the light a property, I called the albedo a property. Do you understand the difference between those two statements?

    Are you saying that the albedo of a surface isn't a property of the surface? Consider a distant observer, they would measure the sphere to reflect more light then the dish and come to the conclusion that they have different properties, even though they were made of the same material.

    incidentally, if I had meant that the sphere and disc were made of the same material, I would have said so.

    No Billy, you've still got the wrong end of the stick, this is about your failure to correctly infer the context of the discussion, nothing more.

    in the context of the original discussion we're talking about and ideal greybody. The albedo of an ideal greybody is the same regardless of the angle of incidence. You failed to infer this and subsequently got everything wrong. I mean come off it, Andre has even said that it's not the assumption that a disk and a sphere of the same radius intercept the same amount of energy that he has a problem with, but rather, it's the treatment of the earth as an ideal greybody that he has the problem with.

    a sphere and a disc with the same albedo, behaving as ideal grey bodies have the same properties.
    a sphere and a disc of water are made out of the same material but have different optic properties when illuminated by a point source (the sphere reflects more and so has a higher albedo).
    A sphere of water and a disc of none water with an albedo that varies across its surface has the same optical properties (or can) but is a different material.

    Now, I assumed that it was clear from the context of the discussion that because we were talking about radiation intercepted and absorbed rather than heating that we were talking about the optical properties rathrr than other aspects such as material or thermal conductivity, which relate to subsequent steps.

    It would seem that, as Billy T apparently failed to infer that I spite of my efforts to point it out to him in several different ways that my assumption was flawed. And so Billy, I say to you that perhaps next time instead of nowling ahead trying to prove that your answer was actually the correct one stop and make sure you have understood the question correctly. This entire diversion could have been avoided if you had stopped to ask whether I was considering an ideal situation or which properties I was referring to.

    instead you focussed on the wrong question, drew wrong inferences, and came to the wrong conclusion.
     
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  7. Andre Registered Senior Member

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    Meanwhile I wonder about the status of the inert convecting atmosphere model.

    Seems to me that we have only covered sidesteps like energy exchange in adiabatic processes. After all, dry adiabatic goes two ways, going up it cools by the mentioned processes, going down it warms up with exactly the same rate.

    Also it was said that it was irrelevant since it's not an existing situation. The response to that is that the black body model is a whole lot less existing, the one that attemps to explain the difference between 'black body' temp and average global temp, mentioned here below the caption of FAQ 1.1..

    Notice that the term 'convection' is not mentioned anywhere in there. Who can explain why there would be no convection in an 'inert' non radiative atmosphere? And remember the candle and your index finger over it.
     
  8. Trippy ALEA IACTA EST Staff Member

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    Keep up language like this and I will simply walk away from this conversation with you.
     
  9. iceaura Valued Senior Member

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    It's an impossibility, and models nothing here. You forgot about wind, radiation loss to space, etc.

    It's not relevant because no argument connects it to anything belonging on this thread.
     
  10. Trippy ALEA IACTA EST Staff Member

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  11. mello Registered Member

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  12. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    There is a lot of both location and time variation in the observed measurements, but they admit that the sea level is rising at 1.8cm per decade.

    That measurement too can be confused if based on shore lines as the local land mass can be sinking, but think it is now (for two decades at least) based on global measurement from well known satellite orbits with radar refection from the sea surface. They are very accurate. So accurate that the speed of the gulf stream can be inferred from the very slight tilt the surface of the gulf stream has (due to Coriollis effect, making the east edge very slightly above the gravitational potential level, if I recall correctly). I.e. the ocean water is expanding and that is "for sure." The ocean is warming.

    APL, where I worked for 30 years, made one of the first, if not the first, satellite that could measure the sea level to mm accuracy. The main funding was to gain better understanding of earth's gravity and less so the gulf stream. APL also made the first satellite whose orbit was precisely determined by gravity. I worked a little on it, It was called DISCOS. The main satellite had an EXACTLY non-magnetic (gold / platinum alloy) sphere about 1 cm in diameter. The rest of the satellite had tiny thrusters and fired them as need to keep the full satellite in same orbit as that tiny sphere. Hold it in the center of its small chamber (follow the tiny sphere's orbit exactly).

    Discos was expensive to make as every resistors and piece of solder had to be weighed and its exact position noted. I. e. there was no gravitational force from the mass of the satellite itself acting on the tiny sphere - just the earth's gravity. (The tiny precious metal sphere was at the exact mass center of the rest of the satellite!) Because of the high fabrication cost, GPS replaced Discos a few years later but the GPS orbits drift due to residual air and sunlight pressure, etc. and need to be updated by ground measurement. Discos is the most precisely known orbit ever made and did not require ground station data up dates. (US navy wanted to know, even months after all US ground stations had all been destroyed in a full nuclear war, exactly where the nuclear subs were.)

    As a result of Discos data collected the exact shape of the Earth's gravity field is known* to a large number of terms in the spherical harmonic expansion description of it. There values are highly secrete and even how many were accurately determined is too. This secrecy is because where a ICBM is launched from and tracked until it is ballistic and residual air drag then plus and accurate knowledge of the Earth's gravity field determines exactly where it hits the Earth again. Disco let the USSR know that even a perfect "first nuclear strike" could not prevent the soviet union from being destroyed too.

    * The higher order terms of the expansion are a functions of time as sifting ice covers have significant effect - that is how accurately the gravitational field is known.
    I suspect Discos, if it still exist, could keep track of the Artic and Antarctic ice masses.
     
    Last edited by a moderator: Jan 5, 2014
  13. Andre Registered Senior Member

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    889
    I believe I hear him say at 26 seconds:

    which is just about 2.5 times less than 1.8cm per decade.

    Maybe this prersentation of Willy Soon helps:

    https://www.youtube.com/watch?v=1gmW9GEUYvA
     
  14. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Perhas - I only read the link's text, in red, listing the 10 items. Just checked it again. It says 7 INCHES / century.
     
  15. Trippy ALEA IACTA EST Staff Member

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    Which is 17.5 cm/ century which in turn is 1.8 cm/decade (or 1.75 depending on how you round it).
     
  16. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I rounded up - the 0.75 to 0.8 as the rate so sea warming is increasing, especially in the deeper layers - see old graph I posted, but don't have time to find now.
     
  17. Trippy ALEA IACTA EST Staff Member

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    Billy T is quite correct. He contradicts himself. In the video he says 7cm per century, but on the page he links to he says 7inches per century, which as I illustrated is 1.8 cm per decade.
     
  18. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    No - only interesting for its errors and ironic implictions that big money is supporting the GW side, when he basically lives from giving talks that "disprove GW."

    It is true that it is very hard to get + or - 1mm accuracy in large part because the satellite orbit altitude does change by much more than that from its average due to sunlight pressure and residual air drag, and currents in the satellite interacting with Earth's magnetic field mainly; except for the Discos type orbits which follows exactly the influence of Earth's gravity alone, for reasons I discussed in post 1029.

    I do suspect that it is now possible to have sets of three GPS, (or more for greater accuracy still) operating in the highest precision mode (the "military mode") measure the location (especially altitude) of 4 or 5 others (or any satellite with downward looking radar) and using all possible such sets, learn their altitude as a function of time to about that accuracy. Also the correction for both sun light pressure and residual, and even dense air, while very complex can be done. For example the Chinese manned space program must be doing that well as their space craft, sealed from the outside, is delivered to the point on earth where the ground crew is waiting to open the capsule.

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    ChinaDaily/ English, which I read most every day, had several photos of the ground crew waiting for the landing. I noticed no two were standing together talking as would be normal. I guessed the CCP would rather have one "ground hero" instead of two, who gave their life for China. If you look closely at the background of the photo of the three getting accustomed to 1G in chairs (after nearly two weeks in space) you can see 5 or 6 still basically separated members of the ground crew. One of the three in the right photo is China's first female astronaut, a beautiful lady, I think you will agree:

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    Last edited by a moderator: Jan 6, 2014
  19. Trippy ALEA IACTA EST Staff Member

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    GOCE, for example, used a GPS SSTI, however, other methods are available.

    For example, TOPEX/Poseidon, Jason 1, Jason 2, EnviSat, and Cryosat use a system called DORIS. DORIS uses (among other things) a network of 50-60 stations which emit a signal to satellites, the frequency shift of the signal is measured factors such as ground position and altitude can be determined. The only requirement for the installation of a station is electricity, because the stations only transmit, the do not receive.

    Using DORIS in conjunction with LASER altimetry from ground based stations and GPS SSTI allows the measurement of the position of TOPEX/Poseidon, Jason 1, and Jason 2 to an accuracy of +/- 2cm. This, then combines with the number of measurements taken each day (or year, or what ever) to give some very narrow confidence intervals.
     
  20. Trippy ALEA IACTA EST Staff Member

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    I forgot to mention it yesterday but 1 inch = 2.5 cm.

    I started listening to it, but I really don't have the 57 minutes at the moment, and I got turned off by 11 minutes when he had already referred back to the Heartland Institute, the NIPCC, and started slinging around insults like 'The reverend Al Gore'.

    Surely if he has a valid point to make, he can make it without engaging in the petty mud slinging he claims his opponents are engaged in? After all, had he not devoted a portion of the previous 11 minutes trying to impress upon us that he had the moral high-ground?
     
  21. iceaura Valued Senior Member

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    The straight number would be 1.78 rounded to the nearest hundredth, or 1.8 to the nearest tenth, no apology needed. 2.54 cm to the inch is a number memorized by machinists all over the US.

    One of the reasons your math teacher tried to get you to stop talking like that is because you confuse yourself easily. Kids who grow up in US slums sit in math classes trying to reason and do algebra by saying "twice as less" instead of "half", and you know they have a struggle in front of them.

    But it's not as much of a handicap as trying to get one's scientific info from youtube videos. You've been on this forum for how long now, reading posts from Billy and Trippy and the like, and you are posting youtube videos featuring guys like Willie Soon in a technical discussion?
     
  22. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    That sounds lot like my understanding of how the Chinese GPS works - Why it only works within line of sight of a ground station. Can't be used, as US's can, to guide a cruse missile into any chosen small building on the other side of the world. A cheaper, purely defensive, system that has no expensive high precision clocks in satellites like the US's does.
     
  23. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Current cold snap in US is just one of many to come as jet stream losses angular momentum and dips down into even the deep south. I told why in August 2013 here:
    Now even Bloomberg understand more of the same is to come more often:
    As they say:
    "Don't mess around with mother nature - she can be a mean bitch." Ask the 100,000 Philippianoes still homeless in the wake of worst hurricane to ever make land fall.
    Or these people of Colorado where it never flooded before. When photo was taken 400 were still missing and 5 known to be drowned:

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    It a logical chain: Global Warming - more ocean evaporation - more rain - more flooding - more crops lost - more people dead by GW.
    Again I say: man needs to switch to sugar cane based alcohol as his liquid fuel - cheaper per mile driven, more low skill jobs, and completely feasible* with increase of food and fiber production and no forest cleared for zero net CO2 release. Lets tell big oil to go to hell before they send us there.

    * 30+ years of proven alcohol IC engine technology (cleaner burning, less repair cost and slightly more HP than when the same "flex fuel" car is burning gasoline! but range of a tank full is 30% less. - more filling station stops.) and only a small fraction of the world's abandoned pasture needs to become cane fields and at least every 6th year they would be used for soy bean production to replenish the available N2 of the soil naturally and most economically (as done in Brazil) - that is the cause of "increased food / fiber production" the switch to sugar cane alcohol would naturally make.
     
    Last edited by a moderator: Jan 8, 2014

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