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Post by carnyx on Mar 20, 2011 20:55:16 GMT 1
Maybe there is no correlation, but I heard that land tides are about a foot high, which is a pretty large flexure when you think of solid rock. And given the moon-earth barycentre is down inside the earth at around half way to its centre, there must be a continual stirring effect going on. Perhaps this is also a factor in inducing flows within the fluid part of the earth's core. Maybe, the ensuing friction is also helping to keep the earth warmer.
A casual google reveals an estimate of the heating effect of the moon-s tidal friction of around 3.75 terawatts, which is roughtly 1/500th of the estimated solar input of 174 petawatts ... but it is a big number.
And when you think that a proportion of this energy is spend on creating ocean currents, which will quicken and slacken accordingly, then it may have a considerable influence on the weather ( which we all know turns into climate if it goes on long enough!)
Then, we have the tectonic plates supposedly 'floating' on the basalt .. and surely they are also being tugged around by the moon on a cyclic basis?
So, I think Marchesa is raising a good question, which ought to find an answer.
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Post by nickcosmosonde on May 3, 2011 7:22:05 GMT 1
I've just read about a most surprising fact, which may be pure coincidence, but if it is it's a truly flukey one. All the orbits of the planets are ellipses, with the sun sitting at one of the two focii, as Kepler saw and Newton proved. The other focal points of the planets are empty space, and seem to have no dynamical significance. In the case of the Moon's orbit, however, its empty focal point is just about 22,300 miles above the Earth. This happens to be the height at which geosynchronous satellites orbit us exactly once a day, so they only see one face of the Earth. At the focal point of the Moon, anyone located there would only ever see one face of the Moon too, as its rotation is in synch with its orbit. Due to the slight rocking motion of the Moon's synchronous orbit with us, over time we can see about 58% of its surface; but from its focal point this effect completely disappears, and you would only ever see precisely half of its surface, according to Prof Carl Murray, an expert on celestial mechanics at the Uni of London.
He says this can only be a complete coincidence. Can such a neat symmetry be down to pure chance? Any theories?
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Post by StuartG on May 3, 2011 8:09:59 GMT 1
'Happenstance' It Happens at this Instance in time to be so, the Moon has been, and will contiinue to, move. "Yet the Moon is always on the move. In the past it was closer to Earth and in the future it'll be farther away. That it is now perfectly placed to sustain life is pure luck, a cosmic coincidence. Using computer graphics to summon up great tides and set the Earth spinning on its side, Maggie Aderin-Pocock implore...*" or it's coincidence at the moment and may be subject to change, please see terms and conditions. It may be incorrect to say it's Luck, more 'At this time this set of circumstances allows life to be as it is'. *. www.bbc.co.uk/programmes/b00yb5jpCheers, StuartG
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Post by nickcosmosonde on May 3, 2011 8:35:03 GMT 1
Thanks Stuart.
Do we believe this? Any evidence for it?
Far too many such "cosmic coincidences" for my liking.
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Post by eamonnshute on May 3, 2011 10:08:46 GMT 1
The radius of a Clarke orbit is 42,164 km, but the average distance between the two foci of the moon's orbit is 42,840 km. Close, but no cigar.
The similarity depends on the Earth's rotation, the moon's distance and eccentricity all having related values, but this can only be coincidence, and also the Earth's rotation is slowing down and the moon's distance is increasing anyway, so this coincidence is unlikely to be permanent.
As for the statement that "over time we can see about 58% of its surface; but from its focal point this effect completely disappears, and you would only ever see precisely half of its surface ". I think Prof Murray is wrong! I can demonstrate it but it would need a diagram to illustrate it.
Do you have a reference to Murray's work?
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Post by Joanne Byers on May 3, 2011 10:23:22 GMT 1
Have amalgamated two threads about the moon.
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Post by nickcosmosonde on May 3, 2011 11:01:33 GMT 1
The radius of a Clarke orbit is 42,164 km, but the average distance between the two foci of the moon's orbit is 42,840 km. Close, but no cigar. Thanks eamonn; that's all right then! That's okay, I'll take your word for it. No. He was quoted by Robert Matthews in the Sunday Telegraph. A usually accurate source. Thanks Joanne, I hadn't seen this thread before: How can you say the Moon has no effect on the Earth's climate, eamonn? Are you winding the marchesa up? You can't be serious, surely? It's been known for over 30 years that precipitation is in step with the phases of the Moon, for a start. Then the Moon passes through the magnetosphere penumbra and causes a wide variety of dramatic effects, including flux recombination and modulation of the plasma frequency, all of which directly affect the ionosphere, of course, and its total ion density, and generates various ELF atmospheric waves, all of which directly influence cloud formation and, as we now know from the studies of the Venusian atmosphere of such ionic effects, overall global temperature. You count this as "weather" rather than "climate", I suppose?
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Post by eamonnshute on May 3, 2011 11:39:54 GMT 1
How can you say the Moon has no effect on the Earth's climate, eamonn? Are you winding the marchesa up? You can't be serious, surely? It's been known for over 30 years that precipitation is in step with the phases of the Moon, for a start. There is an alleged variation in rainfall during the month of about 1%, which might be real. But climate change means a systematic change over many years, and I am not aware of any evidence that the moon causes that, and I do not see how it could.
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Post by marchesarosa on May 3, 2011 11:51:52 GMT 1
Fascinating. I watched the three video clips in stu's link with great interest and recommend viewing them to other members.
Coincidences do happen, however. For example the coincidence that the moon's and sun's diameters appear the same from earth so that we get spectacular solar eclipses.
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Post by StuartG on May 3, 2011 19:37:58 GMT 1
I'm finding it difficult to get my real meaning over. My fault. We're arguing semantics. Coincidence is often used and the recipient also reads the word 'luck' into the sense. Using the words 'He says this can only be a complete coincidence' where complete is an unnecessary superlative. The events co-incide for it to happen. To use the word or implication, 'luck' when referring scientifically to some event is a no-no. The sound of 'Far too many such "cosmic coincidences" for my liking.' is starting to sound a bit James42-ish, note, I only said sound like. Cheers, StuartG
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Post by nickcosmosonde on May 3, 2011 20:04:15 GMT 1
How can you say the Moon has no effect on the Earth's climate, eamonn? Are you winding the marchesa up? You can't be serious, surely? It's been known for over 30 years that precipitation is in step with the phases of the Moon, for a start. There is an alleged variation in rainfall during the month of about 1%, which might be real. Badley, Woodbury and Brier showed in 1962 that rainfall in both hemispheres showed a clear lunar periodicity. The figures in their paper suggested the variation was closer to 5%. Adderley & Baven confirmed these findings later in the same year. The fact of such a rainfall periodicity in phase with the moon is not "alleged" I think, though I'll take your word for it there might be some disagreement about the size of the variation. Well, the moon's orbit has many cyclic rhythms, some of thousands of years in length. There's an important "Full Moon Cycle" of about 60 years, for example, which correlates well with a clear rhythm of that length in the temperature records. Another important one is the 18.6 year cycle vis-a-vis the sun's equator - there is very strong evidence that this correlates with a clear drought cycle. This is from E.A.Bryant's "Climate Process & Change" (Camb Uni Press 1997): books.google.co.uk/books?id=jyD4sBCg11EC&pg=PA113&dq=edward+bryant+climate+process+and+change+18.6-year+lunar+cycle&hl=en&ei=_E_ATZrLBdSEhQfB1a3HBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CDUQ6AEwAA#v=onepage&q&f=falseI would also be extremely surprised if the main driver of the Pacific Decadal Oscillation and the other principal ocean and atmospheric currents was not this cycle, or the closely related Saros cycle, modulated by our mutual orbit around the Sun. We're talking about mass long-term cyclic tidal movements - they're inevitably going to be correlated causatively with the rhythmic gravitational interactions of the Earth-Moon system in relation to the Sun, surely?
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Post by nickcosmosonde on May 3, 2011 20:11:02 GMT 1
I'm finding it difficult to get my real meaning over. My fault. We're arguing semantics. Coincidence is often used and the recipient also reads the word 'luck' into the sense. Using the words 'He says this can only be a complete coincidence' where complete is an unnecessary superlative. The events co-incide for it to happen. To use the word or implication, 'luck' when referring scientifically to some event is a no-no. The sound of 'Far too many such "cosmic coincidences" for my liking.' is starting to sound a bit James42-ish, note, I only said sound like. Cheers, StuartG No, I'm more or less content to accept this one is probably coincidental. My "far too many cosmic coincidences for my liking" was really in reference to the usual application of that phrase, in the standard counter-arguments against what is known, broadly, as the Anthropic Principle. The idea that, basically, it doesn't matter how astronomically unlikely the structural specifications of the physical or biological universe/solar system/planet etc are, if they weren't just so we wouldn't be here to notice them...
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Post by StuartG on May 3, 2011 20:20:55 GMT 1
Well that's a bugger, we agree. That's no good. Trouble is You said it better than I did, I had to look-up 'Anthropic Principle' but I'm pleased because arrival to its meaning was under my own steam. Cheers, StuartG
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Post by marchesarosa on May 4, 2011 10:24:49 GMT 1
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Post by speakertoanimals on May 4, 2011 16:00:10 GMT 1
Tides in the air cause a very slight and just about measurable pressure difference, but this is swamped by the pressure differences caused by other things (such as day versus night, solar heating versus not heating). weather.mailasail.com/Franks-Weather/Atmospheric-TidesCompared to the pressure differences generated by ordinary weather systems, effects seem to be negligible -- and its just a small-scale periodic fluctuation in weather, at best, NOT climate. As regards moons tidal friction, the relevant number to compare with is not solar heating per se, but radioactive heating (which is why we still have active plate tectonics). So about 3.75 TW for tidal, but around 21TW for radioactive. As regards the moon in the past -- we can study ancient tides by looking at patterns in layered sediments: igs.indiana.edu/geology/ancient/tidaltime/index.cfmSo, we have records which give a tide-by-tide measure, we also have growth rings in ancient corals which enable us to count the number of days in a year, since we have seasonal variation as well. Hence we can compute number of days in a year, and number of days in a lunar month, and figure out how far away the moon had to be to give those numbers. This is another favourite for the YECs, I might add, who are very fond of a mistaken linear interpolation of current measurements of the rate of recession of the moon, hence attempts to pooh-pooh the supposed flaky old-earth hypothesis...................
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