Length of day governed by Earth’s core processes

From the University of Liverpool , something I found interesting because a few years ago, former State Climatologist Jame Goodridge said he saw correlations between length of day and other atmospheric processes.

Variations of Length of Day

Research reveals Earth’s core affects length of day

Research at the University of Liverpool has found that variations in the length of day over periods of between one and 10 years are caused by processes in the Earth’s core.

The Earth rotates once per day, but the length of this day varies. A yeas, 300million years ago, lasted about 450 days and a day would last about 21 hours. As a result of the slowing down of the Earth’s rotation the length of day has increased.

The rotation of the earth on its axis, however, is affected by a number of other factors – for example, the force of the wind against mountain ranges changes the length of the day by plus or minus a millisecond over a period of a year.

Professor Richard Holme, from the School of Environmental Sciences, studied the variations and fluctuations in the length of day over a one to 10 year period between 1962 and 2012. The study took account of the effects on the Earth’s rotation of atmospheric and oceanic processes to produce a model of the variations in the length of day on time scales longer than a year.

Professor Holme said: “The model shows well-known variations on decadal time scales, but importantly resolves changes over periods between one and 10 years. Previously these changes were poorly characterised; the study shows they can be explained by just two key signals, a steady 5.9 year oscillation and episodic jumps which occur at the same time as abrupt changes in the Earth’s magnetic field, generated in the Earth’s core.

He added: “This study changes fundamentally our understanding of short-period dynamics of the Earth’s fluid core. It leads us to conclude that the Earth’s lower mantle, which sits above the Earth’s outer core, is a poor conductor of electricity giving us new insight into the chemistry and mineralogy of the Earth’s deep interior.”

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The research was conducted in partnership with the Université Paris Diderot and is published in Nature.

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125 thoughts on “Length of day governed by Earth’s core processes

  1. Gosh, that almost looks like a temperature graph with the AMO. Please, please, please, do not tell that to Mann. He will blame ADLC (Anthro Day Length Change) on CO2 and want to ban fossil fuels so that one side of the earth does not stay faced toward the sun at all times.

  2. I believe that anything that ‘plays’ with the Earth, Moon, Sun gravity fields effects on the others causes a modulation ofn the Climate that we see. Gravity is the way that energy is interchanged between non-radiating bodies in an orbital paths. That very slow release of ‘frictional energy’ on the other body that acts as a ‘spring’ to allow the other to get away.

    I mean, what other way is there to do it? Interesting?

  3. It would be interesting to see if there is any relationship between the 60 year LOD cycle and the 60 year PDO cycle. Could ENSO events be due to ‘slopping’ Kelvin waves as well as winds?

  4. Ian W says:
    July 11, 2013 at 3:43 pm

    “It would be interesting to see if there is any relationship between the 60 year LOD cycle and the 60 year PDO cycle. Could ENSO events be due to ‘slopping’ Kelvin waves as well as winds?”

    I thin you may have to account for what looks like a 24 year cycle as well as 60 years.

    That would at least split the enregy left to be distributed into more sensible RMS values.

  5. Why is the Earth’s rotation and orbital period slowing (over billions of years of course)?

    Is it due to work between Earth and Solar magnetic fields? … Lief?

  6. Richard III July 11, 2013 at 3:42 pm

    I mean, what other way is there to do it? Interesting?

    The interaction of magnetic fields

  7. Robert of Ottawa says:
    July 11, 2013 at 3:51 pm

    Needs editing, incomprehensible:
    A yeas, 300million years ago,

    “yeas” should be “year”

  8. “The rotation of the earth on its axis, however, is affected by a number of other factors – for example, the force of the wind against mountain ranges changes the length of the day by plus or minus a millisecond over a period of a year.”

    *

    The force of wind? This sounds to me a bit like blowing on your own sail or trying to hold up a swing with your own hands. A bunch of you who are more learned than I might jump on my conclusion there, and so be it, I won’t argue back. Another point, though, is that while mountain ranges seem big to tiny little creatures like us, on scale with the planet they are hardly there at all.

    It doesn’t ring true to me that the wind can push the planet around, even by minute amounts.

  9. Uh, the Y scale here is in milliseconds, to the human eye it might as well be hours. In other words there isn’t much variation in the length of the day, but this chart make it look like there is. Most of this chart is below average so what does average really mean here? Personally I like have longer days, I can get a lot more done in an extra 4 milliseconds or so. This is another example of research money well spent, if we can figure out a way to get 5 more milliseconds out of the day that would really be something.

  10. Robert of Ottawa says:
    July 11, 2013 at 3:58 pm
    Richard III July 11, 2013 at 3:42 pm

    That’s not be . Take that poster down!

    “The interaction of magnetic fields”.

    Indeed. But the magnitudes of energy available are very different. I would call gravity first.

  11. I would have thought tidal forces would have a greater impact than wind against mountains, but I’ve guess I learned something today. :-)

  12. Tom Trevor says:
    July 11, 2013 at 4:01 pm

    “Uh, the Y scale here is in milliseconds, to the human eye it might as well be hours.”

    So you consider that styudying the minute oscilations, that show up here as variations in the msecs, are in now way connected to that beautfull dance that the orbits show?

  13. Most of the change in the length of day is due to the transfer of angular momentum from the earth to the moon due to tidal forces. The moon is accelerated by the tidal bulges into a higher orbit, at the same time the earth’s rotation slows by an equivalent amount to balance the energy. I would expect that settling of heavier elements (Ni and Fe) into the core would tend to counteract the decrease in rotation rate by a lesser amount.

  14. I am of course speaking of long-term changes, over the full history of the earth, not short term changes discussed in the article above.

  15. This parametre is carefully studied by a number of different international organizations including the International Earth Rotation and Reference Systems Service, the Special Bureau for the Atmosphere and the Earth Orientation Centre.

    Yes, the length of day actually changes and this can be caused by the wind-drag (very short-term), ocean-drag (short-term), moon-gravity-drag (millions of years), core and mantle rotation processes (medium-term), and the gravity from the other planets in the solar system (long-term).

    http://www.iers.org/nn_10896/IERS/EN/IERSHome/home.html?__nnn=true

    http://www.aer.com/science-research/earth/earth-mass-and-rotation/special-bureau-atmosphere

    http://hpiers.obspm.fr/eop-pc/index.php?index=mission&lang=en

  16. Bill Illis says:
    July 11, 2013 at 4:38 pm

    “this can be caused by the wind-drag (very short-term), ocean-drag (short-term), moon-gravity-drag (millions of years), core and mantle rotation processes (medium-term), and the gravity from the other planets in the solar system (long-term).”

    I think that the ‘frictional effects’ of Lunar/Earth interaction are underestimated. How the Moon’s gravity ‘plays’ with our Climate by that effect and thus ‘gains’more energy to get away.

  17. This cannot possibly be so … ask any old timer (me too) … the days seem to be rocketing by much faster nowadays.

  18. Interesting concentration on short-term variations. However, over longer periods (millions of years) the earth-moon tidal system is more determinative. The moon is observed to move to a higher, more energetic, orbit (about 1 inch/year) as a result of the earth’s rotation/tidal forces. That energy is subtracted from the earth’s rotation, therefore it slows down.

    Incidentally, that presents a dilemma over a long period. Assuming that Newton’s Laws remain constant, and that the oceans are relatively unchanged, over billions of years, you can back the earth-moon system up. As the moon gets closer, the tidal forces get larger and the process speeds up. Accordingly, about one and a half billion years ago the moon was close enough to cause tides higher than the continental mountains, and the earth is spinning like a top. What’s wrong with this picture?

  19. Robert of Ottawa says:
    July 11, 2013 at 3:53 pm

    “Why is the Earth’s rotation and orbital period slowing?”

    Mainly tidal friction, creating heat which radiates the energy of motion away into space.

    PaulH says:
    July 11, 2013 at 4:14 pm

    I expect ocean tides dominate.

  20. Robert of Ottawa says:
    July 11, 2013 at 3:58 pm

    “The interaction of magnetic fields”

    Needs to be a dissipative force. Perhaps electrical eddy currents could be set up in the core due to magnetic field interactions. That would create resistive heat, which could then radiate away.

    Somehow, the kinetic energy has to be converted to a form which can be transferred out of the local system.

  21. Since plate tectonics began, the earth has been differentiating, with heavier materials sinking toward the core. As a result, the earth should be rotating much faster now, like a spinning skater who pulls their arms closer to their body. It’s obvious the moon’s increasingly higher orbit has counter acted this effect, and has a pronounced effect on the length of day.

  22. I would note that the 5.9 year oscillation is almost exactly 1/2 the period of Jupiter around the sun. Don’t know if it MEANS anything, but it is interesting.

  23. Oh, it’s a model. I was wondering how they knew the variation in length of day in 1890—down to fractions of a millisecond.

  24. One other (tiny) effect is an annual change caused by snow depositing on higher elevations slightly slowing the rotation rate, which speeds up again when the snow melts. I wonder how much longer the day was during the last ice age.

  25. This is why an oil-based economy is such a bad idea. By removing the oil from the Earth, we are taking away the lubricant for all the gears and things in there. When it has all gone, the innards of the Earth will seize up, and the rotation will stop. Then we’ll be really doomed.

  26. Now didn’t we have a story about the “faint young sun” problem a few days ago?

    If this is correct “A year, 300million years ago, lasted about 450 days and a day would last about 21 hours. As a result of the slowing down of the Earth’s rotation the length of day has increased.” I wonder what the LOD and year were 3 billion years ago? Sure doesn’t sound like the temperature of the Earth then was determined primarily by CO2.

  27. “theoretical calculation of how the Japan earthquake—the fifth largest since 1900—affected Earth’s rotation. His calculations indicate that by changing the distribution of Earth’s mass, the Japanese earthquake should have caused Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds (a microsecond is one millionth of a second).

    “In comparison, following last year’s magnitude 8.8 earthquake in Chile, Gross estimated the Chile quake should have shortened the length of day by about 1.26 microseconds and shifted Earth’s figure axis by about 8 centimeters (3 inches). A similar calculation performed after the 2004 magnitude 9.1 Sumatran earthquake revealed it should have shortened the length of day by 6.8 microseconds and shifted Earth’s figure axis by about 7 centimeters, or 2.76 inches”

    “Earth’s rotation changes all the time as a result of not only earthquakes, but also the much larger effects of changes in atmospheric winds and oceanic currents,” he said. “Over the course of a year, the length of the day increases and decreases by about a millisecond, or about 550 times larger than the change caused by the Japanese earthquake.”

    http://www.nasa.gov/topics/earth/features/japanquake/earth20110314.html

  28. Another way to slow the Earth’s rotation is to collect dust and asteroids from space. Tens of thousands of tons of dust hit the earth each year (Internet search found a wide range of numbers, but 50K is representative). Extra mass on the surface has same affect as ice skater holding their arms out: it slows the spin rate.

  29. After reading some of the comments here I’m wondering if Earth’s core has some influence on spelling mistakes. Just sayin’ :)

  30. The earth rotates more than 360 degrees per day. The Sun is in the same place East to West each day at the same time, but the earth moves on the orbit so the Sun has to rotate a little more than 360 degrees to put the Sun in the same place.

  31. Gary Hladik says:
    July 11, 2013 at 6:10 pm

    Neat! Makes sense, if you assume the fan is mostly drawing air equally from all sides (radially inward), redirecting it forward, and that flow is then being reflected so that net flow is balanced on the sides, but overall directed backwards.

    Assuming Lambertian reflection, I get a net backward flow of about 16% max of what it would be if they turned the fan around. You’d probably lose 50% of that from luffing and edge losses, so about 8% relative efficiency overall. That seems about consistent with the speed they got.

    So, the question becomes, is the “fan” (net atmospheric turnover being powered by the Sun) blowing against surface nonuniformities significant enough to significantly drive LOD.

    I’m not convinced, but at least you’ve made me slightly more receptive to it.

  32. Rod may be correct, but this is supposing that the dust is ‘stationary’. If the dust as it falls is moving at the same speed as the earth’s rotation speed in the relative latitude then the fact that there is added mass at the surface will not affect the rotational speed. More to the point, as the earth heats due to CAGW, the oceans and land will expand outwards. This is where the ‘ice skater’ effect comes into play, and so CAGW slows the earth!

    BTW there seems to be an error in someone’s calculations. If the day, 300M years ago, was about 21 hours long then the year would be 365 x 24 /21 days long. This is about 417 days, not 450 days. The implication is that if the year was indeed 450 days long, the earth was in a different orbit, rather father out. Hence the earth must be spiralling into the sun. Once again, blame tidal friction. But if the earth is spiralling into the sun as a result of tidal friction, why is the moon spiralling out from the earth dud to tidal friction. Of course, my calculations could be wrong?

  33. Bill Illis [July 11, 2013 at 4:38 pm] says:

    Yes, the length of day actually changes and this can be caused by the wind-drag (very short-term), ocean-drag (short-term), moon-gravity-drag (millions of years), core and mantle rotation processes (medium-term), and the gravity from the other planets in the solar system (long-term).

    Hear, hear, and really just to name a few of the known “randomizing” elements.

    The biggest failure of imagination of all is that education always seems to put the cart before the horse. It starts with the definition of quasi-”constants”, here is the length of a day, a year, the orbit of this planet and that, etc, so that the student’s understanding comes from the opposite end of the logical spectrum. These quasi-constants are mere observations, snapshots of the sum of countless influences that total up to yield the current state of the observed universe. In reality the whole thing is as close to a random number generator as is possible, it is truly chaotic if we can just detach ourselves from our narcissistic point of view. Every passing comet and asteroid and interstellar event ( perhaps even inter-galactic event ), every new star, nova, supernova, even every change of radiative output of any and all stars will affect something. That is all on a huge macro scale which likely dwarfs the local climatic micro scale that we all obsess over every day.

    You know how we have those astronomy models that show the positions of planets back into the past and forward into the future? Now try accounting for all the randomizing chaotic events that occur in real life out there. One glance at the surface of the moon should demonstrate that the influences that resulted in our current position and orbit, and length of day, etc, is truly unmanageable from a predictability point of view. Any model that says for example: ‘in 3975 years this is where Jupiter will be and this is where our moon will be’ should be accompanied by a disclaimer: ‘in 3975 years this is our best guess where we believe Jupiter will be and this is where our moon will be’. Now tell me again how weather and climate models work? They can’t work because they are constantly being rendered useless by discounted and unaccounted for variables on our tiny little ball of magma, dirt and water. It is like cooking up an Irish stew and predicting where the bubbles will appear and where the solid food will settle. Good luck with that.

    Just imagine the torture future Scientists will experience if a few hundred or thousand years from now the “fringe” theory is verified that the speed of light is variable like the length of a day ( perhaps “C” only represents the maximum speed radiation can travel in the current configuration of the universe, change it and a different “C” is observed ). Anyway, whatever you do, don’t tell today’s Scientific elite that in the future their current textbooks will most likely appear as archaic as Ptolemaic musings do now. ;-)

  34. Dudley Horscroft says:
    July 11, 2013 at 7:27 pm

    The Earth’s orbit should increase with time as the sun loses mass.

  35. Blade,
    It means little in outcomes, but I derive comfort from equating the state of the globe’s temperature to the state of a human body temperature. Each object has multiple influences that can and do affect temperature. There are cycles, but the lengths of the cycles need not be related (think rate of respiration with rate of sleeping with pulse rate. Maybe rough correlations exist some of the time, but nothing you could model well).
    It’s interesting philosophy to discard the constants as primary assumptions, then to do observations with adequate accuracy to derive constants or quasi constants. I’ve often wondered why so many physical equations (before relativity) ended up with exact powers, given that Nature is not supposed to be able to count 1, 2, 3, etc.

  36. skorrent1 says:
    July 11, 2013 at 4:57 pm

    Incidentally, that presents a dilemma over a long period. Assuming that Newton’s Laws remain constant, and that the oceans are relatively unchanged, over billions of years, you can back the earth-moon system up. As the moon gets closer, the tidal forces get larger and the process speeds up. Accordingly, about one and a half billion years ago the moon was close enough to cause tides higher than the continental mountains, and the earth is spinning like a top. What’s wrong with this picture?

    That’s an interesting observation. Before the Cambrian Explosion (a little more than a half billion years ago), life on Earth was just a bunch of single cells and algae, not something that couldn’t survive a rapidly spinning Earth with wild tides. But the algae started over 3 billion years ago. There must have been other factors that neutralized some of the energy transfer.

    • scarletmacaw misses the heart of the dilemma. Forget what “life” was like 3 billion years ago. Geologists tell us that some geologic formations date back 4 billion or more years. But no surface formation could withstand repetitive many-mile-high tidal waves beating at them every few hours. Conclusion: either geologists’ time measurements are way off, or the moon wasn’t around to be that close to the earth. Either way, it raises many more problems.

  37. vukcevic says:
    July 11, 2013 at 10:59 pm
    What is new is that processes in the Earth core are synchronized with solar activity
    ==========
    it is hard to see how the earth could generate a magnetic field without the sun. Everyone likes to think the molten core is the explanation, but that ignores the chicken and the egg problem, as well as the magnetic properties of iron as it is heated.

  38. scarletmacaw says:
    July 11, 2013 at 8:56 pm
    Dudley Horscroft says:
    July 11, 2013 at 7:27 pm

    “The Earth’s orbit should increase with time as the sun loses mass.”

    I would have thought that it was the ratio betwen the two that mattered. And if Earth can leave just a little more of its mass in the great mass deposit bank that is the SUn, then it wil be much lighter on any later jouneys outwards.

  39. The earth rotation is causing the winds to blow, not the other way around. The earth and it;s atmosphere move freely and frictionless through the vacume of space.,The only influence on the speed of rotation is the spread of the mass within the earth, over it’s surface or within the earth moon system. Ocean currents may influence this, wind currents in much lesser values (more air mass around the equator should make a difference and may be you could measure that), but winds slowing down the earth rotation is a cause and effect swap, sorry.

  40. The period of global cooling in the 1960s/70s and the period of warming from the mid 1970s to the late 1990s was predicted by the distinguished scientists, Kurt Lambeck (Australian) and Amy Cazenave (French) (see here: http://tinyurl.com/l5turxx, http://fr.wikipedia.org/wiki/Anny_Cazenave and here http://en.wikipedia.org/wiki/Kurt_Lambeck ) in 1976 using decadal plus variations in the earth’s rotation as the independent variable.

    There are well established, close relationships between the long-term fluctuations in the Earth’s rotation, on the one hand, and the variations in the ice sheet in Antarctica, epochs of atmospheric circulation, global air temperature, regional precipitation and cloudiness, and even in the catches of food fish in the Pacific Ocean, on the other.

    Lambeck and Cazenave (1976), “Long Term Variations in the Length of Day and Climatic Change” published in 1976 in the Geophysical Journal of the Royal Astronomical Society Vol 26 Issue No 3 pps 555 to 573, were the first to report evidence that established the relationship between the Earth’s decadal variable rotation and climate dynamics.

    As LoD shortens, (i.e. the Earth rotates faster) the planet warms; in contrast, as LoD lengthens, (i.e. the Earth rotates slower) the planet cools. There is a time lag of between six and fifteen years between changes in the Earth’s rotation and global temperature.

    Their paper warrants careful study.

    Lambeck and Cazenave (1976) found that:

    “The long-period (greater than about 10 yr) variations in the length-of-day (LoD) observed since 1820 show a marked similarity with variations observed in various climatic indices; periods of acceleration of the Earth corresponding to years of increasing intensity of the zonal circulation and to global-surface warming: periods of deceleration corresponding to years of decreasing zonal-circulation intensity and to a global decrease in surface temperatures. The long-period atmospheric excitation functions for near-surface geostrophic winds, for changes in the atmospheric mass distribution and for eustatic variations in sea level have been evaluated and correlate well with the observed changes in the LoD.“

    Lambeck and Cazenave (1976) argued that the cooling of that the planet experienced in the 1960s arose from a slowing of the Earth’s rotation. They wrote:

    “if the hypothesis [that decadal rotation decrease (increase) results in planetary cooling (warming)] is accepted then the continuing deceleration of[the rotating Earth] for the last 10 yr suggests that the present period of decreasing average global temperature will continue for at least another 5-10 yr.”

    Lambeck and Cazenave (1976) comment further that:

    “Whatever mechanism is finally proposed it will have to explain the apparently significant lag that is found between the LOD and the various climatic indices, temperature and excitations. The interest of this lag suggests that the LOD observations can be used as an indicator of future climatic trends, in particular of the surface warmings.”

    Lambeck and Cazenave (1976) predicted that the cooling would come to an end by the mid 1970s and be followed by a period of global warming because they had discovered that the planet’s rate of rotation had begun to accelerate from 1972. They wrote:

    “Perhaps a slight comfort in this gloomy trend [of global cooling] is that in 1972 the LoD showed a sharp positive acceleration that has persisted until the present, although it is impossible to say if this trend will continue as it did at the turn of the century or whether it is only a small perturbation in the more general decelerating trend.”

    These findings have been corroborated by more recent similarly high quality papers.

    There is a substantial literature about relationships between decadal and longer changes in the Earth’s rotation and climate dynamics.

    Nikolay Sidorenkov summarises a good portion of it in his recently published book The Interaction Between Earth’s Rotation and Geophysical Processes Wiley VCH 2009. Amongst other things he concludes:

    “We have shown that there are strong correlations between the decadal variations in the length of day, variations in the rate of westward drift of the geomagnetic eccentric diapole, and variations in certain climate characteristics (the increments of the Antarctic and Greenland ice sheets, anomalies of the atmospheric circulation regimes, the hemisphere-averaged air temperature, the Pacific Decadal Oscillation, etc).”

    Lambeck and Cazenave (1976) provide a broad overview of how decadal rotation variations over the period 1800 to 1950 change ocean/atmospheric oscillations and thereby global and regional climates using results reported by Horace Lamb in his 1972 treatise, Climate, present, past and future.

    Lamb reported this pattern based on detailed observations of 150 years of climate data:

    Observations of climatic fluctuations during the last two centuries show two principal types of atmospheric circulation alternating typically every 20 – 40 years. The first type (type I) is characterized by an increasing intensity of the zonal circulation at all latitudes and with a poleward migration of the belts of maximum wind intensities. The circulation is accompanied by a decrease in the overall range of surface-air temperatures between the equator and the poles, and by an overall increase in the mean global surface-air temperatures. Ocean-surface temperatures also tend to increase at high latitudes. The type II circulation is characterized by a weakening of the zonal circulation, by a migration of the main streams to lower latitudes and by an overall decrease in temperature. For both types of circulation the migration in latitude and the changing intensities are global phenomena, occurring at all longitudes and in the northern and southern hemispheres although the trends in different regions are not always in phase. Both easterly and westerly winds increase with the type I circulation and both decrease during the type II circulation.

    Sidorenkov (2009) updated these patterns considerably, drawing on an extensive literature.

    Sidorenkov (2009) concluded that because long-term variations in LoD can now be determined with great accuracy, the many-year findings he and others have documented show that the long-term variations in LoD present a unique nature-born integral index of the global climate changes.

  41. Henk Kraa says:
    July 11, 2013 at 11:53 pm

    “but winds slowing down the earth rotation is a cause and effect swap, sorry.”

    Everything is a cause and effect swap. Downwards to ‘thermal ground’ anyway..

  42. Arbab (2009) found an empirical law for the variation of the length of the Earth’s day to increase at 0.002 sec/century (present rate). He found the length of the day found to be 6 hours when the Earth formed.
    For most of Earth’s life day length has been shorter than 14 hours!

    • Talk about linear extrapolations! Anyone like to speculate on the shape of the newly-forming “Earth” if it were rotating every six hours? Maybe the Earth WAS flat, after all!

  43. Apparently Cesium atomic clocks aren’t accurate enough, losing 1 second in a 100 million years or so. So now atomic clock are being mad that are 3 times more accurate. At the current rate of stupidity and war, I am not sure the human race will be worried about losing 1 second in ~100 million years!

  44. Patrick says:
    July 12, 2013 at 1:28 am

    If we can get a better ‘level surface’ with which to survey the future you object? Without enquiry first?

  45. It’s those bloody models again !!!

    There is a relatively large gravitational interaction between the moon and the earth but with the moon moving further, and further away that interactio is diminishing.

  46. Stephen Richards says:
    July 12, 2013 at 1:52 am

    “There is a relatively large gravitational interaction between the moon and the earth but with the moon moving further, and further away that interactio is diminishing.”

    The Moon is still trying to lose all that enrergy and matter it got with that old, brief, encounter betwen it and Earth. Nearly done now, just a few more tweaks to the Earth and that gravity ‘spring’/’low slow rocket’ will let it get away. Only a few more millennia. “Shall I play with the Earth’s Cilmate in the mean time? Might be some more energy there.”

    • RichardLH has it backward. In order to move from a lower to a higher orbit the moon must gain energy, which it gets from the earth’s rotation. The farther away it gets, the less energy is transferred, so the process gets slower. The moon is not on some parabolic trajectory losing energy from some remote “brush with earth”.

  47. Another factor not mentioned above is polar ice. the more ice at the poles the faster the earth rotates. I would expect this to be more effective than core changes which would be very slow compared to earth’s rotation and have little effect.

  48. Factors effecting Earth’s Climate ae well as LOD.

    1. Moon having left Earth’s influence is the true, ‘thermal ground state’ of the Earth.
    2. Until then all the energy stored in orbit by the Moon is here on Eearth some-how.
    3. Leaking away down that long thermal slope to zero.
    4. With top-ups from the slightly varying Sun.

  49. Mike Borgelt says:
    July 11, 2013 at 6:52 pm

    Now didn’t we have a story about the “faint young sun” problem a few days ago?

    If this is correct “A year, 300million years ago, lasted about 450 days and a day would last about 21 hours. As a result of the slowing down of the Earth’s rotation the length of day has increased.” I wonder what the LOD and year were 3 billion years ago? Sure doesn’t sound like the temperature of the Earth then was determined primarily by CO2.

    Was thinking exactly the same thing. Periods of increase in rotational speed (or reduction in the slowdown of rotational speed) appear to correlate well to periods of rising temperatures. Assuming the earth was spinning much more rapidly aeons ago, we could expect it to be warmer than today, other things being equal.

    Further study needed, etc, but it’s another variable that matches climate changes much more closely than atmospheric CO2 levels. It’s also another second-order variable that is likely to be influenced by the solar system.

    I really don’t see much room for CO2 in determining climate other than as a ‘lubricant’, helping to spread heat around the globe more effectively and evenly rather than actually increasing the ‘average’ global temperature in any measurable way. If Venus has a fairly uniform temperature, despite its extremely slow rotation making for very long nights, this would mean I might not necessarily be barking up the wrong tree.

  50. Don’t forget that longer days intersect more incoming sunlight, but then comes the night, with some reversals.
    What are the main differential factors that cause the daytime warming of planets to be at a different rate to the night time cooling?

  51. The earth-moon orbital system is changing. As the tides create friction on the earth from moving the air, sea, and land (yes, the land is moved by the tides, too), energy is lost from the earth-moon system. Angular momentum must still be conserved. This occurs by transferring angular momentum to the moon, raising its orbital distance from the earth, while slowing the spin of the earth (reducing its angular momentum AND rotational energy.
    The tides will stop when the earth’s rotation slows so much that it always keeps one face towards the moon. That event is MANY millions of years away. By my calculations, the day and the month will both be about 1100 hours (about 45-46 days) long, as we currently measure time.

  52. …and other slight changes in characteristics such as earths overall diameter and mass. Imagine a flatter earth would spin faster than one with high continents. As we collect space junk, our masses increases.

  53. More idiocy that tries to measure things that are smaller than the margin of error. For every slowdown in the Earth’s rotation due to wind pushing on mountains, a meteorite impact on the Earth (or within it’s atmosphere) may speed it up, again. Or maybe an impact will add to the rate of slowing. Does this guy pretend to know all the impacts of the impacts (sorry)? How about friction of the atmosphere with the solar winds? Does he know how internal friction with the molten core and magnetic interactions influence the rate of rotation? And as another poster suggested, does he negate or ignore the impacts of tidal forces from (primarily) the moon and other planets?

    More important than those questions are these: are our research universities facing a crisis of idiocy? Do we have too many people doing worthless science to get worthless science degrees, just because they cannot think of how to either make a living (or contribute to society) in a more productive manner?

  54. ENSO, SOI and LOD indices are all driven by the variations in the tidal forcing as I described on WUWT http://wattsupwiththat.com/2013/01/20/analysis-shows-tidal-forcing-is-as-a-major-factor-in-enso-forcing/

    I recently made similar runs using my artificial neural networks for SOI and LOD indices. But for better result I also included the solar wind, the Kp index and the Ap index. However I very much doubt that the planets or the barycenter has anything to do with Earth rotation or ENSO.
    Why the connection with the magnetic indices and the solar wind?
    I don’t know!

    Here is the result for SOI the Southern Oscillation Index

    which gave me a wow impression.

    And here is the graph for LOD.

    Note that the first part between 1997 to the end of 2004 is the training part and the part from 2005 onward is the test part. So the graph in itself is not made as a prediction. Still the correlation at the test part is impressive.

    Next I am going to do the same for the NINO3.4 index.
    I have now after I have analyzed the TAO buoys for the sea current values a much better understanding how the tides drives the ENSO phenomenon than before.

  55. @Per Strandberg
    Any chance you can extract some sort of matrix from your network that could be reduced to a conventional math model?

  56. Based on the misconceptions above I will note the following:

    1) While distinguishing between frequencies of LOD variation is critical, the first, most important determination is whether the process is reversible or irreversible. Both processes are mixed at frequencies across much of the spectrum.
    2) The single irreversible process is tidal braking, but this varies in periods ranging from lunar cycles to eons, the former including primarily: a) lunar/solar phase (full moon, etc.); b) lunar perigee/apogee; c) angle of lunar orbit to the ecliptic.
    3) Over the eons and shorter periods tidal braking varies according to: a) the irreversibly increasing distance of the moon; b) the configuration of the continents (Pangea had comparatively little coastline); c) sea level (high sea level reduces land area and coastline).
    4) Reversible processes include those shown in Vucevic’s link, and vary in frequency from the instantaneous (which of course cannot be measured) to ice age frequency. These processes (atmospheric and ocean coupling, core/mantle coupling, ground ice melting with associated eustatic sea level rise, steric SLR, post glacial rebound, etc.) entail variation of angular momentum within the lithosphere/cryosphere or between the lithosphere, hydrosphere, and atmosphere (all reversibly), and impart no angular momentum to the moon’s orbit or to the earth’s orbital energy.
    5) LOD has been measured with precision since the advent of crystal clocks and the subsequent advent of atomic clocks. It can be reconstructed with moderate precision for the telescopic period, and approximated for the period of historic astronomical observation as far back as Babyolonian Cuneiform records. (The time of day an eclipse is reported to have occurred allows for calculation of average LOD between reported eclipses.)
    6) Accordingly LOD data detail a combination of reversible and irreversible processes so that good data interpretation requires first a sorting out of causal processes of overlapping frequency. Lots of good work has been done toward attribution of LOD measurement, and a whole lot of junk science has been done, some of which shows up at WUWT.
    7) LOD may be correlated to eustatic SLR at a rate of about 0.1ms/cm. This is of course of the reversible sort, and it places constraints on ice mass balance taking into account the uncertainty of the contribution of core/mantle coupling. It should be noticed that this is three orders of magnitude greater than contributions due to steric SLR or long term increase in atmospheric angular momentum due to rising T. Of course there are are competing processes with opposing contributions to LOD, but on the whole warming melts ice which increases LOD. Since we see no such increase, the minute SLR observed must be attributed to thermal expansion (steric SLR).
    8) ENSO involves enormous energy, which is radiated to space irreversibly. Accordingly any tidal contribution to ocean heating of any type is constrained by the measured rate of decrease of the earth’s kinetic energy of rotation, equal to the displacement of the moon’s orbit plus the solar contribution to tidal braking. This amounts to an increase of the whole ocean of 2 thousandths of a degree per century. It is thus impossible to attribute ENSO to the moon.
    9) Whereas tide oscillations do drive small ocean currents, some slight heat transport may turn out to be measurably correlated to tide intensity as governed by lunar orbital parameters.

    I hope this can serve as a starting point for informed discussion. –AGF

  57. RichardLH says:
    July 11, 2013 at 11:36 pm

    I would have thought that it was the ratio betwen the two that mattered. And if Earth can leave just a little more of its mass in the great mass deposit bank that is the SUn, then it wil be much lighter on any later jouneys outwards.

    The centripetal acceleration that keeps the Earth in it’s orbit, decreases as the sun’s mass decreases, and the sun is continually losing mass through the solar wind, as well as converting mass to energy. At any given instant, the Earth’s velocity is slightly too fast to counterbalance the acceleration, so there’s a net velocity component that increases the Earth’s orbit over time. This is a very small effect. Assuming a constant solar wind, it would have increased the Earth’s orbit less than 1% over the age of the solar system.

  58. Another thing, the atmosphere of Venus rotates many times faster than but in the same direction (prograde) as its lithosphere. The average rotation of the earth’s air is also slightly prograde, and must be powered by differential heating of the earth’s surface and air as they rotate in the sun’s direct and re-emitted rays. While mountains must provide friction to any lower atmospheric rotation, it follows that they also function like a Crookes radiometer, the western slopes being warmer in afternoon heat than eastern slopes. Still orogenic wind resistance must be much greater than the radiometer effect, but if this is true it follows that an entirely mountainous planet would not have a rotating atmosphere, at least at low altitude. A jet stream maybe. –AGF

  59. If you want a classic example of an “expert” creating a paper tiger argument you need go no further than the comments by agfosterjr:
    July 12, 2013 at 8:15 pm

    “…It is thus impossible to attribute ENSO to the moon….”

    It is obvious that the ENSO (i.e. El Nino/La Nina events) is not being energised by the Moon (i.e. Lunar/Solar tides). No one with any skerrick of scientific literacy would claim this is the case. This is just a smoke-screen to divert the intellectually timid.

    However, even a junior high student student can tell you that it is possible for the energies produced by a massive steam engine to be governed by a small control valve.

    agfosterjr:
    July 12, 2013 at 8:15 pm
    tries to consolidate his “scientific authority” with the following statement

    “Lots of good work has been done toward attribution of LOD measurement, and a whole lot of junk science has been done, some of which shows up at WUWT.”

    Note how he sets himself up as the arbiter as to what is “good work” about LOD measurements and what he believes is “junk science”.

    This is just an absurd appeal to [self-appointed] authority, rather than using evidence to back your case.

    I let the reader decide who is actually pushing the junk science in this case.

  60. I have some problems with the 450 days of 21 hours compared with the approximately 365.25 days of 24 hours we experience now.

    Everything I’ve seen in the past indicates that the Earth is (slowly) moving into a higher — and thus longer — orbit around the Sun, just as the Moon is doing in regards to Earth. Yet these figures would have Earth experience a year of about 9450 hours 300MYA compared with our current value of around 8766. But since the length of a day has no bearing on the total number of hours in a year that seems like an exactly backward relationship to me. I could have easily believe a figure of 400 or 410 days of 21 hours, since that would be a shorter overall year but 450 I do have problems with.

    Where is my understanding going wrong?

  61. agfosterjr says:
    July 12, 2013 at 8:15 pm

    “Whereas tide oscillations do drive small ocean currents, some slight heat transport may turn out to be measurably correlated to tide intensity as governed by lunar orbital parameters.”

    I think that the slight heat transport that you are
    Are you aware of the following paper?

    http://web.science.unsw.edu.au/~stevensherwood/601_02/papers/Munk_98.pdf

    In this paper – i.e. Munk and Wunsch (1998) they claim that:

    A. Without deep mixing, in a few thousand years, the Earth’s oceans would turn into a stagnant pool of cold salty water.

    B. Hence, the Earth to Pole heat flux of 2000 Terra-watts associated with the meridional overturning circulation [of the oceans] would not exist without the comparatively minute mechanical mixing sources [i.e. deep water mixing].

    C. 2.1 Terra-watts are required to maintain the global [oceanic] abyssal density distribution against 30 Servdrups of deep water formation.

    D. Of the 3.7 Terra-watts of power provided by [Lunar] tidal dissipation in the Earth’s oceans, as much as 1 Terra-watt could be available for deep water mixing.

    E. The winds (~ 1 TW) and [Lunar] tidal dissipation (~ 1 TW) are the only possible source of mechanical energy that can drive the deep mixing of the oceans.

    These numbers have been revised (downward) since this seminal publication but the basic argument still stands.

  62. Sorry, the top of my past post should have read:

    agfosterjr says:
    July 12, 2013 at 8:15 pm

    “Whereas tide oscillations do drive small ocean currents, some slight heat transport may turn out to be measurably correlated to tide intensity as governed by lunar orbital parameters.”

    I think that the slight heat transport that you are referring to is technically called CLIMATE on millennial to decadal time scales. .

    Are you aware of the following paper?

  63. Ian Wilson says:
    July 12, 2013 at 11:23 pm

    agfosterjr says:
    July 12, 2013 at 8:15 pm
    ====================================

    Munk says: “The amount [3.5TW] is tiny compared to the solar radiation of 175,000TW received by the earth, the equator-to-pole ocean heat-flow of 2000TW, and even small compared to heat flow of 30 TW from the earth’s interior.”

    From this IW derives:
    “Hence, the Earth to Pole heat flux of 2000 Terra-watts associated with the meridional overturning circulation [of the oceans] would not exist without the comparatively minute mechanical mixing sources [i.e. deep water mixing].”

    And Munk says his study raises more questions than answers, including question #6 which he leaves unanswered: “Would the general circulation of the ocean be qualitatively different if the Earth had no Moon?”

    And Munk’s paper never mentions ENSO. It seems IW is pressing wine from raisins.

    So Ian, why don’t you identify this mechanism, this spigot that turns on Niños by way of tides? I find no such mechanism in Munk’s paper. He talks about tides mixing the middle and maintaining deep ocean stratification. Not a word about tides and weather. –AGF

  64. AGF,

    Here is the work of Claire Perigaud that has been done
    In collaboration with her research colleagues:
    Dr R. Gross, Caltech/ JPL, USA,
    Dr E. Rignot, Caltech/JPL and UC Irvine, USA,
    Dr D. Waliser, Caltech/JPL, USA

    http://www.aviso.oceanobs.com/fileadmin/documents/OSTST/2009/poster/Perigaudabstract.pdf

    ftp://ftp.cerfacs.fr/pub/globc/exchanges/GOASIS/Fermat_2009.pdf

    http://www.aviso.oceanobs.com/fileadmin/documents/OSTST/2009/poster/Perigaud.pdf

    http://coaps.fsu.edu/scatterometry/meeting/docs/2009_may/posters/perigaud.pdf

    (http://web.gps.caltech.edu/seminars/yly_seminar/past/2011.htm
    Earth-Moon-Sun alignments influencing El Niños and water/air mass momentum)

    Here is some of my work:

    Long-Term Lunar Atmospheric Tides in the Southern Hemisphere
    Ian R. G. Wilson and Nikolay S. Sidorenkov
    The Open Atmospheric Science Journal, 2013, 7, 29-54

    http://www.benthamscience.com/open/toascj/articles/V007/TOASCJ130415001.pdf

    El Ninos and Extreme Proxigean Spring Tides
    A lecture by Ian Wilson at the Natural Climate Change
    Symposium in Melbourne on June 17th 2009.

    http://www.naturalclimatechange.info/?q=node/10

  65. Ian Wilson says:
    July 12, 2013 at 10:31 pm

    “I let the reader decide who is actually pushing the junk science in this case.”

    Don’t sweat it too much. The fellow by the screen name agfosterjr has shown many times in the past that he does not understand the dynamics of energy storage and release or resonance phenomena in general.

  66. Ian Wilson says:
    July 13, 2013 at 2:58 am
    ===========================
    OK, that will take a while. But this I find interesting: “The most intriguing and global impact we had not anticipated is the strong biweekly peak of variability. We found it in the rain, in the winds, in the sea level, in the subsurface currents, in the Outgoing Long-wave Radiation (OLR), in the Significant Wave Height (SWH) data sets. We do not find it in SST.”
    (ftp://ftp.cerfacs.fr/pub/globc/exchanges/GOASIS/Fermat_2009.pdf –pp. 5-6)

    I think SST would be the most desirable link between tides and ENSO.

    Tell us what you think of this paper:

    http://icesjms.oxfordjournals.org/content/56/3/381.full.pdf

    Regards, –AGF

  67. Thank you agfosterjr for your openness to further inquiry.
    I may have unfairly misjudged your earlier comments. Sorry.

    • tadchem says:
      July 12, 2013 at 8:12 am
      ……………
      “The tides will stop when the earth’s rotation slows so much that it always keeps one face towards the moon. That event is MANY millions of years away. By my calculations, the day and the month will both be about 1100 hours (about 45-46 days) long, as we currently measure time.”

      =======

      Interesting proposition! Imagine the earth-moon system viewed by an observer above the North Pole. The earth rotates anti-clockwise (all points heading east). The moon does not really rotate around the earth, we are in a “two planet in the same orbit” system. Before jumping up and down, note that the moon’s orbit, like the earth’s, is always concave to the sun. When the moon is outside the earth, it is farther from the sun and its orbital speed is less than the earth’s, so the earth overtakes the moon. Gravitational pull of the earth then attracts the moon into a lower orbit, and accelerates it, so that the moon, after passing behind the earth, then overtakes the earth. The earth’s pull then attracts the moon out again, and slows it, so the moon crosses the earth’s orbit ahead of the earth, and eventually the earth overtakes the moon again. And so on ad infinitum, or nearly. But note: to that heroic observer, the moon is in a clockwise orbit relative to the earth. If the earth then turns one face to the moon, it means that the earth will have had to change its rotation from anti-clockwise to clockwise.

      Are there errors here? Perhaps, but it seems sound to me.

      Note that there are two satellites of Saturn in a similar joint orbit arrangement as the Moon and the Earth but more pronounced as they are smaller and closer to each other. These are:

      Epimetheus, distance to Saturn 151 422 km, diameter 113 km, orbital period 0.696 days;
      Janus, distance to Saturn 151 472 km, diameter 179 km, orbital period 0.696 days.

      As they are at slightly different distances, Epimetheus on the inner orbit overtakes Janus – it can’t pass it as their combined radii (146 km) is greater than the difference in orbital distances (50 km).
      Their gravitational interaction attracts E[pimetheus out, and Janus in, so Epimetheus is then going slower and falls behind, while Janus goes on ahead. Som many orbits later, Janus has made one more orbiot of Saturn and catches up with Epimetheus, and they change orbits again. Source of data is:

      http://jumk.de/astronomie/moons/saturn-moons.shtml

  68. tadchem says:
    July 12, 2013 at 8:12 am

    uh, tad, you must be reading “modern” science books.

    Don’t be fooled. The Earth cannot transfer angular momentum to the Moon.

    You have been taught that the Moon rotates on its axis, I guess….

    • Oh, please, geran! The moon does rotate (slowly) on its axis. The moon also has angular momentum as measured from the earth (and from the sun, for that matter). Conservation of angular momentum is merely a special case of conservation of energy. You do have that in your physics books, don’t you? As the earth passes energy to the moon, to put it into a higher orbit, it can be measured as a change in angular momentum (in the earth-centered system) of both earth and moon.

  69. ShrNfr says:
    July 11, 2013 at 3:37 pm
    Gosh, that almost looks like a temperature graph with the AMO…

    Yes, and the length seems very similar. And when the earths spin slows down the water will be pushed mainly eastwards because of its inerta, and the top effect will be when deceleration stops and a new acceleration starts. And in combination with the regular ocean currents, hmm..

  70. skorrent1 says:
    July 14, 2013 at 5:07 am

    Oh, please, geran!
    >>>>>>>

    Since you said “please”, I will try to help.

    First, the Moon does NOT rotate on its axis. Let me demonstrate: Consider a race horse moving around an oval track. A viewer in the stands (outside the oval) sees the right side of the horse, as the horse passes nearby. But, on the far side of the track, the viewer sees the left side of the horse. So, it APPEARS the horse has rotated on it axis, But the horse in only following an oval orbit. Exactly the same as our Moon. (And, just as in the case of our Moon, a viewer INSIDE the oval always sees the same side of the horse.)

    There are other errors and misconceptions in your comment, but first it is important you understand this simple point. It gets more complicated from here.

    • Come off it, Geran.

      The moon DOES rotate. See Wikipaedia:

      “With respect to the stars, the Moon takes 27 Earth days, 7 hours and 43.2 minutes to complete its orbit; but since the Earth-Moon system advances around the Sun in the meantime, the Moon must travel further to get back to the same phase. On average, this synodic period lasts 29 days, 12 hours, 44 minutes and 3 seconds. This is an average figure, since the speed of the Earth-Moon system around the Sun varies slightly over a year, due to the eccentricity of the orbit.”

      If your horse starts heading east, then turns left and heads north, then left again and heads west, then turns again and heads south, then finally ends up heading east again, the horse has rotated once, even if the rotation is spread out over a full race track.

      You might not like Wikipaedia, but if you posted there that the moon does not rotate you would be shot down smartish!

    • Ah, geran, but a viewer above the plane of the moon’s orbit notices that the moon must spin completely around once every 28 days or so to keep it’s same face toward the earth. A horse making, essentially, four left turns (or right turns in England) does wind up turning 360 degrees. Explain, please, when is a rotation not a rotation. Always open to correction of “errors and misconceptions”. Hate to think that my professional calculations of missile and satellite paths were wrong.

  71. Dudley Horscroft says:
    July 14, 2013 at 6:52 am

    Exactly my point Dudley, “institutional” science is wrong in several areas, AGW, is only one such area. The Moon is so simple and straight forward that it is a perfect example.

    skorrent1 says:
    July 14, 2013 at 6:56 am

    The difference is the horse is NOT rotating on its axis, nor is the Moon.

    • If you are claiming that “rotation on an axis” does not occur unless the object is stationary, then you have a weird definition of rotation. By that measure, the earth does not “rotate” because while it is “spinning” it is also moving along its orbit around the sun, just as the moon moves along its orbit around the earth.

  72. Geran, to put it another way, if I told my buddies that their spy satellites did not have to “rotate on their axes once per revolution” to keep their camera’s pointed toward the ground, I would have been booted off the project.

  73. skorrent1 says:
    July 14, 2013 at 7:37 am
    If you are claiming that “rotation on an axis” does not occur unless the object is stationary, then you have a weird definition of rotation. By that measure, the earth does not “rotate” because while it is “spinning” it is also moving along its orbit around the sun, just as the moon moves along its orbit around the earth.
    >>>>>>>

    If you really believe I have made such a claim, then your imagination is working REALLY well. So, try to imagine that what you see is what it is. The horse is NOT rotating on its axis, nor is the Moon.

  74. skorrent1 says:
    July 14, 2013 at 7:56 am
    Geran, to put it another way, if I told my buddies that their spy satellites did not have to “rotate on their axes once per revolution” to keep their camera’s pointed toward the ground, I would have been booted off the project.
    >>>>>

    So, intimidation means you are not free to think for yourself?

  75. Just curious, does anyone have the calculation for how many joules of energy is being transferred when the Earth speeds up or slows down one millisecond?

  76. @ Dudley Horscroft July 14, 2013 at 1:09 am
    You say:-

    When the moon is outside the earth, it is farther from the sun and its orbital speed is less than the earth’s, so the earth overtakes the moon.

    Let’s test your statement with some observations. When the waning moon is past its last quarter we can often see it rising in the east in the pre-dawn sky ahead of sunrise. In this case, from my northern hemisphere perspective, the moon is located to the right of the sun. At new moon the moon is closer to the sun than the earth. After new moon we see the waxing crescent moon in the western sky after sunset, now located to the left of the set sun. So this series of observations tells us that the new moon passes from right to left across the daytime sunlit sky.

    For this observation to be true it necessarily follows that at the time of new moon the earth passes the moon “on the outside track” and so is orbiting the sun faster than the moon, even though it is further away. Not convinced by this? Consider the example of the time in 1973 when Concorde chased the Moon Shadow across the Sahara Desert along the Path of Totality Total Solar Eclipse of 30 June 1973 from Concorde 001

    At the time of the eclipse the moon shadow passed from the west over the Atlantic Ocean eastwards across the sunlit Sahara Desert towards the eastern horizon. So the direction of the shadow’s motion is from right to left for a ground based northern hemisphere eclipse observer. We know that the earth is further from the sun at the time off a solar eclipse. The earth is therefore overtaking the moon shadow. The only way this can occur is for the earth to be orbiting the sun faster than the moon when the earth is furthest from the sun.

    A moment’s reflection will show that this is also true for the moon. At the time of full moon it is orbiting the sun faster than the earth even though it is further away.

  77. geran says:
    July 14, 2013 at 6:19 am

    “But, on the far side of the track, the viewer sees the left side of the horse. So, it APPEARS the horse has rotated on it axis, But the horse in only following an oval orbit.”

    You have a fundamental misunderstanding. We never see the “left side of the horse”, i.e., the “dark side of the Moon”. The Moon always shows us the same face.

    Look at it over a month’s time. No matter where you see it, you will always see the Man in the Moon. The Moon is tidally locked. It rotates at essentially the same rate as it revolves around the Earth.

    And yes, the Earth can influence both the orbital angular momentum and the spin angular momentum of the Moon because both bodies are non-rigid.

  78. Bart says:
    July 14, 2013 at 9:25 am

    You have a fundamental misunderstanding. We never see the “left side of the horse”

    >>>>>>

    Bart, ever been to a horse race? How about a track meet? Same principle. Or, you can carry out this experiment on your living room floor. It is not a hard concept. (Use an orange for the Earth and a pencil, or other pointed object, (please be very careful with pointed objects….) to represent the Moon.

    No expensive test equipment involved, but you have to use your brain.

    • Geran: This is getting tedious. I tried your orange/pencil experiment. I started with the marking side of the pencil facing the orange and found that, as I moved the pencil around the orange — always keeping the marking facing the orange — I had to rotate the pencil completely one time to arrive back at the starting point. Gee, what am I doing wrong ;-)? Must be my brain! LOL

  79. geran says:
    July 14, 2013 at 10:02 am

    The stupid. It burns…

    Try this, geran. Suppose the jockey is holding a compass. As he rounds the track, is the needle going to A) stay fixed or B) rotate 360 degrees? In your reality, you would choose (A). That is incorrect.

  80. Anyway, sorry I got involved. I should know by now that you cannot reason someone out of something they have not been reasoned into. Hasta la vista, geran.

  81. Philip M– dudley may be mathematically challenged, but wouldn’t it be easier to just say “At the time of a full moon the moon’s earth-orbit velocity vector is added to the earth’s orbital velocity, while at new moon, it is subtracted.”?

  82. skorrent1 says:
    July 14, 2013 at 10:42 am
    Geran: This is getting tedious. I tried your orange/pencil experiment. I started with the marking side of the pencil facing the orange and found that, as I moved the pencil around the orange — always keeping the marking facing the orange — I had to rotate the pencil completely one time to arrive back at the starting point. Gee, what am I doing wrong ;-)? Must be my brain! LOL
    >>>>>>

    I understand, but please hang in there. I think you may be about to see it.

    As you moved around the orange, you were turning the pencil, not rotating it on its axis. This is just the same as the race horse of race car.

    Also, try this. Assume the orange is the middle of a clock face. Start with the pencil at the “3:00″ position. Position one finger at middle of the pencil. Your finger will represent the axis of rotation. Without advancing the pencil around the clock, rotate the pencil 360 degrees. You will notice that the orange “sees” all sides of the pencil during a full rotation. If the Moon were rotating on its axis, instead of turning, we would see all sides of the Moon, which we do not.

    Hang it there….

  83. Retired Engineer John says:
    July 14, 2013 at 8:38 am

    Just curious, does anyone have the calculation for how many joules of energy is being transferred when the Earth speeds up or slows down one millisecond?
    =============================================================
    The earth’s kinetic energy of rotation is 2.138 x 10^29 J. A sidereal day is 86164 seconds.

    So (2.138 x 10^29J x 2) / (86164 x 1000) = 4.96 x 10^21 J.

    LOD loses 2.3ms/century irreversibly, less a temporary .6ms/century reversibly due to GIA–which doesn’t enter into the equation, so it takes 43 years to lose a ms worth of energy, enough to heat the whole ocean almost 1/1000 of a degree and enough to heat your kitchen with some left over. Plenty of energy but hard to harness. –AGF

  84. geran says:
    July 14, 2013 at 11:16 am
    ============================
    Well geran, surely you will admit that the people on the outside of the racetrack will see both sides of the horse, so that to maintain your stance you must agree that your definition of rotation is one of special perspective. A camera on the inside of the track does not see the dark side of a dark horse. A camera on the outside, trained constantly on the lead horse, sees the horse at all angles, so to that camera man it appears that the horse is rotating. He has the equivalent of a sidereal reference frame, an inertial perspective. I suppose you’re just having fun but I’ve seen better arguments for a flat earth. –AGF

  85. Retired Engineer John says:
    July 14, 2013 at 8:38 am
    ======================================================
    Oops, you probably knew what I meant but make that “LOD GAINS 2.3ms/century irreversibly…”
    –AGF

  86. agfosterjr says:
    July 14, 2013 at 12:08 pm

    ???

    Are you somehow trying to somewhat agree with me, or just confused?

    Where did you ever get the idea that I have defined “rotation”? I have been using the term “rotates on its axis”.

    Hope that helps.

    ???

  87. “Diurnal Time Variations” sounds more scientific to me.
    “Length of Day Variations” is that measured in miles or kilometres? (LOL)

  88. geran says:
    July 14, 2013 at 1:43 pm
    ==================================
    Well do you know about some kind of rotation that doesn’t involve spinning? About an axis?? All astronomers agree that the moon rotates about its axis. This was accepted even before
    Copernicus. If you seriously don’t believe this there’s a flat earth society waiting for your membership.

    How about this: does a ship sailing clear around the globe so a somersault? –AGF

  89. Consensus will elect a prom king/queen.

    and let’s see—is the flat earth society about continuing to believe things that can be so easily disproved??

  90. Definitions certainly are a matter of consensus. You can’t make up your own. If you have a private philosophy consisting of idiosyncratic definitions you will have a hard time communicating. Wheels rotate/spin/revolve about an axle/axis. Whether a wheel has an axle or not, it does have an axis, a center of rotation, which is motionless relative to a perspective stationary relative to the (circumference of) the spinning object (if it is round). A bicycle wheel has an axis of rotation whether it’s spinning over the ground or in a bike shop. A motorcycle wheel has an axis of rotation anywhere it goes, including inside a circus cage cylinder. Assume two gears of equal size, one fastened to a table top, the second spinning around it. Does the second gear rotate or not? Does it revolve or not. Does it not rotate around its center? Does not the moon?

    I pause for reply. –AGF

  91. Geran (1116): “…as you moved around the orange, you were turning the pencil, not rotating it on its axis. This is just the same as the race horse of race car. ”

    So the moon doesn’t rotate, it turns? It doesn’t rotate on its axis, it turns on its axis?

    You’ll have to be patient with all us of inferior intellect, lest you lose your audience. –AGF

  92. agfosterjr says:
    July 14, 2013 at 9:27 pm
    So the moon doesn’t rotate, it turns?
    >>>>>

    There appears to be some progress!

    Yes, the Moon is turning in its orbit, just as the race horse on an oval track. It is NOT rotating on its axis. There are two different motions here. For example, walk in a circle (orbit). Someone standing inside the orbit would see the same side of you. Next try walking the same orbit, while spinning on your axis. The person standing inside the orbit would then see different sides of you. That is why the Moon “rotating on its axis” is easily disproved.

    And, as long as I see some progress, I will be patient. (That is why you do not receive any derisive slurs from me.)

  93. Well by your criteria nothing rotates; all turns. The earth spins while it revolves around the earth/moon barycenter, while the barycenter revolves around the sun, while the sun revolves around the galaxy, while the galaxies move apart. So all you have done is repudiated generally the phrase “rotate around its axis.” You have defined the word “rotate” out of existence, in all but an Aristotelian universe. Not even a bicycle wheel can “rotate” by your definition, even in the bike shop, in a Copernican universe. –AGF

  94. Let me try again. You use “turn” in the sense of revolve, and use “rotate” in the special sense of internal, central perspective. According to which, as I already noted, you ignore the external perspective as would be the case of a cameraman outside the race track, who definitely would see the horse “rotate.” So I repeat, you have invented your own definition of “rotate,” one which has nothing to do with an inertial reference frame but has only to do with special perspective: if the object appears to any observer in the universe not to be spinning, then it is not spinning–or “rotating,” all other observers be damned. –AGF

    • AGF– You have finally plumbed the depths (?) of G’s thought process. He reserves the phrase “rotates on its axis” for situations in which the axis itself is completely stationary. Like Humpty Dumpty, the phrase means only what he wants it to mean “neither more nor less”. But, of course, nothing in the universe is completely stationary– everything being subject to multiple simultaneous motions — therefore his use of the phrase is completely arbitrary.

  95. skorrenet 1, right you are. Of course he would say our definitions are arbitrary. But while you posted I was writing too, and I’ll post it anyway:

    Here’s another angle. If an object spins, does not every point on the object spin? Suppose you you stand in the middle of a merry-go-round and see children holding on near the perimeter. If you stand still you don’t have to turn your head to watch them steadily, while you would have to turn your head to look at someone standing on the ground. Now you might think it redundant to say the children are both revolving and rotating, but you must admit that you and they are rotating together, while the children experience centrifugal force which you do not because they are also “revolving” at some distance from the center. Does that make sense?

    Maybe not. We could just as well say the centrifugal force was due to the rotation, in which case it is in fact redundant to say every point on the disc except the center both spins and revolves. OK, I think I see your point now. But the fact remains that every point on the disc does revolve around the center, and does rotate relative to the non-disc universe. So you would say that the fact that the moon experiences day and night over a synodic month follows from its revolution, not some separate rotation apart from its revolution.

    But this just gets us back to convention and consensus. Since Newton, physicists have defined rotation according to a sidereal or inertial reference frame. And you must admit that for the moon to experience phases–day and night–it must rotate relative to the sun. And if it rotates relative to the sun it must do so about an axis of rotation. The moon must have a north and south pole from which the sun appears to revolve around the horizon, just like on earth. And we don’t care if it wobbles–the earth’s axis wobbles too.

    So if you want to eliminate one or the other of the two terms ‘revolve’ or ‘rotate’ –or in your parlance, ‘turn’ or ‘rotate’ –you would have to get rid of ‘turn’ or ‘revolve’ (relative to a center), not ‘rotate’ (relative to the stars). But ever since we got rid of the celestial spheres we have needed both. The moon really does revolve around the earth/moon center of gravity. And it really does rotate relative to the sun and stars, if not relative to the earth. And your special terra-centric perspective really is a relic of the Aristotelian universe and has not place in modern science. Nor are you entitled to your own definition of terms. So give it up. –AGF

  96. skorrent1 says:
    July 15, 2013 at 8:09 am

    You may need to try the “orange/pencil” experiment again.

    agfosterjr says:
    July 15, 2013 at 8:47 am

    No amount of rhetoric can replace the facts.

    The Moon does NOT rotate on its axis. (See “orange/pencil” experiment.)

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