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.
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.”
The research was conducted in partnership with the Université Paris Diderot and is published in Nature.
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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.
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.
Jimbo says:
July 11, 2013 at 4:57 pm
That is choice 🙂
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.
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.
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.
A.D. Everard says (July 11, 2013 at 3:59 pm): “This sounds to me a bit like blowing on your own sail”
Funny you should mention that. 🙂
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.
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.
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.
“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
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.
After reading some of the comments here I’m wondering if Earth’s core has some influence on spelling mistakes. Just sayin’ 🙂
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.
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.
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?
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. 😉
The Earth’s orbit should increase with time as the sun loses mass.
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.
And in fairness I should admit that I nicked that idea from Wellington in “The Perishers”.
http://www.theauthenticperishers.co.uk/
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.
Not really new, JPL and Potsdam have papers on the subject.
What is new is that processes in the Earth core are synchronized with solar activity, as I have shown here some time ago:
http://www.vukcevic.talktalk.net/SSN-LOD.htm
Now, that should shake geo-solar science from its current slumber.
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.
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.
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.