[gem (OP)]

HI all,

OK BC

You are muddling a whole bunch of things there.
Please clarify your question in terms of angular momentum;
linear momentum and energy, all of which are strictly conserved

All of which are strictly related in wave form, for example,

momentum = energy/phase velocity.

wave momentum is related to wave energy in
a simple and seemingly universal way. there are many different
kinds of wave motion that links them, for example, electromagnetic waves, sound waves, water waves, and certain kinds of traveling waves such as one's on strings under tension.

BC

Are you aware that sound does not follow the inverse square law?

Sorry BC, I don't agree, and I did provide a link in the previous post that states:

The sound intensity from a point source of sound will obey the inverse square law

also given the sound intensity is defined as the sound power per unit area.

http://hyperphysics.phy-astr.gsu.edu/hbase/Acoustic/invsqs.html


gem

Also given the time aspect between transfers how do you exclude thermal radiation in your calculations spontaneously transferring  away from that side of the equation

BC

I don't need to. All transfers, including those carried by photons, conserve momenta and energy

The problem with that is,
the momentum and energy of sound  is carried off in all directions.

which brings us back to, how is the vector direction total maintained for later transfer back to the angular momentum of the solid earth, due to the partially inelastic collisions sending momentum away from the transfer point, in all directions ?

indeed as you say photons conserve momenta and energy but the system does not.
     

[Bored chemist]

Sorry BC, I don't agree,

It is unfortunate that you do not agree with reality, but it is no surprise to me.

"Stokes's law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's viscosity. It states that the amplitude of a plane wave decreases exponentially with distance travelled,"

https://en.wikipedia.org/wiki/Stokes%27s_law_of_sound_attenuation

[Bored chemist]

The problem with that is,
the momentum and energy of sound  is carried off in all directions.

Which means that, on average, it is zero.
So, as it fades, there's no problem.

which brings us back to, how is the vector direction total maintained

It is zero.
As you say, it points equally in all directions and the only way to do that is to have all the vectors "cancel out".

[Bored chemist]

indeed as you say photons conserve momenta and energy but the system does not.

Does it worry you that you are the only one who believes this?

[gem (OP)]

Hi all

OK BC

"Stokes's law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's viscosity. It states that the amplitude of a plane wave decreases exponentially with distance travelled,"

SO Acoustic attenuation is a measure of the energy loss of sound propagation in media. Most media have viscosity, and are therefore not ideal media. When sound propagates in such media, there is always thermal conversion of wave energy caused by viscosity.

Which just confirms what I posted earlier

gem

For the elasticity of the collisions to be immaterial, then it requires explanations of phenomena such as the transfer of momentum via sound waves the majority that also end up as heat, retrieved to the angular momentum.

Attenuation does not include the decrease in intensity due to inverse-square law geometric spreading. Therefore, calculation of the total change in intensity involves the inverse-square law and an estimation of attenuation over the path due to the viscosity of the medium.

gem

how is the vector direction total maintained for later transfer back to the angular momentum of the solid earth, due to the partially inelastic collisions sending momentum away from the transfer point, in all directions ?

BC

It is zero.
As you say, it points equally in all directions and the only way to do that is to have all the vectors "cancel out".

precisely the solid earth transferred angular momentum to the atmosphere reducing the solid earths momentum total.

Which as you say the momentum carried away by sound to be available to be transferred back later is ZERO   

[Bored chemist]

Therefore, calculation of the total change in intensity involves the inverse-square law and an estimation of attenuation over the path due to the viscosity of the medium.

Well done.
You have caught up with what I said a while ago.

[Bored chemist]

precisely the solid earth transferred angular momentum to the atmosphere reducing the solid earths momentum total.

The solid earth (over a reasonable period of time) transfers ZERO momentum to the atmosphere.
Because the momentum carried by the sound sums to zero.
So the loss by the solid earth is zero.


If the Earth lost angular momentum to the air then the air would have to rotate WRT the earth.
Friction would slow it down again until the angular momentum was transferred back.

In the short term, there can be transfers (though they are very near zero on average across the Earth).
Averaged over time they are exactly zero. |(Give or take atmospheric tidal drag).

[gem (OP)]

Hi all,

OK

precisely the solid earth transferred angular momentum to the atmosphere reducing the solid earths momentum total.
Which as you say the momentum carried away by sound to be available to be transferred back later is ZERO 

The solid earth (over a reasonable period of time) transfers ZERO momentum to the atmosphere.
Because the momentum carried by the sound sums to zero.
So the loss by the solid earth is zero.


If the Earth lost angular momentum to the air then the air would have to rotate WRT the earth.
Friction would slow it down again until the angular momentum was transferred back.

In the short term, there can be transfers (though they are very near zero on average across the Earth).
Averaged over time they are exactly zero. |(Give or take atmospheric tidal drag).

In the short term the transfers may seem small when we are considering fractions of a milli second daily variations in the
LOD "however they are not"
If we consider the approximate 0.3 of a milli second variation for one day given in the dates earlier, corresponds to a change in rotational kinetic energy of the solid earth in the region of 1.6 x 10^21 joules for the day in question.
These daily fluctuations are values that are not remotely near to zero.

The fact that the LOD appears consistent over longer time periods can also be explained
by a balance of frictional forces and accelerating forces ( terminal angular rotation) rather than the "born that way" explanation.   

   

[Bored chemist]

If we consider the approximate 0.3 of a milli second variation for one day given in the dates earlier, corresponds to a change in rotational kinetic energy of the solid earth in the region of 1.6 x 10^21 joules for the day in question.

I realise it's terribly "English" to always talk about the weather but...

We are talking about the momentum transfers which definitely sum to zero over the long term.
You are talking about the transfer of heat from the earth to the air.
And that's broadly what drives the weather.
So it is irrelevant.

The hint is in the units.

[evan_au]

The annual component of the change of the length of day of approx  0.34 ms...
If we consider the approximate 0.3 of a milli second variation for one day

I don't know where the variation of 0.3ms in one day came from. This quotes an annual change, not a 1 day change.

The current long-term variation in Earth's rate of rotation is quoted as"+1.7 ms/d/cy", ie every century, it changes by 1.7 ms/day.
- So in a year, you could expect it to change by about 170μs/day (plus short-term variations which might take it up to 300μs/day over the course of some years).
See: https://en.wikipedia.org/wiki/%CE%94T_(timekeeping)#Earth's_rate_of_rotation

[gem (OP)]

Hi all,

If we consider the approximate 0.3 of a milli second variation for one day given in the dates earlier, corresponds to a change in rotational kinetic energy of the solid earth in the region of 1.6 x 10^21 joules for the day in question.

I realise it's terribly "English" to always talk about the weather but...

We are talking about the momentum transfers which definitely sum to zero over the long term.
You are talking about the transfer of heat from the earth to the air.
And that's broadly what drives the weather.
So it is irrelevant.

The hint is in the units.

MMMMM, I believe we already covered the universal link (momentum = energy/phase velocity.)
and if you look at the original question, the units for energy are correct and relevant, to put a scale to what you tried to dismiss as close to zero.
However if you prefer a 0.3 milli sec daily variation in LOD should give a corresponding  ±Δ angular momentum

of aprox = 2.019 x 10^25  Kg m^2  for the day in question

Evan_au

I don't know where the variation of 0.3ms in one day came from. This quotes an annual change, not a 1 day change.

You probably need to look back to post 60 and a few on from there.

But to help, the LOD tends to skip about quite a bit more than you believe, also it has an annual speeding up in the northern hemisphere's summer and slowing down in its winter to a well established pattern of ± 1.5 milli sec as per the link below.

https://en.wikipedia.org/wiki/Day_length_fluctuations#/media/File:Deviation_of_day_length_from_SI_day.svg


And bringing that data into closer detail

https://datacenter.iers.org/singlePlot.php?plotname=FinalsDailyIAU1980-LOD-BULA&id=12 

[Bored chemist]

In every single collision between any two atoms or between atoms and photons or phonons, momenta and energy are conserved.
So they must be conserved in every sequence  and combination of collisions.
So they are conserved in total.

Get back to us when  you can explain how arithmetic fails.

[Bored chemist]

believe we already covered the universal link (momentum = energy/phase velocity.)

Yes we did.
I pointed out that sound waves spread in all directions, so their vector sum is zero.
That cover it nicely.

[gem (OP)]

Hi all

BC

In every single collision between any two atoms or between atoms and photons or phonons, momenta and energy are conserved.
So they must be conserved in every sequence  and combination of collisions.

How does the addition work for a non isolated system ?
https://en.wikipedia.org/wiki/Thermal_radiation

BC

I pointed out that sound waves spread in all directions, so their vector sum is zero.
That cover it nicely.

I think if you look back that was me.

gem

The problem with that is,
the momentum and energy of sound  is carried off in all directions.

which brings us back to, how is the vector direction total maintained for later transfer back to the angular momentum of the solid earth, due to the partially inelastic collisions sending momentum away from the transfer point, in all directions ?

So the problem still remains, a daily change in angular momentum vector due to friction ending up as momentum with a positive value but no longer having a net direction to transfer back to maintain/conserve the LOD

Indeed the random motion of particles can decrease/increase depending on the balance of incoming/outgoing flux of radiation to the Non isolated system under consideration.

Also given the Non inertial conditions of the system this generates forces that can and does accelerate/change the momentum of a droplet of a fluid by altering the gradient of the pressure due to the dynamics of changing density in a gravity field due to the incoming/outgoing flux of radiation to the Non isolated non inertial system under consideration.

[Bored chemist]

How does the addition work for a non isolated system ?

If no particle leaves then no momentum leaves.
If the loss is (on average) isotropic then the net change in momentum is (on  average) zero

[Bored chemist]

So the problem still remains, a daily change in angular momentum vector due to friction ending up as momentum with a positive value but no longer having a net direction to transfer back to maintain/conserve the LOD

As Paul Simon said, "the problem is all inside your head"
"The answer is easy , if you take it logically."

This "a daily change in angular momentum vector due to friction "
Just isn't real.

[Bored chemist]

I realise it's terribly "English" to always talk about the weather but...

For those who didn't get the point.
Gem talks of

1.6 x 10^21 joules for the day

which is quite a lot of energy
But a single hurricane can carry 10^20 J

So, if you consider the weather over the whole Earth, 1.6*10^21 J is not much

[gem (OP)]

Hi all,

BC

If the loss is (on average) isotropic then the net change in momentum is (on  average) zero

The problem with that statement is the frictional coupling between the solid earth and its atmosphere converts  anisotropic motion to isotropic motion.

Also as stated previously, the the Non inertial conditions of the system that generates forces that can and does accelerate/change the momentum of a droplet of a fluid by altering the gradient of the pressure due to the dynamics of changing density in a gravity field due to the incoming/outgoing flux of radiation to the Non isolated non inertial system under consideration is an example of anisotropy due to bulk flows of fluid with a background effect due to density, therefore favoring a specific direction.

So the problem still remains, a daily change in angular momentum vector due to friction ending up as momentum with a positive value but no longer having a net direction to transfer back to maintain/conserve the LOD

Moving on to the points regarding following the energy of the interactions I am highlighting here its the patterns of the fluctuations that could give a insight to the dynamics.
So looking at the annual 3 milli second variation in LOD ( Δ = 1.4477 x 10^22 Joules/day ) 

Given it was down to a necessity to explain the newly discovered three millisecond annual variation in LOD I believe it was the explanation of its time, but I believe there is alternative explanations that will be more satisfactory.
 
https://syrte.obspm.fr/astro/journees2019/FILES/salstein.pdf

The earliest observations of changes in length of day were made at Paris Observatory by Stoyko
and Stoyko (1936), who observed the annual variation of length of day. In 1948, Victor Starr of the
Massachusetts Institute of Technology (MIT) noted that the atmosphere need not conserve angular
momentum, and could share it with the Earth below. Starr started the General Circulation Project
at MIT, and one of its features was calculations of fluxes and changes in atmospheric angular
momentum.

BC

As Paul Simon said, "the problem is all inside your head"
"The answer is easy , if you take it logically."

This "a daily change in angular momentum vector due to friction "
Just isn't real.

Its funny you should take the lyrics route to make a point, because I intend to do similar to start the explanation as to the real dynamics occurring.

Daft Punk Lyrics:

"Like the legend of the phoenix
Our ends were beginnings
What keeps the planet spinning
The force from the beginning"


So look out for "Are you a Daft Punk or a Newton of drift theory ?"

https://earthobservatory.nasa.gov/features/Wegener/wegener.php

[Bored chemist]

The problem with that statement is the frictional coupling between the solid earth and its atmosphere converts  anisotropic motion to isotropic motion.

That bit of the system isn't where things are lost from, so momentum cannot be carried away into space.

You also seem not to recognise that, on any given day, the angular momentum of the atmosphere may be a bit higher or lower than the average but, the total angular momentum of the rock and the air is conserved.
It is conserved because there is no torque acting on the system (apart from a few thing we have discussed, such as the tides).

[gem (OP)]

Hi all,

BC

You also seem not to recognise that, on any given day, the angular momentum of the atmosphere may be a bit higher or lower than the average

So to be clear, I believe it is possible the average angular momentum total fluctuates, for the reasons given previously,
the sharing of angular momentum between the atmosphere and the solid earth became the go to explanation of the underlying annual fluctuation.

I believe it can be explained as terminal velocity.

   
BC

It is conserved because there is no torque acting on the system (apart from a few thing we have discussed, such as the tides).

That indeed is the current thinking, which I believe falls short of the physical reality, I think there is potential alternative explanations as to the fluctuations of LOD that indeed require forces not yet identified.

To explain these forces although a simple mechanism, I will have to go across a broad range of examples and correlations of physical events.

For example a potential link to galaxy rotation curves and G