[Halc]

When the forces are not balanced, due to expansion of the atmosphere that's heated, the volume/droplet of air accelerates, due to the upthrust of the buoyancy effect.
This changes momentum due to the acceleration of bulk motion of fluids, the rate of change in momentum is equal to
   
Δmomentum = ρ.Δv/Δt
 
This is equal to the net force on the volume/droplet.

these forces that change the momentum of a volume/droplet of a fluid come from the gradient of the pressure and gravity.

This occurs due to energy input from outside the system under consideration doing work on the system to increase the volume occupied by mass, which then facilitates the separate spontaneous buoyancy/convection  action/reaction.

All very nice up to here, and doesn't disagree with what we've been saying. Some details are missing like rotation that is inevitable with movement in a rotating frame of reference.

Which  happens independently of the solid surface

This hasn't been demonstrated. For one, the solid surface provides the reaction force to the gravity, required for the buoyancy, so it is hardly independent of the surface.  But as I said, a ball of gravitationally bound gas would still have buoyancy of low density regions, so the surface being a solid isn't a requirement, but the forces from below cannot be ignored.

Therefore the conditions of conservation of momentum are not met.

This also has not been demonstrated, and is an assertion that is not even remotely plausible. Are you saying the warm mass can accelerate upward with no equal and opposite reaction change of momentum elsewhere?

At least we finally have a hard assertion of violation of the conservation laws. You've been hesitant to just come out and say it.

[Bored chemist]

This changes momentum due to the acceleration of bulk motion of fluids, the rate of change in momentum is equal to...

Zero.
It's a conserved property; it can't change, so the rate of change is zero.
If you get a different answer then you are not looking at the whole picture.

Essentially, you consider the hot air rising, but you ignore the cold air falling.
The changes in momenta cancel out.

[Bored chemist]

This hasn't been demonstrated.

The presence of convection currents in the Sun shows that you don't need a solid surface.
It is sufficient that you have other matter to "push against".

[Bored chemist]

Therefore the conditions of conservation of momentum are not met.

The sole condition for that (provided that you look at the whole system) is that the laws of physics are symmetrical with regard to a change in position.
And that condition is met, universally.

https://en.wikipedia.org/wiki/Noether%27s_theorem

Consider , for the minute, the Earth and Sun (and the moon if you like) as the "system"
If you are saying that the Earth experiences a torque due to sunshine then the Sun must experience a counter-torque. Otherwise the angular momentum of that whole system is not conserved, and that suggestion is forbidden.

Since the torque provided to the Earth depends on the weather, the counter-torque must also do so.

What is the mechanism by which the Sun "knows" what the weather is like on Earth so that it can adjust its angular momentum accordingly?

[Bored chemist]

Therefore it needs to be demonstrated if the solid earth can/cannot discriminate between these collision and a meteorite, i

The Earth doesn't make the distinction, but we do.

We distinguish between "the atmosphere", which is part of the Earth and "the meteor" which is not part of the Earth.
There are more interesting cases; when we launched a rocket to take people to space, we slightly altered the rotation of the rock we are stood on.
But when that rocket landed, we re-established the length of the day (give or take the loss of momentum carried by the exhaust fumes).

However, if you consider the system which includes the rocket, the earth and all those fumes, the angular momentum (and linear momentum) remained unchanged through the whole process..

[gem (OP)]

Hi all,

Ok quite a lot to cover so may do it over a couple of posts.

Halc my bold

At least we finally have a hard assertion of violation of the conservation laws. You've been hesitant to just come out and say it.

I don't believe that's what I stated,

gem

Therefore the conditions of conservation of momentum are not met.

So moving on to

gem

Which  happens independently of the solid surface

Halc

This hasn't been demonstrated. For one, the solid surface provides the reaction force to the gravity, required for the buoyancy, so it is hardly independent of the surface.

BC

The presence of convection currents in the Sun shows that you don't need a solid surface.
It is sufficient that you have other matter to "push against".

That's how I understand it.

Now BC I don't believe we can apply the argument for Noether's  theorem in defense of the dynamics under consideration, but wouldn't like to comment against it in regards to the 3 body system you set out for the Sun Earth and Moon.

below a direct quote from the link you provided;
 
"Noether's first theorem states that every differentiable symmetry of the action of a physical system with conservative forces has a corresponding conservation law"

If you follow the link for the "action"  you get;
Action has dimensions of energy × time or momentum × length, and its SI unit is joule-second

and if you follow conservation law you get;
in physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time.

given whats under discussion is down to an input of energy to the system, so it doesn't tick that box 
and the "momentum x length" value is altered for a point mass during these dynamics it doesn't tick that box either.

BC you have raised two other points and Halc there's also something you've raised, that I will try to respond to tomorrow
 

[Halc]

I don't believe that's what I stated,

Therefore the conditions of conservation of momentum are not met.

OK, I perhaps see what you meant. The conditions are met though. The closed system has had no external torque/force applied to it, so its momentum is unchanged by the accelerating mass within. The accelerating low-density mass of air is not a closed system of course, just part of one.

So moving on to

Which  happens independently of the solid surface

The presence of convection currents in the Sun shows that you don't need a solid surface.
It is sufficient that you have other matter to "push against".

That's how I understand it.

And I agree. I've said that buoyancy doesn't require a solid or liquid to push against. But the ground is there in this case, and the atmosphere is definitely getting force applied by it. It seems quite inaccurate to assert that it plays no role in the acceleration of the mass of low density air.

It sounds like you're still working things out.
Consider some complications. We start with the warming of a large region and all the lower atmosphere becomes correspondingly less dense. It can't easily go up because it all wants to go up and all the cold air above wants to go down and they're effectively in each other's way. It's an unstable equilibrium of sorts eventually resulting in turbulence and chaotic motion. That that chaotic motion quickly organizes itself into more stable patterns that we see.

[Bored chemist]

I don't believe that's what I stated,

It is what you stated.

Therefore the conditions of conservation of momentum are not met.

It may not be what you meant, but it is what you said.

[Bored chemist]

given whats under discussion is down to an input of energy to the system, so it doesn't tick that box 

True.
But momentum (apart from radiation pressure) is not added to the system, so it closed in that regard.
You need to recognise that both quantities are conserved and you can't magically change one into the other.

BC you have raised two other points and Halc there's also something you've raised, that I will try to respond to tomorrow

Take your time.
The Moon, Sun and Earth aren't going anywhere.
I'm sure we look forward to your explanation of Earth's weather influencing the Sun's rotation.

[Bored chemist]

and if you follow conservation law you get;
in physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time.

given whats under discussion is down to an input of energy to the system, so it doesn't tick that box

I already explained this to you in a previous thread.

It is, as you keep stressing the importance of the fact, an isolated system.
The atmosphere can't push the world for the same reason that the man on the truck bed can't push the truck.

You seem to be trying to elevate the terms isolated and closed to the status of holy writ.

It's not magical.
Classically:
(1) A system to which you can't add or remove stuff will not change mass
(2) A system to which you can't add or  remove energy will  change energy
(3)A system to which you can not apply a force will not change momentum.
(4) A system to which you can't apply a torque  will not change angular momentum.
Those are pretty much tautologically true.
Since Einstein's day the first pair of those are a bit more flexible, but only in a very clearly defined way.

Historically, in thermodynamics it was important to lump together some of those statements of the obvious.
If you have a system to which you can add or subtract matter then you can't sensibly define what it will do- because it depends on the matter you might add.The same goes for applying forces to it. Those forces just complicate the issue.
So, they invented the "closed system" where tautologies 1 and 3 apply.
 

Similarly, for some calculations, you want to prevent energy entering or leaving the system.
And that's why they invented the "isolated system"- as  a shorthand for a system where tautology 2 also applies.

If thermodynamics dealt with angular momentum they would have invented another term for systems where tautology 4 also applied. They didn't.

But, if they had done, the Earth would be on the list.

[gem (OP)]

Hi all,

Ok Halc,
lets try and address the solid surface issue,
first the atmosphere has weight and does have an interface with the surface be it on land or sea, so contributes the normal force perpendicular to the surface, that stops the atmosphere being in free-fall.
However as stated previously ;
"When the forces are not balanced, due to expansion of the atmosphere that's heated, the volume/droplet of air accelerates, due to the upthrust of the buoyancy effect."

There is however an aspect that the surface is known to participate in the change in motion of the atmosphere/solid earth and due to the change in atmospheric pressure rather than the buoyancy/convection.
Specifically, the mechanism causing this are normal torques against topography/frictional coefficient by a varying atmospheric pressure.
Therefore leaving directional coefficient of friction in this regard being a major factor.

Similarly to the value of tangential torques from the lowest level of the winds upon the Earth’s surface being influenced by directional coefficient of friction.

BC

The Earth doesn't make the distinction, but we do.
We distinguish between "the atmosphere", which is part of the Earth and "the meteor" which is not part of the Earth.

Yes we do but I have not seen yet how the physical aspect of the tangential collision of a meteor with the surface is different, if the increase in motion of an air molecule is achieved without a increased force on the earths surface, and subsequent collision with it. 

Some times it requires someone to suggest a different direction.

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

Take your time.
The Moon, Sun and Earth aren't going anywhere.
I'm sure we look forward to your explanation of Earth's weather influencing the Sun's rotation.

Given the pressure and heat differences and the dynamics that are generated by the EMR input, there is no requirement for the earths weather to impact the Suns rotation.
 
However I like your logic as there are a few consequence's to what I am postulating that would seem to be in a similar vein, you've just not cottoned on to them yet. 

[Bored chemist]

I have not seen yet how the physical aspect...

Well, if you keep thinking about it, and the conservation laws, you might work it out in the end.

Given the pressure and heat differences and the dynamics that are generated by the EMR input, there is no requirement for the earths weather to impact the Suns rotation.

There is if you want the Sun to provide angular momentum to the Earth.
If A pushes B then B must push back on A- or have you decided to add Newton's laws to the ones you are already ignoring?

However I like your logic as there are a few consequence's to what I am postulating that

The consequence of my logic is that your idea is flat out wrong.

you've just not cottoned on to them yet. 

The evidence so far shows that you are not clever enough to patronise me. Don't bother trying.

[Bored chemist]

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.

Did you think anyone had disputed that fact?

[gem (OP)]

Hi all,

BC

Did you think anyone had disputed that fact?

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 don't doubt it wont have been unanimously accepted.

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

The annual component of the change of the length of day of approx  0.34 ms corresponds then to a increase in wind speed  0.9 m/s of the whole of earths atmosphere, maximizing like clockwork every year on/around February 3 each year.

[Bored chemist]

OK, did you think anyone here had disputed it?

[Bored chemist]

The annual component of the change of the length of day of approx  0.34 ms corresponds then to a increase in wind speed  0.9 m/s of the whole of earths atmosphere, maximizing like clockwork every year on/around February 3 each year.

And, if you look at the next bit of the wiki page you see
"10‑day fluctuations of the order of 0.1 milliseconds."
And, if you are right, if the planet + atmosphere are slowing and speeding due to a torque from the Sun then they (by Newton's 3rd law) must be exerting a torque on the Sun.

What's the mechanism for that?

[alancalverd]

As ice and snow melt and the water runs into the sea, so the moment of inertia of the planet decreases, so it spins faster. No surprise there.

[gem (OP)]

Hi all,

Ok lots of points some I will try to address others will be irrelevant, going forward or come into focus along side new questions,

Halc and BC
Halc
The blob and solid surface issue I responded to yesterday, on the importance of topography/coefficient of friction.

BC I understand the thrust of your request, for the mechanism, but point you back to my previous response and the mechanism/dynamics that are occurring.

In 1948 Starr postulated the aspect of transfer of momentum between the atmosphere and solid Earth, In 1970 he postulated this about Earths atmosphere:
"In most fluid systems differences in velocity are obliterated by positive viscosity. In some rotating systems, however, non uniform flows can be maintained by negative viscous effects due to eddies. where the fluid motion is maintained by a constant input of energy."

Alan, regarding the ice and snow melting wouldn't we have to look at the angular velocity of where its stored to where it ends up ? , there is potential for a paradox given we are now experiencing some of the shortest days, since timings began with atomic clocks, and reduction in viscosity cannot fit into current theory.


BC

OK, did you think anyone here had disputed it?

Yes
 

[Bored chemist]

BC I understand the thrust of your request, for the mechanism, but point you back to my previous response

If that response had been adequate, I wouldn't have asked.

What's the mechanism by which the Earth pushes back on the Sun in order to conserve angular momentum for the (isolated) system as a whole??

[Bored chemist]

Quote
OK, did you think anyone here had disputed it?

Yes

Please show us where anyone here said that the solid Earth and its atmosphere don't exchange angular momentum?