[Jaaanosik]

Windmills do affect the Earth rotation.
Windmills are gyros and they are prevented from doing the precession therefore they torque the Earth.
Jano

I went by OP:

If all windmills on earth are designed to catch only eastward wind,  while westward wind can blow freely,  will it accelerate earth rotation?

I am not sure what was changed and discussed.

Apologies for slow response, out and about a lot with poor wifi, so priority is on spammers rather than following threads. Also, apologies if you’ve already covered this as I haven’t been following.

Firstly, congratulations on knowing about precession torque, many people don’t.
I didn’t say they don’t torque the earth, but perhaps being unfair in the interpretation of the OP you quote, perhaps winding you up a bit 

Let’s assume a single east facing windmill on the equator. The only way this will try to precess around the tower (as in the diagram on your post) is if the axis of rotor spin is torqued or rotated in the vertical plane. This will happen as the earth spins, giving a torque vector for the tower pointing out vertically from the earth centre (all very idealised), but 180° later this vector is pointed in the opposite direction so cancels out. So assuming random distribution of all windmills on earth then all those windmill’s towers are trying to torque on different axes and over all the earth will cancel out (apologies to BC if he’s already pointed this out, but short on time at moment).

However, here’s an alternative to consider (again apologies if you already have).
What if you put a single windmill on latitude 45°N 0°E what happens; then add another 45°N 180°E what happens; you can go on adding. Of course you still have to contend with halc’s point about what happens when the force is removed https://www.thenakedscientists.com/forum/index.php?topic=80136.msg609359#msg609359, so you are back to continuing discussion.

We are all correct, nobody defined boundaries of the system in the OP, we can go home now.
Like the question if the effect is the same after day one, day two or it is changing?
If the Sun's external energy input is not going anywhere else (waves, the wind losing energy creating waves, ... any other 'leakage'), just to increase the wind speed then under right conditions (good distribution of the windmills) is going to keep increasing the effect.
This is a hypothetical talk, it can go for long, very long, based on 'endless' possibilities of the boundary conditions.

The real life, apparently measured, what is slowing down the Venus?
Jano

[Bored chemist]

The OP does not define any boundaries of the Earth rotation acceleration question.

Talking about "the Earth" defines a boundary of... the Earth.

The video shows that rotation around one axis can be transformed to rotation around another axis.

The video explains, in some detail, why that "flip" will not, and can not happen to the Earth.

It is relevant, if you watch it till the end. It is being explained why.

Bollocks.
If you watch to the end, it explains why it is not relevant to the Earth.

It's an interesting phenomenon- which the Earth will never exhibit.

[Bored chemist]

We are all correct, nobody defined boundaries of the system in the OP, we can go home now.

"The Earth" - as in the OP- defines a boundary.
But if you want to use that as an excuse to go away without admitting you were wrong, that's fine.

[Jaaanosik]

The OP does not define any boundaries of the Earth rotation acceleration question.

Talking about "the Earth" defines a boundary of... the Earth.

The video shows that rotation around one axis can be transformed to rotation around another axis.

The video explains, in some detail, why that "flip" will not, and can not happen to the Earth.

It is relevant, if you watch it till the end. It is being explained why.

Bollocks.
If you watch to the end, it explains why it is not relevant to the Earth.

It's an interesting phenomenon- which the Earth will never exhibit.

I am not saying the flip is going to happen. The torquing and the small acceleration change is a fact under right conditions, that's all.
Let us take out the windmills and the Earth out of it for now.

What slows down the Venus rotation?
What is happening to the theorem there?

[Jaaanosik]

We are all correct, nobody defined boundaries of the system in the OP, we can go home now.

"The Earth" - as in the OP- defines a boundary.
But if you want to use that as an excuse to go away without admitting you were wrong, that's fine.

Please, explain the Venus rotation slow down.

[Bored chemist]

What slows down the Venus rotation?

You really haven't got the hang of the fact that talking about "the Earth" puts a boundary round the problem, have you?
Such a boundary excludes Venus.
Feel free to start a thread about it.

[Bored chemist]

Please, explain the Venus rotation slow down.

Not windmills.

[Bored chemist]

I am not saying the flip is going to happen.

Then it's kind of tricky to see why you insisted that a video about the flip is relevant...

[Halc]

Please, explain the Venus rotation slow down.

First of all, tidal forces put a net external torque on Venus, as they do on all planets except Mercury.  That is going to reduce the angular momentum in most cases.  Venus is soon slated to be an exception to that, when it accelerates from a state of zero angular momentum.

5 minutes is a difference of about 1/70000 which is admittedly quite a bit. Contrast that with Earth where a 5 minute change to the spin period would be a difference of over 1/300.
Earth is similarly slowing, since the day is no longer some single-digit of hours in length like it used to be. Solar energy has nothing to do with this. It's all tidal forces, which happen whether the sun shines (and makes the wind move) or not.

Secondly, due to the inability to see the surface, it has never been easy to measure the rate of spin, and there is considerable room for error in the measurements.

Thirdly, a change to the spin rate of part of the mass is not necessarily a change to its momentum.  The Earth's spin certainly has measurably changed due to melt of polar ice for instance.  The man-made dam in China has had a measurable impact. These things don't change the total momentum of the system. Do not confuse angular velocity with angular momentum.
So with Venus, the wind and the weather might very much contribute to convection of material from here to there, changing the moment of the system, which affects angular velocity but not angular momentum since it cannot involve external torque. There is much to be learned about what kind of impact is made by such a dynamic system.

[Jaaanosik]

I am not saying the flip is going to happen.

Then it's kind of tricky to see why you insisted that a video about the flip is relevant...

There is nothing tricky. Just pointing out about the angular momentum has to be studied carefully.
Is the Earth's 'dynamo' flipping when the north and south magnetic poles flip?

[Jaaanosik]

Please, explain the Venus rotation slow down.

First of all, tidal forces put a net external torque on Venus, as they do on all planets except Mercury.  That is going to reduce the angular momentum in most cases.  Venus is soon slated to be an exception to that, when it accelerates from a state of zero angular momentum.

5 minutes is a difference of about 1/70000 which is admittedly quite a bit. Contrast that with Earth where a 5 minute change to the spin period would be a difference of over 1/300.
Earth is similarly slowing, since the day is no longer some single-digit of hours in length like it used to be. Solar energy has nothing to do with this. It's all tidal forces, which happen whether the sun shines (and makes the wind move) or not.

Secondly, due to the inability to see the surface, it has never been easy to measure the rate of spin, and there is considerable room for error in the measurements.

Thirdly, a change to the spin rate of part of the mass is not necessarily a change to its momentum.  The Earth's spin certainly has measurably changed due to melt of polar ice for instance.  The man-made dam in China has had a measurable impact. These things don't change the total momentum of the system. Do not confuse angular velocity with angular momentum.
So with Venus, the wind and the weather might very much contribute to convection of material from here to there, changing the moment of the system, which affects angular velocity but not angular momentum since it cannot involve external torque. There is much to be learned about what kind of impact is made by such a dynamic system.

The Sun heats up a planet.
If the radiation and planet cooling is slower compared to the input then the inner temperature of the planet goes up.
The inner parts will start to move faster due to the Sun's external energy input.
This will change the angular momentum.
The change in total energy of the planet will show in the change of the angular momentum.

Edit:
The temperature change works both ways.
If the planet cooling is higher, the inner core gets colder, it 'freezes' then the angular momentum will change as well.
Jano

[Bored chemist]

The inner parts will start to move faster due to the Sun's external energy input.

This will apply both clockwise and anticlockwise.
So.

This will change the angular momentum.

No it won't.

The change in total energy of the planet will show in the change of the angular momentum.

No. By simple symmetry.

Is the Earth's 'dynamo' flipping when the north and south magnetic poles flip?

You would need to explain what you think that means.

There is nothing tricky. Just pointing out about the angular momentum has to be studied carefully.

Yes, and you are steadfastly refusing to do that.

[Jaaanosik]

The inner parts will start to move faster due to the Sun's external energy input.

This will apply both clockwise and anticlockwise.
So.

This will change the angular momentum.

No it won't.

The change in total energy of the planet will show in the change of the angular momentum.

No. By simple symmetry.

Is the Earth's 'dynamo' flipping when the north and south magnetic poles flip?

You would need to explain what you think that means.

There is nothing tricky. Just pointing out about the angular momentum has to be studied carefully.

Yes, and you are steadfastly refusing to do that.

https://www.nasa.gov/topics/earth/features/2012-poleReversal.html
When the iron core is flipping it is changing the outside crust angular momentum as well.

[Bored chemist]

OK, we know the magnetic field flips from time to time.
But that can't mean the core suddenly spins in the opposite direction.
That would tear the Earth apart. There would be mass extinctions etc that would make the end of the dinosaurs look trivial.

So, via interactions with the Sun's and Moon's magnetic fields, the flip of the Earth's magnetic field would produce a small change in spin, but it would be reversed when the spin flipped back.

When the iron core is flipping it is changing the outside crust angular momentum as well.

Just saying this does not make it true.

[Jaaanosik]

The Sun heats up a planet.
If the radiation and planet cooling is slower compared to the input then the inner temperature of the planet goes up.
The inner parts will start to move faster due to the Sun's external energy input.
This will change the angular momentum.

You're just repeating the same fallacious argument over and over without addressing the repeated posts over why it is wrong.

Your argument is a non sequitur, equating 'more wind' with altered angular momentum of the system. You've identified zero net torque to the system, so this cannot be.  If the wind blows harder, it does so in all directions, or it pushes on something to move the other way.  None of those actions changes the angular momentum of the system.

My apologies, in my post https://www.thenakedscientists.com/forum/index.php?topic=80136.msg614647#msg614647 I started to talk about the scenario without windmills.
If the planet heats up internally from the Sun's external energy then the inner parts of the planet start to rearrange and the acceleration/deceleration follows.
Jano

[Jaaanosik]

OK, we know the magnetic field flips from time to time.
But that can't mean the core suddenly spins in the opposite direction.
That would tear the Earth apart. There would be mass extinctions etc that would make the end of the dinosaurs look trivial.

So, via interactions with the Sun's and Moon's magnetic fields, the flip of the Earth's magnetic field would produce a small change in spin, but it would be reversed when the spin flipped back.

When the iron core is flipping it is changing the outside crust angular momentum as well.

Just saying this does not make it true.

If there is the Earth crust (outer shell) and the inner core.
What is going to change the magnetic poles if not the change of the inner core rotation?
How else can the magnetic poles change happen?
Jano

[gem]

Hi all,
so colin thanks for your post in response to Jaanosik"s point  about precession torque.
However given the fact that occurs once the blades are in motion, we need to consider the initial frictional drag that occurs in the direction of the air flow, that then creates the lift to the turbine blades, and the subsequent force that the said drag applies to the tower and its foundations.

Now given it is being argued that although there is torque the average net torque is zero to the system because, If the wind blows harder, it does so in all directions, or it pushes on something to move the other way.
Also the wind blows/moves in cycles/cells so does not favour a net force/change in momentum in one direction.

So in regards to what the mass of the air pushes against this is mostly the mass of other air especially when increasing momentum through the dynamics of changes in density occurring within the atmosphere, and as is well understood these changes in kinetic momentum are happening continually. (renewable) due to solar input to a fluid in a gravitational field creating the change/increase in kinetic momentum, through buoyancy effects.

So consider the design of a anemometer which simultaneously rotates into and away from the wind of equal speed to both halfs in relation to itself, whilst still transferring momentum to favour one direction.

https://en.m.wikipedia.org/wiki/Anemometer

Therefore the coefficient of friction will/should come into consideration to different latitudes. given the established wind patterns, and the conditions as set out as per the OP .

[Bored chemist]

What is going to change the magnetic poles if not the change of the inner core rotation?

Simple physics.

It's one of the interesting fact about the "self excited dynamo"- it can start up with a current either way.
It's also possible to flip it. without changing the direction of rotation.

Now given it is being argued that although there is torque the average net torque is zero to the system because, If the wind blows harder, it does so in all directions, or it pushes on something to move the other way.

Yes.
We make that argument because, if it wasn't true, the air would need to "Pile up" somewhere- and obviously, it doesn't do that.

You seem to have forgotten that the only other thing the air can "brace itself" against is that atmosphere.

You are still the man dancing on the truck bed.

[Jaaanosik]

What is going to change the magnetic poles if not the change of the inner core rotation?

Simple physics.

It's one of the interesting fact about the "self excited dynamo"- it can start up with a current either way.
It's also possible to flip it. without changing the direction of rotation.
...

The physics is far from simple on this topic.
The only thing that is sure is that there are huge relative motion changes beneath the crust because that's the only explanation of the magnetic flip.
The details of this motions are unknown to us.
We have only hypotheses.
The fact is that the angular velocity of the Earth crust rotation is pretty stable compare to what is happening beneath.
The rearrangement of the rotational inertia beneath the crust will lead to angular velocity changes beneath the crust and it will affect the crust as well.
The stuff beneath the crust can take/give rotational energy to the crust.
There is nothing simple about that!

Hmm, the Earth must be hollow.
... I forgot, it is flat!
Jano

[Bored chemist]

The only thing that is sure is that there are huge relative motion changes beneath the crust because that's the only explanation of the magnetic flip.

That's still not true.

You still haven't bothered to look up how a self excited dynamo works (or you haven't understood it)

The rearrangement of the rotational inertia beneath the crust

Assuming you are talking about  the angular momentum, it's a single vector.
How do you "rearrange" it?