The Magnetic Field of Earth's Core: What is the Source?

[Dotini]

Atmospheric circulation velocity; NO variation.

So although the jet stream travels 100-200 mph faster than the surface of the Earth, there is said to be no difference in the atmospheric circulation velocity compared to the Earth's rotation velocity, no net movement of the atmosphere west to east relative to the surface?

 

[Baluncore]

So although the jet stream travels 100-200 mph faster than the surface of the Earth, there is said to be no difference in the atmospheric circulation velocity compared to the Earth's rotation velocity, no net movement of the atmosphere west to east relative to the surface?

"there is said". Where do you get that from?

The charge and movement of the troposphere has very little effect on the Earth's magnetic field.
The jet streams only have a small section and form between much larger slower circulation cells.
https://en.wikipedia.org/wiki/Atmospheric_circulation
https://en.wikipedia.org/wiki/Jet_stream

 

[Dotini]

"there is said". Where do you get that from?

That is what I understood you to say. I'm sorry if I have misunderstood you. Does the atmosphere actually circulate faster than the surface? Or does it not, despite the jet stream from west to east?

What I am trying to learn, rather unsuccessfully, is whether (or not) the jet stream produces a net west to east movement of the atmosphere relative to the surface?

 

[Baluncore]

What I am trying to learn, rather unsuccessfully, is whether (or not) the jet stream produces a net west to east movement of the atmosphere relative to the surface?

Then you need to study the atmospheric circulation as a whole. Don't jump to conclusions.
Net circulation is irrelevant to Earth magnetism as the atmosphere has close to a net neutral charge.

 

[Dotini]

Then you need to study the atmospheric circulation as a whole. Don't jump to conclusions.
Net circulation is irrelevant to Earth magnetism as the atmosphere has close to a net neutral charge.

Yes; the things we understand least we need to study most.

 

[rootone]

Jet streams:
Although these are high velocity winds at altitude, they are just one component of overall atmospheric circulation.
Other atmospheric systems contribute to moving air in the opposite direction with less velocity but in greater volume.
The net effect for the atmosphere as a whole is zero movement in relation to the surface, but locally (and including jet steams), there can be a strong bias for winds to blow in a prevailing direction.

There is no connection I know of between atmospheric circulation systems and the Earth's magnetic field.

 

[Dotini]

Other atmospheric systems contribute to moving air in the opposite direction with less velocity but in greater volume.

Could you cite a reference for this, please?

 

[rootone]

Easterly blowing trade winds at the surface are probably the most famous example of established wind patterns which move large volumes of air from east to west.
https://en.wikipedia.org/wiki/Trade_winds

 

[Chronos]

Venus has an induced magnetosphere due to its dense atmosphere, perhaps Earth has a similar contribution to its magnetosphere.

 

[Dotini]

Easterly blowing trade winds at the surface are probably the most famous example of established wind patterns which move large volumes of air from east to west.
https://en.wikipedia.org/wiki/Trade_winds

Thank you for that citation on the trade wind. In reading it, I could find no substantiation of your notion that "The net effect for the atmosphere as a whole is zero movement in relation to the surface," and that the tradewinds move a larger volume of air than the jet streams. On the other hand, I have found numerous references which tend to suggest a net movement west to east. Atmospheric Angular Momentum (AAM) and Length of Day (LOD)

http://onlinelibrary.wiley.com/doi/10.1029/2006RG000213/full

[2] Angular momentum characterizes the rotation of physical systems ranging from the atomic scale to galaxies. In particular, the global angular momentum M of the atmosphere reflects both the rotation tied to that of the Earth and rotation due to the winds. A wealth of data and theories is available to determine the distribution of angular momentum and to provide the reasons for its changes. Attention is restricted in this review to large-scale motions, although angular momentum is also of key importance, say, in hurricanes or tornadoes. The global atmospheric angular momentum is the integral

http://onlinelibrary.wiley.com/store/10.1029/2006RG000213/asset/equation/rog1654-math-0001.gif?v=1&t=ippj8s7t&s=2c2bab9f874ffdbedcaaf572f9d2096c39ec53ce
of the angular momentum

http://onlinelibrary.wiley.com/store/10.1029/2006RG000213/asset/equation/rog1654-math-0002.gif?v=1&t=ippj8s7t&s=518c5825d4839641914d971653bfaf4b0138cb78
per unit volume over the volume V of the Earth's atmosphere. In (2), r is the position vector pointing from the center of the Earth to the volume element dV of density ρ (see Figure 1). It is customary to assume a dry atmosphere because the contribution of the water substance to the total mass of the atmosphere is small. In principle, the density ρ in (2) also contains the water substance in all phases. The rotation of the Earth is represented by its angular velocity Ω with Ω = 2π/d. The relative velocity of the air with respect to this rotation is v and

http://onlinelibrary.wiley.com/store/10.1029/2006RG000213/asset/equation/rog1654-math-0003.gif?v=1&t=ippj8s7t&s=060425d355ced8d7b10839d0ee943b43171d0166
is the absolute velocity.

Figure 1.

• Open in figure viewer
• Download Powerpoint slide

Rotating Earth and the components Miii of the global angular momentum M in the rotating coordinate system with basic vectors ii. The position vector r points to a volume element dV in space, where the unit vectors eλ, eϕ, and er of the local rotating spherical coordinate system are defined.

Hide
Figure 2
Time and zonal mean of the (a) axial wind term [

w3] in 106 Had s and (b) south-north difference of the mass term [

m3] in 105 Had s as a function of height z (km) and latitude. The terms are integrated over zonal annuli of 5° width and 1000 m depth. Data basis is ERA-40 (1958–2001).-----------------------------------------------------------------------

[6] The laws of angular momentum emerged only slowly in fluid mechanics (see Truesdell [1968] for a lucid account). Bernoulli [1747] may have been first to apply angular momentum concepts correctly in a model of the equatorial easterlies. On the other hand, Hadley [1735]used inaccurate arguments concerning angular momentum in his celebrated treatise on trade winds. A historic account is, however, beyond the scope of this article. For our purpose it is sufficient to state that the axial angular momentum cycle of the atmosphere and its link to the rotating Earth via the torques have been a key topic of meteorology at least since the 1950s. Starr [1948], Starr and White [1951], Lorenz [1967], and others worked out the basic features of the atmosphere's axial angular momentum budget (see Oort [1989] and Rosen[1993] for introductions into historical aspects). The review by Oort and Peixoto [1983]describes the mean distribution of the axial angular momentum in the atmosphere, its transports, with particular emphasis on the role of eddies, and the contributions of latitude belts to friction and mountain torques. In general, good agreement is found between observed changes of M3 and those of LOD as predicted by (15) [Rosen, 1993].

 

[rootone]

OK, I will take a look at the various references, and if there is anything I don't understand I will start a new thread to continue the conversation, as atmospheric circulation is not the original topic for this thread.
On the face of it though I cannot see why the atmosphere (as a whole) would have a different net angular velocity than the Earth's surface since this would require a force external to the Earth acting upon the atmosphere (and in a very specific manner), in order to maintain the differential of the (overall) rates of rotation

 

[Dotini]

this would require a force external to the Earth acting upon the atmosphere (and in a very specific manner), in order to maintain the differential of the (overall) rates of rotation

Yes - sunlight!

 

[jim hardy]

as atmospheric circulation is not the original topic for this thread.

we had one last year, see

https://www.physicsforums.com/threads/Earth's-rotation-and-atmosphere.825307/

 

[ulios21]

Well,
The[/PLAIN] https://en.wikipedia.org/wiki/Earth's_magnetic_field has all information for you

 

[Fervent Freyja]

Some very recent work on the topic: The combined effect of precession and convection on the dynamo action

 

[davenn]

Well,
The[/PLAIN] https://en.wikipedia.org/wiki/Earth's_magnetic_field has all information for you

yeah
that was posted a way back in the second post in the thread

tis always good to read through a thread before posting to save doubling up on the same info Dave

 

[Fervent Freyja]

yeah
that was posted a way back in the second post in the thread

tis always good to read through a thread before posting to save doubling up on the same info Dave

Yes, and this isn't a technical reply davenn...

 

[davenn]

Yes, and this isn't a technical reply davenn...

wasn't intended to be
just helping a very new member to be a little more aware before posting

There was no need for your response, please don't do thatregards
Dave