The source of all energy is the Sun?

[russ_watters]

One other source of earthern energy (heat) may be the rotation of Earth itself. This is not substanciated, or peer reviewed, as far as I know, so it is more of a question that arose in an earlier thread and my hope is that someone has a peer reviewed reference that deals with this...

So why do we spin anyway, and where did our spin energy come from?

Has anybody previously read about such an effect, or have other comments?

The idea of using Earth's rotation is a good one and as with others it may be tricky to identify: Tidal power is actually stealing energy from Earth's rotation.

The original source of this energy is the gravitational potential energy and rotational kinetic energy of the cloud of gas and dust the solar system and Earth formed from.

 

[rootone]

A lot of questions there, but I'll have a go at part of it.
The spin which the Earth now has, arises from the angular momentum originally contained within the nebula from which the solar system formed.
The same applies to the Sun and all the other planets.
In addition to planets spinning, some of that original momentum resulted in planets orbiting the Sun and moons orbiting planets.

 

[mfb]

The energy of the rotation of Earth is hard to harvest without an external anchor. The tides are the method that we can use today.
A space elevator would give another option - lifting mass up the first 36000 km needs energy, but allowing it to travel further up releases energy. At some point you get more out than you put in before. I doubt this will ever be practical given the tiny amounts of energy released per mass lifted.

 

[OmCheeto]

...
As usual, threads involving Classification seldom get us much further on with our deeper understanding.

Oh... Speak for yourself.
As an idiot, I've learned a lot from this, and the "Is there a limit to wind power?" thread.

Lesson #1: I've decided that trying to describe the complex dynamics of the Earth's atmosphere would probably take me 100 years, so I gave up on that.
About all you can do, is look at local phenomena, and try and come up with explanations for "why" "that" is happening "there".

Lesson #2: There's a phenomena called "Atmospheric Tide". Very interesting.

Wiki; "The largest-amplitude atmospheric tides are mostly generated in the troposphere and stratosphere when the atmosphere is periodically heated, as water vapour and ozone absorb solar radiation during the day. These tides propagate away from the source regions and ascend into the mesosphere and thermosphere."​

About all I can make of it, is that it's a solar powered, atmosphere pump.
A few other interesting facts:

a. Although called a "tide", it's primarily thermal driven, vs the gravitationally driven ocean tides.
b. Wiki claims; "This set of periods occurs because the solar heating of the atmosphere occurs in an approximate square wave profile and so is rich in harmonics."
Square wave? On a round planet? In a circular orbit?
Om; "Where on Earth do you get a square wave, you wiki idiots?"
But that triggered my memory of the "Question about solar energy: angle of incidence" thread, where we discovered the "approximate" square wave nature of solar irradiation. Had we no atmosphere, it would be a square wave! (with dual tracking system of course)
c. According to wiki, gravitational atmospheric tide, is negligible, compared to the thermal tide.​

Lesson #3: Everyone knows this one, but it's good to remind oneself of the fact: The surface of our atmosphere is pretty much "locked" to the surface, in comparison to the rest of our atmosphere.
Were it not, the winds at the equator would be about 1000 mph.
But even the rest of the atmosphere is going along for the ride. I've yet to find a relative wind velocity which greatly exceeds 200 mph on the "earth" simulator, at any altitude. Wiki claims that Mt. Washington recorded a speed of 231 mph, but there will always be anomalies outside of the norm. (Fastest tornado wind speed: 318 mph)

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Although the "Coriolis effect" has been mentioned regarding the forward, backward, and circular motions of parts of the atmosphere, I'm curious:
Q: what factor do fluid shear forces play?

Boundary Layers
...
This phenomenon is known as boundary layer separation.
At the edge of the separated boundary layer, where the velocities change direction, a line of vortices occur (known as a vortex sheet). This happens because fluid to either side is moving in the opposite direction.

This boundary layer separation and increase in the turbulence because of the vortices results in very large energy losses in the flow.
These separating / divergent flows are inherently unstable and far more energy is lost than in parallel or convergent flow.

It's been over 3 decades since I've studied boundary layer fluid dynamics, but I think it might be a significant factor. And my knowledge of the Coriolis effect is almost nil, so my apologies if this is a stupid question.

 

[Wes Tausend]

Lesson #1: I've decided that trying to describe the complex dynamics of the Earth's atmosphere would probably take me 100 years, so I gave up on that.
About all you can do, is look at local phenomena, and try and come up with explanations for "why" "that" is happening "there".

One way to look at fluid air movement due to solar heating versus coriolis, is to take a very general, simple macroscopic view.

First, hot air rises. So one may assume that lighter warmed air in the most direct sunlight, that of the equatorial regions, is generally rising. Second, one may assume that heavier cold air in polar regions is generally sinking. Third, since the Earth is turning, there is a centrifugal force in the mix. The lost "airs" must be replaced to maintain equilibrium, so there is a general centrifugal flow of "heavy" cold air along Earth's surface from polar regions towards the tropics while lighter warm air travels towards the polar regions along the upper atmosphere to replace the "lost" arctic air. In other words the heavy cold air is apparently slung to the outside of the merry-go-round by centrifugal force causing lighter warm air to float both to the top and the middle (polar axis). But this movement is all then affected by the coriolis force.

(photo, caption, courtesy of wikipedia)
In the inertial frame of reference (upper part of the picture),
the black ball moves in a straight line. However, the observer
(red dot) who is standing in the rotating/non-inertial frame of
reference (lower part of the picture) sees the object as following
a curved path due to the Coriolis and centrifugal forces present in this frame.

By viewing the planet from the poles, one may think of the individual molecules of air all behaving like the black ball in the Coriolis animation. If one imagines the disc populated with these loose "balls", and a couple of rules whereby they lose density at the outer circumference and cannot escape from the rotating disc system, it becomes self-evident that the heavier dense balls will continuously flow outward from center, while the lightened balls are forced to return to the center axis. And, while this certain flow occurs, the balls(molecules) will all be observed to curve against the direction of rotation. It does seem that in this context, that solar induced convective air flow may counter and even impede the direction of 24 hour Earth rotation via prevailing trade winds at the equator. I am still thinking about that novel possibility. But more than that, it should represent a seriously influencial overview of our atmospheric wind patterns.

Of interest in the above "air fluid" scenario, water is also a fluid, and a similar convective flow occurs within our oceans called Thermohaline circulation. Basically colder, heavier salt water is slung towards the equator and lighter warm salt water flows towards the poles to replace it. Since the warm water is lighter, it flows along the surface (warming our breezes) and the "slung" cold water currents flow underneath. It may strike the reader that cold arctic air generally travels down along Earth's surface from the poles "rubbing" against warm water headed the other way and this is so. Regarding this combination, we possibly now have a seriously influencial overview of our earthly weather patterns versus just wind patterns. And in vogue lately, it is supposed in some circles, that rapidly melting fresh water at the poles, could interfere with ocean currents by replacing heavy, cold saltwater, with lighter mass cold fresh water. If the light, cold polar freshwater is lighter than warm equatorial salt water, the entire polar-bound flow of warm surface water could abruptly stop. Without the precious coastal flow of warm water, coastal regions will, at least, assume the bitterly cold winters we in the continental centers (such as North Dakota) suffer. Probably worse, all temporate regions would again tend to get colder, coast and continent alike, as the Earth suddenly reverts back to it's normal, untempered climate, that of an ice age. Hot equatorial belt... and huge cold planetary ice caps extending far from the poles. Brrr. Well, maybe this idea is wrong. North Dakota was apparently warmer than the east coast this year.

Although the "Coriolis effect" has been mentioned regarding the forward, backward, and circular motions of parts of the atmosphere, I'm curious:
Q: what factor do fluid shear forces play?

It may be that most of the "frictional heat" energy of wind is dissipated this way rather than planetary surface friction. Since it seems more a widely varying momentary local phenomena, it seems incredibly difficult to model in general terms.

Wes
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