Taylor–Couette Circulation

Taylor–Couette Circulation

Earth’s atmospheric circulation is primarily driven by “solar heating” and the “Hadley system provides an example of a thermally direct circulation” according to Settled Science.

The major driving force of atmospheric circulation is solar heating, which on average is largest near the equator and smallest at the poles.

The atmospheric circulation transports energy polewards, thus reducing the resulting equator-to-pole temperature gradient.

Simplitic Hadley cell cross-section

The Hadley system provides an example of a thermally direct circulation.

The thermodynamic efficiency of the Hadley system, considered as a heat engine, has been relatively constant over the 1979~2010 period, averaging 2.6%.

The mechanisms by which this is accomplished differ in tropical and extratropical latitudes.

https://en.wikipedia.org/wiki/Hadley_cell#Mechanism

Convection Cells

Atmospheric circulation is the large-scale movement of air, and is a means by which thermal energy is distributed on the surface of the Earth, together with the much slower (lagged) ocean circulation system.

Latitudinal circulation occurs because incident solar radiation per unit area is highest at the heat equator, and decreases as the latitude increases, reaching minima at the poles.

It consists of two primary convection cells, the Hadley cell and the polar vortex, with the Hadley cell experiencing stronger convection due to the release of latent heat energy by condensation of water vapor at higher altitudes during cloud formation.

Longitudinal circulation, on the other hand, comes about because the ocean has a higher specific heat capacity than land (and also thermal conductivity, allowing the heat to penetrate further beneath the surface) and thereby absorbs and releases more heat, but the temperature changes less than land.

Longitudinal circulation consists of two cells, the Walker circulation and El Niño / Southern Oscillation.

https://en.wikipedia.org/wiki/Convection#Atmospheric_circulation

However, there are a few issues with this “heat engine” view of atmospheric circulation.

Firstly, convection produces localised convection cells [aka Bénard cells].

Rayleigh–Bénard convection is a type of natural convection, occurring in a plane horizontal layer of fluid heated from below, in which the fluid develops a regular pattern of convection cells known as Bénard cells.

Rayleigh–Bénard instability

https://en.wikipedia.org/wiki/Rayleigh%E2%80%93B%C3%A9nard_convection

Secondly, strong atmospheric convection produces thunderstorms that are wedged between the walls of adjacent Bénard cells i.e. atmospheric convection is associated with localised phenomena.

Thunderstorm

Thunderstorms are known to occur in almost every region of the world, though they are rare in polar regions and infrequent at latitudes higher than 50° N and 50° S.

Areas of the atmosphere where vertical motion is relatively strong are called cells, and when they carry air to the upper troposphere (the lowest layer of the atmosphere), they are called deep cells.

Thunderstorms develop when deep cells of moist convection become organized and merge, and then produce precipitation and ultimately lightning and thunder.

Upward motions can be initiated in a variety of ways in the atmosphere.

A common mechanism is by the heating of a land surface and the adjacent layers of air by sunlight.

Isolated thunderstorms contain one or more convective cells in different stages of evolution.

Frequently, the downdrafts and associated outflows from a storm trigger new convective cells nearby, resulting in the formation of a multiple-cell thunderstorm.

Thunderstorms – E. Philip Krider – Encyclopædia Britannica
https://www.britannica.com/EBchecked/topic/594363/thunderstorm

Thirdly, Taylor–Couette Flow produces “roll-like vortices” which are “closely analogous to convection”.

These are in fact roll-like vortices in which the fluid circulates in alternate directions, as if around the surfaces of a stack of doughnuts.

Like Rayleigh–Benard convection, this is a symmetry-breaking process that creates a pattern of a well-defined size.

It isn’t too hard to see that this situation is closely analogous to convection, in which the same kind of symmetry-breaking structure (roll cells) is created.

At a threshold rotation speed, the system becomes unstable so that roll vortices transport part of the inner fluid to the outer edge while a return flow replenishes the inner layer.

Not only is the instability of the same basic nature as that in convection, but the shape of the rolls is the same: roughly square, as wide as the gap between the inner and outer cylinders

Flow – Philip Ball – 2009 – Oxford University Press

In fact, the “roll-like vortices” of Hadley Cells [in cross section] appear to mirror the structure of Taylor–Couette Flow far more than they reflect the structure of Bénard Cells.

Bénard Convection Cells
Igneous and Metamorphic Petrology – Supplemental Graphics
Prof. G. Nelson Eby – Environmental, Earth & Atmospheric Sciences
University of Massachusetts Lowell
http://faculty.uml.edu/nelson_eby/89.304/Material.htm

Hadley Cell Circulation Pattern
The El-Nino (ENSO) Phenomenon – Pierre Madl -2000
http://biophysics.sbg.ac.at/atmo/elnino.htm

Taylor-Couette Vortices

https://en.wikipedia.org/wiki/Taylor%E2%80%93Couette_flow

Fourthly, the Earth’s “six major wind belts” emulate the “roll-like vortices” produced by Taylor–Couette Flow where the fluid “circulates in alternate directions”.

Global wind patterns: Winds are named by the direction from which they blow.

The globe is encircled by six major wind belts, three in each hemisphere.

https://en.wikipedia.org/wiki/Global_wind_patterns

But the British mathematician Geoffrey Taylor found in 1923 that, once the centrifugal force starts to overwhelm the damping effect of viscosity, patterns appear.

First, the column of fluid develops stripes.

These are in fact roll-like vortices in which the fluid circulates in alternate directions, as if around the surfaces of a stack of doughnuts.

Flow – Philip Ball – 2009 – Oxford University Press

Global circulation patterns

However, because the Polar Easterlies are “weak and irregular” is it probably more accurate to state that the Earth has four major wind belts.

The polar easterlies (also Polar Hadley cells) are the dry, cold prevailing winds that blow from the high-pressure areas of the polar highs at the north and south poles towards low-pressure areas within the Westerlies at high latitudes.

Cold air subsides at the poles creating the high pressure, forcing an equatorward outflow of air; that outflow is then deflected westward by the Coriolis effect.

Unlike the westerlies in the middle latitudes, the polar easterlies are often weak and irregular.

http://en.wikipedia.org/wiki/Polar_easterlies

This is an important qualification because the Taylor–Couette Flow that forms around a sphere generates a “very robust” vortical structure with four bands when there is “axial flow”.

The addition of an axial flow in the annulus or a radial flow through porous cylinders alters the critical Taylor number as well as the wavelength and structure of the vortices.

Likewise, the flow is altered by oscillating the inner or outer cylinder axially or azimuthally or by varying the gap between the inner and outer cylinders.

The vortical structure is very robust–Taylor vortices can occur in other geometries including between concentric cones and spheres.

For example, vortices occur at the equator between an inner rotating sphere and a concentric, stationary outer sphere ( Figure 5.).

Schematic of flow between concentric spheres

Taylor-Couette Flow – 2009
Richard Lueptow – Northwestern University
Scholarpedia
http://www.scholarpedia.org/article/Taylor-Couette_flow

This four band vortical structure very closely resembles the mainstream model of atmospheric circulation which indicated “the Ferrel Cell did not exist”.

When I started studying weather and climate it was believed there were three cells: the Polar, Ferrel, and Hadley (Figure 1).

In that theory, the complexity was between the Ferrel and Polar Cells.

Then it was argued that the Ferrel Cell did not exist, and air movement between the Polar and Hadley Cells was extremely complicated (Figure 2).

The more complicated model

Computer Models and Atmospheric Circulation: A Major Failure – 2011 – Dr. Tim Ball
http://drtimball.com/2011/computer-models-and-atmospheric-circulation-a-major-failure/

This four band vortical structure also provides a mechanism that explains how “the high elevation areas of the Greenland ice sheet” can receive precipitation “which mainly originates from subtropical moisture sources” located around 35 degrees north.

The constraint on Ts, excludes high-latitude moisture source regions as major contributors to the precipitation at high elevations on the Greenland ice cap.

Even optimum tuning of the model with the Weathership A area (62″N, 33″W), not far from South Greenland (Fig. l), as a moisture source leads to deuterium excess values at Site G far from those observed.

For the moment, we tune the model using the subtropical Weathership E (35N, 48W) area as a source of moisture.

We present evidence that, in contrast to low elevation stations, the high elevation areas of the Greenland ice sheet receive precipitation, which mainly originates from subtropical moisture sources, under present as well as under glacial conditions.

The origin of Arctic precipitation under present and glacial conditions
S. J. Johnsen, W. Dansgaard, J. W. C. White
Tellus (1989), 418, 452-468
http://www.tellusb.net/index.php/tellusb/article/view/15100

The original technique used to observe Taylor–Couette Flow relied upon sandwiching a fluid between an inner rotating cylinder and an outer rotating drum.

In 1888 the French fluid dynamicist Maurice Couette looked at flow induced in a fluid sandwiched in the gap between two concentric cylinders of different sizes.

To induce flow, the inner cylinder was rotated, which drags the fluid next to the wall along with it.

This is now called Couette flow.

Geoffrey Taylor later modified the device such that the outer drum might be rotated too.

Equipment

Flow – Philip Ball – 2009 – Oxford University Press

However, this setup is modified in the case of the Earth’s four banded vortical structure:
1) The Troposphere represents a fluid with “axial flow”.
2) The Earth represents an inner rotating sphere.
3) The Isopycnic Level [aka Tropopause] represents an outer rotating sphere.

Lurking in the US Standard Atmosphere 1976 is a rather surprising concept that Atmospheric Science appears to have lost down the back of the sofa in recent years.

Isopycnic Level

First off: What is the Isopycnic Level?

The US Standard Atmosphere 1976 can be used to construct the following definition:

1) The Isopycnic Level is where the Density of Air has been observed to vary by less than two percent [relative to the 1976 standard].

2) The Isopycnic Level is at an altitude of about 8 kilometres in the Earth’s Atmosphere.

cumulonimbus-anvil

Atmospheric Science: The Lost Level
https://malagabay.wordpress.com/2014/07/25/atmospheric-science-the-lost-level/

The troposphere is one of the lowest layers of the Earth’s atmosphere; it is located right above the planetary boundary layer, and is the layer in which most weather phenomena take place.

The troposphere extends upwards from right above the boundary layer, and ranges in height from an average of 9 km at the poles, to 17 km at the Equator.

https://en.wikipedia.org/wiki/Tropopause

Therefore, contrary to the Settled Science, it is likely that Taylor–Couette Flow is actually the primary driver of atmospheric circulation in the Earth’s Troposphere.

“these flow patterns may be analogous to those found in a rotating planetary atmosphere”

Flow – Philip Ball – 2009 – Oxford University Press

Plate 2

Plate 3

http://www.amazon.com/Flow-Natures-Patterns-Tapestry-Three/dp/0199604878/ref=sr_1_1?ie=UTF8&qid=1422871467&sr=8-1&keywords=flow+philip+ball

http://www.amazon.co.uk/Flow-Natures-Patterns-Tapestry-Three/dp/0199604878/ref=sr_1_1?ie=UTF8&qid=1422871467&sr=8-1&keywords=flow+philip+ball

Advertisements
Gallery | This entry was posted in Astrophysics, Atmospheric Science, Books, Earth, Fluid Mechanics, Greenland, Science, Vortices. Bookmark the permalink.

5 Responses to Taylor–Couette Circulation

  1. Pingback: Couette Flow 4: Taylor Vortices | MalagaBay

  2. Pingback: Planetary Rotation 1: Atmospheric Corotation | MalagaBay

  3. A C Osborn says:

    So doesn’t the energy to drive this still come from the sun?

    • malagabay says:

      Best guesses so far:
      1) The Heliospheric Current Sheet [aka Parker Spiral aka Parker Propeller] distributes energy throughout the Solar System:

      The heliospheric current sheet is the surface within the Solar System where the polarity of the Sun’s magnetic field changes from north to south. This field extends throughout the Sun’s equatorial plane in the heliosphere. The shape of the current sheet results from the influence of the Sun’s rotating magnetic field on the plasma in the interplanetary medium (Solar Wind). A small electrical current flows within the sheet, about 10−10 A/m². The thickness of the current sheet is about 10,000 km near the orbit of the Earth.
      Heliospheric current sheet
      https://en.wikipedia.org/wiki/Parker_spiral

      Planetary Rotation

      Planetary Motion

      2) But planets within the solar system also “drive” their own sub-systems.

      Moons of Saturn

      The long rotation periods of Mercury [58.646225 days] and the Moon [27.321582 days] are inexplicable outliers in the context of the Solar Wind Turbine.
      However, these long rotation periods are explicable if these bodies were once outer moons [located between Titan and Iapetus] of the planet Saturn.

      Solar Wind Turbines
      https://malagabay.wordpress.com/2015/01/23/solar-wind-turbines/

      3) And the Solar System has a relationship with the Milky Way

      The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of interstellar wind. The Solar System is located in the Orion Arm, 26,000 light years from the center of the Milky Way.

      The Sun is a type G2 main-sequence star. Compared to the majority of stars in the Milky Way, the Sun is rather large and bright.

      The Solar System is located in the Milky Way, a barred spiral galaxy with a diameter of about 100,000 light-years containing about 200 billion stars. The Sun resides in one of the Milky Way’s outer spiral arms, known as the Orion–Cygnus Arm or Local Spur. The Sun lies between 25,000 and 28,000 light years from the Galactic Centre,[133] and its speed within the galaxy is about 220 kilometres per second (140 mi/s), so that it completes one revolution every 225–250 million years.
      https://en.wikipedia.org/wiki/Solar_System

      4) Which take us back to the Clockwork Universe and René Descartes.

      In the history of science, the clockwork universe compares the universe to a mechanical clock. It continues ticking along, as a perfect machine, with its gears governed by the laws of physics, making every aspect of the machine predictable.
      https://en.wikipedia.org/wiki/Clockwork_universe

      Clockwork
      https://malagabay.wordpress.com/2014/08/12/the-clockwork-universe/

      Descartes’ vortex theory of planetary motion proved initially to be one of the most influential aspects of Cartesian physics, at least until roughly the mid-eighteenth century. A vortex, for Descartes, is a large circling band of material particles. In essence, Descartes’ vortex theory attempts to explain celestial phenomena, especially the orbits of the planets or the motions of comets, by situating them (usually at rest) in these large circling bands.
      plenum vortices
      https://malagabay.wordpress.com/about/

  4. Nice post and interesting blog.

    I am not an expert in physics so I would like to know your opinion, a constructive one if possible, about a theory I am working on about global atmospheric circulation versus GHGs forcing and biological productivity. My training comes from Biology and Aerobiology (the link between atmosphere and biological performance) so I have some knowledge about atmospheric circulation but within a restricted range. I have published couple of posts in my blog trying to find feedback in order to identify its limitations, potential wrong assumptions and/or valid features. I would appreciate if you find time to read them and share your thoughts either in the comments or by email at d.fdezsevilla(at)gmail.com.

    New theory proposal to assess possible changes in Atmospheric Circulation (by Diego Fdez-Sevilla) Posted on October 21, 2014 http://wp.me/p403AM-k3
    Why there is no need for the Polar Vortex to break in order to have a wobbling Jet Stream and polar weather? (by Diego Fdez-Sevilla) Posted on November 14, 2014 http://wp.me/p403AM-mt
    Revisiting the theory of “Facing a decrease in the differential gradients of energy in atmospheric circulation” by Diego Fdez-Sevilla. Posted on February 10, 2015 http://wp.me/p403AM-to

    Thanks.
    Diego.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s