As a thought experiment, consider two concentric spheres of 8,000 miles and 8,200 miles diameter spinning on an axis. We shall suspend the smaller sphere inside the larger sphere. The smaller and larger spheres are equidistance to each other at all points. The spheres rotate on a common axis, which we shall call the poles.
As a simplification, we shall fill the space between the spheres with two liquids. One fluid is heavier than the other, and red in color. The lighter fluid is blue in color. The fluids will not mix. The fluids are of equal volume. The total volume of the liquids will completely fill the space between the spheres. We shall mount the sphere on an axis penetrating the sphere through it center and extending out past the outer sphere. We shall arbitrarily designate one end of the axis as the North Pole.
We’ll set the sphere at any place on earth with its North Pole pointing toward space and South Pole pointing toward the earth’s center. We would expect the heavier (red) fluid to migrate to the South Pole and the lighter fluid (blue) to migrate to the North Pole. After an appropriate settling time the liquid in the volume between the spheres would settle with the blue (lighter) liquid in the North half and the red (heavier) liquid in the South half. This is because the force field we call earth’s gravity forces the heavier fluid to displace the lighter fluid.
Let’s change the conditions somewhat by removing the external gravitational field, say by asking Mr. Musk to take the concentric spheres into orbit. We can then spin the globes on their common axis. The lighter (blue) fluid will move toward the sphere’s poles and the heavier (red) fluid will move toward the sphere’s equator. Centripetal force caused the heavier fluid to displace the lighter fluid at the equator of the spheres.
These concentric spheres illustrate the basic concept of horizontal (or tangential) weather. In earth’s atmosphere, the lighter (more buoyant) fluids will centrifitate (as opposed to gravitate) toward the poles, and heavier (less buoyant) fluids will move toward the equator.
This effect of centripetal force is easy to overlook. Centripetal force is proportional to the square of distance from the axis of rotation making it minimal at the poles and maximal at the equator.
Centripetal force on the earth’s surface is small compared to gravitational force. Its effect is complicated because the ground assumes the place of the inner concentric sphere’s outer surface and gravity assumes the place of the outer concentric sphere’s inner surface. It is also nearly zero at the equators and poles. This space is the atmospheric channel.
The forces acting on the fluid (air) are the vector result of both centripetal force and the atmospheric channel. These forces interact with the final effect that motive forces in the atmosphere due to centripetal effects are minimum at the poles and the equator and maximal at about 35 degrees latitude.
Buoyant equatorial air is displaces less buoyant Arctic air. This accounts for all the global weather effects and especially the trade winds, jet streams and deserts on the west coasts of northern continents.
Atmospheric buoyancy acted on by gravity creates tornadoes. Atmospheric buoyancy acted on by centripetal forces creates clusters of tornados, which form hurricanes.
Nature masks this effect effectively because buoyancy differential of polar air and equatorial air is about 5%.
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