The Rule Of Earth's Rotation

There is a fairly clear rule regarding the effect of the earth's rotation on climate and natural geography. The spinning earth acts as a centrifuge so that, at least as a general rule, that which is heavy moves toward the equator while that which is light moves away from the equator. The earth rotates eastward. So, in a similar way, we can say that which is heavy moves east, because the rotating earth imparts it's momentum, while that which is light moves west.

Glacial ice, produced during the earth's periodic ice ages, is heavy. The result is that it is pulled toward the equator. There is also a definite eastward element to the course of these vast ice sheets, as they pick up momentum from the earth's rotation.

The water flowing in rivers is also heavy. In the posting, "The Equatorial Force", I described how, if we consider all of the water in all of the rivers of the world, there is much more water flowing eastward than westward, and there is also more water flowing toward the equator than away from it. Elevation is certainly the primary factor in determination of river flow, but with other factors being equal the Rule Of Earth's Rotation applies.

This principle of flowing water operates not only in rivers, but also in the oceans. Possibly the best-known, and most important, ocean current in the world is the Gulf Stream. This carries warm water from the Carribean area northeastward to northern Europe. Britain, Ireland and, southern Scandinavia are actually at about the same latitude as frigid Labrador, in eastern Canada. But the waters of the Gulf Stream bring a mild climate to the area.

This is because the Carribean sun warms the water at the surface and the rotation of the earth causes it to move both eastward and northward because water of different temperatures do not immediately mix together. These ocean currents are not just because of convection, but also the rotation of the earth. Heavy cold water moves toward the equator while warm water moves away, but with the rotation of the earth imparting eastward momentum.

One the other side of the world, there is also the North Pacific Current, which is very much congruent to the Gulf Stream. In the Brazil Current off South America's Atlantic coast, the direction is reversed because of the direction of the incoming cold current northward off the coast of Africa from which it formed.

The circular motion of a hurricane tends to counteract the earth's gravity so that the hurricane is classified as light, rather than heavy. For more on this, see "The Atlas Barrier" on the meteorology blog. This is why hurricanes move westward and away from the equator. Of course, the hurricane isn't actually moving. The earth is rotating eastward beneath it, with the effect that it moves westward.

Have you ever wondered what it would be like if the earth rotated in the opposite direction, so that the sun rose in the west?

Obviously, there would be no Gulf Stream and the 2012 Olympics would probably not be held in London. But there might be a westward version of the Gulf Stream bringing warm Mediterranean water to the shores of New England and eastern Canada.

North America and the Carribean region would be free from destructive hurricanes. There might be some hurricanes arriving in Europe and north Africa, but hurricanes require dust as condensation nuclei and there probably is not enough of that in green South America.

The Middle East and north Africa would be wet and rainy, instead of dry, due to a prevailing west wind off the Mediterranean and Atlantic Ocean.

The desert regions of southern Africa would likely be lush and green if the earth rotated westward. This is because that desert area has little rainfall due to a cold ocean current offshore, and cold water does not evaporate to form rain as readily as warm water. Instead it is Argentina, on the opposite side of the Atlantic, that would have the cold current offshore. This might create dust, from lack of rain, that would seed hurricanes that would afflict north Africa and Europe.

It is airborne dust from dry Australia that seeds monsoons in south Asia, as seen in the posting "The Australia Sequence" on the progress blog. But, if the earth rotated westward, there would be a west wind here instead of the present east wind, and that would bring rain to most of Australia so that it would not be a source of dust. Even if Australian dust was a source of hurricanes, those storms would move eastward out into the Pacific instead of toward Asia.

This may be a "grass is greener on the other side" kind of thinking, but it seems to me that the world would be better off, in terms of climate, if it rotated in the opposite direction.