This Wobbling Earth!
by Don Elvig
(Kirkwood, Missouri USA)
Tilt in axis - approximately 23°
The earth spins on an axis while on it's annual orbit around the sun in a position relatively perpendicular to the sun. But, not quite in a perpendicular position. There is a slight tilt to our axis, which gives us seasons.
We, of course have summer in the northern hemisphere when the north pole is tilted toward the sun and the sun rays are more direct on the northern half of the world for a longer period of time each day. When we have traveled 180 degrees in our journey around the sun, the south pole is now tilted toward the sun.
Now it is time for our buddies in the south to enjoy the beach tanning season while new igloos are the preoccupation of those in the far north.
During it's spinning through space on it's somewhat usual orbit around the sun our somewhat stable earth wobbles a bit; like a kid's toy top. It doesn't suddenly wobble back and forth like the top. It wobbles relatively slowly.
Others who have studied this can relate the frequency and severity of the wobble. I just know it wobbles. In it's travels it tends to increase it's tilt to a certain point and then like a top stops it's tilt in one direction and begins tilting in a reverse direction.
The resulting effect of the tilting is the rays of the sun become more direct on a farther north position of the earth during the summer and stays there for a longer period of time.
When the more direct rays of the sun beat on a farther north position for a longer period of time a very strange event occurs: Snow and ice begin to melt!
The same event occurs six months later when the south pole gets it's turn to point more directly to the sun.
In a few years, or generations, or centuries, the earth wobble tends to right itself and people in the north/south extremities put on heavier jackets.
One more phenomenon: To add to the complexity of the wobble, the earth's path around the sun is not an exact circle. It is first eliptical and as far as I know we don't travel the same, exact road each year on our journey. Some times each year and some years (generations) we're closer to the sun than other years which also adds to increasing the heat intensity.
I don't see our being able to control this cause for global warming (and freezing) for at least another century or so.
That's what I think.
Barry's Response - The good ol' Milankovitch cycles. They're everywhere, and they do affect our climates on a multi-century scale. Thanks Don.
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