why is the earth's spin wavy in nature.?
110477
If the question is about precession, then wikipedia has an answer:\n\n(The earth's axis undergoes a change in the direction of its axis, very slowly though...it spins like a wobbling top, and if you extend the axis up to the heavens and plotted it over 26000 years, it would trace a small circle in the sky. This is known as precession.)\n\n"The explanation of this is: The axis of the Earth undergoes precession due to a combination of the Earth's nonspherical shape (it is an oblate spheroid, bulging outward at the equator) and the gravitational tidal forces of the Moon and Sun applying torque as they attempt to pull the equatorial bulge into the plane of the ecliptic. The portion of the precession due to the combined action of the Sun and the Moon is called lunisolar precession."\n\nLook up the article in wikipedia with the provided link and you'll have a more detailed explanation along with a detailed diagram (2nd link) showing the circle it traces in teh sky... You can see by the diagram that Polaris will/was not always the north star. At different periods of the earth's history, other stars assumed that role or there was no north star.
465388
The Earth is round for the same reason that things don't fall off it.  Gravity is a force in the universe that attracts all forms of matter equally, this means that pieces of matter will eventually move together and form clumps, if this is happening from every direction then the most likely shape it will form is a sphere.\n\nThis gravitational attraction is pretty small.  However, the Earth is pretty big, so the combined effect of all that gravity is just enough to keep your feet firmly planted on the surface :)\n\nThere are a few other related effects that come into play, such as centrifugal force, which keeps everything spinning and moving.
185111
It's easy to remember if you understand the basics of why the rotation happens. At the equator the air, moving with the earth, has a high west-to-east speed. In each hemisphere, heat drives a general equatorial-polar circulation of air. Because of the high eastward speed at the equator, in the northern hemisphere air moving north from the equator or south toward it appears to bear to the right due to Coriolis effect. (This is often illustrated by a funhouse turntable where someone rolls a ball from the edge toward the center. If the turntable is rotating CCW, like earth viewed from over the north pole, the ball curves right. If someone rolls the ball from center to edge it still curves right.)\nNow consider that air flows toward a low pressure system, and any air with a north or south velocity component curves right. This induces a CCW rotation. Similarly, air flowing away from a high pressure system and curving right induces CW motion. An interesting side effect of inflow toward a low is that conservation of angular momentum causes angular velocity, and thus wind speed, to increase as you approach the center of a low, but not in the case of a high. Thus lows tend to be much more dynamic and occasionally to spawn tornados. \nIn the southern hemisphere, motion along the equator-pole direction results in turning left, so low and high pressure system rotations are CW and CCW respectively.
1027639
Because there is nothing close by to whiz by as Earth rotates, and because it doesn't shake as it rotates. For example, when riding in an airliner at 30,000 feet, it seems to almost be standing still, even though it is flying at over 500 MPH. There is a little shaking from the engines, maybe some turbulence, and the ground drifts sloooooly by. The Earth has no shaking engines, there is no space turbulence and the nearest thing to be seen drifting slowly by is the Moon.
1175270
The earth is round due to its rotation and gravity.  The sphere is a perfect structure.  Think about it, the bubble forms a skin and holds its shape.  Hurricanes are circular, so are whirpools, dustdevils, tornados.
789602
It's also true with water going down the drain. It goes the other way in the southern hemisphere, because of the earths rotation.
1009840
1. Earth's rotation is the reason we have days and nights. Without Earth rotating the sun would shine on one place only and the other side of the planet would be in the dark. Rotation is also the possible reason for its magnetic field.\n\n2. Earth's revolution is the reason for seasons and gravity.
414963
You may be referring to the Coriolis Effect, which governs the rotation of very large fluids (like weather systems on earth), due to differential forces caused by the rotation of the Earth.  In a relatively small object like a pipe (or yes, even a toilet) the direction of rotation is either random or determined by the geometry of the object.
886899
Electromagnetic fields don't cause the earth to wobble. The earth processes like a top and wobbles. As the earth processes the northern and souther hemispheres get different amounts of heat. This drives the weather. This motion of the earth is due to angular momentum from left over from its formation and the procession probably results from collisions with large objects, including the one that formed our moon. To a much smaller extent, some of the wabble is probably due to plate techtonics.  The moon, by the way, acts to stabilize the wabble of the earth.
478834
Because you live in the Southern Hemisphere...In the Northern Hemisphere it goes the other way. Look up the term 'Coriolis effect' for more info.
481150
the earth spins at 1500 mph.  If you take a ball and spin it extreemly fast you will find that the center of the ball will grow and the poles will flatten.  It is like driving a car very fast.  The higher up ion speed you go the lower to the ground it will become.  I has to do with Volocity.
644044
Why does it always spiral the same direction?\n\nIt *doesn't*.\n\nTry the experiment in your bathtub.  It can go either way.\n\nSome people mentioned the "coriolis effect", but for\nsomething as small as a bathtub, this effect is *tiny*.\n\nThe last references below describes experiments where (with\nvery careful controls) this effect was demonstrated, but\nfor most of our experiences, we're seeing other local\neffects (ie. residual currents in the water).  The\nexperimenters literally had to let the water sit for *days*\nin order to let the residual currents die down so that they\nwouldn't overwhelm the vanishingly small coriolis effect.\n\n[By the way, the coriolis effect is *not* vanishingly\nsmall for something *really big* -- like a weather\nsystem.  In that situation, there is a significant\ndifference in the speed (due to the earth's rotation)\nof the portion farthest from the equator vs. the \nportion closest to the equator.]
280145
Very briefly, the combined effects of the sun and earth's rotation provide the energy that drives storms. Solar heating heats the earth's surface, most strongly in tropic regions, and drives a water transport cycle by evaporating water from oceans, lakes etc. into the air. Convection conveys hot, moisture-laden tropical air toward the poles and cold polar air back toward the tropics. And the rotation of the earth causes these air movements to acquire a rotational component (Coriolis force). When cold air masses meet hot, moist air masses, the cold air may rise up over the hot air, or cold air may pass over hot, wet land, either scenario creating an instability. The overturning of this creates convective vertical air movements which may be augmented by the rotation. Downdraft convection is felt as winds on the ground. Within the storm cell, the hot moist air transfers heat to the cold air through water condensation, and this can bring rain or frozen precipitation. Updrafts of warm moist air form precipitation as the air is cooled due to reduced pressure at high altitude. Adjacent updrafts and downdrafts produce a type of wind shear that can cause aircraft to lose lift and crash.
1081261
As the earth rotates on its axis, the atmosphere is rotating with it.  Otherwise there'd be a constant wind, like in a fast-moving car on a still day,  as we were dragged through the atmosphere at the speed of the earth's rotation, yes?   And all winds would blow from east to west, and we know that's not the case.  \n\nBut the rotation of the earth does have an important effect on the weather.   A strange thing about rotating a globe is that a point on the equator has to move much faster to make it all the way around the waist of the globe in 24 hours than a point up around the Arctic circle has to move to make it all the way around the Arctic circle in 24 hours. (you can test this with a piece of string: The length of a piece of string wrapped around a globe at the level of New York is much shorter than a piece of string wrapped around the globe at the equator, right?)\n\n  You know that, looking at the globe with the sun behind your back, as the world turns, the continents pass off to the right (the east). New York crosses into the sun at dawn while San Francisco is still on the dark side of the globe.  Because the surface of the earth at the  equator is rotating faster than the surface of the earth 500 miles north of the equator, so is the air above it.  But the air above the equator isn't attached to the air above a point 500 miles north.  So the faster-moving and slower-moving air rub past each other.  This forms a kind of bow wave at the equator, like the wave that peels back from the bow of a boat as it moves through the water. Think of a big arrow pointing to the right and wrapped around  the equator.  So the air peels  back to either side of the equator, and forms a swirling current--curling counter-clockwise above the equator and clockwise below it.  This is called the coriolis wind.  It's one important factor in where weather comes from.
1069004
For the most part, the atmosphere moves along with the surface of the earth. On the other hand, winds going in any direction tend to grind down mountain peaks.\n\nHowever, if the Earth were not fairly close to round, then the molten lava inside the earth would rupture the crust and deform the earth into a round shape. The main reason the Earth is round is gravity, not wind.
728543
From USA Today:\n\n"Q: Why does most of our weather come from the west if the Earth is rotating the opposite way?\n\nA: When looking down at the North Pole, the Earth spins counterclockwise around its axis. A point on the equator travels at about 1,100 mph, while a point directly at the poles does not move at all. An apparent force called the Coriolis force results from this difference in speeds, deflecting objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The Coriolis force, combined with solar heating patterns across the Earth, create distinctive wind patterns that drive weather systems.\n\nOne prevailing surface wind pattern that results is located in the mid-latitudes, between 30 and 60° North. Solar heating alone, without the Earth's rotation, would produce prevailing southerly winds. The Coriolis force, however, deflects these winds to the right, creating prevailing winds out of the west and southwest (the westerlies). \n\nSolar heating patterns in the tropics, from the equator to about 30° North, combined with the Coriolis force, produce weak prevailing winds out of the east (the easterlies). Southern regions of the USA, including Florida, are affected by the westerlies at times and the easterlies at others."\n\nHope this helps explain it. Check the first link for other weather questions and second link to see a full explanation of the consequences of rotation on weather.
723049
The Earth is, approximately, covered under water;  (approximately 3/4ths of its \n            surface). \n            The Sun and moon --- having Attracting Power on our Planet, while our Planet \n            --- making the terrific speed of 1,037 1/3 miles on its way around the Sun. \n            The Sun draws this water up into the Earth's rotation, which is called \n            gravitation, in a fine mist that the naked eye can hardly detect.  But as this \n            mist ascends higher , and increasing with other mists of water in different \n            currents of the atmosphere, until when she becomes heavier than gravitation. \n            Then she distills back to the Earth in the form of drops of water or drops of ice, \n            which depends on how heavy the mist was, in the current of the air it was in. \n            There are some layers or currents of air --- real cold and warm, and some very \n            swift and changeable.  So when the water strikes one of these cold currents, it \n            becomes solid ice in small, round drops in form or in a light, fluffy form which is \n            called snow.  But this water is not ever drawn above six miles from the Earth's \n            surface by the Sun and moon.  The reason it rains back on our planet is \n            because it cannot get out of the earth's sphere.  With its high speed of rotating \n            around the Sun --- makes it impossible. \n            Earthquakes are caused by the Son of man by experimenting on high \n            explosion.  In fact, that all the above is caused by the Son of man.