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What causes the seasons and the legnth of day
by JJ
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x JJ   - at 1:43 am on Friday April 2 2004 x
x An explanation as to why some people get seasons, and some don't. x
x JJ four seasons Singapore - My contribution, partially also because I'm bored... (It might be useful if you have a globe with you and an object to represent the sun, if you really want to follow this article).

Basically, our Earth is tilted at an angle of approximately 23.5 to the normal. That is, the axis is permanently tilted 23.5 away from the normal, and the Earth revolves around this axis.

As you probably will already know, the Earth's rotation about this axis causes the change from night to day, and its revolution around the Sun causes the change in seasons.

The Earth rotates about its axis anti-clockwise, and it revolves around the sun in that direction, too. It is anti-clockwise simply because clocks (sundials) were invented in the Northern Hemisphere and the shadow moved in what was percieved to be a clockwise direction - obviously, this was due to the eart rotating in the opposite direction. And had clocks been invented in the South, well, the Earth would still probably be rotating in the so-called 'anticlockwise' direction, because the present anticlockwise would have been clockwise, if you get my drift.

Right, take the North Pole for instance. At one instant, when it is at a bearing of, say, 090 to the Sun, at the point where the North pole faces the Sun. Now, rotate the globe about the axis. You will find that, at any given instance, the North Pole is always facing the sun, gicing rise to the phenomenon called the midnight sun - 24-hour daylight, what is termed summer in the North Pole. (The polar bears would be having a whale of a time).

Now look at the South Pole, and rotate the globe again. In direct contrast to the North Pole, you should see that at any given moment, the South Pole always faces away from the sun. This means that it is in a period of total darkness, 24/7. This is what is called winter in the South Pole.

Now take the globe to a bearing of 360 to the sun (the globe is "above" the sun if you look at the sun and the globe in a straight line). Turning the globe, you will find that the amount of time which the North Pole faces the Sun is roughly equal to the amount of time it faces away from the sun - something called the equinox (literally meaning equal night).

Take the globe to a bearing of 270 to the Sun, and you have what the South Pole was experiencing some time ago - complete darkness and a long winter ahead.

If you take a look at, say, Canada, you guys have such long winters because you lie just beneath the North Pole. At any given instant, because of the tilt of the Earth, you face away from the Sun for a much longer period than countries near or on the equator, like Singapore.

I fyou look at Singapore, wherever the Earth is, due to its position, at any given time, the amount of time it spends facing the Sun is almost the same as the amount of time away from it - hence, we don't get the seasons.

So that is a very brief explanation as to how the season's are caused.
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