地球停止旋转，世界将会怎样？

鲍海飞 翻译整理 2011-5-16

有一天，地球竟然突然停止了旋转！看一看，这种情况会发生吗？但是如果一旦发生了，世界会是什么样？

在未来的数亿年间，地球将要停止旋转的几率几乎为零，但是，我们依然可以猜想，如果有一天地球的转动真的停止了，那将会怎样呢，会发生哪些意想不到的情形呢？

地球以每小时1100英里（1miles= 1.609km）的速度在转动。如果我们的星球突然停止转动，环绕在地球周围的大气却依然在以这个速度运动。大气的转动速度如此之快，地球上的东西只要没有固定在岩床上，就将完全把地面上的东西扫得一干二净。这将意味着岩石、土壤、树木、建筑物、人类以及动物，都将被扫进大气中。

在未来几百万年，如果地球的转动速度逐渐减慢下来，而这是最有可能的画面，那地球上将是另外一番光景了。如果地球减慢到一年只转动一圈，称之为同步转动。那么，地球上每个地方就都有一年的时间或处于全年阳光普照、或处于全年黑暗的状态。这非常类似于月球的正面（所谓的正面），有两个星期是被太阳照射，而另两个星期将在黑暗之下。

如果地球完全停止转动那会如何呢？如果是那样，一半的地球将有半年的时间处于白天，而另一半将处于黑暗。下一个半年则倒过来。温度变化比现在更要发生极端的情况。温度梯度将影响风的环流，空气将要从赤道吹向极地，而不是现在的平行于赤道的风系。

地球只是停止了自旋，但是依然在做公转！

更奇怪的是太阳在天空中位置的变化。在上面的场景中，由于地球的轨道和地轴的倾斜，太阳将朝向南面做季节性的上下移动。是季节性的。你将会看到太阳在天空中依然是升起或者降落，就像我们今天看到的，由于地球的转动，太阳的升起是从一个点开始的。

举个例子。比如，我们居住在北纬30度，在夏季的时候，在一个恰好是太阳当头高照的经度，而当秋季来临时，太阳将逐渐趋于水平位置。但是由于太阳在轨道上已经移动了90度，它现在将是在西面了。而当冬季来临时，你将位于地球黑暗的一侧。你只有沿着地球经线移动180度，你才能看到太阳的一半爬上天空，因为在冬季，太阳位于天空中在夏季位置点所处的南方50度。

地球转动还有其他一些效应。地磁场的产生是由于包含地球在内转动引起的动效应。如果地球停止转动，地磁场将不会再产生而逐渐减弱，一直到很低的水平，也就是残留在富铁岩石中化石的剩磁部分。

地球上从此也将不再有北极光了，并且Van Allen辐射带也将消失（James Van Allen of the University of Iowa），而本来免于宇宙射线和其它高能粒子辐射的保护层也将消失，失去了这个保护将极大损害我们的健康。

幸运地是我们的地球一直在旋转着，如果没有了它的旋转，情况将变得糟糕极了！

参考：

What would happen if the Earth stopped spinning?

This very question was emailed to me and so I thought I'd just make it the topic for this week's article. Of course the likelihood for this actually happening in the next few hundred millions years is just about zero. But we can still speculate on what would happen anyway.

Earth is rotating at a speed of about 1100 miles per hour. If our planet suddenly stopped rotating, the atmosphere would still be in motion at that speed. The atmosphere would be moving so fast it would literally sweep the land masses clear of anything not anchored to bedrock, this would mean rocks, soil, trees, buildings, people and animals. All would be swept up into the atmosphere.

If the Earth's rotation slowed down gradually over millions of years, and this is the most likely scenario, it would be a very different story. If the Earth slowed down to one rotation every year, called synchronous rotation, every area on Earth would be in either sunlight or darkness for one year. This would be similar to what the Moon goes through where for two weeks the front side of the Moon is illuminated by the Sun followed by the front side being in darkness for two weeks.

But what if the Earth stopped rotating completely? In that case, one half the Earth would be in daylight for half the year while the other side would be in darkness. The second half of the year it would be reversed. Temperature variations would be far more extreme then they are now. The temperature gradient would affect the wind circulation also. Air would move from the equator to the poles rather then in wind systems parallel to the equator as they are now.

Even stranger would be the change in the Sun's position in the sky. In the above scenario, Sun would just have a seasonal motion up and down the sky towards the south due to the orbit of the Earth and its axial tilt. You would see the elevation of the Sun increase or decrease in the sky just as we now see the elevation of the Sun change from a single point on the Earth due to the Earth's daily rotation.

As an example, say we live at 30 degrees North latitude. In the Summer, at a longitude where the Sun was exactly overhead, it would slide gradually to the horizon as Fall approached, but since the Sun has moved 90 degrees in its orbit, it would now be due west. As Winter approached, you would now be located on the dark side of the Earth. You would have to move to a longitude 180 degrees around the Earth to see the Sun 1/2 way up the sky because in the Winter, the Sun is 50 degrees south of its summer location in the sky.

There would be other effects of the Earth's rotation slowing also. The magnetic field of the Earth is generated by a dynamo effect that involves its rotation. If the Earth stopped rotating, the magnetic field would no longer be regenerated and it would decay away to some low, residual value due to the very small component which is 'fossilized' in its iron-rich rocks. There would be no more 'northern lights' and the Van Allen radiation belts would probably vanish, as would our protection from cosmic rays and other high-energy particles. Losing this protection would cause serious health issues.

Be glad for our Earthly rotation, without it we would be much worse off!