Look at the earth-isn't beautiful?Blue oceans,white polar ice-caps,and verdant green land.Some brown as well,where there aren't as many plants.But why are those parts of our earth barren,and others green?I mean,deserts cover much of Africa and Australia,but not Europe!
看看这个地球，它真漂亮。蔚蓝的海洋，雪白的冰盖，还有嫩绿的绿洲。还有一些事棕色的，那里植被少一些。但是 为什么 地球一部分是荒原，另一部分是绿洲呢?我是说，沙漠覆盖着非洲 和澳洲大半面积,但是欧洲却没有!
Europeans,it turns out,discovered the answer,but in the most unlikely of places the oceans!When sailing from Europe,trade winds pushed ships enthusiastically southwest to the equator,where suddenly,the winds would die.These were the doldrums.And for sailors,they were a pain.They were also annoying to scientists like Galileo,kepler,and Halley.who all had theories about why the wind blew to the southwest : Did the wind somehow follow the wun from morning till night? Or did it have trouble keeping up with the ground spinning beneath it ?
事实证明,欧洲人发现了问题的答案,不过答案在那最不可能的地方 海洋!当人们从欧洲起航,信风主动将船只向西南方向吹动 一直到赤道,在那里,风突然停了.这就是赤道无风带.对于水手来说,这是空空的痛.这个现象也困扰着如伽利略,开普勒,哈雷等等科学家,他们都持着 各种西南风成因的理论.这种风从早到晚随太阳 移动吗?或者是它没法跟上其下大地旋转的速度?
In 1735,a London lawyer and amateur meteorologist named George Hadley came up with an even brighter idea that ultimately helps explain not just ocean winds,but also why our planet has rainforests in a belt near the equator and deserts just north and south of that.Hadley figured that,since the sun warms the Earth must be cooler--and therefore more dense.Just as cold air rushes in through an open door in winter,cool air north and south of the equator must flow toward the warm air in the middle,bringing sailors with it.
在1735年,一位名为George Hadley的伦敦律师兼业余气象爱好者 想到了一个更高明的主意，它不只从根本上帮助解释了海风成因 也解释了为何地球上热带雨林在赤道旁边的一带，沙漠挨在热带雨林的南北方 Hadley发现，正因为太阳照耀着大地时 两级照射最多，其南北方的空气 就会冷些，密度就更大。正如冬天冷空气通过一扇敞开的大门 闯进来，赤道南北方的冷空气必须跟随中间的暖湿气流流动，一并带着出海的水手。
There,in the doldrums,the air didn't actually stop moving,it jsut headed upwards,heat rising to make way forthe denser air flowing in from both sides.And here's where the earth's greens and browns come in:As warm,humid air at the equator rises,it cools,and--since cool air can't hold as much moisture as warm air--it rains A lot.Enough to make rian-forests.
At an altitude of about 17 kilometers,the rising (and drying)air hits the stratosphere,which acts kind of like a ceiling,causing the warm air to spread out and separate-some goes north,some south,As the air departs from the equator,it rains away more moisture,becoming denser and slightly cooler,until finally dry,it sinks,creating the arid bands where many of the world famous deserts lie.
This giant atmospheric conveyor belt,officially called a Hadley cell,brings up both tropical rainforests and deserts,So the locations of greens or browns of the earth come courtesy of a lot of hot air.
这个巨大的传送带学名为Hadley环流圈，它为我们 带来了雨林和沙漠。因此，地球上的翠绿和棕黄 都得归功于这体积庞大的热空气。