孙燕姿的“绿光”真实存在

 　　还记得孙燕姿那首红遍大江南北的《绿光》吗？“翻越过前面山顶、层层白云，绿光在哪里？”——不知道有多少人跟小编一样，以为歌里的“绿光”只是对幸福的比喻。而其实在现实中，“绿光”是真实存在的呢！来看看它的解释吧：

　　Green flashes and green rays are optical phenomena¹ that occur shortly after sunset or before sunrise, when a green spot is visible, usually for no more than a second or two, above the sun, or a green ray shoots up from the sunset point。

　　The reason for a green flash lies in refraction of light (as in a prism) in the atmosphere: light moves more slowly in the lower, denser² air than in the thinner air above, so sunlight rays follow paths that curve slightly, in the same direction as the curvature of the Earth. Higher frequency light (green/blue) curves more than lower frequency light (red/orange)， so green/blue rays from the upper limb of the setting sun remain visible after the red rays are obstructed³ by the curvature of the earth。

　　简单说来就是：在日出和日落时，当太阳只有一小部分在水平线之上，而空气又十分清新的话，绿太阳便会出现，维时仅仅数秒。我们知道，太阳光通过大气层时会被折射，正如三棱镜一样，把太阳光的白光折射为彩虹七色。波长较短的光线会被折射得较多，所以在日出或日落的一刻，我们最先或最后所看见的都应该是蓝光。但是，蓝色的光在空气中较易被散射，不易看见，而往往我们看见的，是比蓝光波长稍长的绿光，这便是绿太阳的由来。可是如果空气中有太多灰尘的话，就连绿光也会被散射开，我们就看不见绿太阳了。

1 phenomena   

n.现象

参考例句：

• Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
• The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系，如果存在着任何联系的话。

2 denser   

adj. 不易看透的, 密集的, 浓厚的, 愚钝的

参考例句：

• The denser population necessitates closer consolidation both for internal and external action. 住得日益稠密的居民，对内和对外都不得不更紧密地团结起来。 来自英汉非文学 - 家庭、私有制和国家的起源
• As Tito entered the neighbourhood of San Martino, he found the throng rather denser. 蒂托走近圣马丁教堂附近一带时，发现人群相当密集。

3 obstructed   

阻塞( obstruct的过去式和过去分词 )； 堵塞； 阻碍； 阻止

参考例句：

• Tall trees obstructed his view of the road. 有大树挡着，他看不到道路。
• The Irish and Bristol Channels were closed or grievously obstructed. 爱尔兰海峡和布里斯托尔海峡或遭受封锁，或受到了严重阻碍。