时差N小时:当天空变成绿色时

这听起来就像是个童话故事。If you look at the horizon at sunset–exactly as the last sliver of sun disappears–you might see a flash of brilliant green blaze across the sky. 日落的时候如果你看看地平线，尤其是在太阳的最后一缕银光消失的时候，你可能会看到一束耀眼的火焰划过天空。Indeed, an old Scottish proverb maintains that whoever sees this flash will always be lucky in love. 的确，有一句古老的苏格兰谚语这么说，看见这道光焰的人总是会在爱情上交好运。While we can't confirm the lucky-in-love part of this, there is a scientific explanation for the flash of green light. 尽管我们无法证实会有桃花运，但对于这束绿光倒有一个科学的解释。As sunlight enters our atmosphere, it bends slightly.当阳光进入大气层，光线会发生轻微的弯曲。 This is due to refraction, the same thing that makes a pencil look slightly askew when you stick it half way into a glass of water. 这是折射的作用，就象把铅笔的一半插入一玻璃杯水中，铅笔会看起来有点倾斜。The atmospheric bending of light rays is greatest when the sun is right along the horizon, at sunrise or sunset. 日出日落时分，太阳恰好贴着地平线的时候就是光线折射作用最强的时候。How does bending sunlight create a green flash? 但弯折的太阳光又是怎样产生绿光的呢？When sunlight is bent by refraction, it separates into different colors, just like light through a prism. 当日光由于折射而弯曲时，光线就会分解成不同的颜色，就像通过棱镜发射不同的光一样。While a prism can make a dramatic rainbow, atmospheric refraction isn't that strong. 然而三棱镜可以折射出漂亮的七色彩虹，而大气的折射作用却没有那么强。It doesn't turn the sun into a rainbow, but it makes the lowest part of the sun seem a bit more red, and the top of the sun seem greenish blue. 它不会将太阳光折射成彩虹，但是它可以使最底部的光变得更红一些，而最顶部的光看上去像蓝绿色。The effect is so subtle, you'd never notice it. 这个变化非常微妙，你可能从来都未曾注意。Except, of course, at sunset or sunrise. 当然，除了在日出或日落的时候。For a split second, when most of the sun's globe is below the horizon, the only part showing is that blue-green sliver along the top. 只有那么一瞬间，当太阳的大部分轮廓低于水平线，仅有的露出来的部分就是顶部的蓝绿色长条。Blue light is scattered by the atmosphere, so what's left is a brief flash of green, the only illumintion in the sky! 蓝光被大气层分散，剩下的就是一缕缕的绿光，天空唯一的光亮处。Please remember, this happens immediately after a sunset. Never look directly at the setting sun. 请记住，这种现象只在日落后的一瞬间发生。要记着可别一直盯着落日看。