时差N小时 当天空变成绿色时

It sounds like something from a fairy tale.

这听起来就像是个童话故事。

If you look at the horizon at sunset–exactly as the last sliver¹ 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 askew² 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 atmospheric³ 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 bent⁴ 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 scattered⁵ 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。

1 sliver   

n.裂片，细片，梳毛；v.纵切，切成长片，剖开

参考例句：

• There was only one sliver of light in the darkness.黑暗中只有一点零星的光亮。
• Then,one night,Monica saw a thin sliver of the moon reappear.之后的一天晚上，莫尼卡看到了一个月牙。

2 askew   

adv.斜地；adj.歪斜的

参考例句：

• His glasses had been knocked askew by the blow.他的眼镜一下子被打歪了。
• Her hat was slightly askew.她的帽子戴得有点斜。

3 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

4 bent   

n.爱好，癖好；adj.弯的；决心的，一心的

参考例句：

• He was fully bent upon the project.他一心扑在这项计划上。
• We bent over backward to help them.我们尽了最大努力帮助他们。

5 scattered   

adj.分散的，稀疏的；散步的；疏疏落落的

参考例句：

• Gathering up his scattered papers,he pushed them into his case.他把散乱的文件收拾起来，塞进文件夹里。