【英语时差8,16】彩虹的鬼表哥

 

Rainbows are one of nature's most ephemeral beauties, but there's a related phenomenon that's even more ghostly.   

These are the pale white, rainbow-like arches that are sometimes seen on foggy days or in dense¹ fog banks. What's responsible for these so-called "fogbows"?

 

Fogbows are created in much the same way as normal rainbows are. Round droplets³ of water in the atmosphere can separate sunlight into different colors, just like a prism or a piece of crystal. This is called "refraction."

 

You'll see a rainbow when the sun is behind you, but it's shining on raindrops in the sky in front of you. Pure sunlight is white--it contains all the colors of the spectrum--but each individual color is refracted out of the droplets at a slightly different angle. A rainbow is the refracted light from millions of tiny raindrops.

 

A rainbow only appears when the water droplets are small enough to be more or less round, but large enough to focus the colors clearly. The best droplet² size for rainbows is about one or two fiftieths of an inch across. Larger drops tend to wobble as they fall, refracting the sunlight haphazardly⁴. Smaller drops can refract the light well enough, but they are too small to focus the colors clearly. The diameter of a fog droplet is only about one five hundredth of an inch, much too small for this sharp focus. The light is refracted just like in a rainbow, but the colors all bleed into one another, and the fogbow appears a ghostly white.  

1 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

2 droplet   

n.小滴，飞沫

参考例句：

• The rate of droplet growth under different conditions can be evaluated.可以计算在不同条件下的云滴增长率。
• The test results showed that increasing droplet size was associated with better stability.试验结果表明，增加液滴尺寸将使稳定性提高。

3 droplets   

n.小滴( droplet的名词复数 )

参考例句：

• Droplets of sweat were welling up on his forehead. 他额头上冒出了滴滴汗珠。 来自辞典例句
• In constrast, exhaled smoke contains relatively large water droplets and appears white. 相反，从人嘴里呼出的烟则包含相当大的水滴，所以呈白色。 来自辞典例句

4 haphazardly   

adv.偶然地，随意地，杂乱地

参考例句：

• The books were placed haphazardly on the shelf. 书籍乱七八糟地堆放在书架上。 来自《简明英汉词典》
• It is foolish to haphazardly adventure. 随便冒险是愚蠢的。 来自《现代英汉综合大词典》