蔚蓝的天空总会给人们带来无尽的遐想，每当我们仰望浩瀚无垠的苍穹，都会深深的陶醉在那片神秘而悠远的蓝色中。不过，天空为什么是蓝色的呢？这里边可是大有玄机。想知道吗？快快读下去吧！

The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air.

However, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue.

As you look closer to the horizon, the sky appears much paler in color. To reach you, the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Less blue light reaches your eyes. The color of the sky near the horizon appears paler or white.

Rayleigh scattering：雷利散射

molecule：分子

radiate：辐射

scatter：散射

（北京林业大学通讯员林宇供稿 英语点津 Annabel 编辑）