蔚藍的天空總會給人們帶來無盡的遐想，每當我們仰望浩瀚無垠的蒼穹，都會深深的陶醉在那片神秘而悠遠的藍色中。不過，天空為什么是藍色的呢？這里邊可是大有玄機。想知道嗎？快快讀下去吧！

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：輻射

scatter：散射

（北京林業大學通訊員林宇供稿 英語點津 Annabel 編輯）