Level 1 · Reading series
Lesson 21 · Why Is the Sky Blue?
Audio track 21
Listen first
Listen once before opening the English passage.
Open the English passage and hover for word help
Sunlight looks white, but it has many colors. When it reaches Earth’s atmosphere, it meets very small particles of air. Blue light travels in shorter waves than red light. The particles scatter blue light in every direction.
That is why most of the sky looks blue. At sunset, sunlight travels through more air. More blue light scatters away, so red and orange light become easier to see.
Check your understanding
After reading, state the main idea in one sentence and find a line that supports it.
Chinese translation
阳光看起来是白色的，其实包含许多颜色。阳光进入地球大气层时，会遇到空气中极小的粒子。蓝光的波长比红光短；这些粒子把蓝光散射到各个方向。
这就是天空大部分时候看起来是蓝色的原因。日落时，阳光穿过的大气更厚，更多蓝光被散射开，红光和橙光便更容易被看见。
Key words and expressions
Key terms have Chinese explanations. Hover over dotted words in the English passage for word help and pronunciation when available.
- sunlight
- 阳光；日光。
- reach
- 到达；抵达。
- atmosphere
- 大气层；包围地球的气体层。
- particle
- 粒子；很小的颗粒。
- shorter than ...
- 比……短；比较结构。
- wave
- 波；本文指光波。
- scatter
- 散射；向各个方向散开。
- direction
- 方向。in every direction 意为‘向四面八方’。
- most of ...
- ……的大部分。
- sunset
- 日落；傍晚。
Background notes (Chinese)
光遇到物体时，可能反射、折射或散射。在地球大气层中，波长较短的蓝光比红光散射得更多。火星的大气和尘埃与地球不同，所以白天的天空颜色也不同。
资料来源：NASA Space Place, Why Is the Sky Blue?