Class Presentation: Why Is the Sky Blue?

Right, everyone, settle down, please.

好了，大家，安靜一下。

Oliver's presenting his science project today.

今天 Oliver 要報告他的自然科學專題。

Um... morning, everyone.

嗯……大家早安。

So, my question today is, why is the sky blue?

那麼，我今天的問題是：天空為什麼是藍色的？

First, sunlight looks white, doesn't it?

首先，陽光看起來是白色的，對吧？

But actually, it's a mix of all the colours,

但其實，它是所有顏色混在一起的，

like a rainbow, from red to violet.

就像彩虹一樣，從紅色到紫色。

Oh, like light through a prism?

喔，就像光穿過三稜鏡那樣？

Yes, exactly! Brilliant.

對，就是這樣！太棒了。

Now, when sunlight comes into our air,

現在，當陽光進入我們的空氣時，

it hits tiny gas particles, much smaller than dust.

它會撞上微小的氣體分子，比灰塵小得多。

Blue light has short waves,

藍光的波長很短，

so it bounces around much more than red light.

所以它比紅光更容易四處彈開。

It's called Rayleigh scattering, and it fills the sky with blue!

這叫做 Rayleigh 散射，它讓整片天空都變成藍色！

Okay, let me show you a quick experiment!

好，我來給大家做個小實驗！

This is just water with a little milk in it.

這只是加了一點牛奶的水。

Could someone turn off the lights, please?

可以請誰幫忙關個燈嗎？

Look! From the side, the water looks a bit blue.

看！從側面看，水有點偏藍。

No way! It really does look blue!

不會吧！真的看起來是藍的！

Hang on, I've got a question.

等一下，我有個問題。

If blue scatters more, why are sunsets red, then?

如果藍光散射得比較多，那夕陽為什麼是紅色的？

Oh... um, good question.

喔……嗯，好問題。

Wait, look at the torch through the end of the glass!

等等，從杯子另一端看手電筒！

Whoa, the light looks orange now!

哇，現在光看起來是橘色的！

At sunset, light travels through much more air,

夕陽西下時，光要穿過多得多的空氣，

so most of the blue gets scattered away.

所以大部分藍光都被散射掉了。

Only the red and orange light reaches our eyes!

只有紅光和橘光能到達我們的眼睛！

Oh, and violet scatters even more than blue,

喔，還有，紫光散射得比藍光還多，

but our eyes are much better at seeing blue.

但我們的眼睛對藍色敏感得多。

So, that's why the sky is blue, not purple!

所以，這就是天空是藍色而不是紫色的原因！

Well done, Oliver! That was excellent.

做得好，Oliver！非常精彩。

You started a bit quietly, though.

不過你一開始聲音有點小。

Next time, speak up from the very beginning.

下次從一開始就大聲說。

I will. Thanks, miss!

我會的。謝謝老師！