Class Presentation: Why Is the Sky Blue?

Right, everyone, settle down, please.

好了，大家，安静一下。

Oliver's presenting his science project today.

今天 Oliver 要展示他的科学项目。

Um... morning, everyone.

嗯……大家早上好。

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

那么，我今天的问题是：天空为什么是蓝色的？

First, sunlight looks white, doesn't it?

首先，阳光看起来是白色的，对吧？

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

但其实，它是所有颜色混在一起的，

like a rainbow, from red to violet.

就像彩虹一样，从红色到紫色。

Oh, like light through a prism?

哦，就像光穿过三棱镜那样？

Yes, exactly! Brilliant.

对，就是这样！太棒了。

Now, when sunlight comes into our air,

现在，当阳光进入我们的空气时，

it hits tiny gas particles, much smaller than dust.

它会撞上微小的气体分子，比灰尘小得多。

Blue light has short waves,

蓝光的波长很短，

so it bounces around much more than red light.

所以它比红光更容易四处弹开。

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

这叫作 Rayleigh 散射，它让整片天空都变成蓝色！

Okay, let me show you a quick experiment!

好，我来给大家做个小实验！

This is just water with a little milk in it.

这只是加了一点牛奶的水。

Could someone turn off the lights, please?

有人能帮忙关一下灯吗？

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

看！从侧面看，水有点发蓝。

No way! It really does look blue!

不会吧！真的是蓝色的！

Hang on, I've got a question.

等一下，我有个问题。

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

如果蓝光散射得更多，那日落为什么是红色的？

Oh... um, good question.

哦……嗯，好问题。

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

等等，从杯子另一头看手电筒！

Whoa, the light looks orange now!

哇，现在光看起来是橙色的！

At sunset, light travels through much more air,

日落时，光要穿过多得多的空气，

so most of the blue gets scattered away.

所以大部分蓝光都被散射掉了。

Only the red and orange light reaches our eyes!

只有红光和橙光能到达我们的眼睛！

Oh, and violet scatters even more than blue,

哦，还有，紫光散射得比蓝光还多，

but our eyes are much better at seeing blue.

但我们的眼睛对蓝色敏感得多。

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

所以，这就是天空是蓝色而不是紫色的原因！

Well done, Oliver! That was excellent.

做得好，Oliver！非常出色。

You started a bit quietly, though.

不过你一开始声音有点小。

Next time, speak up from the very beginning.

下次从一开始就大声说。

I will. Thanks, miss!

我会的。谢谢老师！