Because the sky is blue.

因为天空是蓝色的。

youdao

I like blue, because the sky is blue.

我喜欢蓝色，因为天空是蓝色的。

youdao

Because of the good environment, it is easy for us to see the blue sky now.

因为环境好，蓝天现在很常见。

youdao

But a clear, cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more easily than they do red light.

BBC: rainbow

And the sky is blue, it says, because the sun produces white light which is made up of all the colours of the rainbow.

BBC: rainbow