The blue of the sky paled to a light grey.

天空的蓝色渐变成了浅灰色。

《牛津词典》

The color is magnificent, with the cobalt blue sky in the background and the warm light on the lion.

背景中钴蓝色的天空和狮子身上暖色调的光线，颜色好极了。

youdao

Some residents in the Washington DC area saw a blue light in the sky that moved around and made now sound.

华盛顿地区一些居民看到了天空里的蓝光，在天空里四处移动，并发出声音。

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