It can be described as clear and crisp weather.

Can also be extended to mood, bright future, sunny.

The so-called blue sky is like a shower and the sun is shining high.

The blue sky is as clear as washing. It describes sunny weather.

In Zhang Song Gan Yuan's "Water Tune", he wrote: "Wan Li's blue sky is like washing, and it is bright in the cold, and the curtains are rolling."

The bright sun is high in the sky and shining on the earth. The weather is good.

This word can also be used to describe a bright future and a good situation.