The blue sky is like washing, which means the weather is fine. Which idiom is it?

Explanation: Blue sky: light blue sky. The blue sky is as clear as washing. Describe sunny weather.

From: Song Ganyuan's "Water Tune Song Tou" words: "Wan Li's blue sky is like washing, it is very bright in the cold, and the curtains are rolling in jade waves."

At that time, a flock of geese fell from the sky. ◎ Shen Congwen's Long River Autumn (Quiet in Motion)

There is a cloudless blue sky in Wan Li.

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