literally describing a fresh and clear post-rain atmosphere with a light breeze and a bright moon

雨后初晴，窗外光风霁月，景物显得分外清爽。

having a noble, benevolent, and magnanimous character; openhearted and upright

他一生光明磊落，胸怀坦荡，真可谓是光风霁月。

a period of political stability, peace, and social prosperity

在这一派光风霁月的盛世里，百姓安居乐业。