It's cloudy and cloudy.

Sunny (or partly cloudy): Wan Li has no clouds, the sky is blue, or there are only a few clouds, and the cloud amount is less than 30%.

Cloudy: refers to the fact that clouds cover most of the sky, and the total amount of clouds is above 30% and below 70%. Sunlight can reach the ground through the clouds.

Cloudy day: Clouds are almost all over the sky, and the total amount of clouds is above 70%.