How to explain the weather from the clouds?

For example, clouds are like the "signboard" of the weather/groups of oblate clouds/like snow-white sheep rolling around on the grassland, sometimes like a white feather, sometimes like a white diamond yarn.

Contrast: thin clouds in the sky are often a symbol of sunny weather; Those low and thick clouds are usually signs of rain and snow.

For example, cumulus clouds are a group of oblate clouds.