1, the thickness of the cloud is different, the cloud is thick, the light of the sun and the moon is difficult to transmit, the cloud looks black, and the cloud with thin cloud will look gray.
2. Isolated cumulus clouds, because the clouds are thick, almost all the light is reflected to the sunny side, so it looks white; On the backlight side and its bottom, the light is not easily transmitted and looks gray and black.
The difference between white clouds and dark clouds:
1, cloud thickness is different.
Dark clouds are generally thick and white clouds are relatively thin.
2. Droplets have different densities.
Dark clouds generally have dense water droplets, while white clouds have smaller water droplets density.
Extended data:
Why are there different colors in the air?
At sunrise and sunset, the light slanted in. The water vapor and impurities in the air make the short wave scatter a lot, and the red-orange long wave part is preserved, so the red-orange color appears. When there are ice crystals in the cloud, light will also be diffracted, just like prism splitting. This will create a colorful halo.
Baidu Encyclopedia-Cloud