Hi Nikki Pee

Diba clouds are made of tiny droplets.

According to the concept of light, particles reflect different pigments of light. Small particles with lowest frequency — red, highest frequencies reflects violet. Smallest particles (lowest frequency) to largest particles (highest frequency) reflects these colors (ROYGBIV).

Clouds are composed of different sizes of droplets, they reflect a certain color with accordance to the size of the droplet. Therefore, they reflect ALL kinds of colors.
Again, Physics said that WHITE is the PRESENCE of all colors. With this, we conclude, that because of the different frequencies present the clouds are WHITE.