What lies at the core difference between a bright white cloud and a menacing dark one?
Answer
The size and concentration of the particles, and consequently, the cloud's depth
The primary factor determining cloud color is depth combined with the physical size and concentration of the water droplets or ice crystals within it. Thin clouds scatter light easily, appearing white, whereas thick clouds block light penetration.

#Videos
Why Storm Clouds Are Dark - YouTube
Related Questions
What fundamentally causes a cloud's deep gray or near-black appearance?What lies at the core difference between a bright white cloud and a menacing dark one?Why does the base of a very thick, towering cloud appear dark to someone standing below?What type of precipitation is characteristic of the vast, featureless nimbostratus cloud?Which dark cloud formation is specifically known as the architect of thunderstorms?If a cloud appears profoundly dark but yields no rain, what does this imply about its droplets?What specific accessory cloud structure signals the imminent arrival of a strong gust front, meaning high winds are minutes away?What does observing bright white areas juxtaposed against the dark base of a cloud indicate?When comparing horizontal extent versus vertical energy, what does a massive, dark sheet stretching horizon-to-horizon suggest?How does a dark cloud developing late in the afternoon differ in potential severity compared to one arriving during the morning?