Why are rain clouds gray?

It's common knowledge that most clouds are white, however rain clouds are often a deeper gray. However, why are rain clouds so dark? Let's start by talking about how clouds develop. The air surrounding you is dense with water vapor, which is water in its gaseous state. When the air near the ground heats, it begins to rise, carrying water vapor with it.

As the air climbs higher into the sky, it begins to cool, allowing water vapor to condense upon atmospheric dust from volcanoes, automobile exhaust, and other sources. Clouds are formed when water droplets and ice crystals coalesce or join together. Unlike air particles, which scatter more blue light than other colors (causing the sky to seem blue), microscopic cloud particles scatter all hues of light equally, resulting in white light. In general, the hue of a cloud is determined by its proximity to the sun. When clouds obstruct sunlight, they seem gray. The more dense the cloud, the more light it obscures. When a cloud is around 3,000 feet (900 meters) thick, very little sunshine penetrates the cloud.