Why are the clouds before the thunderstorm colored?

Most of the clouds in the sky are gray, but sometimes there are black, red and purple clouds.

The color of clouds is caused by the reflection of sunlight by clouds, and is closely related to the size, thickness, range and formation time of clouds.

On cloudy days, the clouds cover a large area, covering the sky almost or completely, and it is difficult for sunlight to penetrate, so the clouds are gray.

On cloudy or sunny days, there are several clouds in the sky, and the sun illuminates them. Clouds are usually near white.

In summer, before the thunderstorm comes, a large range of thunderstorm clouds will form. This cloud is usually black because it is so thick that sunlight can hardly penetrate it.

In the clouds in the morning and evening, its color is often red. This is because at sunrise and sunset, the sun shines obliquely through the thick atmosphere. More intense red and orange light shines on the cloud, making it turn red and orange.