Why do rain clouds get dark?

Question

If water is clear, why do rain clouds get really dark?

In: Planetary Science

Answer 1

Light travelling through different mediums (such as from air to water) causes the light to refract (aka bend). With lots of little droplets in the sky, light bounces all around, usually creating the white clouds we see in the sky. Storm clouds are huge, stretching high into the upper atmosphere. They are large enough that very few photons entering the top of the cloud coming from the sun make bounce their way through the cloud to exit the bottom, thus making the cloud appear darker than non-storm clouds.