why does the clouds turn dark grayish when it is about to rain?

Question

doesnt it? it even turns darker

Answer 1

Clouds are made up of tiny water droplets or ice crystals, usually a mixture of both. The water and ice scatter all light, making clouds appear white. If the clouds get thick enough or high enough all the light above does not make it through, hence the gray or dark look. Also, if there are lots of other clouds around, their shadow can add to the gray or multicolored gray appearance. I hav put link below which answers all questions on clouds.

Hope this answers ur question

Answer 2

When it is about to rain,the rain drops in the clouds would have grown bigger in size and are about to fall.At this time the moisture content will also be maximum.When sunlight passes through these clouds,it will be partially absorbed and scattered.In this condition it will look grey.
On the other hand ,if the sunlight is fully absorbed and scattered, it will look black.
The cloud will be white if either it allows all the sunlight to pass through it without absorbing and scattering it or it completely reflects all the light.
As the moisture content is maximum in the rain drops that are about to fall,the moisture will absorb all the sunlight and so the cloud will be black.

Answer 3

It may seem to change because it may be covering the sun. Look at a cloud. Do you notice it is dark on the underside? That's because the light has to go through the thickness of the cloud to get through it. Some thinner clouds are not so dark. Huge thunderheads are almost black.

Answer 4

It's because when precipitation gather in the atmosphere it also collets dust in the upper atmosphere as well. So the more it gathers the more light it blocks out. Also all the water, and ice in the are causes the light to refract.

Answer 5

that's just it, water buildup. the light is being blocked and we see the shadow from the ground.