Chapter 28, Problem 40A

To determine

To explain: The fact that very big particles of droplets absorb more radiation than they scatter so that the rain clouds appear dark.

Explanation of Solution

Introduction: 

The particles of the medium deviate the light in different directions when the light strikes on the particles. This phenomenon is known as the scattering of light. The rain falls in the form of droplets from the clouds. All the droplets in the cloud are joined together to form a big droplet.

Explanation: 

If cloud grows larger, more light is reflected and less light is penetrating through it. When cloud gets thin, the little light will pass through it and the base of the cloud looks dark. 

The water droplets in the cloud joined together to form big water droplets. These droplets absorb more light (radiation) than they reflect (scatter). 

All the light absorbed by the large water droplets, even if any small amount of light gets through into the cloud appears dark. The dark cloud often brings rain. 

Conclusion:

Big droplets absorb more radiation than they scatter and the rain cloud appears dark.