Question

Explain the scattering of light and atmospheric scattering with examples.

Accepted Answer

Scattering of Light is the phenomenon of bouncing off of electromagnetic radiation by the atoms or molecules of the medium through which they are travelling. Early in the morning, when the rays of light enter our darkroom, we see particles shining in the air. The sky is blue throughout the day but reddish during sunrise and sunset. Sunlight while travelling through the earth’s atmosphere before reaching the earth’s surface gets scattered by the obstacles like atoms, molecules, dust particles, water droplets, etc. present in the atmosphere, which is responsible for various natural phenomena like the blue colour of the sky, reddish colour of the sun during sunrise and sunset, etc. In the phenomenon of scattering of light, the incident light gets absorbed by the molecules, followed by its re-radiation in different directions. Thus, due to scattering, the direction of light changes when it strikes the obstacles present in the medium through which it travels.

Atmospheric Scattering. Scattering is the process by which "small particles suspended in a medium of a different index of refraction diffuse a portion of the incident radiation in all directions." With scattering, there is no energy transformation, but a change in the spatial distribution of the energy.

Some effects of scattering in everyday life are:

(1)Red colour of the sun at sunrise and sunset.

The rays have to travel a larger part of the atmosphere during sunrise and sunset because they are very close to the horizon. Therefore, light other than red is mostly scattered away. Most of the red light, which is the least scattered, enters our eyes. Hence, the sun and the sky appear red.

(2) White colour of the sky at noon.

At noon, we know that the sun is overhead and when the sun is overhead, it has less air to travel through. We also know that scattering occurs due to dust and other suspended particles in the air. So, scattering is reduced if the distance to be travelled in the air is reduced. Therefore, the least amount of scattering occurs, resulting in the appearance of white light.

(3) Blue colour of the sky.

Gases and particles in Earth's atmosphere scatter sunlight in all directions. Blue light is scattered more than other colours because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.

(4) Red colour is used as a danger signal.

Danger signals are red because the red colour is scattered the least by air, water or dust molecules. The effect of scattering is inversely related to the fourth power of a given colour's wavelength.

Explain the scattering of light and atmospheric scattering with examples.

Important Questions on Effects of Light

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