Answer:


The upper layer of atmosphere contains very fine particles fo water vapours and gases. These particles are more effective in scattered of light of shorter wavelength mainly blue than larger wavelength. So, the sky appears blue.

Why does the color of the sky appear blue on a clear day?

The color of the sky appears blue on a clear day due to a phenomenon called Rayleigh scattering. This occurs when the Earth's atmosphere scatters the sunlight in all directions, but the shorter blue and violet wavelengths are scattered more than the longer red and orange wavelengths.

Explanation:

Rayleigh Scattering:
Rayleigh scattering is the scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. In the Earth's atmosphere, tiny molecules such as nitrogen and oxygen scatter short-wavelength light, like blue and violet, more effectively than long-wavelength light, like red and orange.

Scattering of Shorter Wavelengths:
When sunlight reaches the Earth's atmosphere, the short-wavelength blue and violet light is scattered in all directions by the molecules in the air. This scattering is more evident when the sun is overhead or at a higher angle, which is why the sky often appears bluest around midday.

Red and Orange Light:
On the other hand, the longer-wavelength red and orange light is not scattered as much and tends to pass straight through the atmosphere or get absorbed by other particles. This is why the sun appears redder during sunrise and sunset when its light has to pass through a thicker portion of the atmosphere, resulting in more scattering of the shorter wavelengths.

Perception of Blue Sky:
Our eyes are more sensitive to blue light, so when we look up at the sky, we primarily perceive the scattered blue light, giving the sky its blue appearance on a clear day.

Other Factors:
It is important to note that the color of the sky can vary depending on other factors such as atmospheric conditions, pollution, and the presence of dust or other particles in the air. These factors can alter the scattering process, resulting in variations in the perceived color of the sky.

In conclusion, the color of the sky appears blue on a clear day due to Rayleigh scattering, where the shorter blue and violet wavelengths are scattered more by the Earth's atmosphere compared to the longer red and orange wavelengths. This scattering phenomenon, along with the sensitivity of our eyes to blue light, contributes to the perception of a blue sky.