When the sunlight reach the earth atmosphere .it is scattered in all direction by the gaseous molecular and other fine particles present in the air because of the shorter wavelength the blue colour is scattered more strongly than the other colour .this is why, the colour of sky appearance blue.

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Why is the color of the clear sky blue?
The color of the clear sky is predominantly blue due to a phenomenon known as Rayleigh scattering. This occurs when sunlight enters Earth's atmosphere and interacts with molecules and particles in the air. Here's a detailed explanation:

Rayleigh Scattering:
- When sunlight reaches Earth, it is composed of different colors of light, each with a different wavelength.
- Shorter wavelengths, such as blue and violet light, are scattered more easily by the gases and particles in the atmosphere compared to longer wavelengths like red and orange light.
- Blue light has a shorter wavelength and is scattered in all directions by the molecules in the air, while red light, with its longer wavelength, is less affected and continues on a more direct path.

Why Blue?
- The blue light scattered by the atmosphere is what we see when we look up at the sky during the day.
- The large concentration of nitrogen and oxygen molecules in the Earth's atmosphere is particularly effective at scattering blue light, giving the sky its blue appearance.
- This scattering effect is also why the sky can appear red or orange during sunrise and sunset when the sunlight has to pass through more of the atmosphere, scattering out the shorter blue wavelengths.
In conclusion, the color of the clear sky is predominantly blue due to the scattering of shorter wavelengths of light by the molecules in Earth's atmosphere. This phenomenon, known as Rayleigh scattering, is responsible for the beautiful blue hue we see above us on a clear day.