The sky appears blue due to:

The sky appears blue because of a phenomenon known as **Rayleigh Scattering**. 1. **Nature of Sunlight**: Sunlight is composed of a spectrum of colors (red, orange, yellow, green, blue, indigo, and violet). Each color has a different wavelength. 2. **The Wavelength Relationship**: According to Rayleigh's law of scattering, the intensity of scattered light ($I$) is inversely proportional to the fourth power of its wavelength ($\lambda$): $$I \propto \frac{1}{\lambda^4}$$ 3. **Scattering Process**: When sunlight enters the Earth's atmosphere, it interacts with gas molecules and small particles. Because blue light has a much shorter wavelength than red light, it is scattered much more efficiently (about 10 times more) in all directions. 4. **Perception**: While violet light has an even shorter wavelength than blue light, the sky appears blue because the Sun emits more blue light than violet, and the human eye is more sensitive to blue. Therefore, when we look at the sky, we see the scattered blue light coming from every direction.