The sky appears blue primarily due to a phenomenon called Rayleigh scattering. Here’s how it works:

Sunlight Composition: Sunlight, or white light, is made up of different colors, each with varying wavelengths. Blue light has a shorter wavelength, while red light has a longer wavelength.

Atmosphere Interaction: As sunlight passes through the Earth’s atmosphere, it interacts with molecules and small particles in the air. Because blue light is scattered in all directions more than other colors due to its shorter wavelength, it becomes the dominant color we see when we look up.

Angle of the Sun: The scattering effect is more pronounced when the sun is higher in the sky, which is why the sky appears bluer during midday. During sunrise and sunset, the sunlight passes through a thicker layer of the atmosphere, scattering the shorter blue wavelengths and allowing the longer red and orange wavelengths to dominate, resulting in beautiful sunset colors.

In summary, the blue appearance of the sky is due to the scattering of sunlight by the atmosphere, with blue light being scattered more than other colors.