Rayleigh scattering occurs when light interacts with particles in the atmosphere that are much smaller than the wavelength of the light. These particles can include molecules such as nitrogen and oxygen, as well as tiny dust and water droplets. When light encounters these particles, it gets scattered in all directions.

It is most noticeable during daytime when the sky appears blue due to the scattering of shorter blue wavelengths of sunlight. Additionally, Rayleigh scattering also occurs during sunrise and sunset, contributing to the vibrant colors seen during these times as sunlight passes through more of the Earth's atmosphere, scattering shorter wavelengths and allowing longer wavelengths to dominate the sky's colors.

The amount of scattering depends on the wavelength of the light. Shorter wavelengths, such as blue and violet light, are scattered more effectively than longer wavelengths like red and orange light. This is because shorter wavelengths interact more strongly with the particles due to their higher energy.

The phenomenon of Rayleigh scattering not only explains the color of the sky but also affects various optical phenomena, such as the colors of clouds, the appearance of stars, and the blue color of water bodies like the ocean.