Rayleigh scattering is the scattering of electromagnetic radiation by particles much smaller than the wavelength of the radiation. In the case of sunlight, these particles are primarily nitrogen and oxygen molecules in the atmosphere.
Here's how it works:
* Sunlight: Sunlight is composed of all colors of the visible spectrum.
* Scattering: When sunlight enters the atmosphere, it encounters air molecules. These molecules scatter the light in all directions.
* Wavelength Dependence: Blue light has a shorter wavelength than red light. Shorter wavelengths are scattered more effectively by air molecules.
* Horizon Effect: When you look towards the horizon, sunlight has to travel through a much thicker layer of atmosphere compared to looking directly overhead. This means more scattering occurs.
* Blue Scattered Away: As blue light is scattered more, it gets scattered away from your line of sight.
* Remaining Colors: The remaining colors in the sunlight, which are mostly reds, oranges, and yellows, are less scattered and reach your eyes, making the sky appear whiter or slightly yellowish near the horizon.
In summary: The whiter appearance of the sky towards the horizon is due to the increased scattering of blue light by air molecules over longer distances. This results in a higher concentration of red, orange, and yellow light reaching your eyes, giving the sky a whitish hue.
