Final answer:
White sunlight appears yellow from Earth due to the scattering of blue light by the atmosphere. This scattering, more efficient for shorter wavelengths, removes some blue from sunlight, making it look yellower. Dispersion also separates white light into a spectrum as seen in rainbows.
Step-by-step explanation:
White sunlight appears yellowish when observed from the Earth's surface due to the scattering of certain wavelengths of light caused by the Earth's atmosphere. The blue and violet light are scattered more efficiently due to their shorter wavelengths, as they interact with the small molecules of air in our atmosphere. This scattering of blue light is also what makes the sky appear blue. As this blue light is scattered in all directions, less of it reaches our eyes directly from the sun. Consequently, the sunlight that reaches a direct line of sight has proportionally more of the longer wavelengths, which are reds and yellows, making the sun appear somewhat yellowish. The phenomenon responsible for this selective scattering of light by wavelength is known as Rayleigh scattering.
Furthermore, the concept of dispersion is demonstrated by the separation of white light into its full spectrum of colors, which occurs when light passes through a medium like a prism or raindrop and is refracted at different angles based on its wavelength. This process can be seen in nature in the form of a rainbow. The light is spread out into its component colors, with violet being refracted more than red, ultimately displaying the full range of visible light colors.