Final answer:
Scattering occurs when particles and gases in the atmosphere disperse light in all directions, being the correct answer for the described phenomenon, not reflection, refraction, or dispersion.
Step-by-step explanation:
The phenomenon being described when particles and gases in the atmosphere disperse light in all directions is called scattering. This process causes the sky to appear blue during the day and contributes to the red and orange hues of sunrise and sunset. While reflection is light bouncing directly off surfaces and refraction is the bending of light as it passes through different mediums, scattering involves the random dispersion of light waves by particles and molecules in the atmosphere. Dispersion is related, as it refers to the separation of white light into its constituent colors, a phenomenon beautifully evident in rainbows.