From the viewpoint of the sender, scattering randomizes light by reflecting it in myriad directions. From the standpoint of the viewer, it randomizes light by combining light from many sources. Several scattering mechanisms are evident in this sunset scene. On the average, skylight is singly scattered, that is, only scattered once. The scattering particles are tiny enough to scatter short wavelengths more than long.
Blue light is scattered more than red, making light scattered from the sky blue.
When the path length through the atmosphere is long, as at sunset, everything but red is scattered and only red light reaches our eyes, making the sun red. The rays radiating from the sun, called crepuscular rays, are due to larger particles in the air causing a certain amount of multiple scattering as well. The few clouds are dark at this viewing angle because they scatter incident sunlight, allowing little to penetrate the clouds, although thin parts of the clouds transmit light and appear bright. The one color that is almost always associated with a specific mechanism is white. The white of clouds is due to multiple scattering off water droplets or ice crystals.