Atmospheric Fog gives an approximation of light scattering through a planetary atmosphere. This can give your outdoor levels a much more realistic look. This total effect includes the following:
The dominant directional light in your level will receive a sun disc effect in the sky. This will be placed infinitely far away, opposite the light's direction.
A sky color that will vary depending on the altitude of the sun (or put another way, how close the dominant directional light's vector gets to being parallel with the ground).
Control over scattering and decay settings, allowing for full control of your atmospheric density.
Best of all, the settings for this Actor are easy to use and quick to set up.