Directional lights

The directional lights simulate a far light source, such as the sun. These lights have an apparent radius though, so you can have soft shadows.

Because they are placed at infinity, distant lights don't have a Decay and the illumination of a point is not dependent from their distance to the light.

A Library/Lights/DistantLight and a Library/Lights/DistantSpotLight (using a tube gizmo).

Our sun has an apparent angle between 0.5 and 1, depending on its elevation.