Ambient Trigger
The Ambient Trigger is a component. It is very similar to an Ambient Manager in that it defines the color of lights and shadows, but in specific areas rather than the level's global environment lighting.
Pick the Light and Shadow colors in the inspector using the color picker.
The Transition Duration field specifies how long it takes for the level's lighting to change when you enter the trigger, in seconds, while the Revert Transition Duration field specifies how long it takes to revert back to the default level's lighting once you leave the trigger.