Environment Object
Use the Environment object to define several global scene parameters such as the scene's environment light (also known as ambient lighting).
By default, only the topmost Environment object in the hierarchy will be rendered. If you want to change the environment during an animation, use the Stage object with a parameter track.
You can use the Environment object with volumetric shaders. Plugins or the optional PyroCluster can be used in this way to create effects such as smoke and fog. Simply apply the shader to the Environment object as a texture.