The Fog helper lets you specify the color and range of fog in your VRML97 world. You can simulate atmospheric effects by blending objects with a color based on the objects' distances from the viewer. For the best visual results, the background (which is unaffected by the fog) should be the same color as the fog.
Specifies the distance from the viewer at which objects are totally obscured by the fog. The smaller this value is, the closer the fog is to the camera, and the less your scene is visible. The larger this value is, the more of your scene is visible to the camera. A value of 0 turns off the effect, making everything in the scene visible. A value of 0 means that there is no fog effect.