NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 16 Light Trespass Light trespass4 is illumination of an area where the illumination is not wanted or needed. A familiar example is a light in the neighbor’s yard shining into bedrooms of a neighboring property. The light is not intended to illuminate the interior of houses on adjacent properties and is neither needed nor wanted by the affected homeowners. A less obvious example is the sight of distant flashing lights on communication towers or wind farms or operating lights on industrial facilities, visible to recreationists in a naturally dark environment within a wilderness viewshed. While such lights have important safety functions, they are not intended to illuminate the wilderness area and are neither needed nor wanted by the viewers within the wilderness. While they would not necessarily be considered obtrusive in a typical city environment with numerous visible lights, they may be very noticeable in the context of BLM-managed lands, where there are typically far fewer visible lights. Light Clutter Light clutter refers to excessive groupings of lights, such as are seen in typical urban environments where there are large numbers of lights of different types. Light clutter may be distracting, confusing, aesthetically impacting, and may contribute to skyglow, light trespass, and glare. Over-Illumination Over-illumination refers to the use of lighting intensity higher than that which is appropriate for a specific activity. An example would be a very brightly lit parking lot where the illumination is far greater than that needed to safely park, locate one’s vehicle, and walk. Over-illumination often contributes to the other types of light pollution previously described and also has economic effects because of wasted light (energy consumed that achieves no useful purpose). Ways that light pollution may affect humans are described in Sections 3.2 and 3.3. Ways that light pollution may affect ecological systems are described in Sections 3.4 and 3.5. 4 The term “light trespass” may have a legal definition in various jurisdictions that includes specific requirements (e.g., thresholds for illumination levels occurring a certain distance from a property line). In this technical note, the term light trespass is a type of light pollution in which light is cast where it is not wanted or needed. Unshielded lighting at this electrical substation in Nevada is a major source of light trespass and glare into the surrounding desert. Light clutter is common in urban environments. Chris Dickens Much of this scene is over-illuminated.
RkJQdWJsaXNoZXIy NTkzMzk=