NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 22 3.3.3 Astronomical and Scientific Effects Skyglow has profound effects on amateur and professional astronomy. It makes dim celestial objects difficult or impossible to see. It also makes long-exposure astrophotography of faint celestial objects difficult because the overall sky brightness causes overexposure (ADSA 2016). Light pollution interferes with spectroscopy, an important astronomical tool that is used for identifying the chemical composition, temperature, and distance of celestial objects. Artificial light masks the spectral lines of celestial objects of interest, with white or bluish light causing much greater problems. As a result, astronomers encourage the use of sodium vapor lamps, as they interfere less with spectroscopy (Kornreich 2015). The advent of light-emitting diode (LED) lighting posed a particular problem for astronomers since the first economically viable outdoor lighting applications used broad spectrum light with high correlated color temperature (CCT). Now, warmer color LEDs (i.e., light sources with lower CCTs) are increasingly being used, which is helpful. Unfortunately, because LED lighting is much cheaper than other forms of lighting, and because many people assume that more lighting is better lighting, the overall trend is an increase in lighting use that continues to cause an increase in brightness of night skies worldwide (Kyba et al. 2017). 3.3.4 Nuisance Effects Light trespass that involves bright lighting at short distances from the viewer can constitute a nuisance effect. Similarly, the visibility of more distant lighting at night has been identified as a nuisance effect of wind energy and other projects, including those located on BLM-managed lands (Sullivan et al. 2012) and elsewhere (Hardy and Eller 2017; van der Zee 2016). The flashing lights of wind turbines have been identified as a nuisance in lawsuits against wind projects (McEowen 2011) and were found to cause stress reactions in research subjects based on annoyance (Michauda et al. 2016). Greenhouse production of marijuana in California has been identified as a source of light pollution and is prominently visible from BLM-managed lands (Wick 2019; Rich et al. 2020). At night, perception of glare depends on the level of dark adaptation of the eyes. Even lights that are not extremely bright can cause glare in very dark environments. Glare can create visual discomfort or temporary visual impairment caused by excessive and uncontrolled light source brightness. Glare can interfere with the ability to view and enjoy the night sky and the ability to perform tasks because of visual discomfort or temporary visual impairment. Griffith Observatory Skyglow has seriously impacted professional astronomy at many observatories as seen at the Griffith Observatory in Los Angles, California. Light from marijuana greenhouses in California, as seen from BLM-managed lands. Glaring banks of light, such as stadium lights, may cause visual discomfort or temporary visual impairment when in direct view.
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