<p>View of the nephelometer, a gray machine with wires and a white cylinder, from below.</p>
<p>This instrument, called a nephelometer, measures light scattering in real-time. These data provide a precise measurement of how air pollution affects what you can see every minute of the day! The National Park Service uses this information to help make decisions about how to preserve the beautiful views in parks. Similar instruments are used at airports to ensure that pilots can fly safely. The visibility distances (visual ranges) shown on the Shenandoah National Park webcam webpage and live data webpage are calculated using nephelometer data.</p>
Mary O'Neill
Taken on 31 July 2018
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