National Parks in the History of Science: Visibility

For most of us, visibility is a subjective sense of how far and how well we can see across a landscape. And it really matters to most park visitors! After all, we want to see these beautiful places. But is there a way to measure visibility in a scientific way, with accuracy and precision? Some atmospheric physicists started figuring that out in the 1970s in the Grand Canyon. They succeeded, and today their methods allow governments worldwide to monitor visibility and enact policies to improve it by reducing air pollution.
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