When forecasters talk about visibility, what do they mean? What’s visible?
Officially, visibility is a measure of how opaque the atmosphere is. When forecasters report on visibility, they are talking about the greatest distance from which prominent objects can be seen with normal eyesight. The National Weather Service uses different visibility “checkpoints” — observing from the surface, observing from the weather station, observing in a certain direction, and observing from an airport traffic control tower.