Note the relatively uniform white haze that obscures the horizon. The haze tends to diminish slightly at higher elevations. These events tend to occur on hot and humid summer days and are affiliated with high ozone, PM2.5, and RH levels, and winds that transport pollutants from urban and industrial areas to the southwest. This is an example of a foggy day in Acadia. It appears similar to a hazy polluted day, but note how the fog tends to be more grey than the white haze and how it does not thin out near the top of the picture.
Fog is most common in the fall and spring.