The Atmospheric Effect is where the mist or haze in the air enhances the apparent depth of the subject. In this case, I took the photo looking west from the summit of Blue Mountain above Deer Park Campground in the Olympic National Park. This is the view looking into the sun. Below is the view looking south — 90 degrees from the photo above. And with a different lens, of course. But notice the lack of the atmospheric effect.
The AE really makes a photograph more beautiful! Interesting.