What a difference...when it comes to the view in The Smokies.  Here are 2 webcam shots from the Look Rock webcam on The Foothills Parkway, a part of the GSMNP:
                                  http://www.nature.nps.gov/air/webcams/parks/grsmcam/grsmcam.cfm

                                                   July 1...visibility less than 25 miles

                                            January 6...visibility less than 129 miles

from: http://www.nps.gov/grsm/naturescience/air-quality.htm
Shrinking ViewsViews from scenic overlooks at Great Smoky Mountains National Park have been seriously degraded over the last 50 years by human-made pollution. Since 1948, based on regional airport records, average visibility in the southern Appalachians has decreased 40% in winter and 80% in summer.
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The Smokies got their name from the blue haze that hangs over the mountains, mostly from evaporation of moisture from the intense plant life.  Or, as explaned on:
\http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/air/blue.rxml

"As tiny hydrocarbon particles released by vegetation chemically react with ozone molecules, they produce particles that selectively scatter blue light, giving the mountains their blue appearance. "