July 30, 2005
US Forest Service: Air Quality Images
Causes of Visibility Impairment
Typical visual range in the western United States is 60 to 90 miles, or about one-half of what it would be without manmade air pollution. In the East, the typical visual range is 15 to 30 miles, or about one-third of the visual range under natural conditions.
Haze is caused by tiny particles that scatter and absorb light before it reaches an observer. As the number of particles increases, more light is absorbed and scattered, resulting in less clarity, color, and visual range.
Five types of particles contribute to haze: sulfates, nitrates, organic carbon, elemental carbon, and crustal material.
article or Introduction to Visibility pdf [Air Resource Managment]
USDA Forest Service Air Quality Images Site Map
More comparison images
from Shining Rock Wilderness (Eastern US)
~You don't need to be reminded that the images above are of relatively pristine areas. Some of these places are hundreds of miles from urban industrial centers.
My childhood memories sparkle for good reason. Visibilty everywhere has gotten shittier in just the past twenty years!
Posted by Cieciel at July 30, 2005 04:58 AM