References: References:

• http://vista.cira.colostate.edu/improve/

• Acidic Deposition:State of Science and Technology (report 24) 1990 Visibility: Existing and Historical Conditions – Causes and Effects• Introduction to Visibility (WC Malm) issn 0737-5352-40 (CIRA-CSU)

What is Visibility?

Historically visibility was thought of in terms of the furthest distance one could see a large black object.

From a scenic vista perspective, there’s more interest in color, line, texture, and form of a scenic landscape feature.

How far can you see?

Great Smoky MountainsNational Park

Yosemite National Park

Glacier National Park

Canyonlands National Park

Big Bend National Park

Layered Hazes

Layered Hazes

The Seeing of a Landscape Feature

Relationship Between Aerosols and Optical Properties

The extinction coefficient is made up of

particle and gas scattering and absorption:

where s, a, g, and p refer to scattering, absorption, gases, and particles, respectively.

ext sg ag sp apb = b +b +b +b

Extinction =

Scattering Efficiency (Q)

Single Particle Efficiency

Particle Size Distribution

Scattering Efficiency as Function of Size

Carbon Extinction Efficiency

Phase Function for Soil and Sulfate

Phase Function for Carbon

Forward and Backward Scattering

On the Nature of Light

Wave-like characteristics of light Electromagnetic radiation Photons and color Why objects are colored Atmospheric optical effects

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