Effects of cloud and humidity on atmospheric extinction coefficient derived from visual range observations in Iranian major airports

2016 ◽  
Vol 37 (3) ◽  
pp. 1474-1482
Author(s):  
Samaneh Sabetghadam ◽  
Masoud Khoshsima ◽  
Farhang Ahmadi-Givi
Keyword(s):  
Extinction Coefficient ◽  
Atmospheric Extinction ◽  
Visual Range

Comparison of the aerosol index from satellites and the atmospheric extinction coefficient above the Canarian Observatories

2004 ◽  
Author(s):  
Antonia M. Varela ◽  
Jesus J. Fuensalida ◽  
Casiana Munoz-Tunon ◽  
Jose M. Rodriguez Espinosa ◽  
Begona M. Garcia-Lorenzo ◽  
...  
Keyword(s):  
Extinction Coefficient ◽  
Atmospheric Extinction ◽  
Aerosol Index

scholarly journals Light Scattering and Particle Aggregation in Snow-Storms

1966 ◽  
Vol 6 (44) ◽  
pp. 237-248 ◽  
Author(s):  
Malcolm Mellor
Keyword(s):  
Extinction Coefficient ◽  
Mass Density ◽  
Ground Level ◽  
Particle Aggregation ◽  
Snow Density ◽  
Visible Radiation ◽  
Topographic Features ◽  
True Value ◽  
Snow Storms ◽  
Visual Range

Abstract Attenuation of visible radiation by falling snow was studied by a method based on brightness contrast between topographic features and the adjacent sky. Extinction coefficient and visual range are related to bulk snow density, and are compared with data for Antarctic blizzards. Since attenuation depends more on the size and concentration of discrete particles than on the mass density of suspended snow, the process of particle aggregation and snow-flake formation during fall is considered by collision theory, and an expression describing aggregation effects is developed. This offers an explanation for the relative constancy of particle concentration observed at ground level during snowfalls of varying intensity. Since there is no strong justification for relating extinction coefficient to snow density, an empirical correlation between extinction coefficient and precipitation rate is given for practical use. It is shown that visual range estimated by eye in hilly terrain may be less than the true value, since sky brightness is locally reduced over broad hill-tops with low albedo.

scholarly journals Light Scattering and Particle Aggregation in Snow-Storms

1966 ◽  
Vol 6 (44) ◽  
pp. 237-248 ◽  
Author(s):  
Malcolm Mellor
Keyword(s):  
Extinction Coefficient ◽  
Mass Density ◽  
Ground Level ◽  
Particle Aggregation ◽  
Snow Density ◽  
Visible Radiation ◽  
Topographic Features ◽  
True Value ◽  
Snow Storms ◽  
Visual Range

AbstractAttenuation of visible radiation by falling snow was studied by a method based on brightness contrast between topographic features and the adjacent sky. Extinction coefficient and visual range are related to bulk snow density, and are compared with data for Antarctic blizzards. Since attenuation depends more on the size and concentration of discrete particles than on the mass density of suspended snow, the process of particle aggregation and snow-flake formation during fall is considered by collision theory, and an expression describing aggregation effects is developed. This offers an explanation for the relative constancy of particle concentration observed at ground level during snowfalls of varying intensity. Since there is no strong justification for relating extinction coefficient to snow density, an empirical correlation between extinction coefficient and precipitation rate is given for practical use. It is shown that visual range estimated by eye in hilly terrain may be less than the true value, since sky brightness is locally reduced over broad hill-tops with low albedo.

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