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On the physics of dusty atmospheres
Author(s) -
ElFandy M. G.
Publication year - 1953
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49707934010
Subject(s) - haze , visibility , particle (ecology) , attenuation , turbidity , atmosphere (unit) , particle size , attenuation coefficient , aerosol , physics , particle number , atmospheric sciences , environmental science , optics , meteorology , chemistry , geology , thermodynamics , oceanography , volume (thermodynamics)
Abstract Measurements of particle size and concentration of atmospheric dust have been made at Alexandria in various degrees of turbidity. Except for ‘dust haze,’ reasonable agreement is obtained between the measurements and Koschmieder's equation for visibility in terms of optical attenuation. In ‘duststorms’ the required attenuation implies a scatter coefficient per particle 8/3 times the cross‐sectional area of the particles, while in occasions of ‘dust’ the scatter coefficient implied per particle is 4 times the cross‐sectional area of the particles. The results are as follows: tbl1Dusty atmosphere Visibility (m) Average concentration (cm −3 ) Average particle diameter (μ) 90% of particles have diameter ≤ (μ) Scatter coefficient per particle/cross‐sectional area of particlesDust haze 5,000–6,000 200 0.5 1.3Dust 2,000–2,500 330 1.3 2.0 4 Duststorm 750–1,000 550 2.0 3.5 8/3