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Five years of turbidity measurements from a network of stations in the United States are analyzed. Measurements are made with the Volz sunphotometer; the instrumentits calibration, and its use are described. The relationship of these measurements to those of Linke and Ångström is briefly discussed. Analysis of the data indicates the following: 1) an annual mean pattern of low turbidity (near 0.05) over the western plains and Rocky Mountains and high turbidity (near 0.14) in the east; 2) observed minimum turbidity near 0.02; 3) an annual cycle of low turbidity in winter and high in summer; 4) lowest turbidity in continental polar air masses and highest in maritime tropical; and 5) no noticeable lowering of turbidity following precipitation.
Flowers et al. (Mon,) studied this question.