Correlation of precipitable water vapour values over the United States with physical and chemical parameters Part I: Seasonal trends with precipitation and its nitrate content. Geographic changes of nitrate

Summary The analysis ofReitan's data on precipitable water vapour in the atmosphere, and data ofJunge on the nitrate content of precipitation, is extended onto a seasonal basis. Computations indicate consistency between precipitable water vapour, precipitation and its nitrate content, within a semiemprical law proposed, and especially for the warmer trimestres of the period July 1956–June 1957. A simple expression correlating the atmospheric content of precipitable water vapour over stations situated between sea level and 580 ft of altitude, with temperature, is suggested and tested. Increasing trends of atmospheric nitrate with latitude are established for all seasons of the period examined.Contribution of the Centro Nucleazione Aerosoli of the National Research Council of Italy, Via Vettore 4 (Monte Sacro),Rome.