Abstract
The concentrations of hygroscopic and non-hygroscopic aerosols in large and giant size ranges were measured at Delhi in different periods during 1960–62. The content of ice-forming aerosols also was estimated simultaneously for brief periods. Observations made during the monsoon season showed marked variations in the content of hygroscopic particulate matter during the day. The content of non-hygroscopic component also showed significant variation from one day to another. The average level of the hygroscopic component is found to rise conspicuously with the amount of rainfall received, while that of the non-hygroscopic component is seen to decrease. Parallel measurements on hygroscopic and ice-forming nuclei suggest that some of the hygroscopic aerosols of oceanic origin might possess ice-nucleating properties.
