It is the purpose of this investigation to study the physics and chemistry of very small atmospheric particles called Aitken particles. The study has three parts: 1) to develop a climatology of aerosols, that is to determine how the aerosol size distribution and number concentration varies with the origin of the air mass being studied; 2) to attempt to confirm the essential features of a model developed by the proposer called "The Cloud Erosion Model". This model predicts very definite changes in the size distribution and number concentration of aerosol as a function of the history of the airmass; 3) to study the possible production of aerosols by photochemistry in the clean arctic air.
