Effect of nonprecipitating clouds on the aerosol size distribution in the marine boundary layer



The size distribution of particles smaller than 0.5 µm has been measured over the tropical Atlantic and Pacific oceans with a differential mobility analyzer. In regions remote from continental influences the size distribution generally has peaks at about .02-.03 µm and at .08-.15 µm with a minimum in the .05-.08 µm radius range. The data provides strong evidence that nonprecipitating clouds play an important role in transferring material from the gas phase and from smaller particles into the 0.08 to .15 µm radius range, and that they are responsible for the doubly peaked size distributions frequently observed over the oceans.