SECT. 2] 



SOLUBLES 



307 



Fig. 3 it is seen that droplets ranging from about 5 [j, to 100 (j. radius are pro- 

 duced. These droplets have fall speeds of 0.4 to 80 cm sec-i. Some of them 

 evaporate almost completely, leaving crystalline sea-salt residues immersed in 

 the atmosphere. Other droplets remain in the air a relatively short time, only 

 partially evaporating before falling back into the sea. 



In addition to the water and dissolved salts, Blanchard (1958) has shown 

 that these droplets carry an electric charge into the air. Organic detritus and 

 surface-film materials are also occasionally observed and it is suspected that 

 living organisms in the form of bacteria or viruses may also become airborne 

 in the droplets (Woodcock, 1955 ; Zobell, 1942). 



1000 2000 



DIAMETER OF BUBBLES (|i 



Fig. 3. The size and salt content of droplets ejected by bubbles of various diameters 

 bursting in sea-water. 



We are concerned here, however, with the solubles only. Among the particle 

 sizes represented in Fig. 3, these solubles have been shown to be almost entirely 

 "sea spray" salts. For instance Junge (1955, 1957) separated the marine 

 aerosol particles ^ 0.8 [j, radius from those smaller. He found that the ratios of 

 the chloride to the sulfate and chloride to sodium among these "giant" nuclei 

 were nearly the same as those found in sea-water. He concluded that these 

 nuclei are largely sea-salt. Twomey (1954) and Woodcock and GifiFord (1949) 

 reached the same conclusion ; the former from a study of the chloride and 

 phase transition point of individual particles, and the latter from the applica- 

 tion of isopiestic and micro-titration methods to the analysis of many particles 

 sampled by impingement. Fig. 4 shows photomicrographs of atmospheric 



