308 



WOODCOCK 



[chap. 6 



sea-salt particles resting upon sampling surfaces. They are shown as crystalline 



masses at low relative humidity and as hemispheric droplets at higher humidity. 



Through the use of the above physical and physical-chemical methods, the 



weights and the numbers of these particles in marine atmospheres have been 



Reluiive humidity 91% 



V 



i i 



zom 



Q^ Relative humidity 42% 



Fig. 4. Photomicrographs of sea-salt 

 deposited on glass sampHng sur- 

 faces which had been exposed 

 to marine air about 5 m above 

 the sea surface. Pictures selected 

 to show some of the largest of 

 the particles, as wet crystalline 

 masses at low relative humidity 

 and as entirely liquid hemi- 

 spheric droplets at high humid- 

 ity. 



SEA-SALT PARTICLE WEIGHTS (IQ-'^ g) 

 10° 10' 10^ 10' 10^ 



10 u I I I I M il 



GD 10 



-nri 1 M ill! 



SEA-SALT 

 |19 m-' 



2.4 5.1 11.0 23.7 



PARTICLE RADIUS AT 99% R.H. 



(fi) 



Fig. 5. Typical distribution curves for sea-salt 

 particles from various altitudes in Hawaii. 

 Air conditionally unstable. Similar distribu- 

 tion patterns are found in marine air of 

 Australia, New England (U.S.A.), Bermuda, 

 the Lesser Antillean Islands and Florida. 



determined at various altitudes, positions and surface-wind speeds. The range 

 of weights found largely corresponds to that produced by the jets which arise 

 from bursting bubbles equal in size to those found in breaking waves in sea- 

 water (Blan chard and Woodcock, 1957). 



