310 



WOODCOCK 



[chap. 6 



of bubbles introduced by snow or rain storms upon aerosol populations have 

 not been adequately measured.) 



It is clear from Fig. 7, assuming an equilibrium or steady-state condition, 

 that the number of the larger airborne particles is more affected by altered 

 wind force than is the number of the smaller. Note, for instance, that a change in 

 wind from force 3 to 7 causes an increase of 30 times in the number of 10~9 g 

 particles, while the 10~ii g particles are increased by 3 times. The detailed 

 physical factors producing this result are not known. It is supposed that 

 stronger winds produce more large bubbles in the sea, consequently, more large 

 particles in the lower air, and that these particles are more likely to mix up to 

 cloud-base altitudes by the added turbulence associated with these winds. 



25001 I 



5 10 15 20 25 



SEA-SALT IN AIR (lO'^gm"') 



Fig. 8. Average total weight of sea-salt particles as a function of altitude and wind force. 

 All measurements made in marine air but in widely separated geographical locations. 



The author has determined the weights of airborne sea-salt among several 

 hundreds of samples taken over the seas at different geographical locations, 

 times, altitudes and surface winds. These observations are summarized on 

 Fig. 8 in a way which shows the average variability of the sea-salt load of 

 marine air as a function of altitude and wind force. The integrated amounts at 

 the various levels and surface-wind conditions were derived and are expressed 

 in the table on Fig. 8, as grams per square meter of surface. 



It should be pointed out that all of the samples represented in Fig. 8 were 

 taken in marine air which had passed over many hundreds and, most often, 

 thousands of kilometers of sea surface. Ample time for an extensive exchange 

 of properties was available, though it is uncertain to what extent an equilibrium 



