Bae 
© C@)sad) 
° Cfd) 
cs’ 
GOETZ AND PREINING 
Fig. 9—Size spectra of natural aerosols; (a) taken from a boat anchored in Santa Barbara Harbor; 
(b) taken from a boat drifting 40 mi offshore WSW of Santa Barbara Island; (c) taken at Mt. Wilson 
Observatory A in heavy haze, B in fog; (d) taken from a boat anchored at the south shore of Catalina 
Island, A count taken immediately after sampling, B count taken after a 48-hr storage (see Table 2). 
sailing, or drifting, to avoid aerosol generation 
by the ship itself. The samples were taken about 
12 ft above the water level. 
The representative of a mountain aerosol (Fig. 
9c) was taken from the dome of the 100-inch 
telescope at Mt. Wilson Observatory. 
For field work the A.S. and its auxiliaries were 
driven by an 800-watt a. c. generator, the instru- 
ment was also equipped with a water-cooling 
system to maintain constant rotor temperature 
during the extended test periods (1 to 3 hr.). 
The analysis (micro-analyzer) was made mostly 
by repeated independent counts Z by two ob- 
servers, since the deposit density was often not 
sufficient for the photometric analysis. AZ was 
interpolated for equidistant Ad and C(d) derived 
according to (3) and (4). Figure 9c is based on 
photometer data, the distribution is plotted in 
terms of C'S’ and of C by assuming the validity 
of S’(d) derived for latex particles of equivalent 
sizes. Table 2 presents the pertinent test data. 
The size distribution of the marine aerosols at 
low wind velocity and high humidity (Fig. 9ad) 
is strikingly similar to the mountain aerosol prior 
to fog formation, it is characterized by a steep 
maximum for 0.22 uw < ds < 0.25 yw (or 0.30 
mw <d, < 0.33 uw), and by a decline of C(d) to- 
ward larger d, somewhat steeper than the cubic 
