PRODUCTIVENESS OF FOG PRECIPITATION 
30 
© | mM! g/mh 
Se} 
W= 0,20 g/m? 
J =20 0 
20 
111 
6 8 lo 
v m/sec 
Fic. 2—Dependence of the amount of water deposit M’ on the wind- 
velocity v, for various wire diameters at a cloud-droplet diameter of 20 
lation of fog droplet collection to possible amount 
in clouds is obtained when the diameter of the 
wire is a minimum. The condition of constant 
relation of deposit amount to wind velocity is 
nearly attained with wire-diameters of 0.1 mm 
(German pattern) and 0.12 mm (Japan pat- 
tern) (Fig. 2). 
Factors influencing the amount of deposit— 
The amount of deposited fog precipitation, aside 
from the efficiency of the wire system, depends 
on (1) the locality and exposure of the gage, and 
(2) the weather situation. The locality factor is 
specified by the height above sea-level, the con- 
tinentality (distance from sea), and the exposure 
to the fog-producing air currents, especially on 
windward slopes. These effects are demonstrated 
for several mountains of Germany in Figure 3 
[Grunow, 1958]. The measurements on Table 
Mountain (Tfb) South Africa, very critically 
evaluated by Nagel [1956], showed rainfall of 
1940 mm and additional fog precipitation amount 
of nearly 3300 mm in 1954. The fog precipitation 
was 170% of the rainfall. 
Increasing amounts of fog precipitation are 
dependent on the weather situation. It is not only 
the direction and velocity of the depositing air 
current, but also the origin of the operating air 
mass, which influences the production of fog 
precipitation. The heaviest deposits occur where 
maritime warm air-masses from temperate or 
