We nade observations of the atmospheric nuclei at the sea coast near Sendai and found that these nuclei contain sea-salt and that their size distribution is expressed by the simple formula
n0r03=
C, where
n0Δ
r0 is the number of sea-salt nuclei which are contained in 1cc of the atmosphere and whose radii range from(
r0-Δ
r0/2) to (
r0+Δ
r0/2) and
C is expressed by
C=2.2
W×10
2, where
W is the amount of sea-salt in 1cc of the atmosphere.
The variation of the relative humidity
H in equilibrium with the sea-salt srop is wxpressed by the empirical formula
H=1-0.52
c, where
c is the ratio of the weight of dissolved sea-salt to that of water in the sea-salt drop.
By using the above two formulae we obtained a new formula expressing the opacity Χ in terms of relative humidity over the sea surface except near the industrial area. This formula is given by
whrer Χ
p is the opacity due to non-hygroscopic particles, ρ
0 the density of sea-salt and
A is a numerical factor (about 9.5) depending on the wave length of light.
Furthermore it was found that by inserting reasonable values for
C and χ
p the result of observation at Valentia can be explained well by the above formula.
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