-15is sero.
Mr. Stanley Greenfield of the Rand Corporation -has
enalyzed another nechanism of precipitationscavefgings
his
is an agglomeration process whereby the agitation of ths small
particle results in a probability of eitiiest« imact on the
water elerent,
The scavenging efficiency is shown in the final
figure as the orcinate with the particle size as the abscissa,
It is seen t atto the.right, with large particles, ths efficiency
is high as/for perticles szaller than 0.1 microns, although for
different reasons, In between, there is a "window" in which
the rezovel by rain may be expected to be low. It ig presumd
that the delayed fallout is associated with particles below 0.1
microns, end therefore readily scavenged.
Tks celzyed fallout, according to this hypothesis, should be
renoved by rain from the atmosphere largely at the level of the —
water cloud since the felling raindrop may not have enough time to
However, actvwal conparison between Strontiuz-90
allow agglomoration.
content of rain and in ths air suggests that a very thick layer of
air most have had its particles scavenged.
i
This suggests that by a
mechanism, still not understood, even the felling croplet is capable
of scavenging the particles of delayed fallout.
To this, one may add yet another bit of evidence which fails
to fit into a sinmle picture, Although Antofagasta with ite ay
weather apparently contains He Strontiu-90, the correlation between
rainfall and delayed fallout is poor either when ons considers ths
totel amount of rzin or the mueber of days with rain.
‘Thus, Paris,
& vet place, shows only helf as much Strontiuc-70 in the soil as
Goes Tamascas, Syria, a cry region.
Tt 4s hoped thet further research on rainfall in relation to
Strontiun-90 content will explain the mucerous discrepancies that
appezr to be present.
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