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uniformly —I have not done a quantitative calculation on this point —I
would judge that two or three times more debris disappears from the
layer between 70,000 and 100,000 ft than could be accommodatedin the
region above 100,000 ft while still giving concentrations there that are
lower than those observed at 100,000 ft, but this figure is a guess.
FROM THE FLOOR: Your illustrations showed values only for
°Sr, Have you calculated the values for other nuclides?
FEELY: We also have calculated stratospheric burdens for “Mn,
Fe, Sb, and '’Rh, I do not have all the data with me. We have mea-
sured ®y and artificial ?2Na and do intend to calculate burdens for
them.
WHITBY: I would like to ask Dr. Owe Berg if he has done any experiments in his drop-coalescence work on the time that it takes the
surface of a drop to reach the equilibrium state? There are some data
that
I
have
seen
and
heard
about which indicate that very freshly
formed drops always tend to coalesce. The thought occurs to me that
perhaps the time required for the surface to reach equilibrium is
affected by trace amounts of surface-active material that might be
present in the drops. Perhaps this would explain the somewhat contradictory data from different investigators. Do you have any comment?
OWE BERG: To my knowledge, very little work has been done on
the new surfaces of liquids. However, a great deal has been done on
new surfaces of solids.
Concerning the effect of a new liquid surface upon the coalescence
of drops, the experiments that you refer to have to be conducted under
controlled conditions of charge on the drops to give information on the
effect of the new surface. I don’t think that it takes any time at all for
the surface tension to become established. The equilibrium within the
drop would be established very rapidly apart, of course, from the
hydrodynamic vibrations of the drop.
On the other hand, the equilibrium between the water in the drop
and the atmosphere around the drop may very well take some time,
particularly at very, very low pressures. I would think, however, that
at ordinary pressures in the ambient atmosphere the aging of the water
surface would be fairly rapid.
SALTER: To clear up a point on the drop-off of the debris at
70,000 ft, I would like to point out that the *Mn concentrations in early
1962 at 60,000 and 90,000 ft at 31°N are about equal andat least an
order of magnitude above those at 70,000 ft. This showsthat, although
the levels of 1961 debris do decrease at 70,000 ft, a second peak of
material from this series is present at the higher altitudes sampled.
The “Mn/"Sr ratio for this new debris sampled at 90,000 ft is about
100 to 1.