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SESSION IIB DISCUSSION
amount that was injected.
But now I see, and I am glad to see, that
we are much more concerned with the actual physical mechanisms
that are involved in fallout, After all, these are the things that will
lead to meteorologists’ understanding a little more about what is
going on. I think that as far as the AEC health problem goes, it is
under reasonable control. I believe the difficulties are internal in
the meteorological profession rather than in not being able to predict
what will come out, given a certain injection into the atmosphere.
NEWELL: I would like to make a comment on what Mr. List said.
Does anyone really know whether the tops of these clouds that are
supposedly penetrating the stratosphere are water or ice? It seems
to me that the majority of the radar echoes from high clouds that we
see in New England, which rarely penetrate the stratosphere, are
from ice, and the ice blows away from the cloud more or less like
the smoke at the top of a chimney. Thus stratospheric debris, even
if it were collected with high efficiency, would be carried away from
the cloud and lost to it as the ice evaporated downstream.
Do we know from actual aircraft flights whether these clouds
were water or ice and whether they were really 15,000 ft above the
tropopause? The temperatures at that altitude suggest that they may
be ice. There is a big question in my mind as to the actual heights of
these showers, particularly those reported by radar at great ranges
where beam-width exaggeration effects can be large.
LIST: The sightings are visual. We do not know the composition,
NEWELL: At the previous fallout conference in 1961, Dr. Kruger
suggested that there were more high-level penetrations of the stratoSphere in the spring. I just wanted to report that after the conference
I collected 10 years of data from the Massachusetts Institute of
Technology Weather Radar Research group and went through it tabu-
lating maximum echo tops for each day. I then averaged these values
by. months and found that the peak radar echoes in New England occurred in July. Is this different in other parts of the country? Dr.
Kruger, where were your measurements made?
KRUGER: Our convective-activity collections, until recently, have
taken place in central Pennsylvania. I do not have any data of the kind
you described, although undoubtedly they could be obtained from
Pennsylvania State University records. We have been collecting from
convective storms for the past three years, and most of them have
occurred during the spring months,