DISCUSSION 93 
area, corresponding to a high intensity level, 
which moved along. Then we took the times at 
which we measured its different positions, which 
formed a line, and plotted distance against time. 
As long as the plot was a straight lne, we pre- 
sumed we were definitely tracking the same 
cell. If a break in the graph occurred, mdicating 
an abrupt change in velocity, or if the cell disap- 
peared, then we ceased tracking it. 
Dr. C. L. Hosler—We are instituting a similar 
study in central Pennsylvania, and going along 
with the idea that much of the influence of the 
topography on the development of these showers 
is thermal, we hope to determine the thermal 
structure of the ground surface by infra-red 
radiation. 
Dr. Horace R. Byers—I think the thing that 
strikes some of us old timers who have worked 
with the classical synoptic pictures is that we 
have thought of the cloud system in connection 
with the warm front as one that is oriented es- 
sentially parallel to the warm front; yet these 
pictures show in all cases the line is more nearly 
perpendicular to this. 
Dr. Austin—These were peculiar warm fronts 
in that respect. These did have a cold front ap- 
proaching so that this cold front may be what de- 
cided the north-south orientation of that band. 
Dr. Tor Bergeron—I understand this was 
mainly a warm-front rain, and of course, I would 
have liked to have seen a thorough and reliable 
ordinary synoptic analysis of the case, first of 
all. Then also I wonder if you have made an 
analysis of the precipitation during the 24 hours 
in the region from all the available rainfall sta- 
tions, because as a result of all my work during 
almost 40 years, I have found that you can do 
quite a lot with that network if you really treat 
it in the best possible way. And you will, for 
instance, find preferred regions where these con- 
vective cells are released. It would have been 
very satisfying for me personally at any rate to 
see such a thorough analysis of the whole situa- 
tion and I wonder if there was such a one? 
Dr. Austin—The cold front approached a 
certain region, then it slowed down and hovered 
in the vicinity of Albany. You can follow its 
progress on 6-hourly or 12-hourly basis maps, 
but within the few hours we were watching the 
precipitation on radar, it was difficult to find 
the exact location of the front. We are carrying 
the surface analysis a little farther, as far as the 
total rainfall was concerned. When we consider 
the total for the whole day, we do find regions 
with heavier precipitations where these preferred 
tracks had been, although such regions are not 
sharply defined. We also found a region of heavier 
rain down in Connecticut. The complete analysis 
is still in progress. The point I want to bring 
out primarily was the space and time scales in- 
volved—the sizes of the rain areas, the sizes of 
the showers, how often they recur—so we can de- 
cide whether, on whatever scale we happen to be 
working, we are considering a turbulent effect or 
organized circulation on this scale. The complete 
analysis is still being carried out. 
