DISCUSSION 
AUGUST - 1936 
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Fic. 2—Isentropic chart for the 315°A surface for August 1936; solid lines are isopleths of mixing ratio 
in grams per kilogram, broken lines represent in meters the height of the isentropic surface, moist and 
dry tongues are labeled M and D, respectively; insert shows departure from normal of precipitation 
for the month in inches, shaded areas showing excess, and unshaded areas deficit 
the mean 700-mb pattern and the precipitation 
anomaly. This is the August which I presume is 
one of the periods treated in Mr. Semonin’s talk. 
You will note the anticyclonic cells are also pro- 
nounced, as in the 1936 case. 
What I am trying to emphasize is that drought 
is generally a very large-scale phenomenon, and 
its modification may require us to deal with 
events quite remote from the immediate drought 
area. One should be very careful not to draw 
conclusions about his efforts to modify drought 
on a large scale by rather localized seeding, par- 
ticularly in areas where there are few clouds, and 
these not of the proper type. As I indicated in 
my earlier talk, all of us as meteorologists must 
be aware of these large-scale problems. 
Mr. R. G. Semonin—The dry period was in 
August 1953, and was very similar to the mean 
pattern you have shown. You had asked how the 
amount of precipitable water is related to pre- 
cipitation. I have been trying to find out for two 
or three years now, and I have found no definite 
relationship. I just wanted to show what the con- 
ditions were during these periods rather than 
imply any relationship between them, but the 
water vapor is present, at least in these dry sum- 
mer periods, and in many cases the latent msta- 
bility is also there. However, there is no mecha- 
nism to release this. We can not burn cornfields, 
of course; they are quite expensive; so we have 
no way of initiating convection. 
Dr. Tor Bergeron—l want to point out the 
High over central Europe and southeastern Swe- 
den that co-existed with the American drought 
in 1955. In fact it was one of the driest summers 
on record in southwestern Sweden; and that was 
one of the first summers that we had our project 
Pluvius working. It almost ruined our project. 
Mr. Namias—Incidentally, I had an article 
published in the Monthly Weather Review 
(Some meteorological aspects of drought, with 
special reference to the summers of 1952-4 over 
the United States, September, 1955) describing 
the 1952 to 1954 drought in relation to the gen- 
eral drought problem. 
Maj. C. Downie—Experiments carried out 
by the Geophysics Research Directorate have 
yielded little encouragement that a drought 
