28 DISCUSSION 
504 | 
24, 
isohypse (Dm) of 500 mb surface 
-24° — — — isotherm (°c) at " " " 
Fre. 23—500 mb map over NW Europe (a) Oct. 25, 1945, 182; (b) Oct. 26, 1945, 07z 
the radar. But precipitation maps will probably 
give a better idea of the rain amount than the 
radar maps; and then direct cloud observations 
from aloft and from the ground together with 
radar patterns will perhaps give the very best 
pictures of the regions where there is release of 
latent heat. That is what I meant. 
Dr. Weickmann—I wonder if the Ohio rains 
can be completely explained as simple oro- 
graphic rains without having to consider the 
release of instability showers? 
Mr. Namias—I will say something about that 
in my paper. Of course, it is rather unlikely that 
the mechanism for long continuous or repetitive 
rains can be ascribed to any simple orographic 
factors without considering the whole general 
circulation. The 1937 case is associated with still 
larger seale phenomena which Dr. Bergeron did 
not mention specifically, although he indicated 
them and lumped them together as ‘synoptic 
phenomena.’ In other words, first the stage must 
be set for the cyclone, which in turn provides 
for the release of small-scale phenomena which, 
as he pointed out, are amplified by orographic 
factors, instability, and the like. 
Dr. Weickmann—lI think we should emphasize 
still more that they may frequently be associated 
with thunderstorms and with quite intense in- 
stability lines. 
Dr. Bergeron—May I answer this last ques- 
tion? I had the intention of also showing you 
the normal January rainfall for North America. 
Referring to that map, the maximum January 
rainfall in the eastern states lies roughly where 
that Ohio flood occurred and peculiarly enough 
to the west of the Appalachians and not on the 
coast, or in the mountains, or down in Florida. 
Now, in this special case, the maximum, not only 
