332 ROBERT M. CUNNINGHAM 
being 21 + 3 knots. The radar positions at 
13h45m are not consistent with the other points. 
Note should be taken of the narrowness of 
the precipitation area in comparison with the 
size of the main cloud mass. The main mass of 
the storm passed over Cheyenne Airport at 
13h00m but only a trace of rain fell in seven 
minutes. Marble size hail was reported three 
miles south of the airport. The hail region out- 
side the main cloud mass is indicated on Figure 
8. As mentioned previously, it is suggested that 
this is a region of outflowing air and the build- 
ing cumulus on the southwest side is a region 
of inflow relative to the slow storm movement. 
One might imagine that, besides the obvious 
vertical motions taking place, there may be a 
consistent horizontal half spiral circulation, in- 
flow rising, hydrometeors growing rapidly, part 
of the flow gaining eastward momentum and 
turning downstream to form the anvil, the other 
part turning westward and descending with the 
heavier hydrometeors. In an earlier stage, most 
of the cloud material would flow out downstream 
in the anvil, (see mid-cloud in Fig. 2), showers 
would fall from the main mass between stronger 
updraft cells, creating a low level downdraft 
region which might induce a steady westerly 
branch of the flow in the upper cloud (particu- 
larly of the more protected volume of vertical 
rising air), creating a steady supply of hydro- 
meteors and therefore a steady downdraft. 
Rotary motion, cyclonic, of the thunder and 
hailstorms in the Denver area have been noted 
by W. B. Beckwith (private communication) 
and in other areas in studies by Fujita [1960]. 
In this paper a great deal has been suggested 
concerning the air circulations in a western hail- 
storm from the analysis of several still photo- 
graphs taken from a high altitude. The actual 
circulations in these storms await the time when 
flow measurements in and around these storms 
are taken with aircraft or by some safer means. 
The intent here was to point out what can be 
gained from a high-altitude view of this type of 
storm in areas where the surrounding atmosphere 
is dry and largely void of other obscuring clouds. 
The intent is also to point out that some large 
Cumulonimbus may not consist entirely of a se- 
ries of cellular elements in various stages of 
their life cycle, but may to some extent consist 
of a steady horizontal and vertical circulation 
system. 
REFERENCE 
Fusira, T., Structure of convective storms, this 
volume, pp. 61-66, 1960. 
Discussion 
(Note: Discussion of this paper is combined with that following the next paper.) 
