EXPERIMENTAL METEOROLOGY 305 
Based on the few seeding experiments made with Project Cirrus 
the rain areas developed over the regions which ordinarily receive 
rain. Thus, if any conclusions might be drawn from these few 
experiments, the type of seeding we conducted might be expected 
to produce an augmented total yearly rainfall rather than a 
redistribution of precipitation. 
Studies of this sort should become an essential part of any long 
range plan of arid lands research concerning atmospheric water 
sources. 
By proper control it might be feasible, for example, to aug- 
ment ground water supplies by causing more precipitation on 
mountain slopes with drainages running into thick gravel depos- 
its. 
Movement of Air in Valleys Bordered by Mountains 
One of the problems involved in seeding clouds from ground- 
based silver iodide ground generators is that of getting the silver 
iodide particles into the cloud to be modified. Several significant 
studies of this phenomenon were made southeast of Albuquerque 
during July 1949. 
On July 14, 1949, an attempt was made by S. E. Reynolds and 
the writer to introduce dry ice into an orographic cumulus, using 
a large pilot balloon. The target cloud was a relatively small but 
vigorously growing orographic cumulus above the western edge 
of the Manzano Mountains about five miles east of the launching 
site. Upon release, the balloon carrying about a half pound chunk 
of dry ice started moving in a southerly direction and was soon 
lost to view. Reynolds and Schaefer then decided to get closer to 
the cloud base, so took another balloon with dry ice over to the 
edge of the mountain nearly under the cloud base. Upon release, 
the balloon, observed with binoculars, immediately started rising 
toward the cloud without deviation. Just before this second bal- 
loon entered the cloud base, the first balloon was seen to join it, 
drifting up rapidly from the south! 
Within less than thirty minutes after the balloons entered the 
cloud a radar echo due to precipitation formed, which was then 
followed by rain. 
