RECOMMENDATIONS 429 
elements on the surface and in the upper atmosphere in the arid 
countries, and specifically along a parallel of latitude through as 
many as possible of the world’s deserts, should be useful in the 
solution of arid and semi-arid zone problems. Intensification of 
observations at the national level will enable arid zone countries 
to benefit even more from the international aspects of the Inter- 
national Geophysical Year. 
6. More effective climatic studies require an increase in density 
and improvement in representativeness of meteorological stations 
(both at sea level and at higher elevations) for surface and upper 
air observations in all arid areas. 
7. Careful attention should be paid to current research studies 
concerning relationships of solar emanations and _ terrestrial 
weather patterns, with particular attention to the effects that 
may bear on arid land problems. 
8. Synoptic and dynamic climatological studies, in different 
arid and semi-arid regions, are essential. Emphasis should be 
placed on interrelationships between the general circulation of the 
atmosphere at upper levels as well as at the surface and the 
precipitation in different parts of the areas and at different times 
of the year. With such studies as a basis for the development of 
understanding, prediction of precipitation within the area in 
question may follow. 
g. Inasmuch as the matter of the evaluation of the results 
following attempts to modify weather and weather processes is 
recognized as offering great possibilities for the peoples of arid 
lands, every effort should be made to develop improved techniques 
for statistical evaluation of weather modification experiments and 
to use the best available present techniques and data in the 
analysis of the results of such experiments. 
1o. An international cooperative program of synoptic observa- 
tions should be instituted to determine the concentration of ice- 
forming nuclei throughout the world, especially during periods of 
the earth’s passage through meteoritic streams. These observa- 
tions should be supplemented by measurements, synoptic if pos- 
sible, of the concentration of naturally and industrially induced 
