MEXICAN RAINFALL 15S 
indices to show the usefulness of land areas for agricultural 
purposes the variability of precipitation should be introduced 
besides the evapotranspiration factor. 
Work to Follow 
In the recently established Institute of Applied Science in the 
University of Mexico work is now going on to investigate the 
precipitation mechanisms that create the above-mentioned con- 
ditions of fluctuation and variability. A classification of weather 
types has been made for surface and upper air circulation over 
Mexico and frequencies of the different types in various parts of 
the year have been calculated. The next step will be to study the 
correlation between these circulation types and precipitation in 
various parts of the country. It is our hope that these investiga- 
tions will become a solid basis for continued work on methods 
for long-range forecasting of precipitation as well as for extensive 
studies of the possibilities for inducing artificial rainfall and of the 
water balance of the country. 
REFERENCES 
1. Conrap, V. anp K. Potiak. 1952. Methods in Climatology. Cam- 
bridge, Mass. 
2. ConTRERAS Arras, A. 1942. Mapa de las provincias climatolégicas 
de la Republica Mexicana. Sria. de Agricultura y Fomento. 
3. LanpsBerG, H. 1951. Statistical investigations into the climatology 
of rainfall on Oahu (T.H.). Hawaiian Rainfall Contributions. Met. 
Monographs. I, No. 3. 
. Pace, J. 1929. Climate of México. Monthly Weather Rev. Suppl. 33. 
. WaLLEN, C. C., anp H. W.-Son AHLMANN. 1954. Some recent 
studies in Sweden on the present climatic fluctuations. 4rch. Met. 
Geoph. Bioklim. Defant Festschrift. 
6. WaLtEN, C. C. 1955. Some characteristics of precipitation in Mexico. 
Geografiska Annaler 31, 1-2. 
nm & 
