SOME ASPECTS OF FALLOUT IN BRAZIL
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A concluding suggestion for such synoptic types of study of the
many stations of South America may not be out of place. The vast
difference between precipitation on the east and west coasts must be
kept in- mind. Studies can be made relating air contamination or fall-
out to precipitation, and the monthly rainfall at a station can be taken
as a practical index of precipitation. Ideally, what is wanted is the
precipitation history of an air mass. In the United States the practical
index can be substituted for the ideal without much prejudice. In South
America, however, where precipitation can differ from place to place
by orders of magnitude and where the most important precipitation
history of an air mass takes place east of the Andes, use of such an
index can lead to wrong conclusions.