Summary
Precipitable water vapor (Wp) and specific humidity, using 1972/1975 radiossonde data over the Amazon basin are presented — High values of Wp are located between Manaus and Iquitos. Mean Wp estimative over the basin is 35mm and the "precipitation eficiency" is 18.2% with a water vapor recycle time of 5.5 days. The mean Wp over Manaus, Belém and Brasília were 44.2, 41.9 and 25.1, respectively, in a 1000/500mb layer.