HYDROGEN ION CONCENTRATION IN RAIN WATER

Continuous measurements of pH precipitation falling from cumulus clouds in semi-arid region(Colorado,USA),and in wet temperate zone(Bologna,Italy)were made.In Colorado the pHwas constant at 7.3 for a period of time,and later changed to 7.0 and remained constant at thisvalue during the remainder of the storm.In Italy the pH fluctuated continuously between theapproximate values of 5.7 and 6.4 during the storm.The changes in hydrogen ion concentrationreflect the chemical composition of cloud condensation nuclei and of scavenged aerosol particles andgases presented in the region.