An experiment on the cloud modification by spraying NaCI saturated solution directly into clouds was conducted. An atomizer was set at the windward slope of a mountain, and droplets of the salt solution were introduced into clouds when the clouds were ascending along the slope and covered the observation points which were located 1800m above sea level.
Marked changes in size spectrum of cloud elements and the following rapid decrease in cloud water content caused by onset of precipitation were observed. This result showed that the first stage of precipitation was induced within a few minutes by spraying a relatively small number of NaCI droplets into the cloud which had been colloidally stable.