Freezing nucleus content of hail and rain in Alberta

The concentration of freezing nuclei in precipitation from different storms have been measured and the variations of nucleus content with space, time, precipitation type and intensity have been examined. It was found that nucleus concentrations are higher in showery rain and in hail than in continuous- type rain. Peaks have been detected in several nucleus spectra and there is some recurrence of such peaks throughout the storms. This type of information may help to improve descriptions of precipitation processes which involve the ice phase.