Dependence of Snowfall on Temperature
D'OOGE has reported1 a correlation between amount of snowfall in inches and temperature at the time of snowfall. His data showed that maximum depth of snowfall occurred at a daily mean temperature of − 11° C. ; Bossolasco2 correlated frequency of occurrence of snowfall with temperature and found maximum occurrence at approximately the same temperature. These observers assumed that the mean daily temperature recorded at the level of observation was a reasonable estimate of the temperature at the level of formation of the snow. From the data presented, conclusions were drawn concerning nucleation of snow crystals.
DEPENDENCE OF THE FORMS OF NATURAL SNOW CRYSTALS ON METEOROLOGICAL CONDITIONS
Abstract Observations were made on the crystal structure of natural snow during a snowfall and related to the meteorological data obtainable for the period of observation. A dependence of crystal type on temperature, in reasonable agreement with the laboratory results of Nakaya, was observed. Further relations were noted which indicated the readiness with which snow-crystal observations can be related to other meteorological conditions.
Analysis of Results of a Group of Cloud Seeding Projects in Pacific Slope Watershed Areas
An analysis of a series of cloud seeding projects conducted in three different Pacific-slope watershed areas, each during several seasons, is presented. Seven separate project-seasons are involved in each of which identical seeding procedures were used. Silver iodide smoke generators were operated at ground level for a total of well over 10,000 generator-hours during these operations. Snowpack and other official precipitation records are examined and target-to-control-area comparisons made in order to bring out the effects of the seeding and apply statistical tests thereto. It is concluded that this evaluation procedure, as applied to the available data, is capable of discerning the effectiveness of cloud seeding in increasing precipitation over a period of several seasons, but is not capable of bringing into focus the many details of interest to the cloud seeder.