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.
Glaciological Literature
THIS selected list of glaciologicalliterature has been prepared by j. W. Glen with the assistance of T . H. Ellison, W. B. Harland, Miss D. M.Johnson, G . T . Warwick and the Staff of the Scott Polar Research Institute. Its field is the scientific study of snow and ice and of their effects on the earth ; for the literature on polar expeditions, and also on the "applied" aspects of glaciology, such as snow ploughs, readers should consult the bibliographies in each issue of the Polar Record. For Russian material the system of transliteration used is that agreed by the U .S. Board on Geographic Names and the Permanent Committee on Geographical Names for British Official Use in 1947. Readers can greatly assist by sending reprints of their publications to the Society, or by informing Dr. Glen of publications of glaciological interest.
Cloud Seeding in the Sierra Near Bishop, California
Cloud seeding operations using dry ice dispensed from aircraft have been carried out by the California Electric Power Company in the High Sierra near Bishop, Calif., since February 1948. Limited visual observations suggest that snow showers can be produced from non-precipitating orographic clouds by seeding, the snow reaching the ground at the higher elevations. Comparison of the annual runoff from the seeded watershed with that from adjacent areas for the three years 1948, 1949 and 1950 showed a positive departure in the 1948-49 season significant at the 1% level. Significant departures did not appear during the other two years, but the average for the three years was significant at the 5% level. From the same analysis it might be estimated that the average annual flow during the three-year period was augmented by 9% with the 90% confidence limits being zero and 18%. On the other hand the unusual circulation prevailing during the 1948-49 winter may have been responsible, at least in part, for the departure in flow during this season. Snowpack comparisons did not indicate a significant increase in the Bishop area, but it is shown that such a result is not incompatible with the possibility that additional precipitation was produced which was not reflected in the snow surveys.