FREQUENCY OF FREEZE-THAW CYCLES.

Abstract

Data from 1300 climatic summaries are used to construct a map for the conterminous United States showing the annual frequency of freeze-thaw cycles. Seasonal maps, as a percentage of the annual map, are based on a smaller number of stations. The highs of freeze-thaw activity, about 250 days per year, are in the mountainous regions of the West where the isopleths exhibit a complex frequency pattern. Since this study is based on observations taken at an elevation of about 5 ft, the results are conservative compared to those that would result from observations taken at a lower elevation.