The Meteorological Aspects of Ice Cover on the Great Lakes*

The formation and break-up of ice on the Great Lakes as observed by regular ice reconnaissance flights conducted by the Meteorological Service of Canada is discussed in terms of the meteorological parameters involved. Ice cover on the individual lakes over the past four years is correlated with the winter temperature regime and an index of the heat stored in each lake using the concept of cumulative degree-days of freezing and thawing. Subjective consideration is also given to the effect of other meteorological factors. As a result of the study, graphs and regression equations have been developed as aids in the prediction of ice cover for the individual lakes. In addition, a comparison of the four years of observations with the 14-yr. period from 1949 to 1963 provides an indication of the average and extreme ice conditions that may be expected for each lake.