Evaporation Experiments

The evaporation experiments reported in this paper were conducted at Duluth, Kewaunee, Detroit, and Buffalo, for the purpose of providing a bas is for estimating the evaporation from the water surfaces of the Great Lakes. In order to be applicable to local conditions, an effort was made to keep the temperature of the water in the pans approximately the same as the temperature of the water in the open lakes. Data were secured which cover a greater variety of combinations of air and water temperatures and wind velocities at the evaporation pans, than any known heretofore. In applying these data to the Great Lakes it was assumed that the evaporation from the open lakes, for a given air temperature, water temperature, and wind velocity, would be the same as the observed evaporation from the experimental pans for the same combination of air temperature, water temperature, and wind velocity. The readings were analyzed and plotted on two charts, from which an estimate of the monthly (or daily) evaporation from the Great Lakes can be made. In these charts it has been assumed that the relative humidity and barometric pressure correspond to the average conditions that existed on the shores of the lakes, at all four stations, during the particular time of the year in which the data were being obtained.