Abstract
There are only a few lakes in Japan, near which both observation data of weather and water surface temperature are available for a long period. The author estimated the evaporation from these lakes by heat budget method, mainly using meteorological factors, water surface temperatures and especially, in Lake Kawaguchi, the vertical distribution of water temperature. The same estimation was done by the evaporation formula based on the turbulence theory. As the results it has been found that the yearly amount and the yearly variation process can be estimated by both methods, and that the neglect of energy storage in the water in the heat budget has a considerable influence upon the monthly amount but not upon the yearly one.
