This book describes studies about how climate affects thermal development in lakes. Numerical models based on physics and mathematical methods were applied to lakes with different sizes, shapes and locations. Also diurnal changes and the shape of the vertical temperature profile were studied. The depth of the lake affects together with other morphological features (e.g. the shape and the size) the one-dimensional basic connection between air and water, more in smaller lakes. Also the surrounding landscape affects the conditions over the lake. A special study area was southern Finland, where...