Freezing of Lakes - Freezing of Lakes and the Evolution of their Ice Cover - page 28

Fig. 2.7 Saturation water
vapour pressure as a function of
temperature at water surface,
and at ice surface

Momentum, heat and moisture transfer between lakes and atmosphere are determined
by atmospheric boundary layer processes. Wind velocity gives the momentum transfer in
terms of the tangential surface stress, and to estimate the drag properly, temperature and
humidity distributions are also needed to account for the stability of the atmospheric
surface layer. True weather data over lakes can be obtained from floats (Fig. 2.8 ). Routine

weather stations are located on land, and using their data for the lake surface needs
particular consideration.

fl

Fig. 2.8 rvi in southern Finland (e.g., Wang et al. 2005; Jakkila et al.

2009). Solar power panels and atmospheric surface layer instrumentation is seen above the lake
surface. Also included are the instrumentations for ice (temperature and light) and water body
(temperature, light, conductivity, flow velocity)

Ice station Lotus, Lake P ää j ä