Formation of thermal stratification in a small temperate lake

SUMMARY.

• 1 The origin of vertical temperature stratification in Erstwhile Water (Lake District, Cumbria, England) was observed.
• 2 At the first stage of the spring warming of the whole water column some discontinuity in the vertical temperature distribution appears in the surface and bottom layers.
• 3 Persistent summer stratification occurred for the first time at the lee end of the lake immediately after a change of wind direction, when the cumulative potential energy deficit dominated the cumulative kinetic energy by about 110^-8 Jcm^-2.
• 4 The results show the importance of the proper choice of initial conditions in computations of total energy, as well as the necessity to consider the spatial distribution of potential and mechanical energy responsible for the summer stratification in the lake.