Lake Stratification & Turnover Simulator

Season

Month January

Surface temp

–

Bottom temp

–

Water column state

–

Temperature scale (°C)

0°13°26°

Layers

Epilimnion — warm, wind-mixed surface layer Thermocline — sharp temperature gradient Hypolimnion — cold, dense deep layer

How it works

Water is densest at 4°C, not at 0°C. In summer the sun warms a thin surface layer (epilimnion) that stays lighter than the cold water below (hypolimnion); the two are separated by a thermocline where temperature — and density — change sharply, and wind cannot mix them. In autumn the surface cools until it matches the deep-water temperature: the density barrier disappears, and wind can drive convection through the entire column (turnover), pulling oxygen down and nutrients up. The same happens in reverse during spring turnover, after a weakly stratified, ice-covered winter.

Month — scrub through a full annual cycle to watch the thermocline build, sharpen and collapse.
Start annual cycle — auto-advances the season continuously; watch the convection arrows appear exactly during the two turnover windows.
Convection arrows — visualise vertical mixing currents; they only appear when the column is close to isothermal (turnover or a well-mixed summer day).

January Weak winter stratification

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