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Why can a lake freeze and thaw repeatedly before a stable ice cover forms?

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ice in lakes and rivers Heat flow through an ice cover (see text).

A lake may freeze and thaw repeatedly before a stable ice cover forms primarily due to the influence of wind mixing and fluctuating air temperatures.12

During the initial cooling phase, wind agitates the surface water, which prevents the formation of a solid, stable sheet of ice. Instead, this mixing creates a layer of small ice crystals. Until this ice layer grows thick enough to withstand the mechanical forces of the wind, it remains vulnerable to being broken up, dissipated, and reformed.13

Additionally, the formation of ice is sensitive to diurnal variations in air temperature. In the early stages of the season, if air temperatures hover near the freezing point, the ice may melt during warmer periods and reform when temperatures drop again. A stable ice cover only persists once the water column has cooled sufficiently and air temperatures remain consistently below the freezing point, allowing the ice to thicken to a degree that it can resist wind-driven disruption.213