Winter weather 1 1 degree, is the surface temperature of 4m water high or the bottom temperature high?

The temperature at the bottom of the water is very high

The temperature drops in winter. If the temperature of the lake is above 4℃, the water on the lake will cool into ice. At this time, the water in the upper layer of the lake will shrink in volume, increase in density, and finally sink to the bottom of the lake. And warm water from the lower layer rises to the upper surface. In this way, the position between the upper cold water and the lower warm water is constantly exchanged, which leads to the gradual decrease of the water temperature of the whole lake. However, this thermal convection phenomenon can only be carried out until all water temperatures reach 4℃. When the water temperature drops below 4℃, the water in the upper layer expands instead, resulting in a decrease in density, so the cold water layer stays on it and continues to cool until the water temperature drops to 0℃, and the cold water layer on it forms ice. The main form of heat exchange in the above stage is convection. When the water surface freezes, the cooling of water depends entirely on the heat conduction of water for heat transfer. Due to the poor thermal conductivity of water, the water temperature at the bottom of the lake is still around 4℃. The abnormal expansion of water ensures that animals and plants in the water can survive in the cold season. The above is my answer, I hope it will help you.