Explain in detail the role of anomalous behaviour of water in preserving aquatic life in regions of cold climates such as polar regions..

Explanation

In cold regions, during winter, the temperature of the atomosphere falls well below `0^(@)C `. As the temperature decreases, the water at the surfaces of lakes and ponds starts contracting. Hence, its density increases and it sinks to the bottom. This process contiues till the temperature of all the water in a lake falls to `4^(@)C `. As the water at the surface cools further, i.e., its temperature falls below `4^(@)C `, it starts expanding instead of contracting .Therefore,its density decreases and it remains at the surface.The temperature of the water at the surface continues to fall to `0^(@)C`.Finally , the water at the surface is converted into ice, but the water below the layer of ice is at`4^(@)C` . Ice is a bad conductor of heat. Hence, the layer of the ice at the surface does not allow transfer of heat from the water to the atmosphere.As the water below the layer of ice remains at `4^(@)C `, fish and the aquatic animals and plants can survive in it.