Advantage & Effects of ANOMALOUS EXPANSION OF WATER

In general, there is increase in volume of a body when heated and decrease in volume when cooled. But water has a peculiar type of expansion i.e., it contracts from 0 degree Celsius to 4°C. when water at 0°C is heated, its volume goes on decreasing up to 4°C. At 4°C, it has the least volume and the highest density. on further heating beyond 4°C only the volume of the water increases such unusual expansion of water is called ANOMALOUS EXPANSION OF WATER.
             Due to anomalous expansion of water the fishes and other aquatic organism are able to survive in Himalayan ponds. In winter when atmospheric temperature falls to 0°C or below it, the surface water turns into ice water at different temperature remains as shown in the diagram. The less density of ice than that of water makes it to float on the water and the bad conductivity of ice does not allow exchanging the temperature in and out of it. Due to it the fishes are safe in ponds.