ANOMALOUS EXPANSION OF WATER
Most of the liquids expands on heating while contract on cooling. However, water at 0oC when heated, starts contracting on heating instead of expanding. After 4oC it starts expanding on heating normally like other liquids. It is also seen that hot water when cooled up to 4oC and its density increases.
However, further on from 4oC to 0oC it expands. At 0 oC the water changes in to ice. Due to expansion, the density of it at 0 oC becomes less than water so ice floats on water. At 0 oC water has maximum density and least volume. This is called anomalous or irregular behavior behavior of water.
Effect of Anomalous Expansion of Water.
In colder climate, when the atmospheric temperature starts falling. The density of water in seas and lakes starts to rise reaching to maximum at 4 degree Celsius. This heavier water at 4 degree Celsius goes to lower depths and replace by warmer water. The process goes on till all the water in the lakes acquires a uniform temperature if 4 degree Celsius. if the atmospheric temperature continues falling below 4 degree Celsius, the water starts expanding and begin lighter it does not sink down. At reaching 4 degree Celsius , waters freezes on the surface but the water below the ice remain at 4 degree Celsius. Since ice a bad conductor of heat, it does not allows the heat contained in water below to escape into the atmosphere through the ice sheet. As a result even in the coldest season, the water at lower depths remain in liquid form, providing life to aquatic animals.
