Question

a. What is the role of anomalous behaviour of water in preserving aquatic life in regions of cold climate?

Answer 1

• The anomalous behaviour of water is that it contracts from 0^oC to 4^oC and beyond 4^oC it expands. Thus, the density of water is maximum at 4^o
• When the surrounding temperature falls, the water in oceans and rivers cools down and say the temperature of whole water reaches 4^o
• Thus, the water reaches its maximum density at this temperature.
• Below this temperature (4^oC), the water layer on the surface expands due to anomalous behaviour of water because of which it's density decreases.
• Thus, this colder layer remains on top  and converts into ice which acts as an insulator and does not allow the temperature of water layer below it to fall below 4^o
• In this way, When the water bodies (such as lakes; rivers; seas;), freeze in cold countries in winter, only the upper surface freezes to form ice.  Water below ice liveable temperature is maintained for the aquatic life, stays at 4ºC and hence, water animals can survive.