Question

Which of the following statements about spring overturn is correct?

1. It occurs when the surface water cools down to 4°C.
2. Increased solar radiation melts the ice, and water at 4°C sinks.
3. It is primarily driven by the cooling of air temperatures.
4. The process involves warm surface water sinking to the bottom.

• A. 1 only
• B. 2 only
• C. All
• D. 4 only

Answer 1

Answer:

B. 2 only

Spring overturn

• In spring and early summer season the increased solar radiation melts the ice cover, which, as it attains a temperature of 4 degree Celcius, becomes dense and heavy and sinks to the bottom, displacing the lower water which moves up.

• This circulation of water is further helped by the prevailing summer winds and is called spring overturn