Question

What is the primary process described in the provided text regarding lake water circulation?

1. Lake water circulation occurs annually in summer and winter.
2. The process of overturn involves the mixing of lake water layers.
3. Overturn primarily helps in distributing dissolved gases and nutrients within the lake.
4. Overturn is a process exclusive to tropical lakes.

• A. ii, iii
• B. iii only
• C. ii only
• D. All

Answer 1

Answer:

A. ii, iii

• Circulation of lake water occurs twice a year, in the spring and autumn (fall) seasons by a process called overturn.

• This circulation is important for lakes which undergo stratification as it allows thorough mixing of oxygen, phytoplankton and nutrients within the lake.

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