QUESTION 14
GS1
15 marks
Account for variations in oceanic salinity and discuss its multi-dimensional effects.
WRITE IN
11 min
250 words
What the examiner wants
Explain what causes salinity to vary across oceans and discuss its wide-ranging effects.
Account for + DiscussGive the reasons that explain it. Explain the different sides of the issue, use evidence, and finish with a balanced view.
Demand-wise check
- 1Factors: evaporation vs precipitation, river inflow, freezing and melting of ice, winds, currents, mixing≈50 words
- 2Horizontal distribution: high in subtropics (~36–37 ppt), low at equator and poles; enclosed seas (Red Sea high, Baltic low)≈50 words
- 3Vertical: halocline; Indian context: Bay of Bengal fresher than Arabian Sea≈50 words
- 4Effects: density and thermohaline circulation, freezing point, marine life and fisheries, climate and monsoon, salt production, navigation≈50 words
Open in about 30 words and close in about 30.
Answer plan
Average salinityControlling factorsHorizontal and vertical patternsEffects (physical, biological, economic, climatic)Conclusion
Where marks usually go
- Only the factors, ignoring 'multi-dimensional effects'
- No examples of seas
Draw this
- Graph of salinity against latitude with the subtropical peaks
Value addition
- DataAverage ocean salinity is about 35 parts per thousand; the Red Sea exceeds 40 ppt while parts of the Baltic are below 10 ppt.Standard oceanography
- MissionNASA's Aquarius (2011–15) mapped global sea surface salinity from space.NASA
Next: plan for one minute, write it in 11 minutes, then get it checked.