Westerlies in southern hemisphere are stronger and persistent than in northern hemisphere. Why?
- Southern hemisphere has less landmass as compared to northern hemisphere.
- Coriolis force is higher in southern hemisphere as compared to northern hemisphere
Which of the statement(s) given above is/are correct?
[UPSC Civil Services Exam – 2011 Prelims]
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (a)
Explanation:
| Aspect | Northern Hemisphere | Southern Hemisphere |
| Landmass percentage | About 40% | About 20% |
| Water coverage percentage | About 60% | About 80% |
| Westerlies | Prevailing winds that blow from the west at midlatitudes. | Predominantly from the southwest in the Northern Hemisphere and from the northwest in the Southern Hemisphere. |
| Strength of westerlies | Stronger in the southern hemisphere due to less land in middle latitudes. | – |
| Coriolis effect | Deflection of circulating air toward right in Northern Hemisphere and toward left in Southern Hemisphere. | – |
- The Northern Hemisphere has more landmass and less water coverage than the Southern Hemisphere. Westerlies are prevailing winds blowing from the west at midlatitudes.
- They are stronger in the southern hemisphere due to less landmass in the middle latitudes, which causes the flow pattern to become more north-south oriented. However, this creates frictional or drags in the motion, ultimately slowing the westerlies down.
- The Coriolis effect is the deflection of circulating air toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere. The amount of deflection depends on the speed and latitude of the air, with stronger winds being deflected more. The Coriolis force is maximum at the poles and zero at the equator.
Therefore, option (a) is the correct answer.
