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Difficulty: MediumPhysical Geography of the World

With reference to global atmospheric pressure belts and prevailing planetary wind systems, consider the following statements:
1. The Trade Winds blow from the Subtropical High-Pressure Belts towards the Equatorial Low-Pressure Belt, deflecting westward in both hemispheres due to the Coriolis effect.
2. The Westerlies are generally stronger and more persistent in the Southern Hemisphere than in the Northern Hemisphere due to the vast expanse of ocean and minimal landmass friction.

Which of the statements given above is/are correct?

  1. A
    1 only
  2. B
    2 only
  3. Both 1 and 2Answer
  4. D
    Neither 1 nor 2

Answer

Both 1 and 2
Both statements are correct. Trade winds move from the subtropical high-pressure belts to the equatorial low and are deflected westward by the Coriolis effect. Furthermore, because the Southern Hemisphere consists predominantly of ocean surface with very few land obstructions, the Westerlies encounter minimal friction and blow with much higher velocity and consistency than in the Northern Hemisphere.

Step-by-Step Solution

1
Analyze Statement 1 regarding Trade Winds direction and deflection.
Statement 1 is correct. Trade winds originate from the subtropical high-pressure cells (30∘ N30^\circ\text{ N} and 30∘ S30^\circ\text{ S}) and flow toward the equatorial low-pressure zone. The Coriolis force deflects them to the right in the Northern Hemisphere (Northeast Trades) and to the left in the Southern Hemisphere (Southeast Trades), causing a westward component in both cases.
Verifies atmospheric pressure gradient and Coriolis force deflection.
2
Analyze Statement 2 regarding the strength of Westerlies in the Southern Hemisphere.
Statement 2 is correct. In the Southern Hemisphere, the vast, uninterrupted ocean expanse offers negligible frictional resistance compared to the land-dominated Northern Hemisphere, allowing the Westerlies to attain high speeds and constancy (known as Roaring Forties, Furious Fifties, and Shrieking Sixties).
Verifies the effect of land-ocean distribution on surface atmospheric drag.

Key Concept

Planetary Wind Systems and Atmospheric Circulation
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Topics

Physical Geography of the World

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