In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason?

[UPSC Civil Services Exam – 2015 Prelims]

(a) Sea surface temperatures are low

(b) Inter-Tropical Convergence Zone seldom occurs

(c) Coriolis force is too weak

(d) Absence of land in those regions

Answer: (b)

Explanation:

The South Atlantic is not conducive to the formation of cyclones due to several reasons:

• The sea surface temperatures are slightly cooler than the optimum temperature required for tropical cyclone formation.
• The area experiences high vertical wind shear throughout the year, which further inhibits cyclone formation.
• Additionally, there is a lack of pre-existing centers of rotation and tropical waves in the region, which also contributes to the absence of cyclones.
• The Intertropical Convergence Zone (ITCZ) remains at or north of the equator, resulting in a lack of synoptic vorticity and convergence necessary for cyclone formation.
• Furthermore, the strong wind shear and absence of ITCZ over the ocean make it challenging to generate tropical cyclones.
• The South Atlantic and South Pacific regions also lack the ITCZ over them, which is a crucial factor contributing to the lack of cyclones.
• Finally, the lower sea temperatures in the region also play a role in the absence of cyclone formation.

Therefore, option (b) is the correct answer.