In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason?
Answer & explanation
Answer: (b) Inter-Tropical Convergence Zone seldom occurs
The reason is (b): the Inter-Tropical Convergence Zone seldom occurs over the South Atlantic and South-Eastern Pacific. Many tropical cyclones grow from disturbances along the ITCZ. In the Atlantic and eastern Pacific sectors the ITCZ stays north of the equator for nearly the whole year, so these southern tropical waters rarely get the seed disturbances cyclones need. For the South Atlantic, NOAA's hurricane researchers name the missing ITCZ, along with very strong vertical wind shear, as the primary reasons for so few cyclones.
- ✗ (a) Cool water from the Humboldt and Benguela currents does keep parts of these seas cool. It is not the reason common to both regions, though. For the South Atlantic, NOAA identifies strong wind shear and the absence of the ITCZ as the primary reasons.
- ✓ (b) The ITCZ supplies the low-level convergence and spin from which many cyclones start. In these sectors it hardly ever shifts south of the equator, so the seed disturbances are missing and cyclones seldom form.
- ✗ (c) Coriolis force is too weak only very close to the equator, roughly within 5° latitude. Elsewhere in tropical latitudes it is strong enough, so it does not explain the absence of cyclones.
- ✗ (d) Cyclones form over warm oceans and do not need land. Land only weakens them after landfall.
Remember · Cyclone genesis needs a warm sea (above 27°C), Coriolis force, low vertical wind shear and a seed disturbance such as one from the ITCZ. The ITCZ rarely reaches the South Atlantic or South-Eastern Pacific, so these seas are nearly cyclone-free.
📘 Read it in NCERT: Class 11 Fundamentals of Physical Geography, Ch 9 (practise this chapter)
Sources
- NOAA/AOML Hurricane FAQ: Why Doesn't the South Atlantic Ocean Experience Tropical Cyclones? ↗ “the primary reasons that the South Atlantic Ocean gets few tropical cyclones are that the tropospheric (near surface to 200mb) vertical wind shear is much too strong and there is typically no inter-tropical convergence zone (ITCZ) over the ocean”
- NCERT Class 11 · Fundamentals of Physical Geography, Chapter 9 “The conditions favourable for the formation and intensification of tropical storms are: (i) Large sea surface with temperature higher than 27° C; (ii) Presence of the Coriolis force; (iii) Small variations in the vertical wind speed”
Question: UPSC Civil Services (Preliminary) 2015, General Studies Paper I. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·
