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RAS question

The Inter-Tropical Convergence Zone (ITCZ) plays a crucial role in the Indian Monsoon. What is the ITCZ?

Correct answer: (D) A low-pressure zone near the equator where trade winds from both hemispheres converge.

The Inter-Tropical Convergence Zone is a low-pressure zone near the equator where trade winds converge, and its northward shift helps set up the southwest monsoon over India.

  1. (A)

    A high-pressure zone over the Tibetan Plateau

  2. (B)

    A cold ocean current in the Arabian Sea

  3. (C)

    A permanent cyclonic system over the Bay of Bengal

  4. (D)

    A low-pressure zone near the equator where trade winds from both hemispheres converge

Explanation

The ITCZ is best understood as an equatorial low-pressure belt where trade winds meet and air rises. NCERT links this directly to the Indian monsoon: in July, the ITCZ shifts to around 20°N-25°N over the Gangetic plain, where it is called the monsoon trough. That shift encourages a thermal low over north and northwest India. As the ITCZ moves north, the southern hemisphere trade winds cross the equator between 40°E and 60°E, are deflected by the Coriolis force, and blow from southwest to northeast. This is why option D captures the core definition, while also explaining the mechanism behind the southwest monsoon.

Why the other options are wrong

  • (A) A Tibetan Plateau high-pressure zone does not define the ITCZ, which NCERT identifies as a low-pressure zone linked to converging trade winds.
  • (B) A cold ocean current in the Arabian Sea is unrelated to the ITCZ, which is an atmospheric convergence zone near the equator.
  • (C) The ITCZ is not a permanent cyclonic system over the Bay of Bengal; it shifts seasonally and forms the monsoon trough over the Gangetic plain in July.

Concept

This tests the mechanism of the Indian monsoon, especially pressure belts, trade winds and the seasonal migration of the ITCZ. RAS repeatedly asks this because monsoon onset, breaks and rainfall patterns depend on this basic circulation logic.

Source

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