In which month is the Inter Tropical Convergence Zone (ITCZ) located around 20°N- 25°N latitude (over the Gangetic plain)?

Correct — B. In July the Inter Tropical Convergence Zone lies over northern India at roughly 20°N to 25°N, across the Gangetic plain, where it is called the monsoon trough.

The ITCZ follows the overhead sun. It sits near the equator in the northern winter and is pulled furthest north at the height of the northern summer, and that northward pull is what draws the south-west monsoon over the subcontinent.

The position the stem quotes is the standard July description, so option (b) is the month.

Why the others are wrong

• (a)
  June — June is the onset month, not the month of furthest advance. The south-west monsoon normally reaches Kerala around 1 June and is still working its way up the country while the belt climbs towards the plain.
• (c)
  May — May is pre-monsoon. North India is under the hot-weather low with the Loo blowing across it, and the convergence belt has not yet settled over the Gangetic plain.
• (d)
  August — August is inside the rainy season, but the latitude band the stem gives, 20°N to 25°N over the Gangetic plain, is the textbook July position of the trough.

The ITCZ is the low-pressure belt where the north-east trades of the northern hemisphere meet the south-east trades of the southern hemisphere. Air converges there, rises, and rains.

Because it tracks the overhead sun, the belt migrates through the year. Its northward swing in the northern summer is inseparable from the Indian monsoon: as the belt reaches the Gangetic plain, the south-east trades cross the equator, are deflected right, and arrive over India as the south-west monsoon.

In its northern-summer position over India the ITCZ is given its own name — the monsoon trough.

Key facts

• The ITCZ is the low-pressure belt where the north-east and south-east trade winds converge.
• In July it lies over the Gangetic plain at about 20°N to 25°N and is then called the monsoon trough.
• The belt shifts north in the northern summer and south in the northern winter, following the overhead sun.
• The south-west monsoon normally sets in over Kerala around 1 June.

Common traps

• Marking June because the monsoon begins then, when the stem asks where the belt sits.
• Picturing the ITCZ as a fixed line rather than a belt that migrates through the year.

No directly related past PYQ was found.