Describe the Hadley circulation and why it creates the ITCZ.

• A. A rising warm air near the equator moves poleward, cools and sinks at about 30°N/S, creating trade winds and the ITCZ where intense convection occurs
• B. The Hadley circulation and why it creates the ITCZ.
• C. The Hadley circulation circulates only in the Tropics; ITCZ is a cold desert belt
• D. The Hadley circulation is a vertical wind shear that suppresses convection

Answer: (B)

The Hadley circulation is a strong, sun-driven loop in the tropical atmosphere. Intense heating at the equator causes air to rise, creating a band of low pressure and vigorous convection there. This rising air spreads out aloft toward the subtropics, cools, and sinks around 30° latitude, forming the subtropical highs. Near the surface, the cooler, now-descending air flows back toward the equator as the trade winds, completing the loop.

The ITCZ forms where the surface convergence of these trade winds meets the rising warm air at the equator. That region experiences sustained uplift and deep convection, producing frequent thunderstorms and heavy rainfall—the hallmark of the ITCZ. Because the sun’s overhead position shifts with the seasons, the ITCZ also migrates north and south with the seasons, following the area of maximum heating.

So, describing the Hadley circulation and why it creates the ITCZ captures how the equatorial heating drives a looping circulation, with convergence and rising air at the equator forming the ITCZ, and subsidence farther north and south establishing the surrounding subtropics.