Which global effect primarily results when the Hadley cell circulation weakens in the tropics?

💡 Explanation

When the Hadley cell circulation weakens, the subsidence of dry air shifts poleward because the rising air mass near the equator is diminished, leading to reduced rainfall and expansion of arid zones beyond the traditional tropics. Therefore equatorial arid zone expansion results, rather than the other options which require fundamentally shifted forcing mechanisms in the polar regions or ocean systems.

• Which consequence results downstream when decreased sediment deposition decreases permeability in an alluvial aquifer?
• Which effect amplifies hurricane spin in the Northern Hemisphere?
• Which mechanism intensifies meandering patterns in mid-latitude coastal streams during El Niño?
• Which outcome occurs when a meandering stream erodes laterally until encountering a resistant geological formation beneath an oxbow?
• Which landscape feature develops when a river's meander erodes through its neck on an alluvial plain?
• Which mechanism causes cyclones to rotate counter-clockwise in the Northern Hemisphere?