Knowra Hadley cell Hadley cell A tropical atmospheric circulation cell in which air rises near the equator, flows poleward aloft, descends in the subtropics, and returns toward the equator near the surface.
Intertropical Convergence Zone : A shifting equatorial belt where trade winds converge, air rises, and heavy rainfall is common. Surface trade winds converge here, feeding the cell’s main branch of rising air.
Subtropical desert : A dry region commonly found near 20°–30° latitude under persistent descending atmospheric air. The cell’s subtropical descent suppresses cloud formation and favors aridity.
George Hadley : An English lawyer and meteorologist who explained the trade winds through atmospheric circulation in 1735. His account supplied the name for the tropical circulation cell.
Hadley cell edge : A diagnostic latitude marking the poleward boundary of the Hadley circulation’s descending branch. Researchers use differing definitions of this boundary to measure circulation shifts.
Trade winds : Persistent tropical easterly winds that blow from subtropical high-pressure regions toward the equator. They form the Hadley cell’s near-surface return flow toward the equator.
Tropical rainforest climate : A climate with consistently warm temperatures and abundant precipitation throughout the year. Frequent ascent near the equator supports the deep convection and rainfall characteristic of this climate.
Hadley’s 1735 trade-wind theory : George Hadley’s explanation that equatorial heating and Earth’s rotation produce the trade winds. It anticipated the circulation concept, though its account differs from modern dynamics.
Hadley cell strength : A measure of the intensity of tropical overturning, often estimated from the circulation’s mass transport. Its trends depend on season, hemisphere, dataset, and the chosen circulation metric.
Subtropical ridge : A belt of high atmospheric pressure near 30° latitude, associated with descending air and weak surface winds. Descending air helps create this pressure belt beneath the cell’s poleward branch.
Subtropical jet stream : A narrow band of strong westerly winds near the tropopause, typically around 30° latitude. Poleward upper-level flow contributes to the angular-momentum structure associated with this jet.
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