Hadley cell
A Hadley cell is a large-scale tropical circulation in which air rises near the equator, moves poleward at altitude, descends in the subtropics and returns toward the equator near the surface. Operating in both hemispheres, it helps explain the trade winds and broad patterns of tropical and subtropical weather.
Structure of the circulation
The Hadley circulation is an overturning loop in each hemisphere. Strong solar heating and rising air near the equator are followed by poleward flow in the upper troposphere. Air descends in the subtropics, broadly around 30° latitude, and returns equatorward close to the surface. This simplified description captures the principal tropical circulation, although actual winds and rainfall are affected by the seasonal movement of solar heating, continents, oceans and other atmospheric processes.
Connection to winds and climate
As surface air flows back toward the equator, Earth's rotation deflects it, helping form the easterly trade winds. The convergence and ascent of warm, moist air near the equatorial low-pressure belt are associated with frequent cloud and rainfall. Descending air in the subtropical high-pressure zones is generally drier; this circulation is one factor related to the prevalence of many arid regions near those latitudes. These are broad climate patterns, not guarantees of local weather or a sole explanation for any particular desert.
A model within global circulation
The Hadley cell is one of three idealized mean circulation cells in each hemisphere, alongside the midlatitude Ferrel cell and the polar cell. The boundaries between these cells are not rigid walls: winds vary with season and weather, and the Hadley circulation can shift and change in strength. The cell's poleward extent is commonly described as reaching the subtropics, roughly near 30° latitude, rather than extending from equator to pole.
Historical origin
English meteorologist George Hadley proposed a circulation model in 1735 to explain the trade winds. His original explanation did not account for the deflecting effect of Earth's rotation. Modern accounts use the name for the low-latitude overturning circulation described by atmospheric science, retaining the historical term while incorporating planetary rotation and observed global circulation.
Key facts
- Type
- Large-scale tropical atmospheric overturning circulation, occurring in both hemispheres.
- Typical path
- Equatorial ascent, poleward flow aloft, subtropical descent, and near-surface return toward the equator.
- Approximate extent
- The low-latitude circulation typically reaches to around 30° latitude, with variable boundaries.
- Associated surface winds
- The returning near-surface flow contributes to the tropical trade winds.
- Historical namesake
- George Hadley proposed a trade-wind circulation model in 1735.
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References
- 1.Global Atmospheric Circulations
National Oceanic and Atmospheric Administration (NOAA), JetStream · other · reliability: high · retrieved 22 October 2026
Supports: Describes the Hadley, Ferrel and polar circulation cells, equatorial heating, poleward flow aloft, subtropical pressure bands and Hadley's 1735 proposal.
- 2.Hadley cell
Encyclopaedia Britannica · other · reliability: high · retrieved 22 October 2026
Supports: Reference description of the circulation, historical model, trade-wind context, Earth's rotation and approximate tropical extent.
- 3.Hadley Cells
Harvard University, Department of Earth and Planetary Sciences · other · reliability: high · retrieved 22 October 2026
Supports: Academic overview of low-latitude overturning, equatorial ascent, subtropical descent and trade winds.
References are suggested by the research engine and may be incomplete. Unverified URLs are omitted rather than guessed.
Article history
- Version 122 October 2026 · EditorCreated by Zapia