Atmospheric circulation redistributes heat, water vapour and momentum through the atmosphere. Unequal radiative heating creates temperature and pressure contrasts; gravity, planetary rotation, friction and the evolving flow constrain the response. A simple direct overturning circulation is modified strongly by the Coriolis force on a rotating planet.
The tropical Hadley cell has rising air in strongly heated regions and a returning lower branch. Midlatitude eddies transport heat and momentum and help maintain the Ferrel cell. These statistical cells summarize a time-varying flow containing waves and storms. They explain why a local radiation imbalance can be balanced by horizontal transport rather than by local radiation alone.
The Southern Oscillation is a large-scale variation of tropical atmospheric pressure and circulation, associated with the coupled El Niño–Southern Oscillation. Its pressure pattern is commonly monitored through the contrast between the eastern and western tropical Pacific.
Changes in trade winds affect ocean upwelling and surface temperatures; those temperature changes can feed back on convection and pressure. The atmospheric oscillation and the oceanic El Niño pattern are therefore connected components of a coupled system. A pressure index is an observational summary, not a complete dynamical model of the phenomenon.
Named after William Ferrel, the thermally indirect middle-latitude mean atmospheric overturning: near-surface flow is poleward and the upper return equatorward. It is maintained largely by eddy forcing and surface stress. Its Eulerian mean thermal transport can oppose the poleward eddy contribution; it is not a second thermally direct Hadley cell.
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Atmospheric circulation refers to the large-scale movement of air in the Earth's atmosphere, which is driven by differences in solar heating and the rotation of the Earth. This circulation is fundamental to weather patterns and climate systems around the globe. The primary features of atmospheric circulation include: 1. **Hadley Cells**: These are tropical atmospheric circulation cells that extend from the equator to about 30 degrees latitude.