Why does the Earth have three atmospheric circulation cells in each hemisphere rather than one?

The presence of three atmospheric circulation cells in each hemisphere can be attributed primarily to the rotation of the Earth and the differences between land and sea. The Coriolis effect, resulting from the Earth's rotation, causes moving air to turn and twist as it travels across the surface. This effect combined with temperature differences creates the distinct circulation patterns known as the Hadley, Ferrel, and Polar cells.

As warm air rises near the equator, it cools and sinks at higher latitudes, creating a cycle of circulation that can be divided into three distinct cells. The movement of air is also influenced by the varying heat capacities of land and water, which leads to differences in temperature and pressure. These variations promote the formation of distinct wind patterns and help establish separate circulation cells.

This complex interplay of Earth's rotation and surface characteristics is critical to understanding global weather patterns. Other factors, such as seasonal climatic changes and geological formations, do play roles in local weather phenomena but do not fundamentally explain the existence of the three cells.