How the Earth Works

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay

The diagram above shows the main components of the earth:

Solid Earth


The domain of life, from several kilometers deep in the lithosphere to 10 km or so above the surface.


The zone of liquid water on the earth, dominated by the oceans but also including lakes and rivers and liquid underground water.


The zone of frozen water on the earth, including the Antarctic and Greenland ice caps, glaciers, and permanently frozen ground (permafrost). The cryosphere is often considered part of the hydrosphere.


Solid Earth

Earth Science

Earth Systems


Earth and the Universe

Atmospheric Circulation

Atmospheric Circulation

The boundaries between wind belts are not fixed but fluctuate and have wave-like geometries.

A loop like the one from the doldrums to the horse latitudes is called a Hadley Cell.

Oceanic Circulation

Surface Currents

Surface currents, shown below, are driven by the winds. Warm water is red and cold water is blue. The Trade Winds propel ocean water westward along the equator, and when it strikes a continent, it is diverted poleward. However, a narrow return flow also occurs along the equator. In mid-latitudes the currents are driven eastward by the Westerlies. The opposing wind belts cause currents in all the ocean basins to form gyres, or giant loops. 

Thermohaline (Deep) Circulation

A combination of surface and deep flow creates a giant global heat conveyor. The coldest and densest water forms off Antarctica and flows along the ocean floors until it reaches an obstacle. Then it rises and joins the surface circulation. As water loops around the North Pacific gyre, it becomes extremely warm. Even though the amount of water that passes from the Pacific to the Indian Ocean is not great, the amount of heat it carries is. It cools a bit rounding Africa, then warms in equatorial latitudes and carries  water up the Atlantic into the Arctic. Finally the water cools and sinks, mixes with cold bottom water, and begins the cycle again.

Hydrologic Cycle 


The Rock Cycle 

Plate Tectonics 

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Last Update February 28, 1997