Put a cold spoon in a hot cup of coffee, and what happens? The handle of the spoon gets warm. The same holds true for soups, and indeed, any warm substance, including air, will slowly impart its heat to a cooler one. Heat energy always moves from a warm place to a cool place.
The Earth behaves in the same way. The equator and the latitudes immediately above and below it do exactly the same thing. See the diagrams labeled “A” and “B” of the Earth’s surface that illustrate this. Since most of the sun’s energy comes into this tropical region, a process was found that distributes this energy. The name given to the first part of the process is called the Hadley Cell. Air currents then transfer this heat to the Ferrel Cell and then on to the Polar Cell.
The two diagrams show how the warm air above the tropic region is moved toward the poles. The “A” illustration is three-dimensional and shows the “cells of air” that encircle the globe. The “B” illustration is a side view of three cells of air that carry heat northward from the equator.
Another diagram of the globe further illustrates this and names all six of these “air cells.” Three of them encircle the globe below the equator and three north of the equator. This image also shows the trade winds from zero to 30 degrees latitude that carried European explorers to the Americas, and the westerlies above 30 degrees that brought them back to Europe.
The significance here is that the normal incoming solar energy together with the extra energy in the atmosphere, which is a result of additional greenhouse gases, is being spread to all areas of the globe. The effects are particularly strong in the North Polar regions, and the impacts here have been profound.