The rotation of the earth creates patterns of prevailing winds that follow the shape and movement of the earth.
The equatorial region is low in wind. In the era of sailing ships, crossing equatorial regions where there was insufficient wind to fill the sails entailed the grave danger of passing through the doldrums. Today the idea of being in the doldrums is used metaphorically.
Winds are named for the direction from which they blow: easterlies blow from the east, westerlies from the west and so on.
North and south of the equator, the easterly trade winds blow through the sub-tropical zones. Westerlies blow over the temperate zones, while the predominant winds that blow in the antarctic and arctic regions are easterlies.