Trade winds are described as the prevailing easterly winds that converge across the equator. The Horse Latitudes -subtropitcal regions at about 30N and 30S- are the main source of the easterly winds that reach the equator. The Hadley Cell is another circulation that contributes to the easterly trade winds of the equator. Near the equator, air rises and is transported towards the poles (poleward). Then it sinks back down near the Horse Latitudes. The Coriolis effect contributes to the trade winds because as the earth rotates clockwise, the turning maintains the easterly wind direction of the trade winds.
Philadelphia Weather Authority 