The ships using the Middle Passage used the trade winds, meaning path or track. The north east Atlantic trade winds above the equator revolved in a clockwise rotation. The south east Atlantic trade winds below the equator rotated counter clockwise. The result is a directional wind from the West African coast to South America. The westerlies which are the portion of these winds located in the Nova Scotia to Europe in the north Atlantic and from Brazil to the southern tip of Africa. The prevailing winds at the equator are calm sometimes called the doldrums. The trade winds are just north and south of the equator. Near the tropics, 25 degrees north and south of the equator the winds calm again in the horse latitudes.
The resulting changes are due to air pressure. Heat rises at the equator creating a belt of low pressure called the doldrums. The air as it rises from the equator it cools and flows towards the earths poles. At the earths poles the cool air is a high pressure. The air flow is forced back to the equator creating the easterlies. This is known as the Coriolis Effect. The most well known trade winds is the alize’, a steady mild wind out of the northeast which blows across central Africa and the Caribbean bring cool temperatures between November and February.