The northeast trade winds are prevailing winds in the Northern Hemisphere at approximately 30 degrees latitude, which have the ability to quickly propel a ship across the ocean. In the Southern Hemisphere, at 30 degrees South Latitude, winds blow from the southeast, creating the southeast trade winds.
According to the National Oceanic and Atmospheric Administration, warm air from the equator rises, flowing northerly toward the North Pole. As it moves away, it deflects to the right due to the Coriolis Effect, which makes an object appear to move to the right because of the movement of the earth. As the air cools, it descends in the tropics, blowing from the northeast toward the southwest as it returns to the equator.
The trade winds from the Northern Hemisphere and the Southern Hemisphere meet in a zone ranging from 5 degrees North Latitude to 5 degrees South Latitude. In this Intertropical Convergence Zone, the winds cancel each other's effect, causing a calm air in the area also called the doldrums. In the past, wind-powered ships preferred traveling in the areas of the trade winds and avoided the doldrums whenever possible. Because of the lack of wind in the ITCZ, a wind-powered ship could find itself stuck for days without enough wind to move forward.