Trade winds are the permanent east-to-west prevailing winds that flow in the Earths equatorial region. They are air currents closer to Earth’s surface that blow from east to west near the equator, about 30 degrees north and south of it. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere, strengthening during the winter and when the Arctic oscillation is in its warm phase. The trade winds have been used by sailors for centuries to travel across the worlds oceans, and they enabled colonial expansion into the Americas and trade routes to become established across the Atlantic Ocean and the Pacific Ocean.
The formation of trade winds involves three factors: maximum heating of the air along the equator, the cycling of air between the equator and the Earth’s poles, and a phenomenon called the Coriolis force. The air around the equator heats up, and that warm air then rises to the higher layer of the atmosphere. While air is cycling through the Hadley Cell, the Earth is spinning, causing the cycle of air to be deflected, and rather than blow north-to-south, the air instead blows east-to-west. This westward deflection of air, aided by the Earth’s rotation, is the Coriolis force, which combined with the cycling of air from the equator, creates trade winds.
Trade winds play a significant role in weather and climate. They can steer storms and help ships travel west. They also feed the Amazon Rainforest in South America with a constant supply of abundant atmospheric moisture and pull away moisture from North Africa, which in turn creates the region’s ancient deserts.
