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Trade winds

earth science Maturity 9-11 Next article →

Trade winds are permanent winds that blow near the middle of our planet.

Map prevailing winds on earth
Map prevailing winds on earth

They flow from east to west in the equatorial region. In the Northern Hemisphere, they mostly blow from the northeast. In the Southern Hemisphere, they blow from the southeast. These winds are part of a larger way the air moves. This system is called a Hadley cell.

Earth Global Circulation
Earth Global Circulation

Within this system, air flows toward the equator near the ground. Higher up, the air moves toward the poles.

These winds work through a specific set of steps. Air begins to descend near the 30° marks in both hemispheres. This creates subtropical ridges, which are areas of high pressure. This sinking air is quite dry because it lost its moisture earlier. As this air moves toward the equator, the Coriolis effect pushes it west.

Earth Global Circulation
Earth Global Circulation

This movement creates the steady trade winds we see. The winds eventually meet at a calm area called the Doldrums. This zone is also known as the Intertropical Convergence Zone.

For hundreds of years, captains used these winds to sail across oceans.

Spanish Galleon
Spanish Galleon

In the 15th century, Portuguese sailors recognized how important these winds were. They called the pattern the volta do mar, which means "turn of the sea." Sailors had to learn how to use the winds to reach places like South Africa. In 1565, Andres de Urdaneta discovered the full wind circulation in the Pacific. Later, between 1847 and 1849, Matthew Fontaine Maury made charts of these winds.

Edmond Halley's map of the trade winds, 1686
Edmond Halley's map of the trade winds, 1686

These maps helped people understand the world's oceans.

Trade winds affect the weather and the land in many ways. They can steer tropical storms across the Atlantic and Pacific oceans. These winds also create a trade wind inversion. This is a layer of warm air that stops clouds from growing too tall.

Earth Global Circulation
Earth Global Circulation

When the trade winds are weak, more rain falls on places like Central America. The winds also change based on the season. They are usually stronger during the winter months. They can also get stronger when the Arctic oscillation is in a warm phase.

These winds act like a giant conveyor belt for the world. They carry huge amounts of dust from the Sahara desert across the Atlantic.

Map prevailing winds on earth
Map prevailing winds on earth

This dust is full of nutrients like nitrate and phosphate. This helps the soil in the Amazon grow better. However, the dust can also change the look of the sky. It can make the sky look white instead of blue. This can even lead to very red sunsets in places like Florida.

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🖼️ Images & Media (4)
File:Map prevailing winds on earth.png
Map prevailing winds on earth.png
File:Spanish Galleon.jpg
Spanish Galleon.jpg
File:Edmond Halley's map of the trade winds, 1686.jpg
Edmond Halley's map of the trade winds, 1686.jpg
File:Earth Global Circulation.svg
Earth Global Circulation.svg
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