The trade winds (alisios in Spanish) are persistent winds that blow from the subtropical high-pressure belts towards the equatorial low-pressure zone (the Intertropical Convergence Zone, or ITCZ). In the Northern Hemisphere, the Coriolis effect deflects them to the right, producing north-easterly trades; in the Southern Hemisphere, to the left, producing south-easterly trades. They are among the most reliable wind systems on Earth, blowing with remarkable consistency.
The name "trade winds" dates from the Age of Sail — trade from the archaic English meaning "path" or "track" (regular course), not commerce, though they were essential for transatlantic commerce. Sailing ships relied on the trades to cross from Europe and Africa to the Americas (the outbound route via the Canary Islands and Caribbean) and returned at higher latitudes using the westerlies. The Canary Islands sit directly in the north-east trade wind belt, explaining their famously pleasant, steady breeze.
Meteorologically, the trade winds are a key component of the Hadley cell — the tropical circulation loop where air rises at the ITCZ, flows poleward at altitude, descends in the subtropics (creating the subtropical highs), and returns to the equator as the trades. Variations in trade wind strength are intimately linked to El Niño and La Niña: weakening trades allow warm water to spread eastward (El Niño), while strengthening trades pile warm water westward (La Niña). Trade wind inversions — temperature inversions at 1–2 km altitude — cap cumulus cloud growth, creating the characteristic fair-weather cumulus fields of the tropics.