A chart from about 1715 shows the trade winds and other known wind patterns throughout the world. National Maritime Museum, Greenwich, London.
Why does the wind blow? The answer, surprisingly, has to do with the Sun. The equator receives much more sunlight than the poles and so is much warmer. Warm air at the equator rises and blows toward the poles while cooler air from the poles moves in below. But Earth's spin twists and deforms these air currents, producing small, consistent bands of wind that circle the planet.
Global Wind Patterns
Bands of regularly circulating winds wrap around the planet, moving warm air toward the poles and sailors across the oceans.
Hadley circulation: Warm air rises at the equator, moves partway to the poles, sinks, and returns to the equator, completing the loop.
Hadley circulation produces belts of westward blowing wind on the surface—the Trade Winds.
Ferrel circulation: In the mid-latitudes, air moves along the surface toward the poles, rises, and curls back upon itself.
Ferrel circulation creates belts of wind on the surface, blowing from west to east—the Westerlies.
Polar circulation: Cold air high in the atmosphere sinks and spreads out away from the poles.
Where's The Wind?
Sailors have long relied on regular wind patterns to carry them around the world and back again. A British chart in the exhibition from about 1715 shows the trade winds and other known wind patterns throughout the world.