The Atlantic wind and current system

Assembled from 21 blocks · 1 evidence · 24 related

1. Story
2. The Atlantic is not an undifferentiated sheet of water but a pair of rotating systems, and every sailing route across it is a description of them. North of the equator the north-east trades blow steadily westward in the belt roughly between 5° and 30° N, while the mid-latitude westerlies blow eastward roughly between 30° and 60° N; together they turn clockwise as the North Atlantic gyre. South of the equator the pattern mirrors, turning anticlockwise. Between the two trade belts lies the doldrums — the intertropical convergence zone — where a square-rigged ship could lie becalmed for weeks. The practical consequence is severe and asymmetric: a ship leaving Iberia can run south to the Canaries and then west on the trades almost effortlessly, but it cannot come home the same way. It must climb north out of the trade belt into the westerlies first. Prevailing wind, not distance, is what made an ocean crossable in one direction and not the other, and it is why the Atlantic opened from its eastern shore.
3. Knowledge
4. The Atlantic wind and current system
5. The Atlantic crossing (Carrera de Indias)
6. Connections
7. The Atlantic crossing (Carrera de Indias)
8. Volta do mar (the return by sea)
9. The Manila galleon (Nao de China)
10. Columbus makes landfall in the Bahamas
11. Urdaneta finds the return route across the Pacific
12. The Atlantic wind and current system
13. Volta do mar (the return by sea)
14. Seville
15. Casa de Contratación (House of Trade), Seville
16. The Columbian Exchange
17. Columbus makes landfall in the Bahamas
18. The Treaty of Tordesillas divides the ocean
19. The Casa de Contratación is established at Seville
20. Evidence
21. The standard single-volume account of Portuguese expansion: Ceuta, the African coast, the Cape route, the carreira da Índia, the Estado da Índia and the institutions that ran them. V55 verification basis: NOT consulted in this session. Boxer is a mid-twentieth-century imperial history and its framing has been substantially revised by later work, particularly on Asian agency and on the limits of Portuguese control; this pack uses it for structure, not for interpretation.