Alfred Crosby in Ecological Imperialism writes that the sailors of Europe who were to later discover American and circumnavigate the globe “went to primary school in the Mediterranean and to secondary school…:” in what he calls “the Mediterranean Atlantic”
From this paper, The Western Sea :Atlantic History before Columbus by Donna A. Vinson which I found with google:
A second phase of late medieval exploration of the Atlantic is characterized by the
discovery and assimilation of the major eastern Atlantic Archipelagos: the Canaries or
“Fortunate Isles” (between 1312 and 1335), Madeira (between 1339 and 1425), and the
Azores (after 1427).
Mariners took what they learned about the winds and currents from navigating the eastern Atlantic islands, and extrapolated that knowledge to understand what they experienced when they ventured across the Atlantic and beyond.
The technique Portuguese mariners learned was called Volta do mar
Used to navigate the Atlantic
for example Christopher Columbus would never have returned from the Americas without applying the volta do mar by sailing northwards from the Caribbean through the Horse Latitudes to catch the prevailing mid-latitude westerlies.
And later the Pacific
the fleet split up, some heading south, but Urdaneta reasoned that the trade winds of the Pacific might move in a gyre as the Atlantic winds did. If, in the Atlantic, ships made the Volta do mar to the west to pick up winds that would bring them back from Madeira, then, he reasoned, by sailing far to the north before heading east, he would pick up trade winds to bring him back to the west coast of North America. Though he sailed to 38 degrees North before turning east, his hunch paid off, and he hit the coast near Santa Catalina Island, California, then followed the coast south to Acapulco.
this should be “pick up the westerlies”
Crosby mentions that the usage of the word “trade” in the phrase “trade winds” is an obsolete usage of the word meaning course or track. In that sense the term “trade route” would be redundant.
Of course the term “trade” is still used today in shipping. Vessels get assigned to various trades, US East Coast - N. Europe or West Coast - Asia etc.