Convergence

The study of ocean and atmospheric sciences is often placed in the same boat. My late godfather, who could best be described as a brilliant eccentric, boasted that the mathematical equations were identical, it was just a question of flipping the signs from negative to positive. This week I was at a meeting in Lisbon where a Norwegian said much the same thing: the only difference between the two, he pronounced with characteristic dryness, was that the sea had “a lot more humidity”.

My godfather, who was a visiting professor at MIT, once gave a lecture on atmospheric physics entirely in Latin. As if meteorology wasn’t hard enough! He could have explained better than I can, dear reader, why I’m being bounced around like a rubber ball in the playful hands of the intertropical convergence.

In oceanography, a convergence occurs when two surface water masses meet, forcing them to sink into the depths of the ocean. An onshore wind will do the same, pushing water against the coastline and forcing it down. In the atmosphere, the area around the equator has these properties too, but in this case the air is pushed up from both sides of the tropics as the trade winds converge. This absence of wind gives rise to the doldrums, a sailor’s nightmare. When I started writing this, the wings of my little cartoon plane were humping the equator, right now the tail section is slap bang on the line of Neptune, as the big plane bounces towards Natal.

Parallel zero, in an ocean that once belonged to Portugal

When Vasco da Gama sailed for India in 1497, he took his three ships (plus a mule, the supply vessel) out from the Tagus Estuary, down to the Fortunate Islands in the usual fashion, but when he reached Cape Verde he struck west, letting the northeast trades push him across the Atlantic on a downwind run to what the Portuguese called Vera Cruz, the true cross.

Before the pilot Pero da Covilhã could make landfall in Brazil, the fleet turned prow to the south, taking advantage of the cyclonic gyre that drives the Brazil current, which flows down the east coast of South America. At the moment we’re still flying against a fifteen knot head wind, and I’m anxiously waiting for that to change as I write these lines.

To the crew of the São Gabriel, São Rafael, and the Bérrio, It seemed as if the officers had gone mad. After all, they were headed for India, to the east. And unlike the misguided Columbus, they were planning to round the Cape of Good Hope, at the tip of what is now South Africa. In The India Road, I explain why the Golfão, or great circle route, was used. By sailing west with the wind, then down the coast of Vera Cruz, the Portuguese vessels would reach the roaring forties, the westerly winds that pushed them back east into the Indian Ocean.

After that, the success of the maritime route to India depended on one word only: the Mausim. The advantage of the Golfão was that the ships need not tack all the way down the coast of the Congo, Angola, and Namibia, opposed by the southern trade winds and the merciless Benguela current. The circle route was so successful that it was used right up to the sunset of the age of sail, when the British and American tea clippers were racing each other to China in the nineteenth century.

There is no evidence, in the sense of what historians term ‘primary sources’, to support the theory I develop in The India Road, that the knowledge was already in Portuguese hands by the time Gama sailed. If the evidence existed, it would surely have been destroyed by the great earthquake of 1755, and the subsequent fire that raged through Lisbon. The blaze obliterated the original Torre do Tombo archive, and the earthquake also hit the beautiful city of Évora, destroying the secondary archives.

But the plans were laid down by King John I, the Perfect Prince, easily the most far-sighted politician Portugal has ever known, and included moving the dividing meridian of the Treaty of Tordesillas 370 leagues west of Cape Verde. The east of that line became Portuguese ocean, sanctioned by the pope himself. So the Portuguese mariners could sail their course in Portuguese waters, without being accused of impinging on Spanish sovereignty. For now, as Abraham the Astronomer would say, my hypothesis stands.

We’re just approaching Natal, one of at least two such places named by the Portuguese explorers. The other one is of course the South African province, which Gama and his men reached around Christmas 1497, five months after setting sail from Lisbon. It’s a wonderful treat to be watching my map as I write, thirty thousand feet above cities named fortress (Fortaleza), saviour (Salvador), clear hills (Montes Claros), and finally river of January (Rio de Janeiro).

I’m also filled with emotion at the way Portugal placed its mark on the world, and filled with anticipation at what I’ll find in this huge land, a nation that is by far the best example of racial integration on the planet. Sovereign debt? Yup, the world owes us big time.

One of  many things I’ll do here over the next two weeks is launch the Portuguese edition of my book in Brazil. This will happen at a Rio bookshop called Arlequim, on Saturday June 25th, shortly before I board the evening flight back home. As insurance for late delivery of books by the editor in Oporto, I’m carrying an extra twenty in my luggage. Thankfully the customs form clearly states that books need not be declared.

Ah look, the wind just changed…

The India Road QR links for smartphones: point your camera and click.

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