The winds that blow the Horn

There are many feared and stormy headlands on the seven seas

There are many feared and stormy headlands on the seven seas. Cape of Good Hope is one, Hatteras another, and the Leeuwin Cape, on the south-west corner of Australia, a third.

Even our own Cape Clear is known to sailors as one that must be "doubled", as they say, with utmost caution.

But the most turbulent cape of all is that at the tip of South America, to the extent that in olden times no seaman was a real ` `salt" unless he had been "three times around the Horn".

And, as the old sea shanty records, many were those who failed to pass this acid test:

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All around old Cape Horn, Ships of the line, ships of the morn;

Some who wish they'd never been born;

They are the ghosts of Cape Horn.

The secret of Cape Horn's storminess can be traced to the differing topography of the northern and southern hemispheres. In both halves of the globe, the mid-latitude winds are predominantly westerly, but in our part of the world the smooth eastward flow of the atmosphere is distorted by a number of very large mountain ranges - the Rockies, the Alps and the Himalayas - which cause it to meander in an undulating stream.

Moreover, the large temperature differences which develop at times between the great land areas of the northern hemisphere and the oceans that surround them periodically distort the flow.

The antipodes, however, are largely free of these distorting complications. The wind patterns, therefore, are simpler and more dependable, providing westerlies steadier and more consistent than their northern counterparts.

In particular, a very strong and persistent band of winds stretches like a ribbon around the world in the zone between 40 and 50 degrees south; mindful of the geographical position, and the periodic ferocity of these local winds, sailors of old christened these regions the Roaring Forties.

The southern tip of South America is the only piece of land of consequence that juts southwards into this troubled zone. Cape of Good Hope stops at a modest 35 degrees south, as indeed does Cape Leeuwin, but the Horn is like a great barrier thrust into this tremendous sweep of winds that runs otherwise unfettered right around the world.

The turbulent eddies that occur as the winds of the Roaring Forties negotiate this unexpected blockage, and the chaotic seas that arise as the massive wind-driven waves crush past the barrier, combine to give Cape Horn its fearsome reputation.