Below 40 degrees south there is no law, and below 50 degrees there is no God, went the sailors’ saying. The Roaring Forties blow between 40 and 50 degrees south, fed by the Hadley and Ferrel cells that carry air south from the tropics and bent eastward by the Coriolis effect into a steady westerly stream. Winds average about 22 miles per hour with gusts past 56, and unlike the Northern Hemisphere, where continents and mountains act as brakes, the Southern Ocean offers an unbroken fetch around the globe, interrupted only by Tasmania, New Zealand, and the tip of South America. Wellington, the only major city in these latitudes, earned the name Windy Welly. In 1611 Dutch explorer Hendrik Brouwer dropped south after the Cape of Good Hope and rode these winds east, cutting the voyage from Europe to Java from a year or more to five months and 24 days.

The Dutch East India Company soon made the Brouwer Route mandatory, and captains learned to run their easting down, reefing hard and surfing the swells with the storm astern, some pushing into the Furious Fifties and Screaming Sixties. The winds appear in the 1982 French film The Roaring Forties, inspired by Donald Crowhurst, and still test round the world racers. Comparing whaling era logs with satellite data, meteorologists found the peak wind belt has moved about 2.5 degrees, or roughly 170 miles, toward Antarctica, pushed by ozone loss cooling the polar stratosphere and greenhouse warming in the tropics, and it has sped up.

• Wind swells in these latitudes can reach the height of five story buildings.
• The story Easting Down by Shalimar follows a steamship captain who regrets trying to outsmart the Forties.
• Southwestern Australia around Perth is losing the winter rain fronts that now pass south over open ocean.
• Australia’s southern coast is seeing faster winter warming as cooling fronts miss the land.
• Wind farms in New Zealand and Tasmania are built to tap the Roaring Forties for power.