thumb|230px|Roaring Forties as they contract towards southern Australia (observed in September 1895).

The Roaring Forties are strong westerly winds that occur in the Southern Hemisphere, generally between the latitudes of 40° and 50° south. The strong eastward air currents are caused by the combination of warm air being displaced upward from the Equator towards the South Pole, Earth's rotation, and the scarcity of landmasses to serve as windbreaks at those latitudes. On average, winds speeds in the region measure around with peak gusts of over .

Similar winds that occur at more southerly latitudes are called the Furious Fifties and the Shrieking or Screaming Sixties, with the greatest winds near the former. These prevailing winds have been moving farther south over time due to climate change.

Use for sailing

thumb|310px|left|The [[Clipper Route, taken by ships sailing from Europe to Australia in order to take advantage of the Roaring Forties]]

During the Age of Sail, ships travelling from Europe to the East Indies or Australasia would sail down the west coast of Africa and round the Cape of Good Hope to use the Roaring Forties to speed their passage across the Indian Ocean, then on the return leg, continue eastwards across the Pacific Ocean and south of Cape Horn before sailing up the east coast of the Americas to home.

It was first used by Dutch explorer Hendrik Brouwer in his Brouwer Route, discovered in 1611, which effectively halved the duration of the trip from Europe to Java, down from a year or more to 5 months and 24 days. "To run the easting down" was the phrase used to describe the fast passages achieved in the Roaring Forties.

The story Easting Down by Shalimar describes the events that befall a steamship unwisely venturing into the Roaring Forties to achieve a faster passage.

In 1982, French filmmaker Christian de Chalonge directed The Roaring Forties, a drama movie inspired by the death of Donald Crowhurst, a British sailor who perished in the 1969 Sunday Times Golden Globe Race.

See also

  • Antarctic Circumpolar Current
  • Clipper route
  • Doldrums
  • Antarctic oscillation
  • Southerly buster
  • Subtropical ridge
  • Winds in the Age of Sail

References