roar·ing for·teez | /ˈrόr-iŋ ˈfόrtiz/
The Roaring Forties are powerful westerly winds that blast the Southern Hemisphere between latitudes 40°S and 50°S. They were named by sailors during the Age of Sail,* who used these winds to aid their passage around the globe.
The Roaring Forties are caused by a combination of the Earth’s uneven heating, rotation, and top-heavy distribution of land mass. Rising hot air at the equator meets cooler air coming from the poles, creating a circular current in the atmosphere called the Hadley cell, which delivers the warm air back to lower altitudes at around 30° latitude. Between latitudes 30° and 60°, the air joins another atmospheric circulation called the Ferrel cell where it continues its low-level progress towards the polar vortex,** all the while being driven east by the Earth’s rotation. In the Northern Hemisphere, the landmasses of North America and Eurasia interrupt the wind’s flow. However, in the Southern Hemisphere, only the southern tip of South America and the islands of Tasmania and New Zealand stand in its way, allowing gale force winds of more than 200km/h and 10 metre swells to generate.
Further south, conditions do not improve with the influence of the Earth’s rotation increasing and the winds intensifying as they near the Earth’s spinning axis. Between 50°S and 60°S has been dubbed the Furious Fifties, and between 60°S and 70°S, it’s the Screaming Sixties. Below 40°S, sailors used to say “there is no law”. Below 50°S, they said “there is no God!”
For sailors caught in the horse latitudes at around 30° north and south of the equator, a lack of wind is the more likely problem. There are competing theories about the origins of the term. It may be related to the idiom “to beat a dead horse” or to the practice of ships riding strong currents as a person may ride a powerful horse. The darkest theory suggests that, becalmed and running out of water, desperate crews were forced to throw their cargo of horses overboard.
* The Age of Sail is the period from mid 16th to mid 19th centuries when sailing ships dominated trade, travel, and naval warfare.
** The polar vortex refers to large areas of cold air that rotate around the Earth’s polar regions.
Introduction Aeolian Alpenglow
Benthos Crepuscular Crispate Crown shyness
Desire lines Dreich Endragoned Edgelands
Frondescence Fumarole Gluggaveður Gossamer
Karst Komorebi Lawrence Long acre
Machair Monkey’s wedding Moonglade
Psithurism Quartz Rakuyou Roaring forties
Snag Soft estate Specular, diffuse and pellucid
Spoondrift Steam fog Swash zone Sylvan