Roaring Forties

{{Short description|Southern Hemispheric westerly winds}} {{about||the Peter Hammill album|Roaring Forties (album)|the painting|Roaring Forties (Frederick Judd Waugh)|the electric company|Roaring 40s}} {{Distinguish|Roaring Twenties}} {{Use Australian English|date=April 2018}} {{Use dmy dates|date=April 2018}} [[File:FMIB 36792 Coup de Vent d'Ouest, au Sud de l'Australie (4 September 1895).jpeg|thumb|230px|Roaring Forties as they contract towards southern Australia (observed in September 1895).<ref name="theguardian">{{cite web |url=https://www.theguardian.com/world/2014/may/12/roaring-forties-shift-south-means-more-droughts-for-southern-australia |title=Roaring Forties' shift south means more droughts for southern Australia |first=Helen|last=Davidson |website=The Guardian |date=12 May 2014 |url-status=live |archive-url=https://web.archive.org/web/20230718080636/https://www.theguardian.com/world/2014/may/12/roaring-forties-shift-south-means-more-droughts-for-southern-australia |archive-date= Jul 18, 2023 }}</ref>]]

The '''Roaring Forties''' are strong westerly winds that occur in the Southern Hemisphere, generally between the latitudes of 40° and 50° south.<ref name=ABCScience>{{cite web |last=Catchpole|first=Heather |date=20 September 2007 |title=Roaring forties |website=ABC Science |publisher=Australian Broadcasting Corporation |series=In Depth |url=https://abc.net.au/science/articles/2007/09/20/2038604.htm |access-date=2011-04-07}}</ref> 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 {{convert|10|m/s|mph|abbr=on}}<ref name="Frierson2024"/><ref>{{cite web|url=https://seos-project.eu/oceancurrents/oceancurrents-c02-p05.html|title=2. The Roaring Forties and the Antarctic Circumpolar Current|access-date=13 October 2025|publisher=Science Education through Earth Observation for High Schools (SEOS)}}</ref> with peak gusts of over {{convert|25|m/s|mph|abbr=on}}.<ref name="Frierson2024"/>

The Roaring Forties were a major aid to ships sailing the Brouwer Route from Europe to the East Indies or Australasia during the Age of Sail, and in modern times are favoured by yachtsmen on round-the-world voyages and competitions. The boundaries of the Roaring Forties are not consistent: the wind-stream shifts north or south depending on the season. The strong and continuous winds in the Roaring Forties make this zone advantageous for wind power in places such as New Zealand and Tasmania.<ref> [https://www.roaring40s.co.nz/ Wind turbine] </ref>

Similar winds that occur at more southerly latitudes are called the '''Furious Fifties'''<ref>{{Citation | author1=Tkalčić, Hrvoje | author2=Eakin, Caroline | author3=Coffin, M F | author4=Rawlinson, Nick | author5=Stock, Joann Miriam | title=Deploying a submarine seismic observatory in the Furious Fifties | publication-date=2022-09-27 | publisher=American Geophysical Union | url=https://trove.nla.gov.au/work/251967122 | access-date=7 February 2024}}</ref> and the '''Shrieking''' or '''Screaming Sixties''',<ref>{{cite news |url=http://nla.gov.au/nla.news-article127073968 |title=Perilous Tow for Polar Ship |newspaper=The News |location=Adelaide |volume=48 |issue=((7,343)) |date=14 February 1947 |access-date=7 February 2024 |page=5 |via=National Library of Australia}}</ref> with the greatest winds near the former. These prevailing winds have been moving farther south over time due to climate change.<ref name="Frierson2024"/>

==Dynamics== [[File:Turbid Waters Surround New Zealand.jpg|thumb|The Roaring Forties in the Cook Strait of New Zealand produce high waves, and erode the shore as shown in this image]]

{{See also|Prevailing winds|Atmospheric circulation}} Hot air rises at the Equator and is pushed towards the poles by cooler air travelling towards the Equator (an atmospheric circulation feature known as the Hadley Cell).<ref name=ABCScience/> At about 30°S, the outward-travelling air sinks to lower altitudes, and continues toward the poles closer to the ground (the Ferrel Cell), then rises up again from about 60°S as the air joins the Polar vortex.<ref name=ABCScience/> This travel in the 30°–60°S zone combines with the rotation of the earth to move the air currents from west to east, creating westerly winds.<ref name=ABCScience/>

The large tracts of open ocean south of 40°S are interrupted only by Tasmania, New Zealand, and the southern part of South America. These relatively small obstructions, which are themselves bordered by large tracts of open water along their southern shores, allow high wind speeds to develop – much higher than near 40°N, where the large continents of Eurasia and North America impede the flow of circum-planetary westerly winds.<ref name=ABCScience/> The latitude ranges for the ''Roaring Forties'' and similar winds are not consistent: all shift towards the South Pole in the southern summer, and towards the Equator in the southern winter.<ref name=ABCScience/> Wellington, the capital of New Zealand, is known as "Windy Welly" because it is one of the few cities situated in these gusty latitudes.<ref name="surfer">{{cite web |title=What are the Roaring Forties? |url=https://www.surfertoday.com/environment/what-are-the-roaring-forties |website=Surfer Today |access-date=18 December 2023 |archive-url=https://web.archive.org/web/20230925093259/https://www.surfertoday.com/environment/what-are-the-roaring-forties |archive-date=25 September 2023 |url-status=live}}</ref>

==Use for sailing== [[File:ClipperRoute.png|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,<ref name="OxfordCompanion">{{cite encyclopedia |editor1-last=Dear |editor1-first=I.C.B. |editor2-last=Kemp |editor2-first=Peter |year=2007 |title=Roaring Forties |chapter=The Oxford Companion to Ships and the Sea |encyclopedia=The Oxford Companion to Ships and the Sea |department=Oxford Reference Online |publisher=Oxford University Press |isbn=978-0-19-860616-1 |oclc=60793921 |url=http://www.oxfordreference.com/views/ENTRY.html?subview=Main&entry=t225.e2007 |access-date=14 April 2011}}</ref> 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. {{sfnp |Estensen |1998 |p=126}} "To run the easting down" was the phrase used to describe the fast passages achieved in the Roaring Forties.<ref name="OxfordCompanion" />

Modern round-the-world sailors also take advantage of the Roaring Forties to speed travel times, in particular those involved in record attempts or races.<ref name=OxfordCompanion/> An old sailor's expression goes, "below 40 degrees south, there is no law; below 50 degrees, there is no God."<ref name="surfer" />

==Impact of pollution== [[File:The cruise of the "Antarctic" to the South Polar regions - no-nb digibok 2008121110001-65.jpg|thumb|240px|A drawing of a square rigged ship with shortened sail passing through the Roaring Forties]]

The peak band of winds has moved approximately 2.5 degrees south in the late 20th century, from a combination of human-induced ozone depletion and greenhouse gas emissions. This has caused faster warming across much of southern Australia (especially in winter) and less rainfall in Western Australia.<ref name="theguardian"/> Wind speeds between 50 and 60 degrees have also increased.<ref name="Frierson2024">{{cite book|url=https://uw.pressbooks.pub/fundamentalsofclimatechange/chapter/roaring-poleward/|via=University of Washington|title=Fundamentals of Climate Change|chapter=11. Roaring Poleward|last1=Frierson|first1=Dargan M. W.|year=2024}}</ref>

==Popular culture== The story ''Easting Down'' by ''Shalimar'' describes the events that befall a steamship unwisely venturing into the Roaring Forties to achieve a faster passage.<ref>{{Cite book | title = The Oxford book of sea stories | year = 2002 | editor-last = Tanner | editor-first = Tony | publication-date = 2002 | orig-date = 1994 | publisher = Oxford University Press | isbn = 0-19-280370-0 | oclc = 1200552340 | url = https://archive.org/details/oxfordbookofseas0000unse }}</ref>

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.<ref>{{Cite web |title=Les 40e RUGISSANTS (1982) |url=http://ftvdb.bfi.org.uk/sift/title/324109 |archive-url=https://web.archive.org/web/20090207074123/http://ftvdb.bfi.org.uk/sift/title/324109 |archive-date=Feb 7, 2009 |website=BFI {{!}} Film & TV Database}}</ref>

==References== {{reflist|25em}}

{{cite book |last=Estensen |first=Miriam |year=1998 |title=Discovery: The Quest for the Great South Land |publisher=Allen & Unwin |location=St Leonards, NSW, Australia |isbn=1864484977 }}

==External links== {{wiktionary}} * {{cite web |title=Clipper ships in heavy weather |publisher=University of Maryland, Baltimore County |place= Catonsville, MD |access-date=2021-05-14 |url=http://userpages.umbc.edu/~dbasha1/clipper.html#Heavy%20Weather |archive-url=https://web.archive.org/web/20170312062522/http://userpages.umbc.edu/~dbasha1/clipper.html#Heavy%20Weather |archive-date=12 March 2017}}

Category:Winds Category:Maritime history of Australia Category:Age of Sail Category:Circles of latitude