The westerlies and trade winds

The Westerlies, anti-trades,^[1] or Prevailing Westerlies, are prevailing winds in the middle latitudes between 30 and 60 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east,^[2] and steer extratropical cyclones in this general manner. Tropical cyclones which cross the subtropical ridge axis into the Westerlies recurve due to the increased westerly flow. The winds are predominantly from the southwest in the Northern Hemisphere and from the northwest in the Southern Hemisphere.

The Westerlies are strongest in the winter hemisphere and times when the pressure is lower over the poles, while they are weakest in the summer hemisphere and when pressures are higher over the poles. The Westerlies are particularly strong, especially in the southern hemisphere, where there is less land in the middle latitudes to cause the flow pattern to amplify, or become more north-south oriented, which slows the Westerlies down. The strongest westerly winds in the middle latitudes can come in the Roaring Forties, between 40 and 50 degrees latitude. The Westerlies play an important role in carrying the warm, equatorial waters and winds to the western coasts of continents, especially in the southern hemisphere because of its vast oceanic expanse.

Behavior[link]

If the Earth were a non-rotating planet, solar heating would cause winds across the mid-latitudes to blow in a poleward direction, away from the subtropical ridge. However, the Coriolis effect caused by the rotation of Earth causes winds to steer to the right of what would otherwise be expected across the Northern Hemisphere, and left of what would be expected in the Southern Hemisphere.^[3] This is why winds across the Northern Hemisphere tend to blow from the southwest, but they tend to be from the northwest in the Southern Hemisphere.^[4] When pressures are lower over the poles, the strength of the Westerlies increases, which has the effect of warming the mid-latitudes. This occurs when the Arctic oscillation is positive, and during winter low pressure near the poles is stronger than it would be during the summer. When it is negative and pressures are higher over the poles, the flow is more meridional, blowing from the direction of the pole towards the equator, which brings cold air into the mid-latitudes.^[5]

Throughout the year, the Westerlies vary in strength with the polar cyclone. As the cyclone reaches its maximum intensity in winter, the Westerlies increase in strength. As the cyclone reaches its weakest intensity in summer, the Westerlies weaken.^[6] An example of the impact of the Westerlies is when dust plumes, originating in the Gobi desert combine with pollutants and spread large distances downwind, or eastward, into North America.^[7] The Westerlies can be particularly strong, especially in the Southern Hemisphere, where there is less land in the middle latitudes to cause the progression of west to east winds to slow down. In the Southern hemisphere, because of the stormy and cloudy conditions, it is usual to refer to the Westerlies as the Roaring Forties, Furious Fifties and Shrieking Sixties according to the varying degrees of latitude.^[8]

Impact on ocean currents[link]

Benjamin Franklin's map of the Gulf Stream

Due to persistent winds from west to east on the poleward sides of the subtropical ridges located in the Atlantic and Pacific oceans, ocean currents are driven in a similar manner in both hemispheres. The currents in the Northern Hemisphere are weaker than those in the Southern Hemisphere due to the differences in strength between the Westerlies of each hemisphere.^[9] The process of western intensification causes currents on the western boundary of an ocean basin to be stronger than those on the eastern boundary of an ocean.^[10] These western ocean currents transport warm, tropical water polewards toward the polar regions. Ships crossing both oceans have taken advantage of the ocean currents for centuries.

The Antarctic Circumpolar Current (ACC), or the West Wind Drift, is an ocean current that flows from west to east around Antarctica. The ACC is the dominant circulation feature of the Southern Ocean and, at approximately 125 Sverdrups, the largest ocean current.^[11] In the northern hemisphere, the Gulf Stream, part of the North Atlantic Subtropical Gyre, has led to the development of strong cyclones of all types at the base of the Westerlies, both within the atmosphere and within the ocean.^{[12][13][14][15]} The Kuroshio (Japanese for "Black Tide") is a strong western boundary current in the western north Pacific Ocean, similar to the Gulf Stream, which has also contributed to the depth of ocean storms in that region.

Extratropical cyclones[link]

A fictitious synoptic chart of an extratropical cyclone affecting the UK and Ireland. The blue arrows between isobars indicate the direction of the wind, while the "L" symbol denotes the centre of the "low". Note the occluded, cold and warm frontal boundaries.

An extratropical cyclone is a synoptic scale low pressure weather system that has neither tropical nor polar characteristics, being connected with fronts and horizontal gradients in temperature and dew point otherwise known as "baroclinic zones".^[16]

The descriptor "extratropical" refers to the fact that this type of cyclone generally occurs outside of the tropics, in the middle latitudes of the planet, where the Westerlies steer the system generally from west to east. These systems may also be described as "mid-latitude cyclones" due to their area of formation, or "post-tropical cyclones" where extratropical transition has occurred,^[16][17] and are often described as "depressions" or "lows" by weather forecasters and the general public. These are the everyday phenomena which along with anti-cyclones, drive the weather over much of the Earth.

Although extratropical cyclones are almost always classified as baroclinic since they form along zones of temperature and dewpoint gradient, they can sometimes become barotropic late in their life cycle when the temperature distribution around the cyclone becomes fairly uniform along the radius from the center of low pressure.^[18] An extratropical cyclone can transform into a subtropical storm, and from there into a tropical cyclone, if it dwells over warm waters and develops central convection, which warms its core and causes temperature and dewpoint gradients near their centers to fade.^[19]

Interaction with tropical cyclones[link]

Storm track of Typhoon Ioke, showing recurvature off the Japanese coast in 2006

When a tropical cyclone crosses the subtropical ridge axis, normally through a break in the high-pressure area caused by a system traversing the Westerlies, its general track around the high-pressure area is deflected significantly by winds moving towards the general low-pressure area to its north. When the cyclone track becomes strongly poleward with an easterly component, the cyclone has begun recurvature, entering the Westerlies.^[20] A typhoon moving through the Pacific Ocean towards Asia, for example, will recurve offshore of Japan to the north, and then to the northeast, if the typhoon encounters southwesterly winds (blowing northeastward) around a low-pressure system passing over China or Siberia. Many tropical cyclones are eventually forced toward the northeast by extratropical cyclones in this manner, which move from west to east to the north of the subtropical ridge. An example of a tropical cyclone in recurvature was Typhoon Ioke in 2006, which took a similar trajectory.^[21]

References[link]

See also[link]

• Polar Easterlies
• West wind
• Ferrel cell

Bill Frisell
Background information
Birth name	William Richard Frisell
Born	(1951-03-18) March 18, 1951 (age 61) Baltimore, Maryland United States
Genres	Jazz, jazz fusion, grindcore, americana, world, experimental rock, soundtrack
Occupations	Musician, composer, arranger
Instruments	Electric guitar, bass, clarinet, tenor saxophone
Years active	1973-present
Labels	Savoy Label Group, Nonesuch, ECM
Website	www.billfrisell.com
Notable instruments
Fender Telecaster, Steve Klein Electric

William Richard "Bill" Frisell (born March 18, 1951) is an American guitarist, composer and arranger.

One of the leading guitarists in jazz since the late 1980s, Frisell's eclectic music touches on progressive folk, classical music, country music, noise and more. He is known for using an array of effects to create unique sounds from his instrument.

Biography[link]

Early life and career[link]

Frisell was born in Baltimore, Maryland, but spent most of his youth in the Denver, Colorado area. He studied clarinet with Richard Joiner of the Denver Symphony Orchestra as a youth, graduated from Denver East High School, and went to the University of Northern Colorado to study music.

His original guitar teacher in the Denver-Aurora metropolitan area was Dale Bruning, with whom Frisell released the 2000 duo album Reunion. After graduating from Northern Colorado, where he studied with Johnny Smith, Frisell went to the Berklee College of Music in Boston where he studied with Jon Damian and Jim Hall.

The ECM Records years[link]

Frisell's major break came when guitarist Pat Metheny was unable to make a recording session, and recommended Frisell to Paul Motian who was recording Psalm (1982) for ECM Records.^[1] Frisell became ECM's in-house guitar player, and worked on several albums, most notably Jan Garbarek's 1981 Paths, Prints. Frisell's first solo release was In Line featured solo guitar and duets with bassist Arild Andersen.

New York City era[link]

Frisell's first group to receive much acclaim was a quartet with Kermit Driscoll on bass, Joey Baron on drums, and Hank Roberts on cello (later slimmed down to a trio when Roberts left). Many other albums with larger ensembles were recorded with this group as the core.

In the 1980s Frisell lived in New York City and was an active participant in the city's music scene. He forged an early partnership with John Zorn—including as a member of quick-change band Naked City—and performed or recorded with many others. He also became known for his work in drummer Paul Motian's trio, along with saxophonist Joe Lovano.

The Seattle years[link]

In 1988 Frisell left New York City and moved to Seattle, Washington.^[2] In the early 1990s Frisell made two of his best-reviewed albums: first, Have a Little Faith, an ambitious survey of Americana of all stripes, from Charles Ives and Aaron Copland (the entirety of Billy the Kid) to John Hiatt (the title song), Bob Dylan ("Just Like a Woman") and Madonna (a lengthy, psychedelic rock-tinged version of "Live to Tell"); and second, This Land, a complementary set of originals. During this time he performed with many musicians, including the more up and coming, such as Douglas September on album 10 Bulls. He also branched out by performing soundtracks to silent films of Buster Keaton with his trio, and contributed to Ryuichi Sakamoto's album Heartbeat.

In the mid-1990s, Frisell disbanded his trio. He continued the trend marked by Have a Little Faith by more explicitly incorporating elements of bluegrass and country music into his music. His friendship with Gary Larson led him to provide music for the TV version of The Far Side^[3] (released on the album Quartet along with music written for Keaton's Convict 13). Since the late 1990s Bill Frisell has lived in Bainbridge Island, Washington, near Seattle.

2000s[link]

Several of Frisell's songs, including his recording of "Over the Rainbow" and "Coffaro's Theme", were featured in the movie Finding Forrester (2000).

In 1999, Frisell was commissioned by the Walker Art Center in Minneapolis, Minnesota to compose Blues Dream, which he premiered on November 15, 1999. He later recorded the work for a 2001 release on Nonesuch.

Also in 1999, he released The Sweetest Punch which featured a seven-piece jazz ensemble reworking the tunes written and recorded by Elvis Costello and Burt Bacharach on Painted from Memory.^[4]

Between 2003 and 2005 Frisell acted as musical director for Century of Song, a series of concerts at the German arts festival RuhrTriennale (produced by Lee Townsend). Frisell invited artists including Rickie Lee Jones, Elvis Costello, Suzanne Vega, Arto Lindsay, Loudon Wainwright III, Vic Chesnutt, Van Dyke Parks, Buddy Miller, Ron Sexsmith and Chip Taylor to perform their favorite songs in new arrangements.

In 2003, Frisell's The Intercontinentals was nominated for a Grammy award; he won the 2005 Grammy Award for Best Contemporary Jazz Album for his album Unspeakable. His 2008 album, History, Mystery was nominated for a 2009 Grammy award for Best Jazz Instrumental Album, Individual or Group. Frisell was also a judge for the 6th annual Independent Music Awards to support independent artists' careers.^[5]

Frisell has united with Matt Chamberlain, Tucker Martine, and Lee Townsend in the Floratone band, and they have released an album on Blue Note (2007), featuring guest performance of Viktor Krauss, Ron Miles, Eyvind Kang.

In 2008, Frisell performed as a featured guest on Earth's album The Bees Made Honey in the Lion's Skull.

In 2009, Frisell featured in a duet rendition of Leonard Cohen's "Hallelujah" with singer-songwriter, Sam Shrieve. The recording was released on Shrieve's debut album Bittersweet Lullabies.

In 2010, Frisell started working with the Savoy Jazz label and released Beautiful Dreamers in August 2010, then a second release of Sign of Life in April 2011. Also, on January 25, 2011, Bill Frisell and Vinicius Cantuária released Lágrimas Mexicanas on the E1 label.

In September 2011, Frisell released All We Are Saying, a full-length offering of his interpretations of John Lennon's music. Frisell's quintet includes violinist Jenny Scheinman, pedal steel and acoustic guitarist Greg Leisz, bassist Tony Scherr, and drummer Kenny Wollesen.

Selected discography[link]

Frisell performing in 2010

Albums[link]

References[link]

External links[link]

Wikimedia Commons has media related to: Bill Frisell

• Official site
• Bill Frisell on NoneSuch Records