William Ferrel


William Ferrel

:"This page is about the meteorologist; for the comedian, see Will Ferrell."William Ferrel (1817 – 1891), an American meteorologist, developed theories which explained the mid-latitude atmospheric circulation cell in detail, and it is after him that the Ferrel cell is named.

Ferrel demonstrated that it is the tendency of rising warm air, as it rotates due to the Coriolis effect, to pull in air from more southerly, warmer regions and transport it poleward. It is this rotation which creates the complex curvatures in the frontal systems separating the cooler Arctic air to the north from the warmer continental tropical air to the south.

Ferrel improved upon Hadley's theory by recognizing an until then overlooked mechanism. This is a quote from his first paper:

The fourth and last force arises from the combination of a relative east or west motion of the atmosphere with the rotatory motion of the earth. In consequence of the atmosphere's revolving on a common axis with that of the earth, each particle is impressed with a centrifugal force, which, being resolved into a vertical and a horizontal force, the latter causes it to assume a spheroidal form conforming to the figure of the earth. But, if the rotatory motion of any part of the atmosphere is greater than that of the surface of the earth, or, in other words, if any part of the atmosphere has a relative eastern motion with regard to the earth's surface, this force is increased, and if it has a relative western motion, it is diminished, and this difference gives rise to a disturbing force which prevents the atmosphere being in a state of equilibrium, with a figure conforming to that of the earth's surface, but causes an accumulation of the atmosphere at certain latitudes and a depression at others, and the consequent difference in the pressure of the atmosphere at these latitudes very materially influences its motions. [Ferrel, W. 'An essay on the winds and the currents of the Oceans', Nashville journal of medicine and surgery, 1856.
* Wikisource:
* Original source: [http://www.aos.princeton.edu/WWWPUBLIC/gkv/history/ferrel-nashville56.pdf An essay on the winds and the currents of the Oceans] (PDF-file 1.4 MB, scanned images of entire pages.)
]

Hadley's erroneous reasoning had been in terms of a tendency to conserve linear momentum, as air mass travels from north to south or from south to north. Ferrel recognized that in meteorology and oceanography what needs to be taken into account is a tendency of an air mass that is in motion relative to the earth to conserve the "angular" momentum (of its angular velocity with respect to the earth's axis).

See also

* Ferrel's law
* Air mass

External links

* [http://www.history.noaa.gov/giants/ferrel.html NOAA biographical info]
* [http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Ferrel.html MacTutor biography]


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  • William Ferrel — Naissance 29 janvier 1817 Pennsylvanie (États Unis) Décès 18 septembre 1891 Virginie Occidentale (États Unis) Champs Météorologie …   Wikipédia en Français

  • William Ferrel — (* 29. Januar 1817 im Bedford , heute Fulton County, Pennsylvania, USA; † 18. September 1891 in Martinsburg, West Virginia) war ein US amerikanischer Meteorologe. Ferrel entwickelte Theor …   Deutsch Wikipedia

  • Ferrel's law — Ferrel s law, named after William Ferrel, is a natural law in physical geography and meteorology.If a body moves in any direction on the earth s surface, there is a deflecting force arising from the earth s rotation, which deflects it to the… …   Wikipedia

  • Ferrel cell — ▪ meteorology       model of the mid latitude segment of the Earth s wind circulation, proposed by William Ferrel (Ferrel, William) (1856). In the Ferrel cell, air flows poleward and eastward near the surface and equatorward and westward at… …   Universalium

  • Ferrel’s law — a body moving in any direction over Earth’s surface will tend to be deflected to right in Northern Hemisphere and left in Southern Hemisphere for American meteorologist William Ferrel …   Eponyms, nicknames, and geographical games

  • Ferrel's law — /fɛrəlz ˈlɔ/ (say feruhlz law) noun the law that all bodies moving on the earth s surface are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. {named after William Ferrel, 1817–91, US meteorologist} …   Australian English dictionary

  • ferrel's law — ˈferəlz noun Usage: usually capitalized F Etymology: after William Ferrel died 1891 American meteorologist, its formulator : a statement in meteorology: a wind in any direction tends to deflect to the right in the northern hemisphere and to the… …   Useful english dictionary

  • Ferrel — Ferrel, William, Meteorolog, geb. 29. Jan. 1817 auf einer Farm in Virginia, gest. 18. Sept. 1891 in Maywood (Kansas), war zuerst Lehrer in Tennessee, trat 1857 in die Redaktion des »Nautical Almanac«, wurde 1867 in die Küstenvermessungsbehörde zu …   Meyers Großes Konversations-Lexikon

  • Ferrel —   [ ferəl], William, amerikanischer Meteorologe, * Fulton County (Pennsylvania) 29. 1. 1817, ✝ Maywood (Kans.) 18. 9. 1891; erforschte die physikalischen Gesetze der Luft und Meeresströmungen der Erde und den Einfluss der Erdrotation auf die… …   Universal-Lexikon

  • Ferrel , William — (1817–1891) American meteorologist Born in Fulton County, Pennsylvania, Ferrel moved with his family to farm in West Virginia in 1829. Receiving only the most rudimentary education, his early scientific knowledge was entirely self acquired.… …   Scientists