ch10 - Jon Ahlquist 12/10/2006 MET1010 Intro to the...

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Unformatted text preview: Jon Ahlquist 12/10/2006 MET1010 Intro to the Atmosphere 1 Chapter 10: Global Wind Systems Three-cell model of atmospheric circulation Intertropical Convergence Zone (ITCZ) Typical surface wind patterns Upper-level pressure and winds Climatological sea-level pressure and surface winds Role of Bermuda High in American history Jet streams Dishpan experiments Computer modeling of the atmospheric circulation Ocean currents Upwelling El Nio General Circulation (p. 256) General circulation refers to average, large-scale flow of the atmosphere. General circulation is summarized in figure on next slide. Lots of information there! Will be followed by 3 more slides that discuss Average vertical motions Intertropical Convergence Zone near equator Average surface winds Fig. 10.2, p. 257 3-cell Model (pp. 257-258) 3 cells in each hemisphere; see next slide. Hadley cell: Hot air rises at equator, moves poleward in upper troposphere, and sinks at 30 latitude where it is cooler, then back to equator in lower troposphere. Polar cell: Very cold air sinks at poles, moves equatorward in lower troposphere, rises at 60 latitude where it is warmer, and then poleward in upper troposphere. Ferrel cell: Consistent with Hadley and Polar cells to its sides, air sinks near 30 latitude, moves poleward in lower troposphere in middle latitudes, rises near 60 latitude, and then equatorward in upper troposphere. Intertropical Convergence Zone (ITCZ) p. 258 The 2 Hadley cells meet at the intertropical convergence zone (ITCZ) near the equator. Region also called the doldrums. ITCZ is N of equator during July, S of equator during December Visible as line of thunderstorms in satellite pictures. Satellite picture below shows ITCZ west of the Americas (Picture from http://VisibleEarth.nasa.gov ) What is the season? ITCZ Typical surface wind patterns (fig. 10.2, p. 257) Weak winds where pressure gradient weak, at belt where circulation cells meet the doldrums near equator where the 2 Hadley cells meet Horse latitudes near 30 latitude where Hadley and Ferrel cells meet Low pressure to left/right of wind in N/S Hemisphere, so: Tropical easterlies and mid-latitude westerlies Jon Ahlquist 12/10/2006 MET1010 Intro to the Atmosphere 2 Upper-level Pressure & Winds (pp. 262-266) Upper-level pressure distribution is determined by temperature. (See fig. 8.2c, p. 193.) Upper-level pressure is high where warm, low where cold....
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This note was uploaded on 07/21/2011 for the course MET 1010 taught by Professor Staff during the Fall '08 term at FSU.

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ch10 - Jon Ahlquist 12/10/2006 MET1010 Intro to the...

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