1 Lecture 16: Wind 2 Introduction to Oceanography Wind speed and direction about 1.5 km above sea level By Trent Schindler (NASA) using satellite data. Public Domain https://svs.gsfc.nasa.gov/4571 Coriolis Effect Movies Movie: University of Illinois (not sure if that’s the original source) http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/fw/crls.rxml
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Lecture 16: Wind 2Introduction to Oceanography
Wind speed and direction about 1.5 km above sea levelBy Trent Schindler (NASA) using satellite data. Public Domain
https://svs.gsfc.nasa.gov/4571
Coriolis Effect Movies
Movie: University of Illinois (not sure if that’s the original source) http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/fw/crls.rxml
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The Coriolis Effect on Earth
National Snow and Ice Data Center, free for educational use, http://nsidc.org/arcticmet/factors/winds.html
• Surface velocity increases from pole to
equator• Points on the equator
must move faster than points near the poles to go around once a day• Latitude velocity
differences lead to curving paths
– Example: Merry-go round
The Coriolis Effect• To an Earthbound observer (i.e., us): • Northern Hemisphere: Earth’s
rotation causes moving things to curve to their right
Moving things: Air masses, oceanic flows, missiles, anything with mass
• Southern Hemisphere: Earth’s rotation causes moving things to curve to their left
National Snow and Ice Data Center, free for educational use, http://nsidc.org/arcticmet/factors/winds.html
Northern Hemisphere: Hurricane Isabel (2003) NASA, Public Domain, http://visibleearth.nasa.gov/view_rec.php?id=5862
But wait – why do storms(including hurricanes and cyclones) go
backwards?
Atmospheric Circulation including Coriolis
Figure from NASA, Public Domain, http://sealevel.jpl.nasa.gov/overview/climate-climatic.html
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Actual forecast of
surface winds
Pacific surface wind forecast-hindcast, National
Weather Service Environmental Modeling
Center/NOAA, Public Domain, GIF by E. Schauble
using EZGif
Atmospheric Circulation including Coriolis
• 3 convection cells in each hemisphere– Each cell: ~ 30o latitudinal width
• Vertical Motions– Rising Air: 0o and 60o Latitude– Sinking Air: 30o and 90o Latitude
• Horizontal Motions– Zonal winds flow nearly along latitude lines– Zonal winds within each cell band
• DUE TO DEFLECTIONS BY CORIOLIS!
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Atmospheric Circulation including Coriolis
3 Cells per hemisphere:Polar
Active (updraft on hot side, downdraft on cold side)
FerrelPassive (downdraft on
hot side!)
HadleyActive
UCLA figure – background image unknown.
Atmospheric Circulation including Coriolis
• Latitudinal winds:– 0-30o:
Trade Winds
– 30-60o: Westerlies
– 60-90o: Polar Easterlies
Figure by Hastings, Wikimedia Commons, Creative Commons A S-A 1.0 Generic, http://en.wikipedia.org/wiki/File:AtmosphCirc2.png
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Atmospheric Circulation including CoriolisCell Boundaries:
60o: Polar Front
30o: Horse Latitudes
0o: Doldrums
Vertical air movement(up at Polar Front and Doldrums, down at Horse Latitudes)
Doldrums
Horse Latitudes
Polar Front
Figure by Hastings, Wikimedia Commons, Creative Commons A S-A 1.0 Generic, http://en.wikipedia.org/wiki/File:AtmosphCirc2.png
Questions
Figure from NASA, Public Domain, http://sealevel.jpl.nasa.gov/overview/climate-climatic.html
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Local Meteorology of Southern CaliforniaMarine layer against the Southern California mountainsPhoto by Dr. Jonathan Alan Nourse, CalPoly Pomona, http://geology.csupomona.edu/janourse/Storms,%20Floods,%20Landslides.htm
– Pole-equator temp difference larger in winter– Speeds up jet stream, big storms get pushed our
way
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Sea Breeze
Jesús Gómez Fernández, Wikimedia Commons, Creative Commons A S-A 3.0, http://commons.wikimedia.org/wiki/File:Diagrama_de_formacion_de_la_brisa-breeze.png
Land warms fastest during the day. Air expands and rises
Ocean surface temperature changes
slowly. Air displaces less dense rising air on land.
Result – wind from sea towards land
Land Breeze
Adapted from Jesús Gómez Fernández, Wikimedia Commons, Creative Commons A S-A 3.0, http://commons.wikimedia.org/wiki/File:Diagrama_de_formacion_de_la_brisa-breeze.png
Land cools fastest at night. Air
contracts and sinks
Ocean surface temperature changes slowly. Air is pushed