1. Coriolis Deflection
2. Atmospheric Processes
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•
Air pressure differences create the global wind field.
Coriolis deflection causes winds to blow in the direction in which they do.
Air Pressure: P = density x g x height
3. Equatorial atmospheric circulation – Walker cell
isobaric
surfaces
Walker
Cell
Strong
convection
in W Pac,
Congo,
Amazon
Trades - return flow in the Hadley/Walker cell system
4. Meridional air circulation cells
5.
Note the strong convection in: a) the western tropical Pacific, b) along ~5-10ºN (ITCZ), and c)
along 40-50º (Polar Fronts)
http://www.ssec.wisc.edu/data/
Animation of last 2 weeks of cloud cover
6. Global Wind Fields
Produced by:
LOW
Ferrel Cell
- Heat flux from
equator to polar
regions
HORSE LATITUDES
- Coriolis effects
on winds
DOLDRUMS
LOW
HORSE LATITUDES
Ferrel Cell
LOW
7. Global Air Pressure Distribution
Icelandic Low
Aleutian Low
8. Summer/Winter
Pressure Variations
Permanent Highs over Indian S Pac, S Atl,
Permanent Low over Southern Ocean
High over N Pac and N Atl modified by
Aleutian Low and Icelandic Low
9. Global wind speeds
Seasonal Variations of ITCZ and
generation of Tropical Depressions
Seasonal excursion of the ITCZ
SE trades become SW when crossing the Equator to the N (Coriolis)
This generates a Tropical Depression
Similar variability of the ITCZ in
the Pacific
Wind Convergence [δu/δx + δv/δy
(10- 5 sec-1)]
(Liu and Xie, NASA)
10. Location of formation of tropical storms/hurricanes
Steered by oceanic tropical anticyclone – Trades / Westerlies
11.
Very rare hurricane in the South Atlantic – March 2004
(Movie of hurricane)