NOTES
Links to summaries of key issues for each topic
VISUALS
Links to images employed in lectures
TEXT
Link to chapter outlines at online learning center
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THIRD REVIEW SESSION
(contd.)
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| Chapter 8. Atmospheric
Circulation |
| Learning Objectives: Understanding of Fundamental
Concepts |
- Atmospheric structure: sequence of layers governed by temperature.
- Composition (principally N2, O
2) and standard pressure 760mm Hg.
- Gases influenced by human activity; CO2 related
to greenhouse effect, CFC's and ozone (O3) hole over
Antarctica, sulfur compounds and cloud nucleation.
- Earth's rotation creates Coriolis force and produces 6 cells as wind
belts.
- Locations of rising air (0° and 60°) low pressure and high
precipation, and of sinking air (30°) high pressure and low rainfall.
- The locations and direwctions of surface winds: NE and SE trade winds,
westerlies and polar easterlies.
- The occurrence of high altitude jet streams at cell boundaries.
- Creation of monsoons by seasonal changes in air pressures related
to differential heating of the land and ocean.
- Influences of mountainous islands yields topographic effects.
- Controls on the generation of hurricanes and their characteristics.
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| Terminology and Details: Specific Components of
the Topic |
- Layers of the atmosphere:
- troposphere (with clouds), stratosphere (ozone layer), mesosphere,
thermosphere, bounded by tropopause, stratopause, mesopause
- Major gases: N2 (78.1%), O2
(20.9%), Ar (0.9%), CO2, inert gases, water vapor
(variable, ~1.4%), dust particles (trace)
- CO2 from fossil fuel combustion: rise from
280 to 350 ppm since 1850
- Chlorofluorocarbons form Cl in stratosphere which destroys ozone,
depleting it over Antarctica during Spring.
- Dimethyl sulfide (DMS) produced by plankton creates climate feedback.
- Earth's rotation: speed decreases with increasing latitude, deflects
moving air masses relative to surface producing the Coriolis effect.
- Atmospheric cells: Hadley 0-30°, Ferrel 30-60°, polar 60-90°;
boundaries: Intertropical convergence zone (ITCZ), doldrums at 0°, horse
latitudes at 30°
- Air pressures: winter low over ocean, high over land, reverse in summer
- Monsoon: changes in winds creating seasonal rains over Indian Ocean
- Hurricanes: formed at 15 - 20° latitude by trade winds over warm
(>27°C) water; intense low pressure systems that move westwards, create
storm surges (elevated seas).
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| Chapter 9. Ocean Circulation |
| Learning Objectives: Understanding of Fundamental
Concepts |
- Surface currents and gyres created by Coriolis force.
- Ekman spiral: wind action on surface waters, deflected by Coriolis.
- Convergence of surface waters in mounds creates geostrophic flow.
- Gyres: circular currents with boundary currents parallel to margins.
- The changes in ocean/atmosphere circulation that produce
El Niño events.
- Upwelling and Downwelling triggered by Coriolis
- The process of deep water formation in N. Atlantic (NADW)
and in the Southern Oceans (AABW); no deep water production in N. Pacific.
- Description of water masses with discrete T/S characteristics.
- Meanders, rings: size, formation, persistence along western
boundary currents
- Global Conveyor: movement of deep water triggered by NADW
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| Terminology and Details: Specific Components of
the Topic |
- Ekman spiral: changes with depth in direction and strength of water
movement leading to Ekman transport at 90° to wind direction
- Geostrophic flow: convergence of surface waters in mounds; circular
motion governed by Coriolis force, gravity.
- El Niño: change in equatorial waters in Pacific,
cause slackening or reversal of trade winds, modify precipitation patterns.
- Global current circulation patterns: gyres, current speeds (fast,
slow, 10-50cm/s) and water temperatures,
- Density: described by salinity and temperature; curved
lines on T-S plots :
- T-S curves show density relationships, and stable and
unstable layering
- Major water masses:
- North Atlantic Deep Water (NADW; 2-4°C, 34.9%
o)
- Antarctic Intermediate Water (AAIW; 5°C, 34.4%
o)
- AntArctic Bottom Water (AABW; 0.5°C, 34.8%
o)
- Surface (>16°C, 36.5%o)
- Mediterranean Intermediate Water (MIW, 13°C, 37.3%
o)
- Zones of convergence and divergence; association with
upwelling
- Approaches to measurement of ocean currents, fixed and
drifting
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Department of Geological Sciences,
1001 E. Tenth Street, Bloomington, IN 47405-1403
Phone: (812) 855-5582 Last updated: 17 September 2000
Comments: simon@indiana.edu
Copyright
2000, The Trustees of Indiana University
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