Chapter 7 The Ocean and Atmosphere

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Chapter 7 The Ocean and Atmosphere Powered By Docstoc
					    Chapter 7: The Ocean and
•   Objectives:
•   Structure/composition of air
•   Sulfur compounds
•   General circulation patterns
•   Coriolis Effect
•   Seasonal Changes
•   El Nino, La Nina
•   Storms
•   Practical Considerations
      Ocean and Atmosphere
•   Can’t separate; closely related:
•   Moderates surface temperature
•   Shapes weather and climate
•   Creates most of sea’s waves and
             Structure and Composition
•   90% of gases = within 9 mi. from surface
•   Troposphere  temp. from conduction
•   Greenhouse Effect; Global Warming
•   Stratosphere: Ozone; depletion
•   Mesosphere: colder
•   Thermosphere: leads to outer space

• 78% N, 21% O in dry air
• Weather =
• Climate =

• Influenced by:
     Solar radiation
     Nearby body of water
     Changing geo and bio conditions
      Measuring Earthshine
How much radiation the Earth reflects.
•       Gases: CO2, CH4, H2O, CFC, N2O
•       Trend: increase in gases  global warming
        of 2-4 degrees C in next 100 yrs.
•       **Unbalances C cycle
•       Possible sea-surface effects:
    –     Affects high latitudes  melt polar icecaps
    –     Affects thermohaline circulation and surface
          winds  modify transfer of heat from low to high
          latitudes  alters Earth’s climate patterns
•   Monitored since 1978
•   CFC’s (1 molecule breaks down 100,000 molecules of
•   Methyl bromide: from single celled algae at surface,
    pesticides, industry, burning of vegetation.
•   Problems:
•   Pollutant at ground level
•   Skin cancer, cataracts
•   Sunburns, earlier wrinkles
•   Suppress immune systems
    crop production
•   Degradation of paint, plastics
    in phytoplankton productivity
Ozone Depletion
        Sulfur Compounds
•   20-40 million T from dimethyl sulfide
    (DMS) from phytoplankton at surface
    (odor of sea)
•   DMS  sulfate & water  sulfuric acid
     acid rain
•   Controls density of clouds over sea
•   DMS changes reflective prop., reduces
    incoming radiation,  heating of ocean
  DMS, excess clouds + sulfur over sea
   less light hitting surface, temp ,
  plant production of DMS 

•   Uneven solar heating  wind
•   Convection current
•   Patterns if world was still
•   CORIOLIS EFFECT: apparent
    deflection of a moving object from its
    initial course when its speed and
    direction = measured in reference to the
    surface of the rotating Earth.
• Earth moves 15 degrees/hour
• All places on Earth don’t move at same
• N. Hemisphere  winds = clockwise
• S. Hemisphere  counterclockwise
• Equator  none

• Coriolis Effect only influences wind
            Wind Bands
• Geographical Equator = 0o
• Meteorological Equator = ITCZ, ~5o N or
  S of Equator
  *Maintains thermal equilibrium
• 3 convection cells of air:
     1. 0o--30o
     2. 30o--60o
     3. 60o--90o
            Wind Patterns
1. Trade winds: bands of moving air
     between 0--30
     movement to right (west)
     steady speed, direction
2. Westerlies: between 30--60
     go to east
     Winds = named for direction of origin
3. Horse Latitudes: 30 degrees N and S
     air = dry, deserts
4. Doldrums: at Equator
     low a.p., moist air, rainforests
     vertical movement of air
5. Polar Easterlies: betw. 60 degrees and
     and the Poles
     6 surface wind bands

Measuring winds: surface, satellites
• Cell circulation: depends on
           1. Seasonal changes
           2. Amount of land
           3. Amount of ocean

**Remember: land doesn’t have the high
  heat capacity of water --> temperature
  fluctuations = greater.

• Pattern of wind circulation that changes
  with seasons due to heat capacities of
  land and water and moving ITCZ.
• Wet summers, dry winters
• In spring: land heats more rapidly than
  ocean, air over land rises and cool moist
  air rushes in to take its place --> rain
• In winter: opposite. Dry surface winds
  move seaward.
Delhi Floods
              Air Masses
• Large body of air with nearly same temp,
  humidity, and density throughout
• characteristics come from where they
  were formed
• mT (maritime tropical) = warm, moist
• mP (maritime polar) = cold, moist
• cT (continental tropical) = warm, dry
• cP (continental polar) = cold, dry
• cold front, warm front, stationary front
• Storms: Regional atmospheric
  disturbances characterized by strong
  winds and precipitation.

• Cyclones: huge rotating masses of low
  pressure in which winds converge and
       Extratropical Cyclone
• Form between each hemisphere’s polar
  and Ferrell cells
• occur in winter
• from 1000-2500 km in diameter (625-
  1600 mi.)
• In North America = nor’easters

• Example: “Perfect Storm”
Perfect Storm
                  The Perfect Storm

The storm—created from a collision between a high
pressure system, a low pressure system and the
remnants from a dying hurricane—sent high winds and
Atlantic Ocean waves crashing into the East Coast, from
New England to Cape Hatteras, North Carolina.
           Tropical Cyclones
• Great masses of warm, humid rotating
• Hurricanes in Atlantic
• Typhoons in Pacific
• Tropical Cyclones in Indian Ocean
• Willi-willis in Australia

• less force = tropical depression -->
  tropical storm
• Hurricane status = 74 mph
• = most powerful storm on earth
• 20 billion metric T of water/day
• Danger: storm surge
           high winds
• Eye: calm, wind shifts direction
• On land, weakens due to surface friction,
  no power source.
           The Saffir-Simpson Scale
Category      1        2         3        4          5
            980 979-965 964-945 944-920          919
            74-95    96-110 111-130 131-155       155
             4-5      6-8      9-12     13-18      18

Damage      Minimal Moderate Extensive Extreme Catastrophic
• Sudden increase in wind speed by 16
  knots, rising to 22 knots or more and
  lasting for at least 1 minute---then
• Associated with cold fronts
• sharp drop in temp.
• roll shaped cloud
• rain shower
• may be snow
Florida, U.S.A Squall Line
Target Name:       Earth
Spacecraft: Space Shuttle

Produced by:       NASA
Copyright: NASA
Copyright Free Policy
Cross Reference:
Date Released:     April
           Practical Considerations
• Preventions:
  gate in Thames
  other precautions?

Decision: prevention or cleanup?
Should historically proned areas be vacated?
Hurricane Katrina
September 2004

Hurricane Frances

             Hurricane Ivan 
Hurricane Ivan