© 2011 Pearson Education, Inc. CHAPTER 6 Air-Sea Interaction

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© 2011 Pearson Education, Inc.

CHAPTER 6Air-Sea Interaction

© 2011 Pearson Education, Inc.

Physical Properties of the Atmosphere

• Mostly nitrogen (N2) and Oxygen (O2)

• Other gases significant for heat trapping properties

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Movement of the Atmosphere

• Air always flows from high to low pressure.

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Winds

Northern Hemisphere–Clockwise High Pressure

–Counterclockwise Low Pressure

Southern Hemisphere - Opposite

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Convection

• Due to density differences

• Warm air rises– Less dense

• Cool air sinks– More dense

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Distribution of Solar Energy

• Concentrated at low latitudes

• Diffuse at high latitudes

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Heat Gained and Lost

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The Coriolis Effect

• Due to Earth’s rotation

• Deflects path– To right in Northern Hemisphere– To left in Southern Hemisphere

• Zero at equator

• Greatest at poles

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If Earth didn’t rotate???

• Simple

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Three-Cell Model of Atmospheric Circulation

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Global Atmospheric Circulation

• High pressures– DRY Cool falling – 30 degree belts– Poles

• Low pressure zones – MOIST warm rising

-Equatorial

-60 degrees belts

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Global Atmospheric Circulation

• Wind Belt and Circulation Cells

Tradewinds Hadley Cell: 0–30 degrees: – Northeast in NH– Southeast in SH

Westerlies Ferrel Cell: 30–60 degrees

Easterlies Polar Cell: 60–90 degrees

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Three-Cell Model of Atmospheric Circulation

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Weather vs. Climate

• Weather – localized conditions, short term

• Climate – regional long-term average of weather

• Ocean Climate Zones Tropical

Temperate

Polar

Weather Fronts……

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Fronts

• Fronts – boundaries between air masses– Warm front – Cold front

• Storms typically develop at fronts.

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Tropical Cyclones (Hurricanes)

• Large rotating masses of low pressure

• Need warm water (>77 degrees)

• Energy from latent heat of condensation

• Classified by maximum sustained wind speed

• Typhoons (West Pacific), Hurricanes (East Pacific, Atlantic)

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Hurricane Intensity

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Historical Storm Tracks

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Hurricane Anatomy and Movement

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Hurricane Destruction

• High winds

• Intense rainfall

• Storm surge – increase in shoreline sea level

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Storm Destruction

• Historically destructive storms

– Andrew, 1992

– Katrina, 2005

– Ike, 2008

– Sandy 2012

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Three-Cell Model of Atmospheric Circulation

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Subtropical Gyres

• Large, circular loops of moving water

• Edges has Boundary Currents

• Centered around 30 degrees latitude

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Subtropical Gyres and Currents

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