© 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

© 2011 Pearson Education, Inc.

Movement of the Atmosphere

• Air always flows from high to low pressure.

© 2011 Pearson Education, Inc.

Winds

Northern Hemisphere–Clockwise High Pressure

–Counterclockwise Low Pressure

Southern Hemisphere - Opposite

© 2011 Pearson Education, Inc.

Convection

• Due to density differences

• Warm air rises– Less dense

• Cool air sinks– More dense

© 2011 Pearson Education, Inc.

Distribution of Solar Energy

• Concentrated at low latitudes

• Diffuse at high latitudes

© 2011 Pearson Education, Inc.

Heat Gained and Lost

© 2011 Pearson Education, Inc.

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

© 2011 Pearson Education, Inc.

If Earth didn’t rotate???

• Simple

© 2011 Pearson Education, Inc.

Three-Cell Model of Atmospheric Circulation

© 2011 Pearson Education, Inc.

Global Atmospheric Circulation

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

• Low pressure zones – MOIST warm rising

-Equatorial

-60 degrees belts

© 2011 Pearson Education, Inc.

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

© 2011 Pearson Education, Inc.

Three-Cell Model of Atmospheric Circulation

© 2011 Pearson Education, Inc.

Weather vs. Climate

• Weather – localized conditions, short term

• Climate – regional long-term average of weather

• Ocean Climate Zones Tropical

Temperate

Polar

Weather Fronts……

© 2011 Pearson Education, Inc.

Fronts

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

• Storms typically develop at fronts.

© 2011 Pearson Education, Inc.

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)

© 2011 Pearson Education, Inc.

Hurricane Intensity

© 2011 Pearson Education, Inc.

Historical Storm Tracks

© 2011 Pearson Education, Inc.

Hurricane Anatomy and Movement

© 2011 Pearson Education, Inc.

Hurricane Destruction

• High winds

• Intense rainfall

• Storm surge – increase in shoreline sea level

© 2011 Pearson Education, Inc.

Storm Destruction

• Historically destructive storms

– Andrew, 1992

– Katrina, 2005

– Ike, 2008

– Sandy 2012

© 2011 Pearson Education, Inc.

Three-Cell Model of Atmospheric Circulation

© 2011 Pearson Education, Inc.

Subtropical Gyres

• Large, circular loops of moving water

• Edges has Boundary Currents

• Centered around 30 degrees latitude

© 2011 Pearson Education, Inc.

Subtropical Gyres and Currents