Transcript Air-Sea Interaction

CHAPTER 6
Air-Sea Interaction
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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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