Interactions between Atmosphere and Oceans

Structure and Circulation of the Atmosphere

The atmosphere

• Composition

– Nitrogen, Oxygen, Other (CO₂, Argon, etc.)

– Water Vapor

– Greenhouse gasses

Structure of the Atmosphere

Structure

- 4 layers

1) Troposphere (0 - 14 km)

- most dense, weather systems

2) Stratosphere (15 - 50 km)

- ozone layer

3) Mesosphere (55 - 85 km)

4) Thermosphere (90 - 500 km)

- upper atmosphere

Condition/state of the Atmosphere

• Condition/state of atmosphere = weather/climate

• Why is the state of the atmosphere variable?

Uneven heating of the earth

• Latitude

• Seasonal

Circulation in the Atmosphere

• Uneven heating - convection

• Ideal circulation - rising warm air - sinking cool air

• Atmospheric pressure => L’s and H’s

• Actual atmospheric circulation doesn’t look like this - why?

Effect of Rotation

• W=>E rotation of the earth on its axis

• Angular versus linear velocity

• Northern Hemisphere - deflection towards the right

• Southern Hemipshere - deflection towards the left

Atmospheric Circulation

• Circulations Cells

– Doldrums (ITCZ)

– Horse latitudes

• Wind Bands

– Polar Easteries

– Westerlies

– Trade winds

Atmospheric Circulation

• Why do weather patterns track from W - E?

• Why do tropical storms track from E - W?

Atmospheric Circulation

• Other influences

– Seasons

– Continents

– Heat Capacity

Seasonal Variations

• Wind moves from

– High to Low pressure

– Counterclockwise - L

– Clockwise - H

• Northern Hemishpere

• ITCZ

– Move further north

During summer than it moves

South during the winter

Why ?

Monsoon effect

• A seasonal effect that results from the differences

in heat capacity between land and water

• 2 seasons - wet and dry

• Sea breezes

The topographic effect

• Warm moist air forced up over mountains

• The Pacific Northwest

– Rain versus rain shadow

Hurricanes

• Form over warm water in the tropics

• Pressure disturbance in the trade wind - easterly wave

• Tropical depression - tropical storm - hurricane

• High winds and heavy precipitation

• Energy comes from water changing state

El Nino/ENSO

• Normal Year

– L in western Pacific

– Trade winds

– Upwelling

• El Nino

– L migrates east - trades reverse

• La Nina

Ocean - Atmosphere Interactions

• Waves

• Surface Currents

• Climate Moderation