Ocean and Atmosphere

Earth’s Heat Budget and Atmospheric Circulation

• Atmospheric properties• Earth’s Energy Budget• Vertical Atmospheric Circulation• Surface Atmospheric Circulation

Atmospheric Temperature

Water vapor saturation pressure

How much water vapor the air can

“hold”

Density of Air

• Which is more dense, DRY air or HUMID air?– Air: N2 (14*2=28)

O2 (16*2=32)

– Water: H2O (2+16=18)

Light molecules displace heavier molecules…

Density of Air

• Humid air is light, and rises• Dry air is heavy, and sinks

Water vapor, convection, condensation

1. Adiabatic Expansion Cooling

2. Condensation Release latent heat of vaporization

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Water Budget

Earth’s Heat Sources• Geothermal = 0.1 cal/cm2/day

• Solar = 2880 0.1 cal/cm2/day

BALANCED BUDGET!

– Wavelength (μm) = 2900 / T (Ko)•SUN = 2900/5600 ≈ 0.5 μm (visible

light)•Earth = 2900/290 ≈ 10 μm (infrared)

Sun’s Radiation

Earth’s Heat Budget

Earth’s Heat Budget

Atmosphere reflection and absorbance

Global Warming: Increased heat absorption in the atmosphere

Seasonal variability in solar radiation

Latitudinal variability in solar radiation

Latitudinal Heat Budget

So what are the effects of uneven heating?

• Less Dense Air:– HOT– HUMID

• More Dense Air:– COLD– DRY

Atmospheric Convection in a NON-Rotating Earth

•LOW Surface Air Pressure

•HIGH Surface Air Pressure

Low & High Pressure

But… The Earth Spins!

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Bombing of Quito from Buffalo

Bombing of Quito from Buffalo

Bombing of Quito from Buffalo

Earth Rotation: Coriolis Effect

• Apparent deflection force due to Earth’s rotation

• Acts on freely moving objects• North Hemisphere: Deflection to the

right• South Hemisphere: Deflection to the left• C = (2Ωsin(lat))v

– V=velocity of a particle in motion– Ω=constant (angular velocity of Earth)

• So:– High v = high C ; High latitude = high C– No Coriolis at equator, maximum at poles

Figure 6.16

Figure 6.17

Atmospheric Convection Cells

Figure 6.19

Global atmospheric generalities

• Hadley Cells (subtropical) are quite stable

• Pressure systems:– Equator: LOW (Doldrums or ITCZ-

Inter Tropical Convergence Zone)– 30’s: HIGH (Horse Latitudes)– 60’s: LOW

Figure 6.21

Horse latitudes Doldrums

Global atmospheric generalities

• Hadley Cell is quite stable• Pressure systems:

– Equator: LOW (Doldrums or ITCZ- Inter Tropical Convergence Zone)

– 30’s: HIGH (Horse Latitudes)– 60’s: LOW

• In between Pressure systems:– WIND!!

• Trade Winds• Westerlies: (Roaring Forties, Screaming

Fifties)

Figure 6.19

Seasonal Wind Variation

Seasonal Wind Variation

Monsoons (Indian Ocean)

Precipitation / Evaporation

Surface Ocean Salinities

Land – Ocean Temperatures

Local Winds: Sea Breeze

Local Winds: Coastal Fog

Local Winds: Mountain or Island Effect