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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”.
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Earth’s Heat Budget and Atmospheric Circulation • Atmospheric properties • Earth’s Energy Budget • Vertical Atmospheric Circulation • Surface Atmospheric Circulation
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
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)
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 HIGH Surface Air Pressure LOW Surface Air Pressure
But…The Earth Spins! FLASH NEWS: The US attempts to stop the axis of Evil by bombing Quito (Ecuador), using cannons located in Buffalo (NY)!
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
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
Doldrums Horse latitudes
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)