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Weather and Climate

Earth’s Atmosphere
Decreasing density with
increasing altitude
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Air has weight and applies
pressure
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Composition – variable?
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Ozone layer
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Weather and Climate

Earth’s Atmosphere
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Solar energy and Seasons
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Terrestrial radiation – Infrared (IR) and Clouds
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Greenhouse effect
• Without it, average T ~ -20 °C ~ -4 °F
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Weather and Climate

Earth’s Atmosphere
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Motion – warm air rises, cool air falls
• Convection
Wind is caused by a pressure difference which is due
to temperature difference
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• High and low pressure regions in the air above 1 km.
• Bigger the difference in pressure, the faster the wind.
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Weather and Climate

Earth’s Atmosphere
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Large scale air movement
• Rises at the equator and moves toward the poles
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Coriolis Effect
• Deflection due to the Earth’s rotation
• Greatest at the poles, zero at the equator
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Weather and Climate

Earth’s Oceans
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Friction from wind pushes the surface waters
Cold water sinks near the poles and rises near the
equator.
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Salt water is denser than fresh water
• Melting ice sheets and the deep ocean currents
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Weather and Climate
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Weather and Climate

Weather
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Relative Humidity = vapor content / vapor capacity
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Evaporation vs. Condensation
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Low T → Slow moving water molecules stick together
• Cloud formation
• Dew, fog, frost and the dew point temperature
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Weather and Climate
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Weather and Climate

Weather
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Forecasting – short and long term trends
• Computer models
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Geologic record of climate in ice
Space weather – solar flares, coronal mass ejections,
magnetic storms
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