Post on 08-Jun-2018
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Chapter 5Atmospheric Water and
WeatherElemental Geosystems 5e
Robert W. ChristophersonCharles E. Thomsen
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Water and Atmospheric MoistureWater on Earth: Location and Properties HumidityHumidityAtmospheric Stability Clouds and FogFrontal Lifting
Water on EarthWorldwide equilibrium
Water is the most common compound on earth (1.36 billion cubic kilometers).Water is naturally balanced on the earth, but eustasy (changes in sea level) still occurs
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Ocean and Freshwater Distribution
Figure 5.3
Water on EarthProperties of Water
Ice:Ice:• Water expands when it becomes ice.• Ice plays a large role in the weathering of rocks and in
highway/road damage.Liquid:• Greatest density of water occurs in the liquid phase (not
ice) • Assumes the shape of its container and is a non-
compressible fluid.Gas:• Invisible compressible gas.
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Three States of Water
Figure 5.4
Humidity: Water vapor in the air
Water on EarthHumidity
Humidity: Water vapor in the air.
Relative Humidity
Actual water vapor content of the airMaximum water vapor capacity of the air
at that temperature= X 100
R l i h idi i d h iRelative humidity varies due to changes in:
• Evaporation• Condensation• Temperature changes
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Relative Humidity
Figure 5.7
Atmospheric Stability
Parcel: A body of air that has specific temperature and h idit h t i tihumidity characteristics.Stability: The tendency for a parcel of air to either remain in place or to ascend/descend.
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Clouds and FogCloud Types and IdentificationFog
Advection fogRadiation fog
Clouds and Fog
Cloud: An aggregation of tiny moisture droplets and ice crystals that are suspended in air.Fog: A cloud in contact with the ground.
Cloud Formation Process:Unstable conditions cause a parcel of air to rise.As the air rises, it cools If cloud-condensation nuclei are present, then water vapor condenses resulting in clouds or precipitation or snow (sublimation/deposition!)
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Atmospheric Lifting MechanismsConvectional LiftingOrographic LiftingFrontal Lifting
Cold fronts Warm fronts
Atmospheric Lifting Mechanisms
Figure 5.27