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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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Buoyancy

Figure 5.14

Adiabatic Processes

Figure 5.15

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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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Clouds and Fog

Cloud Types and Identification

Figure 5.18

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Advection Fog

Figure 5.20

Evaporation Fog

Figure 5.21

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Valley Fog

Figure 5.25 Figure 5.22

Radiation Fog

Figure 5.23

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Atmospheric Lifting MechanismsConvectional LiftingOrographic LiftingFrontal Lifting

Cold fronts Warm fronts

Atmospheric Lifting Mechanisms

Figure 5.27

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Convection over Florida

Figure 5.29

Orographic Precipitation

Figure 5.30

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Cold Front

Figure 5.31a

Cold Frontand

Squall LineSquall Line

Figure 5.31b

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Warm Front

Figure 5.32