Chapter 7 Water and Atmospheric Moisture

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Chapter 7Water and Atmospheric Moisture

• Geosystems 6e
• An Introduction to Physical Geography

Robert W. Christopherson Charles E. Thomsen
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Water and Atmospheric Moisture

• TOPICS
• Atmospheric Stability  
• Clouds and Fog  
• Air masses and Lifting Mechanisms

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Atmospheric Stability  

• Stable and unstable atmospheric conditions
• Involves a parcel of air and its surrounding
  environment in the atmosphere
• Stable atmosphere
• A parcel of air is discouraged from rising
• Kind of weather normally associated?
• Unstable atmosphere
• A parcel of air is encouraged to rise
• Kind of weather normally associated?

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 Examples of Stability
 Unstable AtmosphereParcel of air is encouraged
to rise
Figure 7.20
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 Examples of Stability
 Stable AtmosphereParcel of air is discouraged
from rising
Figure 7.20
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Moisture Droplets
Figure 7.20
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Raindrop and Snowflake Formation
Collision-coalescence process
Figure 7.22
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Cloud Types and Identification  
Figure 7.23
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Cirrus
Figure 7.23
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Cirrostratus
Figure 7.23
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Cirrocumulus
Figure 7.23
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Altocumulus
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Altostratus
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Stratus
Figure 7.23
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Nimbostratus
Figure 7.23
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Stratocumulus
Figure 7.23
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Cumulus
Figure 7.23
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Cumulonimbus
Figure 7.23
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Cumulonimbus Development
Figure 7.24
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Fog  

• Fog a cloud layer at or very close to the
  surface formed when surface air temperatures and
  dewpt temperature are nearly identical
• Advection fog warm, moist air layers moves over
  a cold surface
• Evaporation fog dole air moves over warmer
  water body
• Radiation fog loss of longwave radiation over
  moist surface

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Advection Fog
When warm, moist air moves over cooler body of
water, what happens?
Figure 7.25
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Evaporation Fog
Cold air lies over warmer body of water, and
evaporation from water surface causes saturation
and fog. Also, sea smoke hazard.
Figure 7.26
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Radiation Fog
Loss of longwave radiation at night over moist
surface causes saturation.
Figure 7.28
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Air Masses
Figure 8.2
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Atmospheric Lifting Mechanisms 

• Convergent Lifting  
• Convectional Lifting  
• Orographic Lifting  
• Frontal Lifting (Cold and Warm Fronts)  

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Atmospheric Lifting Mechanisms 
Figure 8.6
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Global Barometric Pressure
Figure 6.11
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Convection over Florida
Figure 8.8
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Orographic Precipitation
Figure 8.9