Chapter 7
Water and Atmospheric
Moisture
Water and Atmospheric Moisture
Water on Earth
Unique Properties of Water
Humidity
Atmospheric Stability
Clouds and Fog
Land and Water Hemispheres
Figure 7.2
Ocean and Freshwater Distribution
Figure 7.3
Unique Properties of Water
Heat Properties
Phase change
Sublimation
Latent heat
Vaporization
Condensation
Heat Properties of Water in Nature
Latent heat of sublimation
Basics about Water:
2 atoms hydrogen + 1 atom oxygen make a covalent
bond (very strong)
so water is very stable
Molecule is shaped like a bent paperclip
•with the O side having a negative
charge and the H side having a positive
charge
•the positive H side attracts the
negative O side of a neighboring water
molecule
•called hydrogen bonding (weak)
Hydrogen bonding
Responsible for the surface tension of water
•allows heavier things like bugs to stand on top of the surface of
water
•allows you to slightly overfill a glass of water without it spilling
over.
Responsible for capillary action
•what happens when you set the edge of a papertowel
down on a puddle of water?
•The water is pulled into the dry part of the towel because each
molecule is drawing the next molecule in
•Same thing happens in soils, which will become important
when we talk about the hydrologic cycle
Phase changes
1. Sublimination
2. Condensation – Evaporation
3. Freezing - Melting
Figure 7.4
Temperature (oC)
Heat
Transfer
Figure 4.10
Boiling
Water Vapor
100
Water
0
Ice
Melting
Heat added
Latent and sensible heat
Temperature (oC)
Boiling
100
Water
0
Ice
Melting
Heat added
Water Vapor
Temperature (oC)
Latent
heat
Boiling
Water
Vapor
100
Water
0
Ice
Melting
Heat added
Water density
Humidity
Relative Humidity
Saturation
Dew point
Expressions of Relative Humidity
Vapor pressure
Specific humidity
Instruments
Relative
Humidity
=
Actual water vapor content of air
Maximum water vapor capacity of air
x 100
Dew Point
Temperature
Figure 7.7
Saturation Vapor
Pressure
Water Vapor in the Atmosphere
Figure 7.9
Global Latent Heat
Figure 4.19
Daily Humidity
Patterns
Figure 7.10
Seasonal
Humidity
Patterns
Figure 7.10
Winter
Summer
Humidity Instruments – hair hygrometer
Figure 7.13
Humidity
Instruments –
Sling Hygrometer
Rate of evaporation is
faster (more heat loss)
when humidity is low
Figure 7.13
Atmospheric Stability
Will the Balloon float up or
stay where it is (or sink
downward)?
If the air in the balloon is less
dense than the air outside
 it floats up
If the air in the balloon is more
dense than the air outside
 it sinks
Adiabatic Processes
Figure 7.16
Clouds and Fog
Cloud Formation Processes
Cloud Types and Identification
Fog
Cloud Formation
Figure 7.20
Moisture droplet
Cloud-condensation nuclei
Cloud Types and Identification
Figure 7.22
Cumulonimbus
Development
Figure 7.23
Advection Fog – air migrates up or down
and becomes saturated with water vapor
Figure 7.24
Advection Fog –Valley Fog
Figure 7.25
Advection Fog – upslope Fog
Radiation Fog
Figure 7.26
Fog Harvesting
End of Chapter 7
Geosystems 5e
An Introduction to Physical Geography
Robert W. Christopherson
Charlie Thomsen