Chapter 7Water and Atmospheric

Moisture

Water and Atmospheric MoistureWater 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

•the positive H side attracts the negative O side of a neighboring water molecule

•called hydrogen bonding (weak)

•with the O side having a negative charge and the H side having a positive charge

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

Figure 7.4

1. Sublimination2. Condensation – Evaporation3. Freezing - Melting

Figure 4.10

Heat Transfer

Heat added

Tem

pera

ture

(o C

)

0

100

MeltingIce

Water

Water VaporBoiling

Latent and sensible heat

Heat added

Tem

pera

ture

(o C

)

0

100

MeltingIce

Water

Water VaporBoiling

Latent heat

Heat added

Te

mp

era

ture

(oC

)

0

100

MeltingIce

WaterWater Vapor

Boiling

Water density

HumidityRelative Humidity  

Saturation

Dew point

Expressions of Relative Humidity  Vapor pressure

Specific humidity

Instruments

Relative Humidity

Figure 7.7

Actual water vapor content of air

Maximum water vapor capacity of airx 100=

Dew Point Temperature

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

Figure 7.13

Rate of evaporation is faster (more heat loss) when humidity is low

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 FogCloud Formation Processes  

Cloud Types and Identification  

Fog  

Cloud Formation

Figure 7.20

Moisture droplet

Cloud-condensation nuclei

Cloud Types and Identification  

Figure 7.22

Figure 7.23

Cumulonimbus Development

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 5eAn Introduction to Physical Geography

Robert W. ChristophersonCharlie Thomsen