Chapter 4: Atmospheric Moisture and Precipitation
States of Water
- 3 states
o
o
o
- change of state due to gain or release of latent heat
- 2 types of upward movement causing Precip:
o 1.
o 2.
- Precipitation-
six names for changes of state
1.
2.
3.
Hydrosphere and the Hydrologic Cycle
- what is the hydrosphere?
- percentages (Fig. 4.2)
-
hydrologic cyclegeneral pathway of hydrologic cycle
-
global water balance:
o basic premise
o your notes:
3 categories of fresh water:
o 1.
o 2.
o 3.
-
Humidity
- Humidity:
- Saturation:
- Warmer air can hold ________ (more/less) moisture
- Colder air holds ________ (more/less) moisture
- various measures
o specific humidity
 units:
 importance:
 variation by latitude:
4.
5.
6.
o dewpoint temperature
 units:
 importance:
o relative humidity
 units:
 importance
 how can RH change?
The Adiabatic Process
- definition:
- compression vs. expansion
- dry adiabatic lapse rate (“dry air” lapse rate)
o value:
o when used?
- wet (or moist) adiabatic lapse rate (“wet air” lapse rate)
o value:
o when used?
- Environmental Lapse Rate (ELR)
o Equation:
-
Lifting Condensation Level (LCL)o Equation:
Air Stability
o Stable
o Unstable
o Conditionally stable
Clouds
- composition:
- two main physical features needed
o
o
- nomenclature:
o by height:
o by form:
o by process:
o see Fig. 4.1 for basic types
-
fog
o definition:
o a few types
Precipitation
- definition:
-
also called hydrometeors (compare with virga)
importance of precipitation:
-
five main forms:
intensity:
-
snow-to-rain ratios:
formation process:
1. cyclonic (frontal)
2. orographic
3. convectional
4. convergence
-
rain shadow