PHYSICAL GEOGRAPHY 120
Online Section
GROSSMONT COLLEGE
TIM CLIFFE
OUTLINE #3
VIII. CONDENSATION PROCESSES: Humidity and Cloud Formation
A. Atmospheric Water
1. water vapor vs. clouds (liquid and/or ice)
2. Phase Changes
a. states of matter
b. energy transformations
B. Measures of Humidity
1. actual water-vapor content
a. Specific Humidity (a “direct” measure)
b. Dew Point Temperature (an “indirect” measure)
2. water-vapor capacity
a. evaporation vs. condensation rate
1) equilibrium state
2) temperature dependency
b. maximum potential vapor content
1) warmer temperatures
2) colder temperatures
3. saturation
a. compare: Dew Point Temperature vs. Air Temperature
b. Relative Humidity
C. Cooling Processes
1. diabatic cooling
a. conductive heat flow (SH transport; e.g., from warm air to cool surface)
1) dew formation
2) fog formation
b. phase changes (SH to LH transformation)
2. adiabatic cooling → cloud formation
a. Equation of State
1) compression: resultant temperature-change
2) expansion: resultant temperature-change
b. adiabatic “lapse rates”
1) “Dry Adiabatic Lapse Rate” (DAR)
2) “Wet Adiabatic Lapse Rate” (WAR)
a) saturated-air, uplift, and cloud formation
(1) expansional (adiabatic) cooling
(2) condensational (diabatic) warming
b) rising saturated-air → net cooling rate
c. example: Orographic Effect
1) windward precipitation vs. leeward “rainshadow”
2) measures of humidity (place-to-place, up-and-over the mtn)
3) role of condensation (especially: windward vs. leeward)
3. cloud vs. fog formation
IF: The actual humidity remains constant from 4am to 3pm …
THEN: Explain what happens to (1) Dew Point and/or Specific Humidity;
(2) Capacity; and
(3) Relative Humidity
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D. Lifting Processes (Cloud Formation)
1. free convective uplift (buoyant “heat convection”)
a. differential heating
b. cumulonimbus cloud formation
1) warm, moist, unstable air
a) condensational LH input
b) convective precipitation
2) thunderstorm potential
2. forced-lifting mechanisms (i.e., regardless of temperature/buoyancy)
a. orographic uplift
b. frontal uplift
c. cyclonic uplift
1) Midlatitude Cyclones
2) Tropical Cyclones
E. Compressional (Adiabatic) Warming
1. Santa Ana winds
2. Chinook winds
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IX. TRAVELING WEATHER SYSTEMS
A. Midlatitude Weather: Winter and Spring
1. characteristics
a. daily variability
b. comparison to other latitudes
2. Air Masses
a. high-pressure (H) regions
1) air-mass “source regions”
2) air-mass classification
a) temperature characteristics
b) humidity characteristics
b. Air Masses Effecting North America (especially winter/spring)
1) east of Rockies (cP vs. mT)
a) temperature and vapor capacity
b) specific humidity and dew point
c) relative humidity
2) West Coast (mP)
3. Weather Fronts
a. Warm Fronts
1) characteristic cloud family
2) precipitation characteristics
b. Cold Fronts
1) characteristic cloud family
2) precipitation characteristics
c. Occluded Fronts
B. Midlatitude Cyclonic Storms (“Wave Cyclone”)
1. initial setting
a. stationary “Polar Front” (zone of abrupt “temperature contrast”)
1) poleward: cold (thermal) Polar Anticyclone
2) equatorward: Subtropical Dynamic High
b. “Polar Jet Stream” aloft
2. Polar Front cyclogenesis
a. upper-level Jet Stream divergence
b. surface Cyclone development
c. resultant rising air
3. mature Midlatitude Cyclonic Storm
a. cP and mT advection
b. cyclonic and frontal uplift
c. Cold Front passage
1) pre Cold Front passage
a) surface wind directions
b) temperatures
c) actual humidities (dew points)
d) pressure trend
2) post Cold Front passage
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d. energy source
1) abrupt “temperature contrast”
a) resultant Jet Stream aloft
b) "storm track" (Jet Stream)
2) springtime LH enhancement ("Severe Weather" in Tornado Alley)
4. Occluded Stage (the “dying stage”)
a. cold-air wedge
b. warm vs. cold air: mixing (finally!)
1) effect on energy source
2) storm dissolution (weakening/dying)
C. Tropical Cyclones (Hurricanes/Typhoons)
1. comparison against Midlatitude Cyclones
a. areal coverage (size)
b. isobar spacing and geometry
1) lack of “kinks”
2) implication: no fronts or jet
c. environment of formation
1) regions of formation
2) time-of-year
d. energy source (Know the difference vs. a Midlatitude Cyclonic Storm!)
1) ultimately requires: warm ocean-water
2) directly fueled by: massive condensation (LH → SH)
2. United States situation
a. East and Gulf Coasts: Gulf Stream and Gulf of Mexico
b. West Coast: California Current
X. EARTH MATERIALS (An Overview)
A. The Internal Earth (~ 4,000 miles thick)
1. Layering of the Earth
a. compositional layering (based on density-segregation)
1) oxygen-rich rocky-exterior (mainly “silicates”)
Know the difference between the
a) Crust
mostly-Metallic vs. the mostly(1) Oceanic vs. Continental Crust
Silicate. Know which Silicates:
(2) base of the Crust (“Moho”)
Felsic vs. Mafic vs. Ultramafic.
b) Mantle
2) metallic interior (Core)
b. structural layering (based on differences in material-state, not composition)
1) of the very-upper Earth (~ upper 180 miles/300 km)
a) Lithosphere
b) Asthenosphere
2) of the Core
a) Inner Core
b) Outer Core
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2. Isostacy
a. mechanical support vs. buoyancy support
1) analogy: house on Del Cerro vs. houseboat on SD Bay
2) for Lithosphere: buoyant flotation atop Asthenosphere
b. elevation of Earth’s surface
1) reflects: isostatic equilibrium
2) isostatic disequilibrium
a) cause: by changing Lithospheric thickness
(1) tectonic thickening/thinning
(2) gradational thickening/thinning
(3) glaciation/deglaciation
b) response: isostatic adjustment
B. Crustal Materials
1. Elements and Compounds
a. The Elements (of the Periodic Table)
1) atoms and subatomic particles
2) the Rutherford Model of the atom and Nuclear Theory
3) valence electrons and ions (anions and cations)
4) most-common Crustal Elements
a) Oxygen
b) Silicon
b. Compounds (e.g., Silica)
1) Elements in combination
2) ionic vs. molecular Compounds
2. Minerals
a. Mineral composition
1) Single-Element (less-common; e.g., gold)
2) Compounds (most-common; e.g., quartz or feldspars)
b. Mineral Groups
1) Silicates
a) the most-common rock-forming Mineral Group
b) “felsic” vs. “mafic” vs. “ultramafic”
2) other examples (e.g., Carbonates)
3. The Rock Cycle
a. Uniformitarianism: development of an assumption for the Earth Sciences
1) James Hutton and his discoveries
a) Unconformities (Siccar Point, Scotland)
b) Hutton’s Section (Edinburgh, Scotland)
2) rejection of Werner’s Neptunism (or of the 20th Century Creationism of the 7th Day Adventists)
b. processes and components of an integrated Rock Cycle
1) Tectonically-driven processes
2) Gradationally-driven processes
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C. Rock Classification (and Examples)
1. Igneous (“crystalline”) Rocks
a. Plutonic (Intrusive environment)
1) slow cooling → coarser-grained (phaneritic texture)
2) examples: granite or gabbro
b. Volcanic (Extrusive environment)
1) fast cooling → finer-grained (aphanitic texture)
2) example: basalt (including “pillow” basalts if erupted underwater)
2. Sedimentary Rocks
a. depositional environments
1) terrestrial sediments vs. deeper-marine sediments
2) higher-energy vs. lower-energy environments
b. examples: shale, limestone, sandstone, conglomerate
3. Metamorphic Rocks
a. protolith
b. low vs. high grade metamorphism
1) foliated (examples: slate→schist→gneiss)
2) non-foliated (example: marble)
XI. PLATE TECTONICS: Development of a model for the Earth Sciences
A. Plate Boundaries
1. Diverging Plate Boundaries → tearing-apart Continents; producing Ocean Basins
a. Sea-Floor Spreading (“Spreading Zones”)
1) production of midocean ridges (MOR’s)
a) central “rift valley” (due to extension)
b) magma production → by “decompression-melting”
(1) composition → “mafic” magmas
(2) eruptive characteristics → relatively non-violent
(3) related “hydrothermal” activity (similar to Hot Springs on land)
(4) thus: this new rock is warm and buoyant
c) thus: spreading ends up producing a bigger “ridge” than “rift”
2) at MOR → creation of new oceanic rock
a) rigid-solid silicates (Oceanic Lithosphere)
(1) Crustal component → “mafic”
(2) Mantle component → “ultramafic”
b) warm and buoyant
3) spreading of Oceanic Lithosphere
a) becomes older
b) becomes colder (especially downward, thus thickening the mantle-component)
c) thus: becomes denser
4) earthquakes → occur at shallow depths
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b. Oceanic Lithosphere → Layered
1) initially: igneous activity at MOR
a) above Moho: layered “mafic” Crust
(1) volcanics (extrusives) → basalts
Basalt vs. Gabbro:
✓ Compositionally equivalent
(a) at surface: “pillow” basalts
✓ Texturally: aphanitic vs.
(b) “plumbing” that feeds the pillows: sheeted dikes
phaneritic
(2) plutonics (intrusives) → gabbros
b) below Moho: “ultramafic” Mantle-component (“depleted mantle”)
2) eventually: deposition on top
a) marine sediments
b) with age: thickening away from MOR
c. support atop a plastic-solid (the Asthenosphere)
1) “ultramafic” composition
2) capacity to flow
d. examples (as given from around the World) From 2nd Video
2. Converging Plate Boundaries → Mountain Building and the production of Continents
a. “Ocean-to-Continent” → Subduction Zone
1) subducting plate
a) denser plate (“mafics” (vs. the “felsics”))
b) angle-of-subduction → relative to age (i.e., to density of the Oceanic plate)
2) trench (with sedimentary fill off the continent)
3) accreted terranes
4) volcanic arc
a) magma production → by adding of water (acts like a “flux” → “wet melting”)
(1) eruptive characteristics → violent!
(2) “arc” → because Earth = sphere (not flat) (e.g., press on a ping-pong ball!)
b) steep, active, violent “stratovolcanoes”
5) earthquake distribution
a) sloping downward
(1) deeper away from trench
(2) shows angle-of-subduction
b) unique characteristics
(1) deepest quakes (> 9.0 R)
(2) strongest quakes (e.g., 2004 Indonesian 9.0 and resultant Tsunami)
6) examples
b. “Ocean-to-Ocean” → Subduction Zone
1) subducting plate
a) denser plate (but remember: both are “mafic”)
b) relationship to age (remember: older has more ultramafic-mantle (by cooling))
2) trench (deepest trenches, with little sedimentary fill (e.g., Mariana’s Trench))
3) accreted terranes
4) volcanic island arc
a) magma production → by adding water (acts like a “flux” → “wet melting”)
(1) eruptive characteristics → violent!
(2) “arc” → because Earth is a sphere (not flat) (e.g., press on a ping-pong ball!)
b) steep, active, violent “stratovolcanoes”
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5) earthquake characteristics → similar to “Ocean-to-Continent” Subduction Zones
6) examples
c. “Continent-to-Continent” → Collision Zone
1) no subduction (“felsics” are too buoyant to subduct (too low-density))
2) a “suture zone” (not a “subduction zone”)
a) folded/faulted mountain belts
b) exceptionally-thickened Continental Lithosphere
(1) highest elevations on Earth
(2) longterm isostatic implications
3) no magma production (thus: no active volcanoes)
4) earthquakes
a) broad distribution
b) strongest quakes (> 9.0 R)
5) examples
3. Transform Plate Boundaries → One plate grinding past another plate
a. most-commonly found at MOR’s
1) MOR’s (because Earth is a spherical surface) → segmented
2) MOR Segments → offset
b. MOR Offsets → lateral plate-motion
c. earthquakes → shallow
d. no magma production (generally)
e. examples
1) simple examples → all MOR Offsets
a) “fracture zones” vs. “transform plate boundaries”
b) age distribution of basalts
2) complex example → San Andreas Fault Zone
B) “Pacific Ring of Fire”
1) surrounded by subduction zones (trenches and volcanic arcs, thus Hawaii hit by tsunamis)
2) why no “Atlantic Ring of Fire” yet?
a. Atlantic Ocean is relatively new (< 200 million years old)
b. still-opening by the continued-breakup of Pangaea (spreading from MidAtlantic Ridge)
c. thus: not yet any Oceanic Lithosphere that’s dense enough to subduct
3) United States (“the 48”)
a. west coast = tectonically active (i.e., plate boundary)
b. east coast = tectonically passive (i.e., located in the middle of a plate)
C) California’s Tectonic Setting
1) far north → Converging Plate Boundary
a.
b.
c
d.
“Cascadian Subduction Zone”
convergence: Juan de Fuca (off of CA = “Gorda”) Plate vs. North American Plate
magma production → by “wet” melting
result: arc volcanics and infrequent massive earthquakes (> 9.0 R)
2) Cape Mendocino to Salton Sink → Transform Plate Boundary
a. “San Andreas Fault Zone”
b. lateral motion: Pacific Plate vs. North American Plate
(1) relative motion of San Diego/LA/SF vs. the N.A. Plate
(2) seismically active (but < 8.0 R)
c. no magma production (generally)
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3) far southeast → Diverging Plate Boundary (early-stage MOR/Rift-Valley/sea-floor production)
a. Baja → rifting off of Mexico (opening of the Gulf of California)
b. extends north to Salton Sink (contrary to video)
c. magma production → by “decompression” melting
4) eastern CA (eastern Sierra, across Nevada, to Utah’s Wasatch Range)
a. complex extensional tectonics
(1) down-dropped basins
(2) isostatically-rising ranges (e.g., recent uplift of Sierra or our Peninsular Ranges)
b. magma production → by “decompression” melting
PHYSICAL GEOGRAPHY 120
Online Section
GROSSMONT COLLEGE
TIM CLIFFE
Review “Wx” Questions - Exam #3
1. Consider the three groups-of-measures related to atmospheric humidity:
a. How can Specific Humidity (or Dew
Point Temperature) be increased?
Decreased?
b. What determines “Capacity?”
Describe the relationship graphically:
Describe the relationship in English:
c. How can RH be increased?
Decreased?
2. For a constant Dew Point all day long, how will the Relative Humidity change, commonly, from
a) 6am to 2pm?
b) 2pm to 5pm?
c) 5pm to 6am?
3. Compare mT vs. cP air masses in terms of
a) actual vapor content
b) capacity
c) RH
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4. Given the air-flow as shown up-and-over a mountain:
a) What happens to temperature?
A→B:_______
B→C: _______
C→E:_______
b) … at what rate?
A→B:_______
B→C: _______
C→E:_______
c) What happens to "capacity?"
A→B:_______
B→C: _______
C→E:_______
d) What happens to Specific Humidity? A→B:_______
B→C: _______
C→E:_______
e) What happens to Dew Point?
A→B:_______
B→C: _______
C→E:_______
f) What happens to RH?
A→B:_______
B→C: _______
C→E:_______
5. Use the Equation of State to explain adiabatic processes.
6. To produce a cloud (in very-general terms) requires: ____________ of ________________ air.
Lifting / Sinking
Saturated / Unsaturated
So, during cloud production, what two processes are reflected in the WAR? Be thorough.
7. Thus, explain the production of a "rainshadow desert."
8. On "Condensation" Video-Lecture #10, make sure you can answer the series of questions
posed from 4:50 to 7:17, from 7:17 to 9:15, and from 9:15 to 11:42.
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9. Draw a slightly-occluded Midlatitude Cyclonic Storm in map-view using 5 or 6 isobars and the
standard symbols for an Occluded Front, a Cold Front, and a Warm Front.
a) What kind of air temperatures are located on either side of each frontal type?
b) What kind of clouds and precipitation are associated with the Cold vs. Warm Front?
c) Which is most-likely to produce Thunderstorms, especially in Springtime?
d) Following passage of a Cold Front, what happens to skies, winds, temperatures, and DP's?
e) Following passage of a Warm Front, what happens to skies, winds, temperatures, and DP's?
10. Compare and contrast (e.g., in terms of isobar shape, cause, latent heat content, etc.):
(a) Midlatitude Cyclonic Storms in winter
(b) Midlatitude Cyclonic Storms in springtime
(especially in Tornado Alley)
(c) Tropical Cyclonic Storms
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