PHYSICAL GEOGRAPHY

SPRING 2008

How to Study for this exam:
1. Review all quiz questions, be sure you know the right answers.
2. Study your lecture notes, get notes from another student for days you missed.
3. Look at all pictures and diagrams, and captions in text, and be sure you understand them.
4. Ask questions on the email list, ask questions in class, Prof. Freidel's office hours.
5. If you have time, re-read sections of the text that were more difficult for you to understand.

THIS STUDY GUIDE HAS NOT YET BEEN EDITED FOR THE FIRST MIDTERM, SPRING 08

Concepts and Terms that may be on the exam

This exam is cumulative in that I assume you understand Terms and Concepts from the first third of the semester, such as Albedo, Continentality, and Temperature gradients as they relate to Terms and Concepts listed below.

Air Pressure:
High Pressure -- Sinking air, Associated with stable air, sunny skies (not necessarily warm temperatures)
Low Pressure -- Rising air, Associated with unstable air, clouds, maybe precipitation
Cold air-- tends to be higher pressure, dense because cold
Warm air -- tends to be lower pressure, less dense because warm
Air pressure, Gravity -- highest pressure near sea level, air pressure decreases with altitude

Driving Forces in the Atmosphere (Why does the wind blow?):
Pressure Gradient Force -- pulls air from High Pressure to Low Pressure
Coriolis Force --bends air to right in the No. Hemisphere, to the left in So. Hemisphere, none at equator, strongest at poles, strongest at high velocities, none at zero velocity
Resisting forces: Friction -- slows down surface winds
Cyclone: air circulating into a low pressure cell, counterclockwise in N. Hemisphere
Anticyclone: air circulating out of a high pressure cell, clockwise in N. Hemisphere

Global Atmospheric Circulation
Be able to draw globe showing winds and High/Low pressure cells
Tropical Circulation (including ITCZ and Subtropical Highs)
Intertropical Convergence Zone(ITCZ) (low pressure, rising air, thunder storms)
Subtropical High Pressure Cells) (sinking air, hot deserts)
Polar Front (boundary between Subtropical Air and Polar Air)
Westerly winds, Polar Jet Stream, Westerly cyclonic storms, Cold fronts and Warm fronts
Polar Highs (Polar Easterly winds)

Jet streams
Polar front, polar jet stream -- located right above the polar front at the top of the troposphere, westerly
Subtropical jet stream -- located right above the descending part of the Hadley cell, also westerly

Local Winds
Land-Sea breezes
Mountain-Valley breezes
Katabatic winds -- cold air drainage, very high winds, especially in Antarctica
Santa Ana winds -- Southern California, blowing down from the Great Basin in fall
Chinook winds -- warm winter winds off the Rockies, snow eaters, in western Great Plains
Monsoonal Winds, Monsoons -- as they affect seasonal precipitation
Where do monsoons occur? Why? What causes monsoons? (winter offshore dry, summer onshore wet)

Water on Earth
Hydrosphere -- Ocean Circulation
Wind driven surface ocean currents
Subtropical gyres --circulate around the Subtropical Highs; horse latitudes in the center, clockwise in N, counterclockwise in S (anticyclonic flow)
Warm and cold ocean currents
Gulf Stream -- carries warm water up to the North Atlantic, helps keep Europe warm
Cold water upwelling -- east sides of ocean basins, west sides of continents, at ~35oN&S Lat
Influence of Coriolis effect and winds
North Atlantic Deep Water -- ocean deep water circulation, also called "thermohaline" circulation (thermo=heat, or in this case cold; haline= salty or saline)
Potential effects of shutting down of thermohaline circulation

Hydrologic Cycle, Hydrosphere
How much, and where? proportions of salt water with fresh, where most is located, stored
Unique properties of water: solid, liquid, gas, phase changes
Latent heat -- stored during vaporization, released during condensation
Sensible heat -- heat you can feel or measure with a thermometer
Relative humidity, percentage of actual water vapor in air relative to vapor content at saturation
Dew point temperature

Adiabatic processes
Environmental lapse rate -- Actual change in temperature with elevation
Average lapse rate in atmosphere -- 6.4 deg C/1000 m, or 3.5 deg F/1000 ft
Dry adiabatic lapse rate -- 10 degrees C per 1000 meters, in UnSaturated AIR, no condensation!
Wet or Moist adiabatic lapse rate -- varies with water vapor content (temperature at saturation), between 4 and 9 deg C/1000 m, avg. 5 deg. C/1000 m -- latent heat released during condensation slows rate of cooling, so air cools more slowly with elevation than when air is not saturated
Air parcel cools adiabatically when rising, warms adiabatically when sinking (at dry ALR)
Temperature inversion -- when layer of warm air overlies cold surface air

Condensation, clouds, and fog
Condensation nuclei -- aerosols, dust particles onto which water condenses into droplets
Dew and frost -- do not fall, so NOT precipitation, caused by longwave radiation leaving surfaces at night
Radiation fog, advection fog, upslope fog

Cloud classification
By vertical development: stratus and cumulus
Stratus clouds are caused by evenly rising air over a large area -- flat lying layers
Cumulus clouds are caused by uneven, turbulent rising and sinking air -- piled up, convective
By elevation: cirrus, alto, etc.
Also nimbus, cumulonimbus, lenticular clouds, and other interesting types
What do different clouds tell you about weather (e.g. fronts approaching)?

Precipitation
Requires mechanism for uplift, cool to dew point temperature
Requires also condensation nucleii, dust, salt crystals suspended in air
Four Mechanisms of Uplift -- (1) convective, (2) orographic, (3) frontal, (4) convergent
(Be able to draw diagrams and describe mechanisms of uplift)
Formation of Clouds and Precipitation

Stable and Unstable Atmospheric Conditions
Rising air associated with unstable conditions
Rising air cools because of expansion, resulting from lower air pressure
Unstable -- rising air, moisture condensation, clouds, possible precipitation
Sinking air associated with stable conditions
Sinking air warms through compression, a result of moving down to higher air pressure
Stable -- sinking air, water droplets evaporate, dry conditions, no clouds

Air Masses -- How formed, Where formed, classification
By temperature -- Polar, Tropical
By moisture -- Continental, Maritime
Know letter designations and temperature, moisture characteristics
cP, cT, mP, mT
How do air masses influence the weather in different places?

Weather
Orographic precipitation, rainshadow effect (why?)
Warm fronts and Cold fronts -- be able to draw cross-sections and describe associated weather
Midlatitude Cyclonic storms -- how and where they form, life cycle, role of air masses, Polar Front, Westerlies, Jet Stream
Weather associated with midlatitude wave cyclone
Thunderstorms and associated hazards -- hail, lightning, downbursts, intense rainfall (flooding), tornadoes
Tornadoes -- conditions for development, role of air masses, wind shear
Hurricanes -- (briefly) hazards of high winds, high tides, floods, intense rain, tornadoes,
What drives hurricanes? what conditions are necessary for development? Needs deep layer of very warm ocean water (warmer than 80 deg. F), Coriolis force, weak upper level winds (e.g. weak tropical jet stream)

Climate
What is climate? Average weather over 30 years of record
Climate Distribution: Understand relationship between climate at a particular place and:

Latitude -- solar radiation receipts
General Atmospheric circulation patterns, Hadley cell, ITCZ, winds
Semipermanent highs and lows
Wind patterns -- Trade winds, Westerlies, Polar Easterlies
Typical storms -- e.g. westerly cyclones, hurricanes, tornadoes, etc.
Distance from ocean -- (land-sea differences) continental and maritime influence
Ocean currents -- e.g. cold water upwelling, warm Gulf Stream
Air masses -- source, temperature, moisture characteristics
Topography and Relief -- e.g. elevation, location of mountains, aspect

Climate characteristics
Temperatures: mean annual, seasonal range, diurnal range (night vs day)
Precipitation: sources, seasonality, frequency, intensity, type (rain, snow), cloudiness
Where are there areas that are humid year round, where are there deserts, where is it warm year round, where is it cold? (Study Map Fig. 7.5, pages 224-225)

Koppen Climate Classification -- know first and second letters, third letters for B climates

Tropical climates, Af, Aw
ITCZ and Easterly trade winds
Hadley Cell circulation, semipermanent subtropical highs
Diurnal and seasonal temperature and precipitation characteristics
Monsoon climate -- seasonality of winds and precipitation
Savanna climate, wet and dry (why?)

Subtropical Deserts, Rainshadow Deserts--BW, Arid, BS, Semiarid (steppe), hot (h), cold (k)

Midlatitude climates -- subtropical (Cf, Mesothermal) and subpolar (Df, Dw, Microthermal)
Midlatitude cyclonic storms, westerlies, seasonal migration
Mediterranean (Cs) -- dry summer, wet winter -- why?

Polar climates, tundra ET, and ice sheet or ice cap EF

Natural climate variation (Do Not Emphasize)
This century, last few hundred years, Little Ice Age, Medieval warm period
Present interglacial -- the Holocene, last 10,000 years
The Pleistocene, ice ages, last ~2.5 million years, why?
Great ice sheets over northern hemisphere, Canada, Europe, sea level drops

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Last updated 4/7/08