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GEOG 203 Midterm 1 Review.doc


Department
Geography
Course Code
GEOG 203
Professor
Bruce Murphy
Study Guide
Midterm

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Midterm 1 Review
Geography: Enironmental Systems Midterm #1 Review
Lecture 1:
Earth has four spheres
Hydrosphere: Earths water exists in the crust, the atmosphere and on the surface
Biosphere: The intricate interconnected web that links organisms with their
physical environment
Lithosphere: Earths crust and a portion of the upper mantle
Atmosphere: A thin gaseous veil surrounding the earth, held to the planet by the
force of gravity
Open system is open to its surroundings, and a closed system is one that is shutoff to its
surroundings. Planet earth is a good example of a closed system as very little matter exits earth
or enters earth from space
Positive feedback is when a response to a change is amplified, and negative feedback is
when the response is reduced.
Attributes of environmental systems
Function, Scale, Feedbacks, Equilibrium states
Lecture 2:
Radiation emission
All bodies that possess energy emit 'radiation'
Temperature is a measurement of how much internal energy a body has
The higher the temperature of a body, the more radiation it will emit, and the
shorter the wavelengths
Radiation reception
Absorbed, reflected (if the surface is reflective and has a relatively hig albedo),
transmitted
Sun surface is 6000 degrees celsius and emits shorter wavelengths around 0.5um
Earths surface is about 15 degrees and emits longer wavelengths at around 10um
lambda(max)=(2898/T)
Earth orbit is eccentric meaning there is a perihelion January 4 (closest to sun) and
aphelion July 4 (farthest from sun) accounts for a 0.2% difference in sunlight received 100,000
year cycle
Earth wobbles between 22 and 24 degrees tilt 41,000 year cycle

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The average insolation (Incoming Solar Radiation) from the sun when it is at its average
distace is 1370 W/m^2
If averaged over an sphere an not a disk, it is 342 W/m^2, insolation varies over a curved
surface
Sun is directly vetical over the equators at the equinoxes, and over the tropic of capricorn
or cancer (23.5 degrees) on the solstices, occur on the 21-23 of March, June, September, and
December
The daily net radiation is positive approximately south of the 40 degree latitude, and tends
to be negative north of the 36 degree latitude. Incoming minus outgoing radiation
Four main layers of the earths atmosphere
Thermosphere: 80km-300km, high energy, low density
Mesosphere: 50km-80km
Stratosphere: 18km-50km contains ozone layer
Troposhere: Final layer or the atmosphere, 90% of atmospheric mass, supports life
The normal environmental lapse rate is 6.4 degrees centigrade/1000 metres
Consider, if earth was a blackbody it would effecitively radiate at -15 degrees, but its
average is 18 degrees. This is due to the greenhouse effect of gases in the atmosphere
Lecture 3:
Earths average albedo is 31%, meaning 31% of the incoming shortwave solar radiation is
reflected back to space
Some average albedo values
Fresh snow (80-95), grass (25-30), water bodies (10-60), forests (10-20),
crops/grasslands (10-20), asphalt (5-10)
Water bodies can vary greatly depending on their latitude, if the sun is
directly overhead, more radiation is absorbed (less albedo). If the sun is low in the sky
the water has a higher albedo
Energy transformations in the radiation budget
Radiative loss: depends on the temperature of the body
Sensible heat: transfer – surrounding soil, air, and water are heated
Latent heat transfer – Uptake and release of energy as water changes
phase
With increasing cloud cover the prediction for the affect on albedo can be misleading
Thick stratus clouds (low to surface) tend to generally cool because they reflect alot
of the suns rays
Thin cirrus clous tend to let the suns rays pass through

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Insolation average map is generally reflective of the latitude of locations, but over
rainforests a depression can be seen, and over the deserts it tends to be the highest. This is
certainly due to cloud cover, a depression is also seen around the ICTZ
Max insolation occurs around noon, coolest time of day is right before sunrise, warmest
time of day around 3-4pm just after insolation is max (there is a slight lag). Longwave
radiation is fairly consistent
SW^-SWv LW^-LWv = Net Radiation = Q*
Net shortwave flux = K Net longwave flux = L = Q*
Where Q* is the total radiant energy gain or loss at the surface
Q* is partitioned into 3 types of heat
Q(E) = Latent heat flux by evaporation
Q(H) = Sensible heat transfer into the atmosphere (via conduction and
convection)
Q(G) = Heat conduction into the ground
Q*=Q(E) Q(H) Q(G) [W/m^2]
Differences in earth surface characteristics influence partitioning
ability of material to absorb, transmit, emit, reflect radiation
ability to conduct and convect heat from the surface
ability of moisture for evaporation
Dark, wet soils: Low albedo, high conductivity, high heat capacity
Snow: High albedo, low conductivity (air in pores)
Dry sand surface: High albedo, low conductivity (air in pores)
Buildings: Low albedo, high heat capacity, no water
High Q(H) results in air-layer (above the surface) heating. Check out slides about Pitt
Meadows, BC and El Mirage Desert Station
The highest net radiation occurs over the earths tropical oceans, and rainforests (absorb
radiation)
Lower net radiation occurs over deserts and polar regions (high albedo)
Most Latent heat of evaporation occurs over the oceans with warm currents, as well moist
land surface, subtropics have dry air that accelerates latent heat evaporation
Least Latent heat of evaporation occurs over dry desert locations, cold polar
climates, and high altitudes
Global sensible heat, warming of atmophere (air-layer) heating occurs mainly in
subtropics, with dry landscapes, cloud free skies, and almost vegetation free land
Moist vegetated surfaces expend less heat in Q(H) and more in Q(E)
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