This site is 100% ad supported. Please add an exception to adblock for this site.

GEO 202 Midterm1


undefined, object
copy deck
Earth's Diameter
-12,756 km () -12,714 km (up and down)
-set of things linked by flows of energy and matter
-has properties not present in any of the parts (car has ability to move, but it's parts can't)
Earth's system components
-Geosphere (land)
-atmosphere (air)
-hydrosphere (water/ice)
-biosphere (life)

-output may affect operation of system
positive feedback
-output drives the system to grow in size or response
-example: microphone, snowcover
negative feedback
-output drives system to shrink in size or response
Snowcover as a positive feedback
-it reflects the sun's rays much more than bare ground
-fraction of incoming radiation reflecting back to space
-boundary between two states
-"tipping point"
-many systems have more than 1 equilibrium state

atmospheric structure

-lowest layer (0-18 km)
-90% of atmosphere by mass
-thickness varies with season
-temperature lowers as you go upward

normal lapse rate
-6.4 degree C/km
-temp stops lowering and starts rising
- ~-57 degree C

-18-50 km
-temp increases upward
-0 degree C
-50-80 km
-temp decreases upward
-~-80 degree C
-above 80 km
-temp rises upward
-temps are greater than 1000 degree C in upper part of thermosphere

Stratospheric Ozone
-lots of ozone (O3)
-sometimes called "ozonosphere"
-O3 absorbs UV

Ozone production
-O2 + UV = O + O
-O2 + O = O3 + heat
-slower at high altitudes

Ozone destruction
-O3 + UV = O2 + O + heat
-faster at high altitude
Ozone losses
-CFCs (chlorofluorocarbons)
-CFC biproducts destroy ozone without being destroyed themselves
-1 chlorine atom destroys 100,000 O3
-predicted by Rowland and Molina

-stable at the Earth's surface
-broken down in the stratosphere by UV radiation
Why a hole over Antarctica and in September?
-conditions in antarctic spring are particularly destructive to O3 by CFCs
-isolated, extremely cold air in antarctic winter (june, july) yield polar stratospheric clouds
-surfaces of crystals: CFCs --> Cl2
-Cl2-->Cl when hit by sunlight in spring
-Cl destroys O3 very quickly

Earth's energy
-3 sources
-the sun (fusion of H into He)
-radioactive decay/fission (decay of radionuclides)
-gravity (earth, sun, moon)

Ultimate source of energy for petroleum/gasoline
ultimate source of energy for nuclear power
-radioactive decay
ultimate source of energy for hydro-electric power
ultimate source of energy for coal
ultimate source of energy for geothermal energy
-radioactive decay
ultimate source of energy for lifting a boat with the tide
the sun's primary outputs
-electromagnetic radiation (light)
-solar wind (electrically charged particles escape from the sun
solar winds
-mostly protons and electrons
-move from sun in steady stream (takes about 3 days from sun to earth)
-sunspots contribute to solar wind
-as they come close to earth, they interact with magnetosphere

sunspot cycle
-sunspot activity has about 11 year cycle
-continuous records since 1749
effects of solar winds
-solar winds interact with upper atmosphere
-electromagnetic radiation

-incoming solar wind electrically charges atoms, molecules in atmosphere
-charged atoms glow
amount of solar energy intercepted by a surface
solar constant
-average insolation received at top of the atmosphere
-1372 W/m2
earth's energy balance
-input - output = change in storage
-area facing sun = pi*r2
-surface area = 4pi*r2
-average global insolation = 1/4 solar constant = 343 W/m2

-high albedo=highly reflective
-earth's average is 31%
-all bodies emit radiation
-amount goes up as temperature to 4th power
earth's energy balance with actual numbers
-no change is storage
-input: insolation=343 W/m2
-outputs: reflection=106, radiation=237

driving forces of wind
-coriolis force

-force per unit area
-average atmospheric pressure= 1013 mb
-air moves from high to low pressure

what does the coriolis force do to wind patterns
-N hemisphere: CCW around lows, CW around highs
-S hemisphere: CW around lows, CCW around highs
thermohaline circulation
-deep ocean currents produced by differences in temp and salinity with depth
-water vapor content in air
dew point
-temperature at which a given parcel of air is saturated
specific humidity
-(mass of vapor)/(mass of air)
-"absolute humidity"
-tendency of an air parcel to stay at the same altitude (unstable air rises or falls)
-depends on density (warmer air=less dense)
environmental lapse rate
-lapse rate at a particular time/place
adiabatic processes
-temperature change without loss of gain of hear to surroundings (pressure)
-rising air expands, as air expands it cools
common adiabatic processes
-compressed air
-diesel engine
-air conditioners

dry adiabatic rate (DAR)
-rate dry air cools by expansion (or warms by compression)
-DAR = 10 degree C/1000 m
Moist Adiabatic rate (MAR)
-rate moist air cools by expansion (or warms by compression)
-MAR=6 degree C/1000m

stable air
-if rising air becomes more dense than surrounding air -environmental lapse rate (ELR)
unstable air
-rising air becomes less dense than surrounding air
conditionally unstable
generates lifting
-convergence and convection

-airflows in conflict force lifting and displacement of air upward
-air passing over warm surfaces gains buoyancy and lifts
-an air mass is forces to move upward over a mountain range
-along the leading edges of contrasting air masses
-appear dull, gray, and featureless
-stratus clouds that yield precipitation
-drizzling rain
-appear bright and puffy
Alto clouds
-middle level clouds
-feathery strokes
-towering giant
fundamental needs of water for 1 person
-5 to 10 gallons per day
american domestic use of water
-150 gallons per day
all use of water in the US
-1350 gallons per day
5 key facts to the hydrological cycle
-driven by the sun
-compartments are not same size
-compartments have different residence times
-processes highly variable in time and space

water budget
-summary of inputs and outputs
-input - output =change in storage
examples of issues with water
-salmon and ecosystems
-dam removal
-power generation
-water supply and irrigation
-pollution and water quality

-water below the ground surface
-majority of world's fresh water
-20% of US water supply
-40% of US domestic water

-water saturated geologic unit that stores and transmits significant quantities of water
water table
-boundary between saturated and unsaturated zones
properties of rock that determine a good aquifer
-(volume of voids)/(total volume)
-granite has low
-gravel has high

-ability of rock or soil to transmit fluid
-clay has low
-gravel has high

Darcy's Law
- Q= kC(deltaH/L)A
Q=flow rate (discharge)
deltaH=drop in water level
L=sample length
DeltaH/L=head gradient
A=sample area

inputs in water budget
-precipitation (PRECIP)=rain or snow
outputs in water budget
-total water evaporated from plants and land surface
-all water that flows away (surface or subsurface
measuring output:streamflow
-discharge (volume of flow per unit time
-stage (water level in stream)
-fastest moving water in channel
Calculating water balance problem
-calc input by multiplying basin area by PRECIP
-calc output by multiplying basin area by ET, multiplying runoff by seconds in a year, add these two values together

actual evapotranspiration
-ET that actually occurs (ACTET)
potential evapotranspiration
-ET that could occur if water were lying on the surface at all times (POTET)
-short term conditions of the atmosphere
-long term average of weather conditions (temperature & precipitation)
-constantly changing
-many different timescales of change

How do we know about the earth's past climates?
-historical records
-sedimentary records
-tree rings
-ice cores

historical records
-droughts, floods, other disasters often recorded
sedimentary records
-many sediments laid down in annual cycles
-contain info like quantity, type of sediments, fossils, and pollen
tree rings
-trees grow faster in moist, warm weather than in dry or cold
-annual growth cycles recorded
-record of weather (avg)

-animal and plant communities change with climate
-knowledge of flora & fauna= knowledge of climate
-smooth edged plants more common in warmer climates

-same # of protons, different # neutrons
-different atomic weights
-isotopes have difference abundances in nature
-behave differently in environment

O-18 and O-16
-oxygen 16 most abundant (99.8% of all O, O-18 is most of rest)
-Water with oxygen 18 heavier than with 16
-18 less likely to evaporate, more likely to fall as precip
-18 and 16 change ratios with temperature

ice cores
-ice traps air bubbles
-annual precip cycle
-glaciers hold ice for long time
-drill through ice to get sample
-measure O-18, O-16 ratio

-annual growth
-measure O-18, O-16 ratio, also carbon
-high quality data

scales of climate change
-tectonic (Ma)
-orbital (ka)
-shorter times (10s-100s of years)

Tectonic Scale Climate Change
-climate change on scale of 10s of Ma
-most of last 600 Ma warmer than now
-current climate is interglacial within "ice age"

what drives climate change on tectonic scale?
-ocean currents
-volcanic act

-tendency of land to experience more thermal variation than water
ocean currents
-opening of Drake's passage 20-25 Ma
-increases albedo in S Hemisphere
-"earth's thermostat"
-plate tectonics produce erosion, weathering
-weathering "scrubs" CO2 from atmosphere
-warmer climates=more weathering (& vice versa)

-more highlands=more weathering, lower CO2
volcanic activity
-CO2 (faster tectonics=more CO2)
Orbital scale climate change
-milankovitch cycles
milankovitch cycles

-shape of orbit
-period=~100,000 years
-earth's axis wobbles like a top
-period=~26,000 years
-change in angle of ecliptic
-period=~40,000 years

Deck Info