GEO 202 Midterm1
Terms
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- Earth's Diameter
- -12,756 km () -12,714 km (up and down)
- systems
-
-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) - feedback
- -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
- albedo
- -fraction of incoming radiation reflecting back to space
- thresholds
-
-boundary between two states
-"tipping point"
-many systems have more than 1 equilibrium state - atmospheric structure
-
-troposphere
-stratosphere
-mesosphere
-thermosphere - troposphere
-
-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
- tropopause
-
-top
-temp stops lowering and starts rising
- ~-57 degree C - stratosphere
-
-18-50 km
-temp increases upward - stratopause
-
-top
-0 degree C - Mesosphere
-
-50-80 km
-temp decreases upward - mesopause
-
-top
-~-80 degree C - Thermosphere
-
-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 - CFCs
-
-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
- -sun
- ultimate source of energy for nuclear power
- -radioactive decay
- ultimate source of energy for hydro-electric power
- -sun
- ultimate source of energy for coal
- -sun
- ultimate source of energy for geothermal energy
-
-radioactive decay
-gravity - ultimate source of energy for lifting a boat with the tide
- -gravity
- 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
-auroras
-electromagnetic radiation - auroras
-
-incoming solar wind electrically charges atoms, molecules in atmosphere
-charged atoms glow - input
- insolation
- insolation
- 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 - outputs
-
-reflection
-radiation - reflection
-
-high albedo=highly reflective
-earth's average is 31% - radiation
-
-all bodies emit radiation
-amount goes up as temperature to 4th power - earth's energy balance with actual numbers
-
-no change is storage
-input=output
-input: insolation=343 W/m2
-outputs: reflection=106, radiation=237 - driving forces of wind
-
-pressure
-coriolis force
-friction - pressure
-
-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
- humidity
- -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" - stability
-
-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
-varies - 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
-ELR>DAR - conditionally unstable
- -DAR>ELR>MAR
- generates lifting
-
-convergence and convection
-orographic
-frontal - convergence
- -airflows in conflict force lifting and displacement of air upward
- convection
- -air passing over warm surfaces gains buoyancy and lifts
- orographic
- -an air mass is forces to move upward over a mountain range
- frontal
- -along the leading edges of contrasting air masses
- stratus
- -appear dull, gray, and featureless
- nimbostratus
-
-stratus clouds that yield precipitation
-drizzling rain - cumulus
- -appear bright and puffy
- Alto clouds
- -middle level clouds
- cirrus
- -feathery strokes
- cumulonimbus
- -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
-
-conservative
-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
-floods
-water supply and irrigation
-transportation
-pollution and water quality
- groundwater
-
-water below the ground surface
-majority of world's fresh water
-20% of US water supply
-40% of US domestic water - aquifer
- -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
-
-porosity
-permeability - porosity
-
-(volume of voids)/(total volume)
-granite has low
-gravel has high - permeability
-
-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)
k=permeability
C=1.0x10^7
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
-
-evapotranspiration
-runoff - evapotranspiration
- -total water evaporated from plants and land surface
- runoff
- -all water that flows away (surface or subsurface
- measuring output:streamflow
-
-discharge (volume of flow per unit time
-stage (water level in stream) - thalweg
- -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)
- deficit
- -POTENT >PRECIP
- weather
- -short term conditions of the atmosphere
- climate
-
-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
-fossils
-isotopes
-ice cores
-corals - 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) - fossils
-
-animal and plant communities change with climate
-knowledge of flora & fauna= knowledge of climate
-smooth edged plants more common in warmer climates - isotopes
-
-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 - corals
-
-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?
-
-continentality
-ocean currents
-weathering
-highlands
-volcanic act - continentality
- -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 - weathering
-
-"earth's thermostat"
-plate tectonics produce erosion, weathering
-weathering "scrubs" CO2 from atmosphere
-warmer climates=more weathering (& vice versa) - highlands
- -more highlands=more weathering, lower CO2
- volcanic activity
- -CO2 (faster tectonics=more CO2)
- Orbital scale climate change
- -milankovitch cycles
- milankovitch cycles
-
-eccentricity
-precession
-obliquity - eccentricity
-
-shape of orbit
-period=~100,000 years - precession
-
-earth's axis wobbles like a top
-period=~26,000 years - obliquity
-
-change in angle of ecliptic
-period=~40,000 years