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105 Cards in this Set

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earth's water resevoirs distribution
ocean: 97% (& source to other res.)

ice / glaciers

groundwater

lakes

atmosphere
water transfers between reservoirs are balanced @ rate of
10^12 m^3 / yr
more precip than evapotranspiration over land due to
excessive evaporation over ocean
latent heat
energy req. to change liquid to gas

(energy converted back to heat when vapor condenses into clouds)
evaporation
occurs when enough energy for the fastest moving molecules to break free of the bonds at liquid's surface

with more and more energy applied more and more evaporation bc molecules move faster on avg
change in state
energy absorbed v released
absorbed from solid -> gas
(sublimation)

released from gas -> solid
(deposition)
saturation vapor pressure
# of molecules that can be held by an amt of air

-depends only on temp

-increases w temp (warmer air can hold more water)

**Goes up ~5% every *C
condensation (cloud formation) occurs when
air reaches saturation

--can be acheived by adding water vapor or cooling the air
monsoon
strong change in wind direction (seasonal)

-normally requires heating of large land mass near ocean

-india , se asia

-connected w ITCZ

-influence SW u.s.
india / se asia
summertime heating of land mass leads to buoyancy

rising air replaced by moisture filled air from ocean


wintertime cooling creates high surface pressure air reverses direction and flows to lower pressure air over ocean
vertical structure of ocean
top less salty & warmer
--upper mixed seasonally by wind

-upper seperated from lower by large density gradient *PYCNOCLINE*
wind stress
wind moves upper ocean water

-coriolis effect means water in NH moves clockwise (deflected to rt)
-and CCW... deflected to Lft in SH
4 factors determining water movement
1. coriolis effect

2. ekman transport

3. geostrophic balance

4. westward intensification
ekman transport
happens in response to coriolis effect, wind stress, friction

water appears to move in spiral downward

-over the top 100 m of water the water moves 90* to the right of the wind direction (the ekman layer)

*LEADS TO CONVERGENCE
--creating a pile of water
(area of high pressure)
geostrophic flow
"balanced flow"
geostrophic = 'earth turning'

happens when movement due to pressure gradient balances movement due to coriolis effect

*flow follows a circular pattern.. (the pressure gradient causes movement downhill but it turns until the prssure grad and coriolis force balance
westward intensification
circular currents are skewed due to coriolis effect (hill spread out to west)

currents at western edge of gyres moves fastest

-coriolis effect increases w latitude & velocity
western boundary currents
fast deep narrow
-warm nutrient poor clear

*N atlantic gulf stream
*S atlantic brazil current
eastern boundary current
slow shallow wide
-cold nutrient rich

*N atlantic canary current
*S atlantic benguela current
antarctic circumpolar current
(west wind drift)
south of 40* S
-goes completely around globe
-largest volume flux
-driven by westerlies
subtropical gyres
transport heat from equatorial ocean to poles
up-welling / down-welling
required to balance mass

subtropical gyre center's convergence requires mass sinking for balance

subpolar gyre center's divergence requires upwelling for balance
up-welling
-upwelled water = rich in nutrients (& oxygen)

-when nutrient rich water uplifts and enters sunlit zone, photosynthesis can occur
(upwelling regions biologically rich / diverse)
---fishing!
visible light in seawater
blue penetrates farthest

top 250m = photic zone
equatorial upwelling
ekman transports to rt in NH and lft in SH ... so DIVERGENCE... so must have upwelling!!
coastal upwelling
equatoward winds go along E boundaries of continents
-ekman transport away from shore
-surface water replaced by subsurface water
convergence & downwelling
nutrient starved open ocean
ekman transport allows.. .
water to pile up in middle of ocean basins
--higher height = pressure gradient = balanced geostrophic flow in large gyres
deep ocean circulation
deep h2o properties largely determined by properties of water at surfface

high density of surface water due to heat loss to atmosphere leads to sinking of surface water and deep water formation
density of seawater
more salinity = denser

colder = denser
sea surface salinity (SSS)
depends on
the balance of evaporation / precipitation
to form deep water
don't only need temp to drop... need salinity too!
deepwater might not form in N pacific bc
not salty enough
thermo-haline circulation
driven by temp & salinity -- (Density)
--- aka deep ocean circulation

surface water can become dense enough to sink due to
-cooling (polar regions)
-sea ice formation (fresh water freezes as ice ... leaves remaining seawater very salty)
-intense evaporation (mediterranean)
3 main thermo-haline water masses
1-N atlantic deep water (salty)
2-antarctic bottom water (cold)
3-antarctic intermediate water (relatively fresh)
C14 related to ocean water
the less c14 the older the water

(C14 decays @ half life of 5730 yrs)
time scale of
surface ocean circulation
v
deep ocean circulation
surface circ : weeks - months

deep circ : 500 - 3500 yrs
ocean conveyer ...
carries salt poleward (allows for deep water formation
structure of earth
(atmosphere
hydrosphere
lithosphere
atmosphere : nitrogen & oxygen
hydrosphere : water
lithosphere:
-crust: silicates (Oxygen rich)
-mantle: silicates , magnesium, iron
-core: iron, nickel
compression (P waves)
v
shear (S waves)
S waves can't pass thru liquid

P waves shorter WL

*tell us density of inner earth**
cooling = convection
-leftover heat from planet formation
-radioactive decay
-friction (freezing / settling of Fe)

convection in outer core / mantle due to cooling
--mostly Fe ... gives rise to magnetic field

*magnetic strips ... reversals of poles symmetrical around mid-ocean ridge (where youngest seafloor is.. where sea floor is forming)
recycling of crust due to
spreading and subduction
-relativity
-DNA structure
-plate tectonics

ATTRIBUTED TO
relativity - einstein - 1905

DNA structure - watson & crick , franklin - 1953

plate tectonics - ewings 1968 drilling confirms vine & matthews 1963, hess 1962, wilson, wegener
igneous rocks
formed by molten material
(granites, basalts)
sedimentary rock
formed by eroded sediments

sand - mud - lime-stones
metamorphic rock
rocks exposed to heat in earth's interior

gneiss , marble
continental crust
formed from less dense materials ... thicker ... higher than oceanic crust

-lost by weathering

-cycling = cycling of key elements
geologic cycling of carbon
atmosphere --- photosynthesis and respiration
---to life---
---life dies ... = burial of organic carbon

buried organic carbon=
-calcium carbonate precipitates
-released from volcanoes as co2
carbon can bond readibly and reversably from
H, O, N & other carbon atoms
organic carbon
molecules with Carbon AND HYdrogen (CH4)

associated w life..
inorganic carbon
limestone, seashells, co2

oxidized form

-more stable
oxidized, intermediate, reduced
carbon
oxidized = most stable... organic C tends to move toward this state over time (CO2)


intermediate - carbohydrate - organic

reduced - CH4 - hydrocarbon - organic
photosynthesis formula
energy + co2 + h2o
----->
CH20 + O2
measure carbon in
gigatons (Gt)
steady state when
input = output

(so levels don't change)
residence time
avg length matter spends in reservoir

res. size / input
or
res. size / output
flux of carbon from terrestrial to atmosphere
60 GTC / yr
terrestrial production of organic C thru photosynthesis balanced by
respiration
&
decay
the ocean C cycle
biologal activity removes C from upper ocean into deep ocean

allowing new CO2 to enter upper ocean from atmosphere
ocean's biological pump
the organic matter created by photosynthesis sinks to deep ocean where it decays back into co2

-deep water becomes enriched in co2
-recycled back to surface

-conveyer belt from N atlantic to pacific

(respiration in deep water)
long term rock C cycle
weathering of Ca containing silicate minerals
use of Ca by organisms to build calcium carbonate shells

RESULT = uptake of Co2
controls of silicate weathering rates?
time
temp
precip
exposure of fresh rock surface
vegatation (roots provide acid)
feedback loop of weathering
increased temp = increased weathering
increased weathering removes CO2
less CO2 = lowering temp

*neg feedback loop*
buried organic C =
coal
oil
gas

-weathering of rocks = release of fossil fuels as co2
(over 100s - millions of years naturally)

--humans speed up process by burning fossil fuels to 10s of yrs
-----put C cycle out of balance
seasonal variations in co2
caused by terrestrial biosphere
(photosynthesis, respiration)
balance between silicate rock weathering & volcanic degassing
stabilizes climate & co2 over millions of yrs
pushes C cycle away from equilibrium?
changes in solar lum. (heating)
changes in sea floor spreading rate
-more spreading = more ocean = more volcanism

ice ages
O18 related to cooling?
cooling enriches O18 relative to normal oxygen

growth of ice sheets inriches O18 rel to normal oxygen
C13 related to cooling periods
the more C13 in fossils means less co2 in ancient atmosphere

bc when there's less co2 they're forced to use C13 more
(photosynthesizers prefer normal c12 carbon to the heavier c13)
orbital variations
eccentricity: influences radiation amt

obliquity (tilt): affects seasonal contrast

precession : strength of seasons
Milankovitch
1924

solar energy changes w seasonal contrasts
which vary due to variations in earth's orbit
-lead to climate variation
optimal conditions for glaciation
1. low obliquity (low seasonal contrasts)

2. high eccentricity & NH summers during aphelion
(cold summers in N)

--ice & snow not completely melted during summer (most land in NH)
co2 and climate vary together!
more co2 means warmer
ocean cycling of C feedback
seems to reinforce glacial - interglacial cycle
first significant fossil fuel use and increase of CO2?
1750
exponential increase in co2 after
1850
1920 decrease in atmospheric co2 concentrations?
when forests were re-established

problem w re-growth forests = reduced capacity of land to take up more carbon
land use changes
forest to pasture increase amt of co2 in atmosphere by decreasing photosynthetic capacity
clearcutting increase in co2 can be offset
by the increase in total co2, increasing photosynthesis

--- does not last long
---- can't count on it in the long run
peterbations of C cycle
cycling of C between atmosphere and terrestrial biosphere increased due to land use changes

cycling between atmosphere and ocean increased due to rising atm co2 (more exchange over same area)

carbon stocks in all reservoirs increasing!!!!
earth system "discount"
-help decarbonizing the system
shown by the fact that there is less co2 in the atmosphere than is emmited

-but effect likelky to decrease
rise in co2 due to land use change
(amt)
1.5 GTC / yr
fossil fuel rise in co2
(amt)
8 GTC / yr
every molecule of co2 emmited matters
atmospheric lifetime of co2 is long..... stays for long time
help from earth's C reservoirs?
currently soak up 1/2 of the current C emissions
effect of wind on ocean circulation
wind causes friction at ocean surface

-wind drags ocean in same direction it blows
why don't ocean currents move exactly same way as wind blows?
due to coriolis effect

-water deflected rt in NH
-deflected lft in SH
(deflections ~20-25* from wind direction)
ekman spiral occurs due to
friction between wind and water surface
-some energy from wind transferred to water
-that layer of water moves and drags water below it
--kinetic energy is transferred down each water layer
--but friction causes some of the energy transferred to be lost as heat
---- each level moves slower than above level

-still subject to coriolis effect:
-when water starts to move its deflected rt to the path of the layer above (in NH... left in SH)

---deeper below the surface the more the layer is deflected

net movement = 90* angle to wind direction = "ekman transport"
upwelling occurs
where divergence occurs at surface

-water rises from below to replace it
---coooler
deep ocean circulation depends on temp and salinity.... therefore called::
thermo-haline circulation
"bottom water"
densest water in ocean

at poles surface waters cooled to freezing pt... surface water freezes ... water left is very salty ...
the resulting cold salty water is more dense and sinks
and goes toward the equator
the thermo-haline conveyor belt
process in which deep water is transported around globe

deep water first forms in N atlantic
-downwelling occurs w water of rel low densities

--water moves S to antarctic
then to indian and pacific oceans
-finally to N pacific where it resurfaces

*recycling of ocean nutrients
*impact on climate
*when animals in surface water die they sink to bottom water making them nutrient rich .... thermohaline circ. brings these nutrients back to surface waters
ocean modifying global temp
-excess solar energy transported poleward when warm surface water flows to poles to replace bottom water forming at poles

*high spec heat
ekman transport affected gyres
pushes water to center of gyres
3 sources of heat in earth's interior
1. radioactive decay

2. leftover heat from formation

3. frictional heating from settling of iron w/i liquid outer core
driving force of plate movement
-friction between asthenosphere and lithosphere

-the push of the mid ocean ridge

-density increases as oceanic lithosphere cools... pulls opp end of plate into subduction zone

-tendency of plate to cool as sinks and become denser
Pwaves
v
S waves
P waves (primary waves)
-result from compression in earth's interior
-material alternately compressed & stretched
(slinky)

Swaves (secondary)
-transmitted as displacements perpendicular to overall direction of wave travel like movement of wave on a string
lithosphere
v
asthenosphere
lithosphere
-cool rigid shell

asthenosphere
-can rise buoyantly as a hotspot
theory of continental drift not immediately accepted in 1920's
bc continents couldn't plow thru the rigid sea floor (which was thought to be required)

-ori by wegener
deserts occur
where uplift is supressed and therefore there's less moisture

or where subsiding air... due to convergence (30*)

-also occur on west coasts of continents bc of cold offshore ocean currents
-cold currents reduce evaporation and cool air that moves over them... inhibiting convection and precipitation
-"littoral deserts"
-low saturation vapor pressure makes the precipitation that does fall small
ekman's theory predicts
1- surface current will flow 45* to the surface wind path

2- flow wil be reversed approx 100 m below surface (the current at 100m will flow opposite that of the surface current)

3- there will be reduced speed as u go deeper
divergence occurs in ocean
in equator region of atlantic
-NE trades result in westward flowing surface current
--since water deflected 90* to rt of wind means water flows due N

SE trades @ equator produce westward flowing current
since net ekman is 90* left ... water directed due S

--DIVERGENCE AT EQUATOR
divergent areas along coast
SW coast of N america

W coast of N africa
reason for very distinct ocean gyres
areas of convergence and divergence produce slight variations in elevation ... this gradient causes downslope force on water due to gravity

-sea surface about 50 cm higher in center of gyre than at edges ...
-water is pushed outward down gradient from center
... as it flows its deflected by coriolis effect until it balances the pressure gradient
--resulting in the two forces acting in opposition causing flow of water off to the side
(circular flow of water around gyre parallel to ocean slope

**GEOSTROPHIC CURRENT**
-clockwise in NH
-CCW in SH
... in same direction as original wind driven flow
... water tends to spiral inward as moves around gyre
... convergence in gyre results in downwelling
east v west parts of gyre
west side - narrow fast flowing current

east side - more diffuse spread out ... tendency to be divergent
europe is warmed by
the warm N atlantic drift