Chapter 2 Earths Climate System

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Chapter 2Earths Climate System
Friday, 1/16/09

• Principles of
• Terrestrial Ecosytem Ecology
• Chapin, Matson and Mooney

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First essay assigned and due 1/23 at class
time. See web page.
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The Earths Radiation Budget
Why do ecosystem ecologists care?
Solar radiation generates climate as well as
the fuel to run the internal functions of
ecosystems.
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Planet
How much leaves, and in what form?
How much comes in?
Ecosystem
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Solar in longwave and solar out
System is OPEN to energy, CLOSED to
materials. (except for the occasional meteorite)

Outer space boundary
All energy enters and departs as electromagnetic
radiation. (No energy obtained or lost in mass or
mass flow)
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Solar constant maximum amount of solar
radiation that the Earth can receive (top of the
atmosphere at the equator) 1,367 watts per
square meter (what?)
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Solar constant 1,367 watts per square meter
(what?) 2 cal/cm2/min How much energy is
that?
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2
2 calories per square cm per minute
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2 calories per square cm per minute 20,000
calories per sq. m per minute
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2 calories per square cm per minute 20,000
calories per sq. m per minute 20 kcals (food
calories) per sq. m per minute
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2 calories per square cm per minute 20,000
calories per sq. m per minute 20 kcals (food
calories) per sq. m per minute 1200 kcals per
sq. m per hour.
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Since a lite beer 100 kcal/can, then a 12
pack 1200 kcals, therefore The solar constant
energy content of 1 twelve pack of skunky
beer per m2 per hour!!!!
How many minutes of solar energy is in your
power bar???
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2 calories per square cm per minute 20,000
calories per sq. m per minute 20 kcals (food
calories) per sq. m per minute 1200 kcals per
sq. m per hour. How many power bars is
that? For a 12 hour day 14400 kcals less
than 1/2 gallon of gas.
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Energy input to the earths surface varies as a
function of latitude and other
variables Nonetheless, An approximation of
energy input here is 1.3 million kcals/m2/yr
Energy equivalent of about 41 gallons of
gas.
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The fate of Energy About 30 of energy exits the
plant UNUSED.as reflected short-wave
radiation. Reflectivity of an object albedo
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Reflected energy
Fig 2.2
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Fate of incoming solar radiation 30 ? albedo
(shortwave energy reflected back to space by
clouds (20), atmosph. (6) and earths surface
(4) w/o heating the reflecting
surface) REFLECTED ENERGY IS UNUSED AND DOES
NOT IMPACT CLIMATE OR ECOLOGICAL PROCESSES! 1
INCREASE IN ALBEDO COULD REDUCE TEMP.OF PLANET BY
ABOUT 0.67oC
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Albedo Albedo of Fresh, flat snow ? 90
(why you burn on slopes!) Thick stratocumulus
clouds ? 80 Cloud avg. 55 Calm water w/
low angle of insolation ? 78 Calm water w/
vertical angle of insolation 2 Chalk,
light-colored buildings and rock gt 40 Sand
40 Yellowing deciduous forest in autumn gt
30 grasslanddeciduous forest gt coniferous
forest lt30 (earths surface (not atmosph)
dominated by water)
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We can control this, the output
We dont control this Its a forcing function
Unused energy Heat energy Water, water
vapor Nutrients Other stuff
Light energy Heat energy Water Nutrients Other
stuff
THE ECOSYSTEM AS BLACK BOX, (the ecosystem as
mechanism in Earth Science Dynamics)
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(No Transcript)
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Albedo change Snow (90) to land (20)
water ( 10) All of a sudden, there energy
being pumped into the system
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Land use change can also have large effects on
albedo Conversion of grassland (ca 20
reflectance) to dark fallow field (5
reflectance) OR to light sandy soils
(desertification, 40 reflectance) Where does
the energy go when reflectance has changed?
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100 original amount of solar input - 30 albedo
from all sources - 19 atmospheric cloud
absorption 51 of original insolation that
penetrates to the Earths surface and
is transformed into if over timethe surface of
the earth is not gaining in energy content, then
the input must be balanced with outputs. These
outputs are 23 latent heat energy used to
evaporate H2O 7 sensible heat ? kinetic
energy of atoms 21 longwave radiation 51
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What is happening with the net radiation balance
to explain global warming???
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2.16 Human population growth and resource use
save us from another ice age?
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Figure SPM.2
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FAQ 9.2, Figure 1