S104 BOOK 1

Global warming
1. ice shelf disintegration
2. sea level rise
  1. 0.09m - 0.88m by 2100
    1. loss of land
      1. very gradual
  2. dominated by thermal expansion as water warms
  3. ice sheets melting = sea level rise
    1. ice shelves float = no change
    2. ice to water vapour = sublimation
3. greenhouse effect
  1. Greenhouse gases
    1. CO2
      1. main anthropogenic greenhouse gas
        burning fossil fuels
    2. H2O (g)
      1. most abundant
      2. precipitation
    3. more gas = warmer
    4. anthropogenic climate change
    5. a gas that can absorb ir
      1. only if molecule contains more than 2 atoms, or 2 different atoms
  2. increase in temp caused by earth 'trapping' heat
  3. atmosphere critical to effect
    1. ir from surface, some absorbed by atmos, reemitted and some absorbed by surface
      1. more absorbing to ir the atmosphere is the higher the GMST
        infrared absorbtivity higher = more absorbed = higher GMST
Earth surface temperature
1. surface temp - not actually surface= just above
  1. every day at set times
    1. calculate mean
      1. all the values added together then divided by number of results
2. 30-year mean surface temp
  1. 30 year GMST
3. GMST
  1. sum of all mean surface temp / number of locations
  2. last 100 yrs warming
    1. rate of increase
      1. 20000 years - 10oC
    2. 0.5oC /century
  3. evidence from ancient organisms
    1. vegetation inhabited region
      1. fossils
      2. pollen grains
      3. lake bed silt
        deeper sample - older
        changes in proportion of pollen = changing climate
        pollen diagram
  4. glacial period
    1. integlacial periods
    2. ice age
  5. Sun source of all energy
    1. equal in and out energy transfer GMST constant
      1. leaky tank model
        steady state
      2. GMST rises until rate of surface loss by surface equals rate of gain
      3. if GMST vwere to rise total mass of water vapour in atmosphere would increase
  6. 15oC
4. urban heat island
uncertainties
1. quote as half a division on recording device i.e 0.5mm
2. experimental uncertainties
  1. i.e. series of measurements over 2 minutes show range of values
    1. random uncertainty
      1. scattered fairly randomly around some mean value
      2. one overall
      3. can be estimated by repeating - spread of results indicate random uncertainty
      4. PRECISE
  2. systematic error
    1. i.e thermometer scale out slightly
      1. systematic uncertainty
        ACCURATE
        offset from 'true'
energy
1. Heat
2. SI unit of energy = joule J
  1. cannot create or destroy
  2. power is rate at which energy transfer takes place
    1. power = energy transferred / time taken
      1. rate of energy transfer
3. convection
  1. conduction
    1. saucepan of water on hot plate
      1. water warms - increase in volume
        thermal expansion
        decreases density
        rises up
  2. enables more evaporation
    1. requires energy
      1. latent heat
        no temp change
        sweat from body surface cools
  3. air heated by ground rises up, temp decreases, vapour condenses - clouds
    1. higher temp, air holds more vapour
      1. relative humidity
        how saturated air is
    2. latent heat
    3. latent heat energy given out by condensation heats surrounding atmosphere
units and maths
1. speed m s -1
2. mass kg
3. ratio - no units
4. metric ton = 1000 kg
5. time s
6. distance m
7. area m2
8. always include units
9. graph
  1. title
  2. axis variable/unit
10. tables
  1. units in header
11. scientific notion
  1. 1<>10
12. sig fig
  1. certain + one digit
  2. in sums answer uses least sig fig in qu
13. energy J
  1. power = J s -1
    1. also called W
14. density = mass/volume
  1. kg m-3
15. pressure = pascal Pa
16. % = parts per hundred
  1. %x1000000 =ppm
17. equations interchangealbe
  1. coupling
solar radiation
1. light, visible radiation
2. ir
  1. emitted by earth surface
    1. atmosphere
      1. re-emits energy from sun and surface
    2. space
3. uv
4. solar luminosity
  1. 1 m2 intercepts 1370 W m2
    1. solar constant
      1. Atmosphere affects solar radiation
        absorbtion - solar radiation converted to heat
        scattering - redirection of radiation (clouds/aerosols good!)
        all directions up and down!
        reflection from surface - into space
        ice and snow reflect most
        oceans least
      2. radiation reaching surface absorbed
        higher surface temp!
      3. 20% absorbed atmosphere, 49% absorbed by surface,31% returns to space
        mean rate returned to space = albedo
earths atmosphere
1. mixture of gases
  1. molecules collide with each other
    1. exert pressure
2. 100km thick
  1. below 10k troposphere
    1. above stratosphere
    2. fairly mixed gases/aerosols
3. n2 o2 ar h2o(g) co2
Water cycle
1. reservoir
  1. oceans most
    1. ice and snow next
2. precipitation
  1. global mean annual precipitation = 1000mm
  2. transpiration - roots, stem leaves atmosphere
feedback
1. inc in orig. leads to furth inc.
  1. +ve feedback
2. inc in orig leads to decrease in orig
  1. -ve feedback
carbon cycle
1. chemical basis for all life
  1. organic carbon
    1. forms lots of different chemical compounds
2. biogeochemical cycle
  1. biological cycle
    1. living things
    2. atmosphere
    3. soil
    4. surface ocean
      1. solar rad., mixes wind and wave
        dissolved carbon
        more in cold water
        degassing
        plankton
        particulate carbon
        some drops to deep ocean
        link to geochemical cycle
        biological pump
      2. top 100-200m
    5. short residence time
    7. green plants = pump resp + photosy.
      1. resp + photosy. = burning fossil fuels
      2. decomposition
  2. geochemical cycle
    1. very long residence time
    2. deep ocean
      1. by 1km temp -1
      2. upwelling + sinking
    3. rock
      1. volcanoes
    4. sediment
      1. lithification
        sedimentary rock
        uplifting and weathering
        erosion
        carried in streams etc
        organic material - no oxygen - coal
        burning releases the stored carbon
        deforestation leads to less carbon taken out of atmosphere
    5. linked
    6. biological pump = leak between

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S104 BOOK 1

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	Criado por Theresa Cleaver aproximadamente 10 anos atrás