Earth's Life Support Systems Flashcards
Outline the importance of water? (4)
- Allows molecules to mix
- Oceans (71% earth surface) absorb heat and release slowly
- Clouds + ice reflect 20% incoming radiation
- Water vapour (greenhouse effect) maintains average 15ºC
How is water used in plants? (5)
- Photosynthesis
- Respiration
- Transpiration
- Makes up 65-95% of organisms
- Metabolic functions
How is water important economically? (5)
- Generates electricity
- Irrigates crops
- Recreation
- Public demand
- Industries
How is carbon an economic resource?
- Fossil fuels power economy
- Manufacturing products
- Agriculture
- Raw materials
What are the three main stores of the water cycle?
- Atmosphere
- Oceans
- Land
What are the main processes in the water cycle? (5)
- Precipitation
- Evaporation
- Transpiration
- Run-off
- Ground flow
What are the main stores of the carbon cycle? (6)
- Sedimentary rocks
- Oceans
- Fossil fuels
- Peat
- Atmosphere
- Plants
What are the main processes in the carbon cycle?
- Photosynthesis
- Respiration
- Decomposition
- Oxidation
- Combustion
- Volcanic activity
What percentage of the Earth’s water is stored in oceans?
- 97%
What percentage of the Earth’s water is stored in the cryosphere?
- 2%
Where is 99.9% of the Earth’s carbon stored?
- Sedimentary rocks
What are stores of carbon also called?
- Carbon sinks
What are inputs into the atmosphere in the water cycle?
- Evaporation of water
- Transpiration of water
How does moisture leave the atmosphere in the water cycle?
- Precipitation
- Condensation
How is water lost from the cryosphere?
- Melting
- Sublimation
How does water move between ground and land stores?
- Run-off
- Infiltration
- Percolation
What strands combine to form the global carbon cycle?
- The slow carbon cycle
- The fast carbon cycle
What is the residence time for carbon in rocks?
- 150 million years
How much carbon is circulated in the slow carbon cycle per year?
- 10-100 million tonnes
How is the slow carbon cycle linked to volcanic activity?
- Carbon stored in sedimentary rocks gets subducted
- Vented onto atmosphere during eruptions
How are carbonaceous rocks formed as part of the slow carbon cycle?
- Partly decomposed organic material is buried under younger sediment
- Forms carbonaceous rock
- Eg coal, oil, natural gas
Where does carbon circulate fastest?
- Atmosphere
- Oceans
- Biosphere
- Soils
How much faster are the transfers in the fast carbon cycle than in the slow carbon cycle?
- 10-1000 times
What are the key components of the fast carbon cycle?
- Land plants
- Phytoplankton
What is the water balance equation?
- Precipitation = Evaporation + Streamflow +/- Storage
What forms does precipitation come in?
- Rain
- Snow
- Hail
- Sleet
- Drizzle
Outline the varying characteristics of precipitation with physical geography?
- High latitudes - snowfall remains for long time, large lag time
- Intensity
- Duration
- Some locations have concentrated rainy season
How much moisture in the atmosphere is transpiration responsible for?
- 10%
What is the simple basis of cloud formation?
- Phase change of vapour to liquid as air cools to its dew point
What happens at the dew point?
- At critical temperature air becomes saturated with vapour, causing condensation
Describe cumuliform clouds.
- Flat bases, vertical development
How do cumuliform clouds form?
- Air heated through contact with Earth’s surface
- Air parcels rise (convection) and expand due to reduced pressure and cool
- When reaching dew point, condensation begins and clouds form
How do stratiform clouds form?
- Air mass moves horizontally across a cool surface eg ocean
- Air mixes with turbulence, known as advection
Describe stratiform clouds.
- Wide, flat clouds that form in stable conditions
- Lower in atmosphere, can cause fog
Describe cirrus clouds.
- Wispy
- High altitude, > 6,000 meters
Why do cirrus clouds not impact the water cycle significantly?
- Formed of ice crystals
- Do not form precipitation
What are clouds?
- Visible aggregates of water, ice or both that float in free air
Define environmental lapse rate.
- Vertical temperature profile of lower atmosphere
- Temp falls by 6.5ºC per km height gained
Define dry adiabatic lapse rate.
- Rate which dry air parcel cools
- Cooling due to adiabatic expansion is 10ºC per km
Define dry air.
- Air with humidity less than 100%
Define saturated adiabatic lapse rate.
- Rate which saturated air parcel cools as it rises
- Condensation releases latent heat
- Cooling rate is 7ºC per km
What are lapse rates?
- Describe vertical distribution of temperature in lower atmosphere
- Describe temperature changes within air parcels as they rise
What is atmospheric instability?
- Air is warmer than surroundings
- Less dense, more buoyant
- Air rises freely in a convection current
What temperature is the dew point at?
- 8ºC
When does a cloud or air parcel stop rising?
- When atmosphere is stable
- Parcel and surrounding air is same temperature
What are the flow paths of rainwater that do not enter storage?
- Infiltration by gravity into soil, through flow into stream/river channels
- Overland flow across surface as a sheet or trickles into stream/river channels
How does interception storage capacity affect interception loss?
- Dry surfaces retain most water
- Saturated surfaces retain little water
How does wind speed impact interception loss?
- Evaporation increases with wind speed
How does vegetation types impact interception loss?
- Greater losses from grasses than agricultural crops
- Trees have higher losses than grasses
How does tree species influence interception loss?
- Losses are far greater from evergreen conifers than deciduous trees
- More water trapped between conifer needles, increasing evaporation
How can lithology influence percolation?
- Permeable rocks increases percolation
- Water joins ground flow
- Impermeable rocks reduce percolation and increase run off
What is the term for exchanges in the carbon cycle?
- Fluxes
How does precipitation move carbon between stores?
- Atmospheric CO2 dissolves in rainwater
- Increasing due to anthropogenic emissions
- Increases acidity of surface waters
How does photosynthesis move carbon between stores? How much is transferred annually?
- Moves from atmosphere to land plants and phytoplankton
- 120 gigatonnes
- Respiration releases CO2 into atmosphere
What is carbonation?
- Acid rain slowly dissolves limestone and chalk
- Releases carbon into streams, rivers, oceans and atmosphere
How much carbon is transferred by weathering annually? Name an example that shows the effectiveness of weathering.
- 0.3 billion tonnes
- Norber Brow, Yorkshire where limestone surface has been lowered by half a meter in 13,000 years
How can naturally occurring forest fires help ecosystems?
- Fire increase the decomposition of material to make nutrients accessible
- Opens forest canopy, creates new habitats, increases biodiversity
How much carbon dioxide is transferred from the geological store to oceans, atmosphere and biosphere by combustion?
- 10 gigatonnes
What are the two mechanisms of carbon sequestration?
- Physical pump
- Biological pump
What does the physical pump of carbon sequestration involve?
- Mixing of surface and deep ocean waters by vertical currents
- More even distribution of carbon vertically and globally
What is downwelling in carbon sequestration?
- Currents move dissolved CO2 polewards, cools and becomes denser, sinks
How does carbon that has undergone downwelling rejoin the carbon cycle?
- Moves into area of upwelling
- Cold, carbon-rich water rises and CO2 diffuses into atmosphere
What is the biological pump of carbon sequestration?
- Photosynthesis by phytoplankton
- Phytoplankton accumulate carbon on ocean floor or releases into oceans as CO2
- Crustaceans extract carbonate to create skeletons, end up as sediments and is lithified to form chalk and limestone
How does vegetation cause carbon fluxes?
- Land plants eg rainforests, boreal forests store loads of carbon
- Most extracted from atmosphere through photosynthesis
