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A-Level Geography > 1 Water and Carbon Cycles > Flashcards

1 Water and Carbon Cycles Flashcards

1
Q

What is the ‘Goldilocks zone’?

A

The Earth is the ‘right’ distance from the sun for water to exist in large quantities in liquid form

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2
Q

Use the comparison of Mars and Mercury to Earth to support the importance of liquid water to life

A

On Mercury, 48 million miles from the sun, surface temperatures of 430C mean that only water vapour can exist
On Mars 141 million miles, -65C, water exists at the pole in the form of ice - although there might be very small amount of liquid water too

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3
Q

How does water help to create benign thermal conditions on Earth?

A

Oceans (71% of Earth’s surface) moderate temperatures by absorbing heat, storing it and releasing it slowly

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4
Q

How do cloud moderate the environment?

A

Made up of tiny water droplets and ice crystal reflect around a fifth of incoming solar radiation and lower surface temperatures

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5
Q

How do ocean currents moderate the environment?

A

Redistribute heat from the equatorial regions towards the poles, preventing excessive heating and cooling of different parts of the planet

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6
Q

How does water vapour moderate the environment?

A

Greenhouse gas
Absorbs outgoing long-wave radiation, helping maintain a global average surface temperature of 15C (approx 35C warmer than it would be without)

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7
Q

Why is water important for flora (plants)?

A

Plants area nearly all autotrophic (manufacture their own food)
Photosynthesis - production of glucose from CO2 and water using solar radiation
Transpiration - of water from leaf surfaces cools plants
Respiration - converts glucose to energy by reacting with oxygen, releasing water and CO2 in the process
Require water for rigidity and a medium to transport minerals

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8
Q

Why is water important for fauna (animals)?

A

Makes up 65-95% of all living organisms
Crucial for growth, reproduction and other metabolic functions
Respiration converts glucose to energy by reacting with oxygen, releasing water and CO2
Medium for all chemical reactions and for vital processes such as blood and nutrient circulation

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9
Q

Why is water important for human uses?

A

Used in industry, to generate electricity, to irrigate crops, for recreation and leisure, for drinking water and sanitation

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10
Q

Why is carbon important to life on Earth?

A

Life is carbon based - amino acids (proteins), carbohydrates and nucleic acids
Economic resource - fossil fuels (coal, oil and natural gas)
Carbon-based crude oil is a raw material in manufacturing of products (plastics, paint, synthetic fabrics)
Biomass - agricultural crops and forest trees store large amounts of carbon available for human use as food, timber, paper, textiles and many other products

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11
Q

What is carbon?

A

Common chemical element
Stored in carbonate rocks such as limestone, sea floor sediments, ocean water (dissolve CO2), the atmosphere (CO2 gas) and in the biosphere

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12
Q

Describe the global water cycle

A

Closed system
3 main stores - atmosphere (smallest) , oceans (biggest) and land
Moves via precipitation, evapotranspiration, run-off and groundwater

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13
Q

Draw the global water cycle

A
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14
Q

Describe the global carbon cycle

A

Closed system
Long-term storage in sedimentary rocks (99.9% of all carbon)
Most of the carbon in circulation moves rapidly between atmosphere, ocean, soil and biosphere
Processes: photosynthesis, respiration, oxidation (decomposition, combustion) and weathering

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15
Q

Why can the water and carbon cycles be regarded as both open and closed?

A

Global:
Closed systems driven by the Sun’s energy (external)
Only energy cross boundaries

Smaller scales (drainage basin or forest ecosystem):
Open systems
Material also crosses boundaries

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16
Q

How is Earth’s water stored?

A

Oceans - 97%
Freshwater - 2.5% of water
Glacier and Ices caps - 2% total (68.7% of freshwater)
Aquifers - 0.7% total (30.1% of freshwater)
Lakes - 0.01
Soils - 0.005
Atmosphere - 0.001
Rivers - 0.0001
Biosphere - 0.00004

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17
Q

What are some inputs of water into the atmosphere?

A

Water vapour evaporated from the oceans, soils, lies and rivers, and vapour transpired through the leaves of plants - Evapotranspiration

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18
Q

How does water leave the atmosphere?

A

Precipitation and condensation
Ice sheets, glaciers and snowfields release water by ablation (melting and sublimation)

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19
Q

Where does precipitation and meltwater drain to?

A

Drains from the land surface as run-off into rivers
Most rivers flow to oceans, some to inland basins
Majority of water as precipitation reaches rivers only after infiltrating and flowing through the soil

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20
Q

Where does the water go after infiltration?

A

Water under gravity may percolate into permeable rocks or aquifers
This groundwater eventually reaches the surface as springs/seepages and contributes to run-off

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21
Q

What are the main stores of the global carbon cycle?

A

Atmosphere, oceans, carbonate rocks, fossil fuels, plants and soils

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22
Q

How much carbon is in each of the stores?

A

Carbonate rocks, limestone and chalk, and deep-ocean sediments are by far the biggest carbon store (60000-100,000,000 billion tonnes)
Oceans as dissolved CO2 (38,700)
Atmosphere (600)
Land plants (560)
Soils/peat (2300)

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23
Q

What carbon stores are involved in the slow carbon cycle?

A

Carbon stored in rocks, sea-floor sediments and fossil fuels which are locked away for millions of years
10-100mil tonnes/year

24
Q

Describe the slow carbon cycle

A
  • CO2 atmosphere->ocean
  • Marine organisms (eg molluscs and coral polyps) build shells and skeletons of CaCO3 by combining C and Ca
  • Organisms die, sink to sea bed, over millions of years, burial, heat and pressure converted to carbon-rich sedimentary rocks (typically held for 150mil years)
25
Q

How else may sedimentary rocks form?

A

Layers of fluvial-transported sediment, eroded or weathered from the terrestrial environment accumulate on sea/lake beds

26
Q

How do fossil fuels form via the slow carbon cycle?

A

Organic tissues undergoing the same process, forms fossil fuels (oil and natural gas)
On land, burial and compression of tree and plant matter in tropical and sub-tropical swamps 300MaBP saw the formation of most of the Earth’s coal

27
Q

Why may carbon be lost from the sedimentary rocks long-term store?

A
  • Rocks on ocean floor are subjected at destructive plate margins (enter asthenospheric mantle store) -> may be vented back into atmosphere during volcanic eruptions as CO2
  • Tectonic forces elevate rocks above surface, vulnerable to chemical weathering (carbonation). CO2 released into atmosphere, C(aq) returned to oceans via river runoff
28
Q

What is the fast carbon cycle?

A

Carbon circulates rapidly between the atmosphere, ocean surface, biosphere (living organisms) and soils
10-1000x faster than slow cycle
10-100bil tonnes of carbon flux/year

29
Q

Describe the fast carbon cycle (in the ocean)

A
  • Land plants and phytoplankton in the oceans absorb CO2 via photosynthesis
  • Respiration by animals/plants oxidises glucose -> CO2 product and released into atmosphere
  • Decomposition of dead organic matter by detritivores (bacteria, fungi) also releases CO2 to the atmosphere
  • For organic matter buried in anaerobic condition before it can decay, this carbon may be transformed into fossil fuels (carbonification) and enter the slow cycle
30
Q

Describe the fast carbon cycle (atmosphere and ocean)

A

Natural or oceanic sequestration:
- Atmospheric CO2 diffuses into surface ocean water (reversible)
- Typical residence time in ocean of 350 years
- Carbon (aq) may be used in shells and skeletons of marine organisms (fast to slow)

31
Q

What is a flux?

A

Transfer/exchanges between carbon stores

32
Q

What is the water balance equation?

A

Summarises the flows of water in a drainage basin over time
Precipitation (P) = Evapotranspiration (E) + Streamflow (Q) +_ Storage

33
Q

What are the principal flows in the water cycle?

A

Precipitation, evaporation, transpiration, run-off, infiltration, percolation, through flow, sublimation, condensation

34
Q

What is evaporation?

A

Liquid -> gas water
Input of heat energy to overcome the bond strength
Energy absorbed as latent heat and released later in condensation
In drainage basin, water may evaporate from leaf surfaces, ground surface or soil

35
Q

What does the rate of evaporation depend on?

A

Temperature and sunlight - higher temperature and sunlight means more energy for bonds
Humidity - if air is saturated no evaporation
Wind speed- stronger winds replace air for evaporation

36
Q

What is transpiration?

A

Diffusion of water vapour to the atmosphere from the stomata of plants

37
Q

What does the rate of transpiration depend on?

A

Temperature and wind speed
Water availability to plants
Vegetation types - some minimise transpiration loss

38
Q

What is precipitation?

A

Water and ice that falls from clouds to the ground
Rain + snow (most common), hail, sleet, drizzle

39
Q

When does precipitation form and when does it leave?

A

Forms when vapour in the atmosphere cools to its dew point and condenses into tiny water droplets or ice particles to form clouds
Eventually, they aggregate, reach a critical size and gravity overcomes the updraft of the air leave the cloud as precipitation

40
Q

How does precipitation vary in character and what effect does this have?

A

Impacts the drainage basin hydrological cycle

41
Q

How is snowfall stored and how is this different?

A
  • Most rainfall is transferred rapidly from where it falls into streams and rivers via overland flow and through flow
  • Snowfall is stored as interception storage (on vegetation) or surface storage (on ground), possibly for weeks/months in high latitude or altitude location, before being delivered to rivers and streams when spring thaws arrive
  • Considerable lag time between precipitation and runoff
42
Q

What is precipitation intensity?

A

Volume falling in a certain time period - high intensity precipitation (10-15mm/ht) is likely to result in rapid overland flow

43
Q

What is precipitation duration?

A

Length of time that a precipitation event lasts - low pressure systems bring frontal rainfall to the UK that can last many hours
Storm Desmond - 341mm in 24hrs

44
Q

What may precipitation be like in semi-arid places?

A

Precipitation may be so seasonal that rivers do not flow during the dry season
Precipitation is concentrated in a rainy season, river discharge is high and flooding is common

45
Q

What is condensation?

A

Gas->Liquid water
Air is cooled to its dew point, at which temperature it becomes saturated with water vapour (cold air cannot hold as much vapour), so some water must condense out
Tiny droplets of water vapour may coalesce to form clouds

46
Q

What are the 3 types of clouds?

A

Stratiform
Cumuliform
Cirrus

47
Q

What are cumuliform clouds?

A

Flat bases and considerable vertical development
Most commonly formed through convection, heating of the Earth’s surface and overlying atmosphere through solar insolation
Cumulus clouds -> showers
Cumulonimbus clouds are due to intense convection (heights of 10-12km) ->thunderstorms and heavy rain

48
Q

What are stratiform clouds?

A

Form in long layers
Develop where an air mass moves horizontally across a cooler surface (ocean), reducing temp of air mass uniformly over a large area
Can bring persistent rain of light/moderate intensity

49
Q

What are cirrus clouds?

A

High altitude, wispy clouds formed from ice crystals
Do not produce precipitation and so have little influence on the water cycle

50
Q

Why might cooling occur?

A
  • Air warmed by contact with warm land or sea surface rises through the atmosphere by convection. Air rises, pressure falls, expansion and pushes against surroundings. Requires energy - parcel loses internal energy and cools
  • Advection: air mass moving horizontally over a cool surface (eg glacial lake)
  • Air mass rising to cross mountains
  • Relatively warm air mass mixing with a colder one
51
Q

What are lapse rates?

A

How temperature changes with height through the atmosphere
Typically, temperature decreases with altitude as air molecules are further from Earth’s surface (source of radiation)
Temperature inversion - temperature increases with altitude

52
Q

What are the 3 types of lapse rate?

A

Environmental lapse rate (ELR)
Dry adiabatic lapse rate (DALR)
Saturated adiabatic lapse rate (SALR)

53
Q

What is Environmental lapse rate (ELR)?

A

Vertical temp profile of lower atmosphere at any given time
‘background lapse rate’ - how most of the atmosphere is changing (affects parcels of air within atmosphere)

54
Q

What is Dry adiabatic lapse rate (DALR)?

A

Rate at which a parcel of dry air cools (I.e. less than 100% humidity so condensation is not taking place)

55
Q

What is Saturated adiabatic lapse rate (SALR)?

A

Rate at which a saturated parcel of air (condensation is occurring) cools as it rises
Condensation release latent heat so SALR is lower than DALR

A-Level Geography (10 decks)

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