Flashcards in Water and Carbon Cycles Deck (83)
compare and contrast open, closed and isolated systems. use examples for each
open systems allow both matter and energy to pass through the system boundaries, such as the atmospheric cycle. Closed systems only allow energy to pass the system boundaries, such as the energy balance of the earth in the atmosphere, which interacts with radiation from the sun but no matter. Isolated systems do not allow either matter or energy to pass through the system boundaries, and are much rarer to find. On a local scale, an isolated system could warm soup in a flask, as the vacuum flask means there is no interaction with energy or matter.
define closed systems
a system in which only energy, not matter, can pass through the system boundaries
define an open system
a system where both energy and matter can interact past the system boundaries
define isolated systems
a system where neither matter nor energy can pass through the system boundaries
what is positive feedback
where an event's consequences are amplified by subsequent events triggered by the initial event
give an example of positive feedback on a local, regional and global scale
local: soil degradation as a result of overgrazing will lead to further degradation as rainfall will sweep away nutrients, meaning less vegetation will grow there, so more soil will be washed away by heavy rainfall
regional: evapotranspiration reduced by reduced rainfall will mean less rainfall, so less evapotranspiration
global: climate change resulting in ice sheets containing trapped GHG means climate change will be further enhanced, melting more ice sheets
what is negative feedback?
when an event's consequences are reduced by subsequent events triggered by the initial event
give examples of negative feedback locally, regionally and globally
local: volcanic eruption releases carbon into surroundings, however this fertilises soils and leads to more plant growth, so less CO2 is present.
regional: increase in CO2 levels means more vegetation in an area, so less CO2 as it becomes locked in the biosphere
global: increase in temperatures world wide increase transpiration, so more sunlight is reflected, meaning a decrease in global temperatures
give the definition of an output
things which are removed from the system
give examples of outputs for the water and carbon cycles
evaporation removes water from the cycle back to the atmosphere while in the carbon cycle combustion releases carbon to the atmosphere
give the definition of an input
things which are added to a system
give examples of inputs in the water and carbon cycles
measurement of the rate of flow of material between the stores over time
stationary things within the system
define dynamic equilibrium
when inputs and outputs are balanced
the movement of something within a system, often between stores
give the throughputs of the water cycle (7 items)
throughflow, stemflow, infiltration, percolation, groundwater flow, overland flow, channel flow,
absorbs food, animals
humn activity and pollution causes
human activity and pollution causes
give the major stores of the water cycle (water basin not global)
atmosphere, water table, aquifers, lakes, oceans
give the major stores of water on earth
hydrosphere, cryosphere, biosphere, lithosphere, atmosphere
give the major flows in the carbon cycle (9 items)
photosynthesis, respiration, consumption, excretion and death, sequestration, formation of sedimentary rocks, combustion, weathering, volcanic eruption
give the major stores of the carbon cycle in order of size
marine and sedimentary rocks ( 100,000 billion metric tonnes), oceans ( 38 000 bmt), fossil fuels (4000 bmt), soil (1 500 bmt), atmosphere (750 bmt), plants (560 bmt)
what is evaporation?
the process in which water in a liquid form becomes a gas by gaining energy. this energy often comes from the sun in the form of radiation, and the water vapour rises into the atmosphere. it then cools and condenses to form clouds.
when water vapour which has condensed to form clouds form droplets around duct particles, or simply become too heavy to remain in the atmosphere, so fall as rain, snow or hail.
what is evapotranspiration?
when water absorbed by plants evaporates in the exposed leaves and stems, when the plant respires (exchange of gases). water is lost more easily, in high temperatures or fast winds.
what is the role of interception in the water cycle?
interception is the process in which precipitation is delayed in reaching the surface due to vegetation blocking its path. interception affects hydrographs, reducing the peak flow as the rainfall takes longer to reach the river channel, so the lag time is greater and so the river has more time to discharge the excess rainwater, meaning the river level rises less.
what is sublimation?
this is when solid water (ice) becomes water vapour without going through the liquid state
what is infiltration?
when precipitation which reaches the surface enters the soil, draining downwards.
what is percolation?
when water moves vertically downwards from above to below the water table
what is groundwater flow?
the movement of water 4 km below the surface to another store
what is overland flow, or surface runoff?
when saturated soil cannot absorb any more water, so additional precipitation or meltwater flows on the surface towards a store
what percentage of the earth's water is saline?
what percentage of the planet's water is freshwater?
what percentage of the earth's freshwater is in the cryosphere and groundwater
68.7% cryosphere, 30.1 groundwater
what percentage of the earth's freshwater is stored on the surface?
what is the dew point?
the temperature at which water condenses
what are the two ways in which clouds can form?
condense on a condensation nuclei (dust)
cools down to sublimate into hoar frost
what is the evaporation rule regarding how much radiation is needed to evaporate water?
the more water is available, the harder it is to evaporate
how much of the world's land was covered in ice 18000 years ago?
when were sea levels 50m higher than today?
3 million years ago
what is ablation?
when glacial ice or snow melts or evaporates
what is calving?
the breaking off of chunks of glacial ice
what is fog?
fog is a cloud which touches the ground
ho do we define ice caps?
masses of ice on land which are smaller than 50,000 km sq.
how do alpine glaciers form?
snow or ice flows from ice caps become compact
why does permafrost, as well as glaciers, play such an important role in climate regulation?
permafrost contains bubbles of trapped GHG, such as methane (CH4) and carbon dioxide (CO2)
what is cryoconite and how does it pose a problem regarding the cryosphere?
cryoconite is a mixture of soot and algae, filling up small holes in the ice, and as it is black in colour, the ice absorbs more light, so heats up and melts, releasing trapped bubbles of GHG. this reduces the albedo potential of the ice, as less light is reflected, so the surface temperature increases.
who is James Balog?
a photographer, who's work in recording ice sheet retreat in Greenland, Alaska and the Arctic, shows that human activity has led to the huge melting of ice there.
how many people would be affected by a sea level rise of 3 feet?
what are moulins?
steep- sided canyons where meltwater has eroded the ice.
by how much did the Columbia Glacier in Alaska retreat by in 3 years?
how many out of the 1400 glaciers in the Yukong Territory have disappeared?
300 in 60 years
by what height are some glaciers shrinking by?
Empire State Building
water stored below the water table in saturated soil rock
define water table
the level below which the ground is saturated with water
what is soil moisture?
water stored in the oil above the water table
how does soil type affect how much water is stored there?
different soils have different pores which hold different amounts of water, such as clay which holds 40-60% of the soil volume as water, while sand only holds 20-45%
what percentage of the soil volume in clay can hold water?
what percentage of the soil volume in sand can hold water?
what percentage of water is stored by interception in needle-leaf forests
define soil moisture budget
the soil moisture budget shows the level of water in the soil, which is affected by precipitation and evapotranspiration.
what is soil moisture recharge?
when precipitation exceeds evapotranspiration, adding to soil moisture
define soil moisture utlisation
when evapotranspiration exceeds precipitation
what is soil moisture deficit?
when evapotranspiration is greater than precipitation
what is soil moisture surplus?
when precipitation exceeds evapotranspiration
what is the equation to calculating soil moisture budget?
P= SF + E +/- change in S
Precipitation = streamflow + evapotranspiration +/- change in storage
rearrange the equation for soil budget for change in storage
P - SF - E = change in S
what are tributaries
rivers or streams which join the main channel
the point at which two rivers join to become one channel
what are physical reasons for a flashy hydrograph? 6 items
drainage basins round in shape will cause flashy hydrographs as each point on the basin is equidistant to the river.
steep-sided drainage basin edges will funnel water quickly to the channel
saturated land will increase surface runoff
high precipitation intensity
low vegetation density
impermeable rock type
what are physical reasons for subdued hydrographs?
long and thin river basins will mean the water will take more time to reach on point on the river
a low relief drainage basin will mean the water is not funnelled to the channel
low precipitation intensity
high vegetation density
what are human reasons for flashy hydrographs?
deforestation reduces interception and decreases bankfull capacity
furrows in fields drain water to the channel
ploughing wet soil damages subsoil, creating an impermeable layer so increasing overland flow
overgrazing can damage the soil
urban surfaces are largely impermeable
what are human factors for subdued hydrographs?
afforestation increases interception so increase lag time
terracing on hills stops water flows
ploughing loosens the soil so increases infiltration
lakes and reservoirs capture water and stop it from entering the channel directly
why is deforestation a cause of flashy hydrographs?
deforestation not only reduces interception in an area, but soil becomes exposed, so is easily drained to the river channel by heavy precipitation, and the sediment is deposited on the river bed, reducing the bankfull capacity as the channel becomes shallower
define base flow
normal day-to-day discharge of the river ans is the consequence of slow moving soil throughflow and groundwater seeping into the channel
what is lag time?
the time between peak rainfall and peak discharge
define a river's discharge
the amount of water in a river flowing past a certain, measured in cubic metres per second, cumecs
what is bankfull?
bankfull is the maximum discharge that a river channel is capable of carrying out
what is peak discharge?
the point on a flood hydrograph when river discharge is at its greatest
define storm hydrograph
a graph of discharge of a river over the time period when the normal flow of the river is affected by a storm event