water and carbon cycle Flashcards
systems?
systems- a set of interrelated components working together towards some kind of process
what are systems made up of?
inputs —> matter or energy is added to the system
outputs —> matter or energy leaves the system
stores —> a part of the system where something is held for a period of time
flows —> a link between 1 store and another, along which something moves
boundaries —> the edge of the system (the line between 1 system and another)
example:
drainage basin system:
- water enters as rain (input)
- the systems watershed is the boundary
- some water is stored in the soil and in vegetation
- water travels from the drainage basin to the river and then down the river (flows)
- it leaves the system where the river meets the sea (output)
open system, closed system and equilibrium?
open system —> energy and matter enter and leave the system// example: drainage basins are open systems - energy from the sun enters and leaves the system, water (precipitation) is an input and river discharge into the sea is an output
closed system —> energy can enter and leave but matter cannot enter or leave (matter can be water) —> it can only cycle between stores
dynamic equilibrium —> inputs and outputs are equal and the system is in equilibrium —> no overall change to the system
positive feedback and negative feedback and examples?
positive feedback —> when a chain of events amplifies (increases) the impacts of the original event
negative feedback —> when a chain of events nullifies (reduces or stops) the impacts of the original event
positive feedback examples:
- temperatures increase —> ice melts —> less ice cover —> less of the suns energy is reflected —> more of the suns energy is absorbed —> temps increase
- temperatures increase —> ocean temp increases —> warm water less able to dissolve gas —> CO2 released into the atmosphere —> more CO2 to act as a greenhouse gas —> temp increase
negative feedback examples:
- co2 in atmosphere increases —> extra co2 causes plants to grow —> plants remove co2 from the atmosphere —> amount of co2 in the atmosphere decreases
the whole earth can be broken down into smaller subsystems such as?
the earth can be seen as 1 system made up of lots of subsystems
hydrosphere —> all the water on earth —> it may be in liquid form (rivers and oceans), solid form (ice stored in the cryosphere) and gas form (water vapour stored in the atmosphere)
lithosphere —> the outermost part of the earth, including the crust and upper parts of the mantle
cryosphere —> all the parts of the earth where it is cold enough for water to freeze e.g. glacial landscapes
atmosphere —> layer of gas surrounding our planet
biosphere —> where living things are found, including plants, animals, fungi, insects and bacteria
how are the spheres linked?
biosphere and lithosphere:
- plants put carbon into soil
- nutrients from rocks help the biosphere grow
biosphere and hydrosphere:
- plankton and other marine producers take up carbon in ocean water
lithosphere and hydrosphere:
- weathering release carbon into rivers + streams
lithosphere and atmosphere:
- volcanic eruptions release carbon trapped inside the earth into the atmosphere
- weathering releases carbon into the atmosphere
atmosphere and hydrosphere:
increased ocean temp —> warm water less able to dissolve gas —> CO2 released into the atmosphere
how is the atmosphere linked to the hydrosphere
hydrosphere —> atmosphere (increased ocean temp —> warm water less able to dissolve gas —> CO2 released into the atmosphere)
drainage basin and water shed?
drainage basin —> the area surrounding the river where the rain falling on the land flows into that river//catchment area for water
water shed —> area of high land that separates the drainage basins (the boundary of a drainage basin is the watershed)
inputs, outputs, stores and flows of the water cycle?
inputs:
- precipitation
outputs:
- evapotranspiration
stores: (CIGSS)
- channel storage - water held in a river
- interception - water stored by trees
- groundwater - water stored in the ground in the pore spaces of rocks
- soil storage - water stored in the soil
- surface storage - water in puddles, ponds and lakes
flows:
- stemflow - water running down a plant stem or tree trunk
- surface runoff/overland flow
- infiltration - water moving from the ground into the soil
- throughflow - flow of water through soil (downhill)
- percolation - water moves from soil into rocks
- groundwater flow - flow of water through rocks
- channel flow- movement of water within the river channel
water?
the hydrosphere contains 1.4 sextillion litres of water
most of this is saline water in oceans and less than 3% is freshwater (freshwater is needed for humans to survive)
where is fresh water found?
cryosphere (69% fresh water is found here)
groundwater (30% of freshwater is found here)
liquid freshwater e.g. lakes and rivers (0.3% of freshwater is found here)
water vapour in the atmosphere (0.04% of freshwater is found here)
why can only a small amount of water on the planet be used by humans?
- water must be physically and economically accessible for humans to be able to use it e.g. groundwater is hard to access and it’s not cost effective extract it
4 water stores (TOAC)
terrestrial water —> water found in the ground, in the soil, in lakes, in rivers and in wetlands —> rivers and lakes are the most accessible water in the terrestrial system
oceanic water —> water found in oceans —> 97% of all water is found in oceans —> oceans are the biggest store of water
atmospheric water —> water found in the atmosphere —> mainly water vapour and some liquid water (rain droplets) —> around 13000km^3 of water is found in the atmosphere
cyrospheric water —> all of the frozen water e.g. glaciers
global hydrological cycle
water is continuously cycled between different stores in a closed system
states of water?
- water is made up of 2 hydrogen molecules and 1 oxygen molecule
- strong hydrogen bond between these molecules leads to water surface tension —> lots of energy needed to change its state
- water can change between solid, liquid and gas form —> for water to melt/boil, it has to gain energy —> for water to condense/freeze, it has to lose energy
- sublimation —> change of state from a solid to a gas with no liquid stage
- deposition —> change of state from a gas to a solid
what is latent heat
as the water molecules become heated by the sun, they become agitated and they try to break the bonds between them however there’s not enough heat in the sun ray to do this so
the water molecules absorb energy from their surroundings to give them the final energy that they need to break the bonds between them
as latent heat is taken from the surroundings, it cools the surroundings down
confluence and tributary
confluence —> where 2 streams meet
tributary —> small stream
hydrographs and definitions
hydrographs —> shows river discharge over a period of time
flood hydrographs—> shows river discharge around the time of a storm event
discharge —> volume of water that flows into a river per second
(volume of water - m^3)
(discharge is measured in m^3/s —> cumecs )
lag time —> the delay between peak rainfall and peak discharge —> this delay happens because it takes time for rainwater to flow into a river
peak discharge —> when the river discharge is at its greatest
rising limb —> where the river discharge increases as rainwater flows into the river
falling limb —> where the river discharge decreases because less water is flowing into the river
Flashy:
• Short lag time
• Steep rising and falling limb
• Higher flood risk
• Higher peak discharge
Subdued:
• Long lag time
• Gentle rising and falling limb
• Lower flood risk
• Lower peak discharge
what affects hydrographs shapes? (peak discharge and lag time)
size of drainage basin —> larger drainage basins collect more precipitation so they have higher peak discharge// have a long lag time —> water has to travel a long distance before it reaches the river channel
ground steepness —> water flows more quickly downhill so steep ground will mean a short lag time// steep land —> less time to infiltrate —> higher runoff —> peak discharge is higher
soil type —> impermeable soils —> water doesn’t infiltrate —> increases run off —> increase peak discharge// clay soils become saturated very quickly —> results in rapid overland flow —> shorter lag time —> water reaches channel more quickly
vegetation —> more vegetation means more interception —> lag time will be greater as trees slow the movement of water into the river channels// peak discharge is lower —> more interception so less water reaches the channel
physical factors affecting the water cycle
precipitation and storms —> storms generate more precipitation —> saturate the soil, allowing no more infiltration —> increasing surface runoff —> increased peak discharge
seasonal changes
summer:
-higher temperature cause the ground to be harder and more impermeable —> infiltration decreases —> surface runoff increases
winter:
-frozen ground prevent infiltration —> increase run off
-winter —> water will freeze —> reduce size of flows through drainage basins and increase size of stores
vegetation
summer —> more vegetation —> more water lost through evapotranspiration —> reduces run off and peak discharge
winter —> less leaves on trees —> less interception —> increases run off and peak discharge —> flooding more likely// less evapotranspiration —> less moisture to condense and form clouds —> less rain
human factors affecting the water cycle
land use —> construction creates impermeable surfaces —> reduces infiltration —> increases runoff —> water passes through the system much more rapidly —> flooding more likely
deforestation —> reduces interception, evapotranspiration, and infiltration
water abstraction —> more water is abstracted to meet demand in areas where population density is high —> reduces amount of water in stores like rivers etc// during dry seasons, even more water is abstracted from stores —> stores are depleted further
farming practices (PILC)
ploughing breaks up the surface so more water can infiltrate —> reduces surface run off
crops increase infiltration and interception —> reduces run off// evapotranspiration also increases which can increase rainfall
livestock trample and compact the soil, decreasing infiltration —> increases run off
irrigation (artificially watering the land) —> can increase runoff if some of the water can’t infiltrate
how does agriculture impact the water cycle (positive feedback)
deforestation to create space for crops —> less evaporation —> less rainfall —> ground becomes drier and less fertile —> new areas of land are cleared for farmland
evaporation, condensation and cyrospheric processes?
the magnitude of each store varies overtime
evaporation:
- liquid water changes state into a gas —> it gains energy from solar radiation
- evaporation increases the amount of water stored in the atmosphere
- magnitude of evaporation flow —> if there is lots of solar radiation and a large supply of water —> evaporation levels will be high
- if there is not much solar radiation and a little supply of water —> evaporation levels will be low
- e.g. long term changes in climate can affect the magnitude of evaporation flow —> during the last glacial period, temps were lower so evaporation was lower
condensation:
- water vapour changes state to become a liquid —> it loses energy to the surroundings
- magnitude of condensation flow —> depends on the amount of water vapour in the atmosphere and the temperature
- if there is lots of water vapour in the atmosphere and there’s a large/ rapid drop in temperature —> condensation levels will be high
cyrospheric processes:
- cyrospheric processes change the amount of water stored as ice in the cryosphere
- during colder periods, the magnitude of the cryosphere stores increases —> water is transferred to the cryosphere as snow and less water is transferred away through melting
- during warmer periods, the magnitude of the cryosphere store reduces —> water is transferred away from the cryosphere through melting and there’s less rain so less snow
changes in cryosphere over a large timescale:
- causes by changes in global temperature
changes in cryosphere over a short timescale:
- caused by annual temperature fluctuations —> more snow falls in the winter than in summer
how do clouds form?
- clouds form when warm air cools —> makes water vapour condense into water droplets which gather as clouds —> when water droplets get big enough, it falls as precipitation
- however water droplets are too small to form clouds on their own, there must be tiny particles of other substances (e.g. dust or soot) to act as condensation nuclei
what causes precipitation?
other air masses —> warm air is less dense than cool air —> when they meet, the warm air rises —> this makes it cool (it cools down as it rises) so it starts to condense —> creates frontal precipitation
topography —> when warm air meets mountains, it is forced to rise —> this makes it cool so it starts to condense —> creates orographic precipitation e.g. the pennines
convection —> the sun heats up the ground and moisture on the ground evaporates and rises up in a column of warm air —> as it gets higher, it cools —> this causes it to condenses —> results in convective precipitation
why do some parts of the earth receive more radiation than other parts? —> more solar radiation —> more evaporation and condensation
- Curvature of the earth —> more solar radiation is received and absorbed near the equator than at the poles —> the suns rays strike the earth most directly near the equator —> while at the poles the rays strike at a steep angle
- The radiation travels through a greater depth of atmosphere nearer the poles —> more radiation is lost to scattering and absorption by gases/particles in the atmosphere
- Snow and ice reflect a lot of the suns radiation back into space
global atmospheric circulation?
what does the global atmospheric circulation do?
- equator receives more heat from the sun than the poles so the purpose of global circulation is to redistribute this heat
what happens in a low pressure area and a high pressure area?
- low pressure —> air rises —> clouds form
- high pressure —> air sinks —> sun
**how does the global atmospheric circulation work?
- temps at the equator are high as the sun’s energy is more concentrated —> high temp creates low pressure so air rises —> clouds form which leads to rainfall
- when the air reaches the top of the atmosphere, it needs somewhere to go —> the air travels north and south of the equator —> the air sinks around 30° north and south of the equator —> creates high pressure —> sun
- high temps creates low pressure so air rises at around 60° north and south and descends at around 90° north and south
