Model (def)
Idealised representation of reality
System (def)
A group of interacting, interrelated or independent elements that function together as a whole.
Open system (def)
A system with both inputs and outputs of matter and energy
Closed system (def)
A system with inputs and outputs of energy but not matter
Dynamic equilibrium (def)
A system of balance where inputs equal outputs in a constantly changing system. The equilibrium can be altered by certain events or occurrences.
Give examples of what events may change an equilibrium?
Burning fossil fuels and increases of carbon in the atmosphere, rising global temperatures and the melting of permafrost
Inputs (def)
Additions to a system
Outputs (def)
The removal of aspects from a system
Stores (def)
An accumulation of an aspect of a system
Transfer or flow (def)
Movement of water and carbon between systems
Negative feedback (def)
When a change in a system causes other changes that have the opposite effect, therefore nullifying the initial change
Give an example of negative feedback
Increasing carbon in the atmosphere raises temperatures and promotes vegetation growth. As this happens, more photosynthesis occurs and therefore removes carbon from the atmosphere.
Positive feedback (def)
When a change in a system causes additional changes of similar nature, causing the initial change to be enhanced
Give an example of positive feedback
Increasing temperatures cause ice to melt, leaving more ocean exposed to the sun. This decreases the planet’s albedo, meaning it absorbs more solar radiation, increasing the temperature further and melting more ice.
Atmosphere (def)
The air that surrounds the earth
Lithosphere (def)
The outermost solid layer of the earth, comprised of 100km of crust and upper mantle
Hydrosphere (def)
All water on or surrounding the earth (oceans, seas, lakes, rivers, atmospheric water eg clouds)
Biosphere (def)
All living things on Earth
Cryosphere (def)
Frozen parts of the Earth’s surface including ice caps, frozen oceans, glaciers and snow
Precipitation (def)
The input into a drainage basin system, including all forms of moisture.
Interception (def)
+ how would you describe this store?
The storage of water when it lands on vegetation or structures before reaching the surface. A TEMPORARY store.
Surface storage (def)
The storage of water on the surface, including puddles, ponds and lakes
Soil moisture (def)
The storage of water in soil, held in small gaps between water particles.
Groundwater storage (def)
The storage of water in ground rocks of permeable rocks
Groundwater storage takes different forms. Which rocks store water in what ways?
Limestone stores in CRACKS
Sedimentary rock stores in BEDDING PLANES
Chalk stores in PORES
Channel storage (def)
The storage of water in a river channel. During the transportation of water it is in a store
Vegetation storage (def)
Storage of water in vegetation. Plants take up water from soil into their roots.
Surface runoff (def)
The horizontal flow of water over land either in small channels or over the whole surface
Stem flow (def)
Downward flow of water from interception storage to the surface.
Throughfall (def)
Downward flow of water as it drips from one leaf to another
Throughflow (def)
Horizontal flow of water moving between soil particles of water
Interflow (def)
Horizontal movement of water through rock above the water table
Infiltration (def)
Downward movement of water from the surface into the soil
Percolation (def)
Downwards movement of water from soil to permeable ground rock
Groundwater flow (def)
Horizontal movement of water through rocks below the water table
Baseflow (def)
Groundwater flow that feeds into rivers
Channel flow (def)
Movement of water in the river channel moving towards the sea
Evaportaion (def)
Output of water when it is heated and turned from a liquid into a gas. Rate can be affected by temperature, humidity, wind etc.
Transpiration (def)
Output of water where moisture is taken into plants through their roots, moved to leaves by capillary action and then evaporates through leaves as a gas.
Evapotranspiration (def)
Combined output of water from evaporation and transpiration.
What is the difference between potential and actual evapotranspiration?
Potential: the potential amount of evapotranspiration that would occur were water available.
Actual: the actual amount of evapotranspiration based on limited water supplies.
Condensation (def)
Give example
Transfer of water from a gaseous to a liquid state (eg formation of clouds)
Condensation (def)
Microscopic particles on which water vapour condenses to form cloud droplets
Dew point (def)
The temperature at which water vapour in the air becomes saturated and condensation begins
Sublimation (def)
Transfer from a solid state (ice) to a gaseous state (water vapour)
Deposition (def)
Transfer from a gaseous state (water vapour) to a solid state (ice)
Latent heat (def)
Heat required to convert a solid into a liquid or vapour, or liquid into vapour without a change in temperature.
Discharge (def)
The output of water from a river channel out to sea
Aquifer (def)
A vast underground reservoir commonly formed in rocks such as chalk and sandstone
Impermeable surface (def)
Does not allow water to pass through
Urbanisation (def)
What does urbanisation lead to?
Increasing proportion of people living in urban areas opposed to rural areas.
Leads to the removal of vegetation with impermeable concrete and tarmac.
Deforestation (def)
What does deforestation lead to?
The removal of trees from rural areas.
Leads to surface runoff, soil erosion and reduction in soil water stores.
Drainage basin (def)
The area of land that is drained by a river and its tributaries
Source (def)
Describe the characteristics of the river at this point.
The point were the river begins.
The river channel is very narrow and shallow. Discharge is low.
Mouth (def)
Describe the characteristics of the river here.
The point where the river meets the sea.
River is wide and deep, with lots of discharge.
Watershed (def)
The edge of the drainage basin
Tributary + confluence (def)
Small rivers that meet and feed into a wider river channel
The point at which two rivers meet
Flood hydrograph (def)
A graph showing the discharge levels of a river following a storm event as well as rainfall.
Lag time (def) What does the length of lag time indicate?
Time between peak rainfall and discharge.
The longer the lag time, the less likely a flood is
River regime (def) What factors affect river regime?
Pattern of discharge over the course of a year.
Geology, vegetation, urbanisation, shape of drainage basin, rainfall intensity.
Soil moisture budget (def)
The description of changes to the soil water store during a year. Determined by precipitation and evapotranspiration.
Soil moisture utilisation (def)
How is effiency of extraction affected by levels of soil moisture?
The extraction of soil moisture by plants for their needs.
As soil moisture levels reduce, the efficiency of the withdrawal by plants decreases.
Soil moisture deficit (def)
What causes this?
The point at which soil moisture falls below field capacity. Caused by lack of precipitation and heavy evapotranspiration.
Field capacity (def)
The point at which a field becomes saturated
Soil moisture surplus (def)
What causes this?
The period when soil is saturated and therefore moisture cannot enter, therefore flowing over the surface.
Caused by high precipitation and low evapotranspiration
Soil porosity (def)
Pores or spaces in soil, which have the ability to hold large pockets of water.
Water balance (def) (Name all four)
An equation used to express the relationship between the main water stores. Lithosphere, hydrosphere, cryosphere and atmosphere.
Hill slope system (def)
The way in which water moves down a typical hill slope towards a rive, involving stores and transfers
Irrigation (def)
The supply of water to land through channels, streams and sprinklers in order to promote crop growth.
Water table (def)
The upper level of saturated rock
Water abstraction (def)
The extraction of water from rivers and groundwater aquifers
Saltwater intrusion (def) What can cause this?
The movement of saltwater into an aquifer, potentially causing contamination. Can be caused by over abstraction from a groundwater aquifer.
Relief/orographic rainfall (def)
Rainfall formed due to warm, moist air being forced to rise by the relief of the land. Once risen, the air cools and condenses to form rain.
Frontal rainfall (def)
Rainfall formed when warm air meets cold air. As it is less dense, warm air rises above cold air, cooling, condensing and forming rain.
Ablation (def)
Outputs from a glacial system due to melting (size of glacier decreases)
Accumulation (def)
Inputs to a glacial system due to snowfall (builds glacier)
Photosynthesis (def)
The process whereby plants use light energy from the sun to convert water and CO2 into glucose and oxygen using light energy. Removes CO2 from the atmosphere and grows vegetation.
Respiration (def)
A chemical process that happens in all cells, which converts glucose into energy. Carbon is released into the atmosphere but less than is originally absorbed. Vegetation naturally a carbon sink.
Decomposition (def)
The process where carbon from bodies of dead organisms/organic matter is broken down by decomposers, producing CO2. Eg microorganisms decompose leaf litter and carbon is returned to the atmosphere.
Combustion (def)
The process where carbon is burned in the presence of oxygen and converted to energy, CO2 and water. Done when fossil fuels are burned and when wildfires happen.
Sequestration (def)
The long term storage of carbon in plants, soils, rock formations and oceans.
Diffusion (def)
The movement of carbon between oceans and the atmosphere due to a stark difference of concentrations between the two stores.
Weathering (def)
The breakdown or decay of rocks in their original place at, or close to the surface. Can be done chemically or biologically.
Burial and compaction (def)
When organic matter is buried and then compressed by overlying sediment.
Carbon budget (def)
A way of using data to describe the amount of carbon which is stored and transferred within the carbon cycle.
Carbon sink (def)
Anything that absorbs more carbon than it releases
Carbon source (def)
Anything which releases more carbon that it absorbs.
Mitigation (def)
Any method used to limit or prevent something from happening.
Carbon capture and storage (def)
The technological capturing of carbon emitted from power stations. Following this it is compressed into a liquid and stored several kilometres below ground.
Renewable energy (def)
Energy generated from sources that can be renewed and used multiple times eg. hydroelectric power, tidal power, wind turbines.
Carbon farming (def)
Where one type of crop is replaced by another that has greater productivity and can absorb more carbon from the atmosphere.
Hydrocarbons (def)
Compounds formed of carbon and hydrogen which are the basis of fossil fuels such as oil and gas.
Lithosere (def)
A vegetation succession originating on a bare and rocky surface. Initially colonised by lichens, mosses and then grasses, small trees, large trees.
Seral stage (def)
A stage within a sere.
Sere (def)
A stage within a sere.
Vegetation succession (def)
The sequence of changes that take place as plant life colonises bare rock, sand, water or salty areas.
Climatic climax (def)
The final stage of seral succession. Vegetation remains relatively unchanged unless destroyed by an event such as fire or human interference.
Humus (def)
The organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms.
Milankovitch cycles (def)
Changes in the shape of the Earth’s orbit and tilt that cause glacial periods and interglacial periods. Long term natural cause of climate change on Earth.
Enhanced greenhouse effect (def)
Rising global temperatures due to greenhouse gases being pumped into the atmosphere from human activities.