Summary Geography A-Level Notes - Water and Carbon Cycles

Geography – Water and Carbon Cycles

Natural systems:
Coasts are natural systems:
Inputs - entities that enter the system e.g. sediment through longshore drift.
Outputs - e.g. sediment being washed out to sea
Flows/transfers - these corelate to processes such as erosion, weathering, transportation
and deposition
Store/components - landforms such as beaches, dunes and spits.

Open system - energy and matter can enter and leave system
closed system - matter cant enter and leave system but energy can


System affected by feedbacks:
Negative feedback- change in the system can cause other changes that have the opposite
effect.

o Large amounts of CO2 emitted, CO2 in atmosphere increases, Extra CO2
causes plants to increase growth, Plants remove and store more CO2 from
atmosphere, Amount of CO2 in atmosphere reduces.

Positive feedback - change in the system causes other changes that have a similar effect.

 Temperature rises, ice covering cold parts of earth melts due to higher
temperatures, less ice over means less of the sun's energy is reflected, less of the
sun's energy is being reflected means more is absorbed by earth.

Earth can be seen as one system made up of subsystems:

 Cryosphere - Parts of earths system where cold enough for water to freeze
 Lithosphere- outermost part of earth (includes crust and upper part of mantle)
 Biosphere - part of earths system where living things are found
 Hydrosphere - includes all water on earth
 Atmosphere - Layer of gas between earths surface and space


All these systems are interlinked
matter and energy move between subsystems
changes in one system can effect another




The Water Cycle:

, water stored in solid, liquid and gas form:
Hydrosphere contains 1.4 sextillions of water

 most is saline water in oceans (less than 3% is fresh water)
 of earths fresh water:
o 69% frozen in Cryosphere
o 30% groundwater
o 0.3% liquid fresh water on Earths surface
o 0.04% stored as water vapour in atmosphere
 water must be physically and economically accessible for humans to use
 water can change from solid, liquid and gas forms



Water constantly cycling between stores:

 water continuously cycled between different stores - global hydrological cycle
o is a closed system (no inputs and outputs)



Magnitude of store varies over time and in space:

 amount of water in each store varies over range of scales from local to global
 magnitude of each store depends on amount of water flowing between them
 different flows occur at different range of spatial and time scales



 Evapotranspiration - when liquid water changes into gas
o evaporation increases amount of water stored in atmosphere
o magnitude of evaporation flow varies by location and season
 Lots of solar radiation, large supply of water, warm and dry air -
evaporation will be high
 not much solar radiation, little available liquid water, cool air that's
nearly saturated - evaporation will be low
 Condensation- when water vapour becomes a liquid
o happens when air containing water vapour cools to dew point (change from
gas to liquid)
o water droplets can stay in atmosphere or flow to other subsystems
o magnitude of condensation flow depends on amount of water vapour in
atmosphere and temperature
 Cloud formation and precipitation
o essential parts of water cycle
o clouds form when warm air cools down - causing water vapour to condense
into water droplets and gather as clouds
 when droplets are big enough, they fall as precipitation
o several things that cause warm air to cool: