Geography- Water and carbon cycle

Example of a closed system

Energy is a input (sun by photosynthesis) and output (respiration) amount of carbon stays the same as there are no inputs or outputs of matter

Example of a open system

Drainage basins are an open system- energy from the sun enters + leaves the system. Water is an input as precipitation + output as river discharge to the sea.

What is dynamic equilibrium

Inputs and outputs of a system are balanced. Flows and processes continue to happen but there are no overall changes to the system.

Positive feedback example

Temperatures rise - ice covering cold part of the earth melt due to higher temperatures - less ice cover means less of the suns energy is reflected - less of sun’s energy being reflected means more is absorbed by earth

Negative feedback example

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 the atmosphere reduces

What is meant by the term store in a system

Where matter or energy builds up

What is meant by the term boundary in a system

The limit of a system

Name 5 subsystems

Cryosphere- All the parts of earth where it’s cold enough for water to freeze

Lithosphere- Outermost part of Earth. Crust and upper parts of the mantle

Hydrosphere- All water

Biosphere- Where all living things are found

Atmosphere- Layer of gas between the Earth’s surface and space

Difference between a open and closed system

In an open system energy and matter can enter and leave an open system such as in a drainage basin- water is an input as precipitation and output as river discharge. However, in a closed system matter can’t enter or leave- carbon cycle the amount of carbon always stays the same as there are no inputs or outputs of matter.

How can positive feedback alter natural systems

A positive feedback loop amplifies the change in inputs or outputs. This means the system responds by increasing the effects of change, moving the system even further from its previous state.

One change that can cause water vapour to condense

The magnitude of condensation flow depends on the amount of water vapour in the atmosphere and the temperature. If there is a lot of water vapour in the air and there’s a large or rapid drop in temperature, condensation will be high

What is the impact that global warming has on the water cycle

Long term changes in the climate can also affect the magnitude of evaporation. During the last glacial period temperatures were lower so evaporation was lower.

3 stores of water in a drainage basin

Vegetation storage

Surface storage

Soil storage

Seasonal changes in the water balance

In wet seasons precipitation exceeds evapotranspiration. This creates water surplus. The ground stores fill with water so there’s more surface runoff and higher discharge so river levels rise.

In drier seasons precipitation is lower than evapotranspiration. Ground stores are depleted as some water is used and some flows into the river channel but isn’t replaced by precipitation