Systems Flashcards
Define input
The addition of material or energy into a system.
E.g. precipitation, leaf fall or seeds carried by winds.
Define output
The removal of material or energy from the system
Eg runoff, evaporation, seed dispersal
Define store
The individual elements of a system where energy or material is stored.
Define flow (transfer)
The relationship between the components that involves the movement of energy or mass.
Define positive feedback.
A cyclical sequence of events that amplifies or increases change. It promotes environmental instability.
Define negative feedback
A cyclical sequence of events that nullifies or dampens down the effects of a system. It promotes stability and a state of dynamic equilibrium.
Define dynamic equilibrium.
A state of balance within a constantly changing system.
Example of an input in a drainage basin
Precipitation
Example of input in the woodland carbon cycle
Precipitation with dissolved CO2
Example of an output in the drainage basin
Runoff
Example of an output in the woodland carbon cycle
Dissolved carbon within runoff
Example of energy in the drainage basin
Latent heat associated with changes within the water (eg condensation)
Example of energy within woodland carbon cycle
The production of glucose through the process of photosynthesis
Examples of stores within the drainage basin
Trees, puddles, soil
Example of stores within the woodland carbon cycle
Trees, soil, rocks
Examples of flows within a drainage basin
Infiltration, groundwater flow, evaporation
Examples of flows within the woodland carbon cycle
Burning, absorption
Example of positive feedback in a drainage basin
Thermal expansion and melting freshwater ice causes rising sea levels.
This can destabilise ice shelves, increasing the rate of calving.
This leads to an increase in melting, leading to a further sea level rise.
Example of positive feedback in a woodland carbon cycle
Increased temperatures due to climate change causes a melting of permafrost.
Trapped greenhouse gases are therefore released.
This enhances the greenhouse effect further - causing a further increase in temperatures.
Example of negative feedback in a drainage basin
Increased surface temperatures leads to an increase in evaporation from the oceans.
This leads to more cloud cover.
Clouds reflect radiation from the sun, resulting in a slight cooling of surface temperatures.
Example of negative feedback in a woodland carbon cycle
Increased atmospheric CO2 leads to increased temperatures.
This promotes plant growth and the rate of photosynthesis.
In turn, this removes more CO2 from the air - which counteracts the rise in temperature.
What is an isolated system?
These have no interactions with anything outside of the system boundary - they have no inputs or outputs.
Rare un nature, most common in controlled laboratory experiments.
What’s an open system?
Where matter and energy can be transferred from the system, across the boundary and into the surrounding environment.
Eg ecosystems.
What’s a closed system?
They have transfers of energy into and beyond the system boundary, but not the transfer of matter.
On a global scale, the water and carbon cycles are _______ systems.
Closed - there are no inputs or outputs.
On a local scale, the water and carbon cycles are ______ systems.
Open
