Natural Systems Flashcards
What are systems made up of
Inputs - when matter or energy (e.g. solar energy) is added to the system.
Outputs - when matter or energy leaves the system.
Stores (or components) - where matter or energy builds up.
Flows (or transfers) - when matter or energy moves from one store to another.
Boundaries- the limits of the system.
Example of a system
In a drainage basin system, water enters as rain (input). The system’s 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 systems
Both energy and matter CAN enter and leave an open system - there are inputs and outputs of both.
Example: drainage basins are open systems -energy from the Sun enters and leaves the system. Water is input as precipitation, and output as river discharge into the sea.
Closed systems
Matter CAN’T enter or leave a closed system.
- it can only cycle between stores.
Energy CAN enter and leave a closed system.
- it can be input or output.
Example: the carbon cycle (see p.10) is a closed system -energy is input (e.g. from the sun by photosynthesis) and output (e.g. by respiration), but the amount of carbon on Earth stays the same because there are no inputs or outputs of matter.
Dynamic Equilibrium
there are lots of small variations in the inputs and outputs of a system (e.g. the amount of precipitation entering a drainage basin system constantly varies). These variations are usually small, so the inputs and outputs remain about balanced on average. The system is said to be in dynamic equilibrium.
Positive feedback
Positive feedback mechanisms amplify the change in the inputs or outputs.
This means the system responds by increasing the effects of the change, moving the system even further from its previous state.
Negative feedback
Negative feedback mechanisms counteract the change in the inputs or outputs.
This means that the system responds by decreasing the effects of the change, keeping the system closer to its previous state.
Cryosphere
The cryosphere includes all the parts of the Earth system where it’s cold enough for water to freeze, e.g. glacial landscapes.
Lithosphere
The lithosphere is the outermost part of the Earth. It includes the crust and the upper parts of the mantle.
Biosphere
The biosphere is the part of the Earth’s systems where living things are found. It includes all the living parts of the Earth - plants, animals, birds, fungi, insects, bacteria etc.
Hydrosphere
The hydrosphere includes all of the water on Earth. It may be in liquid form (e.g. in lakes and rivers), solid form (ice stored in the cryosphere) or gas form (e.g. water vapour stored in the atmosphere). It can also be saline (salty) or fresh.
Atmosphere
The atmosphere is the layer of gas between the Earth’s surface and space, held in place by gravity.
The earth is one system made up of lots of subsystems
Matter (e.g. water and carbon) and energy move between the subsystems the output of one cycle is the input of the next, - then the output of that cycle is the input of the next, and so on…
Because of the way that matter and energy move from one subsystem to the next, the Earth system is said to be a cascading system
