Water and Carbon cycles: Key terms

system

a set of interrelated parts which work together ; a flow of energy and matter in a dynamic equilibrium

open system

a transfer of energy and matter between the system and the environment, with external inputs and outputs

closed system

there is a transfer of energy between the system and the environment, but not matter(e.g. global hydrological system)

isolated system

no interactions with anything outside system boundary; no input or output of matter/energy(e.g. a controlled lab experiment)

input

the addition of energy and/or matter into a system (e.g. precipitation in a drainage basin system)

output

the result of all the processes within a system, moving from system outside( e.g. runoff, evaporation and transpiration - evapotranspiration - from vegetation, moving moisture from a drainage basin system)

energy

the ability to do physical work, predominantly coming from the Sun, for instance in a drainage basin system in physical geography

stores/components

a part of the system where energy/mass is stored and/or transformed (e.g. interception from vegetation ; soil moisture : in drainage basin systems)

flows/transfers

links between stores/components which includes movement of energy/mass. (e.g. in drainage basin systems: infiltration from vegetation, groundwater flow)

positive feedback

when an action’s effect are multiplied by knock-on effects (e.g. rising sea levels→ destabilise ice shelves → increase rate of calving → increase melting and sea levels )

negative feedback

when an action’s effects are nullified by knock-on effects( e.g. increased surface temperature→increase in evaporation→more cloud cover, reflecting Sun’s radiation→slight cooling of surface temperature)

dynamic equilibrium

a system in which there are short-term fluctuations occurring over a changing long term baseline- achieved via positive/negative feedback.

positive feedback amplifies and can even cause a new dynamic equilibrium, if it crosses the threshold.

threshold

a critical “tipping point” in a system

lithosphere (global hydrological cycle)

part of the Earth made up of rocks and soils,, which may contain groundwater

hydrosphere (global hydrological cycle)

all water on Earth’s surface

cryosphere (global hydrological cycle)

water held in form of ice, glaciers, ice caps and sheets, sea ice

atmosphere (global hydrological cycle)

water held in atmosphere (vapour)

biosphere (global hydrological cycle)

water held within living matter