Water and carbon

• Flow / Transfer


  A form of linkage between one store/component and another that involves movement of energy or mass
• Input


  The addition of matter and/or energy into a system
• Store / Component


  A part of the system where energy/mass is stored or transformed
• System


  A set of interrelated components working together towards some kind of process
• Elements


  The things that make up the system of interest
• Attributes


  The perceived characteristics of the elements
• Relationships

  Descriptions of how the various elements (and their attributes) work together to carry out some kind of process
• Isolated systems

  These have no interactions with anything outside system boundary. There is no input or output of energy or matter
• Closed systems


  These have transfers of energy both into and beyond the system boundary but not transfer of matter
• Open systems


  These are where matter and energy can be transferred from the system across the boundary into the surrounding environment. Most ecosystems are examples of open systems
• Dynamic equilibrium

  When there is a balance between the inputs and outputs. This means that the stores stay the same.
• Positive feedback

  Where the effects of an action are amplified or multiplied by subsequent knock-on or secondary effects
• Negative feedback

  Where the effects of an action are nullified by its subsequent knock-on effect
• Atmospheric water

  Water found in the atmosphere; mainly water vapour with some liquid water (cloud and rain droplets) and ice crystals
• Cryospheric water

  The water locked up on the Earth's surface as ice
• Hydrosphere

  A discountinuous layer of water at or near the Earth's surface. It includes all liquid and frozen surface waters, groundwater geld in soil and rock and atmospheric water vapour
• Oceanic water

  The water contained in the Earth's oceans and seas but not including such inland seas as the Caspian Sea.
• Terrestrial water

  This consists of groundwater, soil moisture, lakes, wetlands and rivers
• Sea Ice

  When water in the oceans is cooled to temperatures below freezing.
• Ice Sheets

  Mass of glacial land ice extending more than 50,000km2
• Ice caps

  Thick layers of ice on land that are smaller than 50,000km2
• Alpine glaciers


  Thick masses of ice found in deep valleys or in upland hollows
• Permafrost


  Ground that remains at or below 0oc for at least 2 consecutive years
• Rivers

  Act as both a store and a transfer of water. Streams of water within a defined channel
• Lakes


  Collections of fresh water found in hollows on the land surface. Larger than 2 hectares in area
• Wetlands

  An area of marsh, fen, peatland or water, weather natural or artificial, permanent or temporary, with water that is static or flowing where there is a dominance by vegetation.
• Groundwater


  Water that collects underground in the pore spaces of rock.
• Soil water


  Held together with air in unsaturated upper weathered layers of the Earth
• Biological water


  Constitutes the water stored in all the biomass
• Atmospheric water

  Water that is found in the atmosphere, most commonly as a gas, such as water vapour
• Evaporation

  Occurs when solar radiation hits the surface of water or land and causes liquid water to change state from a liquid to a gas (water vapour)
• Condensation

  Air cools and holds less water vapour. This means that if it cools sufficiently then it will get to a temperature at which it becomes saturated (dew point temperature). Excess water in the air will then be converted to liquid water.
• Interception storage

  The precipitation that falls on the vegetation surfaces (canopy) or human-made cover and is temporarily stored on these surfaces. This type of water can be evaporated directly to the atmosphere, absorbed by the canopy surfaces or ultimately transmitted to the ground surfaces
• Overland flow

  The tendency of water to flow horizontally across land surfaces when rainfall has exceeded the infiltration capacity of the soil and all surface stores are full to overflowing
• Percolation

  The downward movement of water within the rock under the soil surface. Rate vary depending on the nature of the rock.
• Run-off


  All the water that enters a river channel and eventually flows out of the drainage basin
• Saturated


  This applies to any water store that has reached its maximum capacity
• Stemflow

  The portion of precipitation intercepted by the canopy that reaches the ground by flowing down stems, stalks or tree trunk
• Transpiration


  The loss of water from vegetation through pores (stomata) on their surfaces
• Storm & rainfall event

  An individual storm is defined as a rainfall period separated by dry intervals of at least 24 hours and an individual rainfall event is defined as a rainfall period separated by dry intervals of at least 4 hours