Key Knowledge (water) Flashcards
system
a set of interrelated components working towards some kind of process
flow/transfer
a form of linkage between one store/component and another that involves movement of energy or mass
store/component
a part of the system where energy/mass is stored or transformed
input
the addition of matter and/or energy into a system
how might a pond work as a system
- inputs: precipitation, leaf fall during autumn, seeds carried by winds and birds
- flows/transfers: photosynthesis, infiltration, transpiration
- stores: water, soil, plants
- outputs: water infiltrating into the soil below, evaporation, seed dispersal
types of systems
- closed: energy is transferred into and out of the system. all matter is enclosed e.g. the global water and carbon cycle [sediment cell]
- open: matter and energy can be transferred from the system into the surrounding environment e.g. the drainage basin (water) or a woodland (carbon) [coastal system]
feedback types
- dynamic equilibrium
- positive feedback
- negative feedback
dynamic equilibrium
the balanced state of a system. when opposing forces, or inputs and the equilibrium is equal
positive feedback
occurs where the effects of an action are amplified by changes to the inputs/outputs
negative feedback
occurs where the effects of an action are nullified by changes to the inputs/outputs/processes
sea ice melting positive feedback example
- temperature increase (change)
- sea ice cover melts and shrinks
- ocean water absorb more solar radiation than highly reflective sea ice
- temperature warms
- sea ice cover melts and shrinks
- temperatures warm
surface temperatures decreasing negative feedback example
- surface temperature decreases slightly
- decrease the earths albedo
- decreased evaporation from the oceans
- fewer low clouds in the atmosphere
- surface temperature increase slightly
- increases in the earths albedo
- increased evaporation from the oceans
- more low clouds in the atmosphere
phases of change
- sublimation (solid->gas)
- deposition (gas->solid)
- condensation (gas->liquid)
- evaporation (liquid->gas)
- melting (solid->liquid)
- freezing (liquid->gas)
fusion
where a solid becomes a liquid and vice versa
vaporisation
when a solid becomes a gas and vice versa
breaking bonds
because of this strong bond a lot of energy is required for a phase change (fusion, vaporisation and especially sublimation)
latent heat
- as water molecules become heated by the sun they become agitated and begin to try to break the bonds between them
- however there is not enough heat in the sun to do this
- the water molecules absorb energy from their surroundings to give them the final energy that they need to break the bonds between them
- this energy is called latent heat
- as latent heat is taken from the surroundings it cools down the surroundings (why air remains cool)
condensation
- latent heat is released by the water molecules as they slow down and join together
- so: evaporation could be thought of as a cooling process
- meaning condensation
salinity
salt content
the hydrosphere - where is water
- only 2.5% of global water is fresh water, with 1.2% of that being surface fresh water
- groundwater is very important (London’s natter is 70% groundwater) but the ground could sink -> if you extract too much salt water may contaminate
the hydrosphere - the 4 locations of global water v
- atmospheric water (water vapour with some liquid water (cloud/rain droplets)
- cryospheric (ice)
- oceanic (oceans but not inland seas)
- terrestrial (groundwater, soil, moisture, lakes, wetlands and rivers)
oceanic water
- average depth of 3682m
- covers 72% earths surface
- only 5% explore
cryospheric water
- large parts of arctic ocean is sea ice
- does not raise sea levels when ice melts
ice shelf (cryosphere)
large area of ice on sea, ice sheets and glaciers move out to sea
ice sheet (cryosphere)
glacial land ice covering more than 50,000km squared
ice cap (cryosphere)
glacial land ice covering less than 50,000 km squared (still big)
glaciers (cryosphere)
rivers of ice melting across land (usually found in deep mountain valleys)
permafrost (cryosphere)
land that remains frozen(top layer may melt in summer - active zone)
formation of clouds
- Clouds form when air becomes saturated, or filled, with water vapor. Warm air can hold more water vapor than cold air, so lowering the temperature of an air mass is like squeezing a sponge. Clouds are the visible result of that squeeze of cooler, moist air. Moist air becomes cloudy with only slight cooling.
- global atmospheric circulation is the main factor that determines cloud formation and rainfall
terrestrial water
- surface water (river ponds and lakes)
- rivers (stores/transfers)
- lake (if bigger than 2 hectares)
- wetlands (main ecosystem of the arctic)
- groundwater (water underground on spaces of rock)
- soil water (water held along with air in unsaturated layers of soil)
- biological water (water stored in biomass)
- biomass (all living and formerly living material)
atmospheric water
- equivalent to entire surface of planet covered in 25mm water (average of 12,900km cubed)
- 0.04% of worlds freshwater - 0.001% of worlds water
- amount atmosphere can hold doubles with 10 degrees Celsius rise (water exists in all 3 states in atmosphere)
precipitation
rain, snow, hail and sleet
interception
when water is caught by trees and plants
infiltration
when water enters the ground
stem flow
water lands on plants and runs down their stems
overland flow
anywhere water flows over the land surface
through flow
when water flows through the ground (through soil layer) (relatively slow)