Earths Life Support Systems Flashcards
why is water important for our climate?
- occupies 71% of earths surface
- absorbing heat, storing it and releasing it slowly.
why is water important for people?
- generate electricity
- sweating
- satisfying public demand
- food manufacturing
why is water important for animals?
- cooling by panting and sweating
- chemical reactions in the body
why is water important for plants?
- to ensure they don’t wilt
- photosynthesis
stores of the water cycle
- lithosphere
- biosphere
- hydrosphere
- cryosphere
- atmosphere
lithosphere
rigid outer part of the earth, consisting of the crust and upper mantle. it is divided into tectonic plates.
biosphere
the space at the earths surface and within the atmosphere occupied by living organisms
hydrosphere
all the waters on the earths surface such as lakes and seas
cryosphere
the frozen part of the earths surface, including polar ice caps, continental ice sheets, glaciers, sea ice and permafrost
atmosphere
the envelope of gases surrounding the planet
inputs into the drainage basin water cycle
- precipitation (moisture that falls to the ground: rain, snow, sleet, hail, fog)
processes of the drainage basin water cycle
- condensation (when water vapour in the atmosphere turns into liquid water. it is caused by warm air rising and then cooling:
- the ground is heated up by the suns energy or insolation.
- through the process of convection a parcel of warm air will rise.
- because the parcel of air is warmer than its surroundings it is therefore less dense and buoyant.
- the atmosphere is now unstable.
- as the parcel of air cools it will eventually reach its dew point.
- this is the temperature at which a given concentration of water vapour in air will begin to condense.
- this is when condensation occurs and a cloud starts to form.
processes and flows on the ground
- when it rains most of the ppt falls directly onto the ground with about 10% of it falling directly into the river channel and flowing straight out into the ocean. (channel ppt).
- some ppt never reaches the ground because it is stopped from doing so by vegetation. (interception).
- ppt is stored temporarily on branches, leaves and stems from there in two possible ways:
- throughfall (the process which describes how wet leaves shed excess water onto the ground surface) and stemflow (the flow of intercepted water down the trunk or stem of a plant).
- the intercepted water evaporates up into the atmosphere directly off the plant and it leaves the drainage basin before reaching the ground (interception loss).
factors affecting interception loss
- interception storage capacity
- wind speed
- vegetation type
- tree species
how does interception storage capacity affect rate on interception loss?
- when vegetated surfaces are dry they can retain a lot of water, so initially most rainfall is intercepted.
- however as rain continues and the vegetation becomes saturated intercepted water will be lost by throughfall and stemflow.
- interception loss therefore depends on how long the rain lasts for and how heavy it is.
how does wind speed affect the rate of interception loss?
higher wind speed = more evaporation = more interception loss
how does vegetation type affect the rate of interception loss?
- interception loss from trees is greater then from grassland because they have a large surface area to intercept water.
- interception loss is greater from grassland than from agricultural crops.
how does high infiltration capacity influence infiltration rates and flows into the rivers?
- sandy soils have large particles and large pores so there is high infiltration capacity and more throughflow.
- in contrast, clay soils have small particles and small pores so there is a low infiltration capacity and more overland flow.
how does saturated soil influence infiltration rates and flows into the rivers?
- if all soil pores are filled with water, there will be less infiltration and more overland flow will occur. this is called saturated overland flow.
how does arable land in winter influence infiltration rates and flows into the rivers?
- fields are ploughed so bare soil result in more infiltration leading to more throughflow.
how do coniferous trees influence infiltration rates and flows into the rivers?
- trees are evergreen and pine needles also have high water retention so there is lots of interception loss so soils are drier in a rainstorm event.
- this means there will be less infiltration and less throughflow.
how does rock type influence infiltration rates and flows into the rivers?
- if the area was underlain by permeable limestone, then the rock has natural joints s there will be more percolation so more groundwater flow so less overland flow.
- if the area was underlain by impermeable slate, then there would be no percolation. this means that the water remains in the soil pores so there will be more throughflow. when the soil saturation is reached then there will be more overland flow. this is called saturated overland flow.
outputs from the drainage basin water cycle
- evaporation (when water is taken up into the atmosphere from liquid to vapour).
- transpiration (loss of water from vegetation stomata as it goes into the atmosphere).
- evapotranspiration (sum loss of water from the surface of the earth combined).
- sublimation (snow and ice changing into water vapour in the air without melting into water first).
- run off (water discharged in surface streams, includes water that travel over land and through channels but also water that infiltrates and travels underground).
factors affecting rates of transpiration
- temperature
- wind speed
- water availability to plants
- seasons
