1.B - the water cycle as a system Flashcards
what are the main stores of water?
- oceans
- polar ice and glaciers
- groundwater/aquifers
- lakes
- soils
- atmosphere
- rivers
- biosphere
how much water do the oceans store?
- 137,000 thousand cubic kilometers
- 97% globally
how much water does the land store?
- 39,000 thousand cubic kilometers
- 0.7% globally
what is worrying about the amount of water stored in polar ice and glaciers?
- as they melt due to global warming this will greatly increase the volume of water in oceans = SL rise = flooding
what challenges are there with most of the water being stored in oceans?
- 97% of water stored in our oceans
- salt water = toxic to most crops and also can’t be drunk by humans
- desalinisation is very expensive and quite inefficient
what are aquifers?
water bearing bands of porous/permeable rock
what are ice sheets?
floating sheets of ice permanently attached to a land mass
what are the flows in the water cycle system?
- evapotranspiration
- precipitation
- ablation
- infiltration
- run off
- groundwater flow
define evapotranspiration
combined loss of water at the surface through evaporation and transpiration by plants
define precipitation
moisture (rain, snow, hail) falling from clouds towards the ground
define ablation
the loss of ice and snow, especially from a glacier, though melting, evaporation and sublimation
define infiltration
the vertical movement of rainwater through the soil
define run-off
the movement of water across the land surface
define ground-water flow
the horizontal movement of water w/in aquifers
what does condensation refer to?
- condensation refers to the change of state from water vapour into liquid water.
- clouds form as a result of condensation in the atmosphere.
- this will happen when air is cooled so that it reaches its dew point.
in what ways does air reach the dew point?
- it can occur when air rises upwards due to being warmer than surrounding air (convection). As the air rises, its pressure drops and it expands and cools until its dew point (adiabatic expansion)
- air can be forced to rise over mountain barriers and so again it cools by aidiabatic expansion as it rises
- air may also be forced to rise as it meets colder air at a front
- finally if a mass of air will cool if it moves across a relatively cooler surface (advection). this may happen as air moves from sea to land in the winter
what is a cumuliform cloud?
- flat bases and considerable vertical development
- form when air is heated locally through contact w/ the Earth surface
- this causes heated air parcels to rise freely through the atmosphere (convection), expand (due to the fall in pressure w/ altitude) and cool
- as cooling reaches the dew point, condensation begins and clouds form
how do cumuliform clouds form?
- form when air is heated locally through contact w/ the Earth surface
- this causes heated air parcels to rise freely through the atmosphere (convection), expand (due to the fall in pressure w/ altitude) and cool
- as cooling reaches the dew point, condensation begins and clouds form
what is a stratiform cloud?
- develop where an air mass moves horizontally across a cooler surface (often the ocean)
- this process, together with some mixing and turbulence is known as advection
what is a cirrus cloud?
- wispy, cirrus clouds which form at high altitude, consist of tiny ice crystals
- unlike stratiform cloud and cumuliform clouds, they don’t produce precipitation and therefore have little influence on water cycle
what is precipitation?
- precipitation is the water and ice that falls from clouds towards the ground (e.g rain, snow, hail, sleet and drizzle)
- it forms when the atmosphere can no longer hold water as vapour and additional water vapour reaches its dew point to form clouds.
- eventually these droplets of water/ice coalesce to form precipitation
- generally, warmer climates allows more vapour to be condensed, form clouds and precipitate.
- when it is cold, there is not as much energy for evapotranspiration, thus less clouds/precipitation
how does temperature affect precipitation?
- generally, warmer climates allows more vapour to be condensed and form clouds and precipitate.
- when it is cold, there is not as much energy for evapotranspiration, thus less clouds/precipitation
how does precipitation affect rivers?
- the type of precipitation and when it falls can also influence the nature of a river regime, which shows how much water is flowing in a river throughout a year.
- for example in some parts of the world such as East Africa or the Mediterranean, rain may only fall in the rainy season and so this may be the only time you see rivers flowing.
- summer = more glacial melt
what influences the flow of a river?
- interception storage capacity, wind speed, vegetation type, tree species (coniferous all yr round, decidous cant intercept rainfall in winter)
- vegetation = interception. mitigate against flooding. also bind the soil together = its not eroded into the river and won’t build up river capacity = less flooding
- rock type (permeable or not). impermeable rock = flashy rivers.
- steepness of valley/relief = high levels of surface run off if sides are steep. will impact speed of runoff and throughflow
- climate/time of year
- people = tarmac/urban areas increases river flow = erosion of banks end up in river channel = decreased capacity
- the amount and type of precipitation = heavy rain will saturate the ground quickly = icnreased SRO and river flow