1a Flashcards
The importance of water in supporting life on the planet (all)
- understanding evolution of life
- clouds reflect solar radiation
- water vapour absorbs radiation
- oceans absorb heat
importance of water in supporting life (1)
key to understanding evolution of life on earth as it provides a medium that allows organic molecules to mix and form more complex structures
importance of water in supporting life (2)
clouds, made up of tiny water molecules reflect 1/5 of incoming solar radiation and lower surface temps
importance of water in supporting life (3)
water vapour absorbs long wave radiation from the Earth helping to maintain average global temps almost 15% higher than they would otherwise be
importance of water in supporting life (4)
oceans, which occupy 71% of earth’s surface moderate temperature by absorbing heat, storing it and releasing it slowly
uses of water in agriculture
irrigation, pesticide, fertilizer, grow fresh produce, sustain livestock
uses of water in industry
steel making, food manufacture, dying, paper manufacture, brewing
uses of water in domestic
drinking water, sewage disposal, generate electricity, washing and cleaning
uses of water in recreation
swimming pools, golf courses, man made lakes, fountains
uses of water for flora
photosynthesis, carrying nutrients around, keeps plants firm and upright (turgid), seaweed and algae absorb C02 dissolved in water
uses of water for animals
stay hydrated, digest food, frogs and turtles need water to lay eggs and reproduce
define atmosphere
- thin layer of gases surrounding earth
- seals the planet and protects us from the vacuum of space
- protects us from electromagnetic radiation given off by sun and meteors
define hydrosphere
- total amount of water on planet
- can be liquid, vapour or ice
define cryosphere
frozen part of hydrosphere
glaciers, ice caps, ice bergs
define lithosphere
earth’s crust and uppermost mantle
hard and rigid part of earth
split into tectonic plates
define biosphere
earths crust, waters, atmosphere that supports life
3 main stores in earths global water system
oceans (97%)
land
atmosphere
what is water cycle driven by
sun’s energy
only energy crosses boundary of cycle
how does water move between stores
precipitation, evapotranspiration, run off, ground water flow
are smaller scale systems open or closed
open
matter abd energy can cross system boundaries
% of global water stored in oceans
97%
% of global water stored in polar ice + glaciers
2%
% of global water stored in groundwater
0.7%
% of global water stored in atmosphere
0.001%
% of global water stored in lakes
0.01%
% of global water stored in rivers
0.0001%
% of global water stored in soils
0.005%
why are oceans biggest store?
deep capacity of oceans
surface run off and precipitation flow into oceans
why is atmosphere one of smallest stores?
water moves very quickly in and out of it
average store time for water molecule in atmosphere
9 days
define desalination
removal of salts and minerals from salt water or saline water
define system
any set of interrelated components or objects which are connected together to form a working process
define subsystem
a set of elements, which is a system in itself, and a part of a larger system
open system
both mass and energy are allowed to transfer across a system boundary
closed system
flow of energy in and out
no matter can flow across system boundary
has fixed mass
at what scale is the water cycle open?
drainage basin scale
what is a drainage basin
an area of land delineated by a watershed, within which all surface water from rain, melting snow, or ice converges to a single point at a lower elevation
precipitation
the falling to earth of any form of water- rain, snow, hail, sleet, mist, fog
condensation
water droplets condensed from the air, usually at night, onto cool surfaces near the ground.
dew forms when the temperature of the surface falls below the dew point of its surroundings
ablamation
the natural removal of snow or ice from the surface of a glacier or snowfield. This can occur through melting or sublimation and, at or near the snout of a glacier, it can also occur by calving (forming icebergs).
sublimation
a chemical process where a solid turns into a gas without going through a liquid stage
inputs to the water cycle
precipitation, condensation, snowmelt (ablamation)
outputs to the water cycle
evaporation, sublimation, volcanic water vapour
evapotranspiration
water evaporated from the oceans, soils, lakes and river and water transpired through the leaves of plants
water cycle
The movement of water between the atmosphere and Earth. It includes: Evaporation, Condensation, Precipitation, Surface Runoff, Transpiration and Perspiration.
transpiration
When plants release water through pores in their leaves back into the atmosphere.
the diffusion of water vapour to the atmosphere from the leaf pores (stomata) of plants
surface run off
Water that cannot be absorbed into the surface (the ground is too dense or saturated) but runs along it
humidity
The amount of water vapor in the air warm air can hold more water vapor than cool air.
relative humidity
The percentage of water vapor in the air compared to the maximum amount of water that the air can hold at a particular temperature.
ground water
All the water that soaks into the ground, found under the Earth’s surface
interception
precipitation that does not reach the soil, but is instead intercepted by the leaves, branches of plants and the forest floor. It occurs in the canopy
infiltration/ percolation?
the process by which water on the ground surface enters the soil
dew point
the temperature at which condensation begins
Water balance equation
P=Q+E +/- S
precipitation= streamflow +evapotranspiration +/-changes in storage
The balance between inputs and outputs in a drainage basin is known as
the water balance
what is the water balance equation?
summarises the flows of water in a drainage basin over time. It states that precipitation is equal to evapotranspiration and streamflow, plus or minus water entering or leaving storage:
Storage within a drainage basin – the options:
soil moisture recharge
When the soil becomes saturated, excess water will have difficulty infiltrating into the ground If it cannot infiltrate into the soil it will run over the surface as overland flow.
Storage within a drainage basin – the options:
soil moisture utilisation
When evapotranspiration is greater than precipitation there is a reduction in the amount of water stored with the soil. This continues until the point where soil moisture is used up.
Storage within a drainage basin – the options:
soil moisture deficit
Eventually all the available water stored in the soil will have been used up.
Storage within a drainage basin – the options:
soil moisture recharge
When precipitation is greater than evapotranspiration the pores of the soil are refilled with water until it reaches it’s field capacity.
the principle flows linking stores in the water cycle
- Evaporation
- Transpiration
- Condensation
- Precipitation
- Run-off
- Infiltration
- Percolation
how does precipitation form
when vapour in the atmosphere cools to dew point and condenses into tiny water droplets. Eventually these water drolet aggregate (stick together), reach a critical size and leave the cloud as precipitation
factors affecting precipitation
- rainfall quickest to enter streams and rivers as overlandflow
- this is sped up if surfaces are impermeable (urban areas)
- or in areas of steep relief
- in mountains precipitation often fals as snow
- may remain on ground for several months, meaning longer time lag between snowfall and run off
- in areas that get a lot of precipitation, ground may be saturated therefore increasing overland flow and reducing time lag
- this can lead to flooding
factors that affect transpiration
- light- in bright light stomata open wider to allow more oxygen in for photosynthesis- transpiration increases
- temperature- evapouration and diffusion faster at higher temperatures- transpiration faster
- wind- water vapour removed quickly by air movement, speeding up transpiration
- diffusion of water vapour out of leaf slows down if leaf is already surrounded by moisture air- transpiration slower in humid conditions-
3 main types of cloud
cirrus clouds
cumuliform clouds
stratiform clouds
global atmospheric circulation
affects weather patterns around the world and therefore flows and stores in the water cycle. It is the large-scale movement of air, and together with ocean circulation is the means by which thermal energy is redistributed on the surface of the Earth.The Earth’s atmospheric circulation varies from year to year, but the large scale structure of its circulation remains fairly constant.
define The Hadley Cell
a large scale atmospheric convection cell, which is influential in weather patterns and therefore affects the water cycle.
explain the Hadley Cell
At the equator, moist air is warmed by the Earth’s surface, decreases in density and rises.
The rising air moves polewards and creates a low pressure zone near the equator.
As the air moves poleward, it cools, becomes more dense, and descends at about 30 degrees, creating a high pressure area.
The descended air then travels toward the equator along the surface, replacing the air that rose from the equatorial zone, closing the loop of the Hadley Cell.
adiabatic expansion
Air warmed by contact with the ground or sea surface, rises freely through the atmosphere. As the air rises and pressure falls it cools by expansion This vertical movement of air is also known as convection.
advection
Air masses move horizontally across a relatively cooler surface
orographic uplift
Air masses rise as they cross a mountain barrier or as turbulence forces their ascent.
mixing
A relatively warm air mass mixes with a cooler one.
define lapse rates
Lapse rates describe the vertical distribution of temperature in the lower atmosphere, and the changes that occur within an air parcel as it rises vertically away from the ground.
• Measured as degrees lost per km.
• There is an average heat loss with altitude
• There are different rates of heat loss for rising parcels of air
cloud formation
Clouds are visible ‘groups’ of water droplets or ice that float in the air. They form when water is cooled to its Dew Point
Three different lapse rates: Their interaction explains the formation of clouds
Environmental Adiabatic Lapse Rate- The average rate of temperature decrease with altitude (6.5˚C per km of height gained)
Saturated Adiabatic Lapse Rate- The rate at which a saturated parcel of air cools as it rises through the atmosphere (7˚C per km of altitude). Higher than the DALR as Latent heat is released during condensation
Dry Adiabatic Lapse Rate- The rate at which a parcel of dry air cools as it rises (10˚C per km of altitude)
How clouds form by convection
The ground heated by the sun warms the air in contact with the surface.
Because the air is warmer than its surroundings it is less dense and therefore boyant.
This situation known as atmospheric instability, results in air rising freely in a convection current.
When its internal temperature reaches the dew point (8 ºC) condensation occurs and cloud starts to form.
The air continues to rise so long as its internal temperature is higher than the surrounding atmosphere.
how can evaporation be accelerated
- Evaporation is accelerated as temperature increases.]
- Evaporation potential is higher in hotter areas
- Evaporation potential is higher over large stores of water and in areas of high rainfall.
the oceans, seas, lakes and rivers provide what percentage of moisture in the atmosphere
90%
plant transpiration provides what percentage of moisture in the atmosphere
10%
Throughfall
Vegetation intercepts a proportion of precipitation, storing it temporarily on branches, leaves and stems. Eventually this moisture either evaporatesor falls to the ground. Rainfall that is briefly intercepted is known as throughfall.
Factors increasing interception loss
- higher temperature
- type of tree- coniferous (keep leaves all year and have waxed coating so water can be held)
- low humidity
- more wind (more evap, more int loss)
Ablamation
loss of ice from snow, ice sheets and glaciers due to a combination of melting, evaporation and sublimation.
what are storm hydrographs
graphs that show how a drainage basin responds to a period of rainfall.
They are useful in planning for flood situations and times of drought as they show the discharge (amount of water reaching channel via different pathways) that originated as precipitation
short lag time
in areas with large amounts of run off, overland flow and saturated overland flow lag times will be short
long lag time
in areas with large flows through throughflow and groundwater flow this lag time will be much longer
factors affecting lag time
- soil type- clays less infiltration, sandy soil more infiltration
- slope of land- water falling on steep land runs off more quickly and infiltrates less that it would on flat land
- land cover- concrete surfaces have more run off
- vegetation cover- slows run off and allows more infiltration
- soil moisture conditions- soil moisture surplus – saturated soils cause more run off that soils in deficit, utilisation or recharge which encourage infiltration
