Water cycle

Flussdiagrammknoten

• water cycle

• Reservoirs of available water Oceans and sea ice - 1370Ice caps and galciers - 29 groundwater - 8 lakes - 0.1soil moisture - 0.1atmosphere - 0.013riivers - 0.001biosphere - 0.001 water reserviors on the continents are negligible in terms of volume small reserviors are importan becuase ofthier role in the water cycle 

• Exchange processesthey all constantly exchange water except -water trapped in pores of sedimentary rocks -only very slow exchange due to geologicalprocesses processes are evaporation and sublimation evapotranspiration precipitation infiltration percolationsurface runoff and ground water flow 

• the global water cycle flukes in liquid water equivalents per year Vapour transport (sea to land) = river + ground water flow reservoirs remain constant over  = steady state 

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• water and tectonic cycle water is cycled through inner earth over geological time scales it is taken into the lithosphere by subduction of connate water in sedimentary rocks and lossed by volcanic emissions, when these qual each other they are in a steady state and so they are indepndent cycles - they don't really effect each other. 

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• the water budget concept 

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• Steady state and residence times Steady state = sum of all sources = sum of all sinks so there fore the reservoir stays constant aswell - allowing reidence times to be calculate, thses are useful for looking at the time-scale of turnover in reservioirs. 

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• solar  radiation 

• Solar radiation is the highest in the visible spectrum at wavelengths 500 nanometers 

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• Black body radiation the hotter the radiation body the shorter the emiited wavelengths so there fore incoming solar is short waved - uv absorbed by ozone - little abosorption by water and carbon dioxide outgoing radiation is long waved - absorbed by water vapour and carbon dioxide 

• Global heat budget 

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• Incoming solar radiation three fundamantal processes - refelction and scattering - back to space- this is via clouds and gas molecules from the earths surface -absorption via the ozone, clouds and water vapour - absorption via the earths surface the earth approx. absorbs 65% of the incoming solar 

• Outgoing radiaition required return of absorbed radiaition -radiation emitted from earths surface to space = 5.5%-radiaition emitted back to the atmosphere back to space = 59.5%heat transported from earths surface to atmosphere = 42% -evaporation =  29.5%-conduction and re-emission = 12.5%

• 35% of incoming solar radiaition gets trapped in the Aatmosphete 

• Antropogenic Green house effects this is caused by gases being absorb in infrared regions - places left by water - carbondioxide -most abundant and is a natural and anthropogenic sources -Methane is next - Nitrous oxide - CFCs =- tace constituents and currently phased out all models predict significant tempreture rise by atleast 1.2 to 5.8 warmer average 3.5 

• Ice coes reveal bygone climates windborn dust deposits cause banding with annual layers - help with dating also reveal past greenhouse gas concentrations 

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• Recent records it provides a pre-industrial concentrations of green house gases - glaciers - reaches back as fair as 800000 a BP there has been the strongest increase in recent years 

• what greenhouse gases are most important? GWP depends on -infrared absorbance -atmospheric lifetime - longer = higher Global warming potentials relative to carbon dioxide Gas    Lifetime / a        GWP CO2             5-200              1  = 61% CH4           12                      21  = 15%               N2O           114         290  = 4% CFC’s        45-50000  >1500 = 8%Anthropogenic enhancement of the greenhouse effect calculated over 100 years 

• What is the role of the oceans- Oceanic uptkae moderates atmospheric carbon dioxide concnetrations  -Ocean acidification -greenhouse gas emissions from oceans -changes in ocean circulation - weakening of gulf stream = change in waters -sea level rise - melting and themrl expansion, coastline changes, flood risks 

• measurement of sealevel rise - tide gauges - local -satellite altimneters - global complemented by models which consider -ocean currents and tides -thermal expansion -volume gain current trend ~ 3mm per annume 

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• coastlines sealevels have all ready moved by 100's km due to sea level change caused by -natural climate variabilty - 1 mm - anthropogenic - 15 cm then +40 cm