Geography - ELSS

• Reasons why water is so valuable

  71% stored in oceans

  Oceans regulate temperature by absorbing heat and slowly releasing it

  Clouds reflect 1/5 of the suns radiation which lowers temperature

  Used for chemical reactions in the body

  Photosynthesis, respiration and transpiration require water
• Reasons why carbon is so valuable

  Stored in carbonate rocks such as limestone and within oceans as dissolved CO2

  Stored in the lithosphere, hydrosphere , atmosphere and biosphere

  Economic resource, fossil fuels and many raw materials require carbon
• Stores and residence times of the water cycle

  atmosphere - 10 days

  land - varies

  oceans - 3000 years
• flows of the water cycle

  precipitation

  evapotranspiration

  evaporation

  run-off / groundwater flow
• water balance equation 


  precipitation (p) = evaporation (e) + run-off (q) +/- storage (s)

  +ve water balance - precipitation exceeds evapotranspiration

  -ve water balance - evapotranspiration exceeds precipitation
• water cycle budget


  the annual volume of water movement by flows between stores
• ablation


  the loss of snow and ice through melting, evapotranspiration and sublimation
• sublimation 


  the change of water state from ice to vapor
• infiltration


  the vertical movement of rainwater through the soil
• perlocation


  the movement of surface and soil water into underlaying permeable rock
• stores and residence times of the carbon cycle

  atmosphere - 6 years

  oceans - surface = 25 years

  - deep = 1250 years

  terrestrial biomass - 18 years

  sedimentary rocks - 150 million years

  sea floor sediments

  human activity

  soil
• flows of the carbon cycle


  combustion

  weathering

  respiration

  decomposition

  oxidation

  photosynthesis

  volcanic activity
• the slow carbon cycle


  CO2 stored in rocks, sea floor sediments and fossil fuels

  locked away for millions of years

  CO2 diffuses from atmosphere into oceans, marine organisms combine dissolved carbon with calcium to form calcium carbonate (CaCO2)

  when organisms die and sink form carbonate sedimentary rocks

  estimated 10-100 million tonnes a year is circulated by this cycle
• the fast carbon cycle

  land plants and phytoplankton from the surface level of the ocean are key

  photosynthesis means they absorb CO2 and combine with water to form carbohydrates

  decomposition returns CO2 to atmosphere

  oceans absorb CO2 from the atmosphere and release it over 350 years approximately

  10-1000 times faster than the slow carbon cycle
• Precipitation and a carbon flux


  Atmospheric CO2 dissolves into rainfall and forms a weak carbonic acid

  rising anthropogenic emissions have increased the acidity of rainfall

  increased acidity of surface level oceans possibly harms marine life
• photosynthesis as a carbon flux

  averages about 120GT a year

  plants use energy via photosynthesis to produce glucose to maintain growth, they release CO2 via respiration
• respiration as a carbon flux

  carbohydrates are converted to CO2 and water

  living organisms absorb oxygen which ’burns’ carbohydrates and provides energy

  links with the fast carbon cycle
• decomposition as a carbon flux


  bacteria an fungi break down organic matter and release CO2 into the atmosphere

  Rapid - warmer, humid climate

  Slow - tundra, dry, cold environment
• weathering as a carbon flux

  carbonation releases carbon from limestone into streams, rivers, oceans and atmosphere

  freeze-thaw weakens rock with no chemical help, but does increase the area exposed to chemical attack

  biological (chelation) - dead organic matter decay in soils
• Combustion as a carbon flux

  Organic matter reacting in the presence of oxygen

  releases CO2 as well as nitrogen oxide and sulfur dioxide

  speeds up carbon cycle and clears ‘jam’

  burning fossil fuels are useful for global economy but speeds carbon transfers
• carbon sequestration (physical pump) as a carbon flux


  involves mixing of surface and deep water due to vertical currents

  CO2 enters surface level oceans by diffusion

  downwelling occurs at the poles

  carbon molecules stay deep within the oceans currents slowing movement to areas where upwelling occurs and carbon returns to atmosphere
• carbon sequestration (biological pump) as a carbon flux


  carbon exchanged through marine organisms

  photosynthesis fixes atmospheric and dissolved CO2 in some marine organisms

  others extract carbonate ions from sea water to floor shells

  fixed carbon either ends up on oceans form sediments or is released by decomposition into the oceans
• Processes of the water cycle

  Diagram:

  
• Water balance 


  A summary of the flows within a drainage basin overtime

  Equation = $P=$$E+$$Q+$$-Storage$

  P = precipitation

  E = evaporation

  Q = streamflow
• Transpiration as a process of the water cycle


  diffusion of water from leaves to the atmosphere

  responsible for approximately 10% of moisture in the atmosphere
• Precipitation as a process of the water cycle

  Dew point - critical temperature When air becomes saturated and can’t hold any more water

  intensity - the amount of precipitation in a given time

  duration - length of time precipitation events last

  concentration - seasons can cause variations in rainfall
• Processes of the water cycle

  Diagram

  
• Adiabatic expansion 


  when air pressure is high, particles collide regularly = lots of kinetic energy

  as air parcels rise it expands = pressure drops = temperature drops

  less collisions between particles
• absolute humidity 


  how much water an air parcel can hold

  measured in g/m3
• relative humidity 


  percentage of water an air parcel can hold
• cumuliform clouds


  vertical development

  when air is heated locally through contact with the Earths surface

  this causes a diabetic expansion and the clouds begin to form
• stratiform clouds 


  layers of clouds develop when air masses move horizontally across a cooler surface (advection)
• cirrus clouds


  form at very high altitudes

  made of tiny ice crystals

  don’t have an effect on the water cycle as doesn't produce precipitation
• formation of clouds


  Air, warmed by contact with the ground or the sea rises which means pressure falls and adiabatic expansion occurs

  air masses move horizontally (advection)

  air masses rise as they cross mountain barrier or as turbulent air forces their ascent

  a relatively warm air mass mixes with a cooler air mass
• Lapse rates


  A change in temperature when moving upwards through the atmosphere
• Positive lapse rates


  When the temperature decreases with elevation

  Zero when temperature is constant with elevation
• Negative lapse rates 


  When temperature increases with elevation (temperature inversion)
• Environmental lapse rates (ELR)

  The vertical temperature profile of the lower atmosphere for a given place at a given time

  Temperature usually decreases with height/altitude

  In average, temperature decreases by 6.5 degrees every KM
• Dry adiabatic lapse rates (DALR)


  The rate at which ‘dry air cools’ - less than 100% saturated

  On average temperature drops by 10 degrees every KM
• Saturated adiabatic lapse rates (SALR)

  The rate at which saturated air cools

  On average temperature drops by 7 degrees every KM

  Condensation releases latent heat into the air