The atmosphere Flashcards
CO2 composition
0.04%
Oxygen composition
21%
Ozone composition
0.000007%
Rare gases composition
1%
Nitrogen composition
78%
Thermal stratification
-The troposphere is warmed by the absorption of infrared energy emitted by the Earth. Temps normally
greatest near the surface, declining with altitude.
-The stratosphere is warmed by the absorption of UV light from the Sun. The temperature is lowest at the bottom of
the stratosphere, increasing with altitude.
Absorption of UV
Ozone layer (monatomic, diatomic, triatomic)
Delaying the escape of infrared energy
visible light -> heat -> emitted as infrared
Raises temps by:
-warm atmosphere emitting IR absorbed by earths surface
-warm atmosphere reduces heat loss by conduction from lands and oceans.
Ocean currents
wind blows over oceans -> creates currents -> distributes heat -> warm water to higher latitudes
Heat distribution
most suns energy absorbed at tropical regions -> warm surface heats atmosphere above -> heat distributed to higher latitudes by warm winds
Transport of water vapor
Winds transport water vapor to areas with little to no precipitation
Structure of the atmosphere
Thermosphere (highest altitude, lowest atmospheric pressure)
–Mesopause
Mesosphere
–Stratopause
Stratosphere
–Tropopause
Troposphere (lowest altitude, highest atmospheric pressure)
CO2 human activity
-combustion of fossil fuels
-drainage of marshes and bogs
-ploughing of soils
CO2 relative effects per molecule
1
Chlorofluorocarbons (CFCs) human activity
-Aerosol propellants
-refrigerants
-solvents
-expanded foam plastics
CFCs relative effect per molecule
25000
Tropospheric ozone human activity
-photochemical breakdown of NO2 and reactions with oxygen
Tropospheric ozone relative effects per molecule
2000
Oxides of nitrogen human activity
-Reacts at high temps in vehicle engines or power stations
-Fertiliser use
Oxides of nitrogen relative effects per molecule
160
Methane human activity
-Anaerobic respiration of microbes (paddy field, landfill, intestines of livestock)
-Formation of fossil fuels
Methane relative effects per molecule
25
Sea level rise
-Thermal expansion of water (expansion of water by heating is slow process due to high specific heat capacity of water and as the ocean is large and only surface layer is heated)
-Melting ice (only land ice adds to sea level rise as sea ice occupies the same volume when melted.
What are ocean currents caused by
-wind
-evaporation
-heating and cooling of water changes density
-changes in salinity
North Atlantic Conveyor
-Movement of layers of surface deep water in the North Atlantic Ocean which distribute heat energy and control the climate
-Warm water from tropical Atlantic Ocean travels north-eastwards to North West Europe through prevailing winds.
1. Water drawn to surface
2. Water cools away from the equator
3. Water becomes denser as it sinks
4. Cold water at great depth
Changes in North Atlantic Conveyor
- Water drawn to surface
- Water cools as it flows away from the equator
- Greenland icecap melts due to increased temps which dilutes the cold sea water (freshwater is less dense), so it sinks slower, slowing down the current.
4.Return current is slowed
What is El Nino?
The name given to the natural change of current in the Pacific ocean. Usually every 2-7years but happening more frequently due to GCC
What are conditions like in normal year (El Nino)
-Trade winds blown westwards causes deep cold water to be drawn upwards, bringing rich nutrients, causing algal blooms on the surface which feed the rich food web, important for fishing communities too. (South America)
- Water gets warmer travelling westward bringing warm currents to Australia (therefore more rainfall as higher PET)
What are conditions like in El Nino year?
-Rich food web by SA collapses as current and wind reverses, so no nutrient upwell
-Temps drop by Australia and increase by SA, so rainfall patterns change
Global impacts of El Nino
-Droughts in NE Africa, S Africa and China
-Fewer hurricanes in N Atlantic
-Fewer tropical cyclones in Japan
What is La Nina
-Where winds blow more strongly in normal direction, so water currents speed up and there is a greater temperature difference between the west and the east
What impact does reduced snow and ice cover have?
Reduces albedo, so less sunlight is reflected away and more absorbed so there is further heating.
Glacier formation
Snow falls on land and is compacted into ice. When mass increases, it gradually flows downhill and forms a glacier
Why and how does a glacier retreat?
Moving to lower altitudes and warmer temperature causes the front end of the glacier to melt faster than it moves forwards so ice front retreats up the valley
Why and how does a glacier extend?
Glaciers may extend due to:
-increased snowfall
-meltwater from surface lubricated the ice so it can slide over the rock and extend out of the valley further (without increasing its mass)
Ice sheet
Ice covering an area over 50,000km squared (Only 2 exist- on Antarctica and Greenland
Ice cap
Ice covering less than 50,000km squared and thick enough to have its own topography
The breaking up of ice shelves + sheets
-Break off and float in the sea causing icebergs. Do not add to sea level rise as they’ve already displaced the seawater
-Once iceshelve have broken off, ice sheets can access sea more rapidly and add to sea level
What causes changes in climactic processes
retention of more heat energy in the atmosphere
What are jet streams
Strong winds that blow from west to east in meandering paths along the upper troposphere, to equalise pressure and temperature. Do not move in straight lines due to coriolis effect
Changes in wind patterns
Polar areas as they are warming up faster than areas on the equator, so jet streams created by temperature differences are becoming smaller. Creates longer more intense weather.
Changes in precipitation
-higher temps= more evapotranspiration=more rainfall
- air may have to move further to find a cold area before vapour cools enough to condense as rain or snow
-changes in wind can carry humid air to new areas causing increased rainfall there
Ecological impacts of GCC due to abiotic factors
-Temp rise= plants grow faster=more food for herbivores
-Precipitation changes cause wetlands to grow or shrink
-Oak trees have deep roots so many be able to survive droughts better than beech trees with shallow roots
-Timing of ecological events such as migration and nesting many change due to temp change e.g. emerging of pollinators earlier, when no flowers.
-colonisation of new species in new areas changing species distribution
Ecological impacts of GCC due to abiotic factors- specific example
Bats in the UK
-Warmer shorter winters increase survival of hibernation
-Warmer weather increase population of food species
-Wetter, stormier weather reduces feeding time for bats, reducing survival
Ecological impacts of GCC due to biotic factors
-Population declines in one area, yet population increases in another
-Isolated populations due to sea level rise creating islands etc, leads to smaller gene pools
The difficulties in monitoring climate change
-Temporal scales (short term or long term)
-Spatial scales (local, regional or global)
-Interconnected systems (atmosphere, biosphere and hydrosphere interconnecting e.g changes in jet stream may increase temperatures)
-Natural fluctuations (variability of solar output , earths orbit, earths changing surface. Can all hide or exaggerated anthropogenic changes)
-Time delay between cause and effect (e.g atmosphere can warm up quickly, but takes a long time for oceans to reach the same temp)
-Historic data
Data collection
-Historic
-Proxy
-Ice cores
-Satellites
-Monitoring ocean currents
-Computer models
What is historic data
-Collected on past atmospheric conditions
-May be unreliable due to lack of sophisticated equipment or lack of data on global scale
-E.g. temp recorded in towns may have shown a temp increase due to population rise (heat island effect) rather than GCC
What is proxy data
-Making an estimate about one factor that cant be measured by using a related factor which can be measured
-E.g.Some coral species produce large coral heads with annual growth rings which can be used to predict past sea temps
What is ice core data
-Air bubbles trapped in ice provide info on the composition of the atmosphere at that point in time. There are annual accumulations of snow build layers, some dating back to 800,000 years ago
-Radio isotope analysis can be used to estimate the age
What is satellite data
-Sensors carried by satellites collect data on factors such as wind velocity, ocean currents, temp, wave height, ice cover, vegetation cover etc.
Satellite examples
-Low Earth Orbit (LEO) satellites in polar orbit collect detailed data of the whole Earths surface
-The Gravity Recovery and Climate Experiment (GRACE) collects data on water distribution, ice sheet mass changes, and other climate-related phenomena.
How are surface ocean currents monitored
Satellies or buoys
How are deep ocean currents monitored
Argo floats-sink to particular depths for specific duration to collect data such as temp and salinity
What are computer models used for
understanding climate systems
Negative feedback mechanism example
high temps-> increased evaporation -> increased condensation -> more clouds form -> clouds have albedo effect -> reduced temps
Negative feedback definition
Reduce size of the original change
Positive feedback mechanism example
increased temp->melt ice->reduce albedo-> further warming
Positive feedback definition
increase size of the original change
ADD FLASHCARDS
FOR OTHER FEEDBACK LOOPS
Control of CO2
-less fossil fuels
-low carbon emission energy sources
-carbon sequestration
-CCS
Control of methane
-reduced landfill (recycling)
-reduced livestock production
-improved recovery of gas from coal mine
Control of NOx
-catalytic converters, so harmful gases are converted into nitrogen and oxygen
-public transport
-addition of urea into power station effluent to reduce NOx
Control of CFCs
-Alternative materials such as butane + propane in aerosols, HCFCs in fridges and alcohol in solvents
-Alternative operations such as trigger and pump action spray, roll on deodorant
Control of tropospheric ozone
-same as NOx
How does CCS work
- Capture of CO2 or removal from fuels
- Transport by road, shipper or pipeline
- CO2 stored in depleted oil fields, gas fields, aquifers or secondary oil recovery
Why is stratospheric ozone important?
-prevents most high energy uv from reaching the earths surface
-if uvb is not absorbed then will be absorbed by living cells causing skin damage, DNA damage, skin cancer, cataracts etc.
Is UV-A absorbed
not absorbed by ozone or diatomic oxygen
Is UV-B absorbed
almost fully absorbed by ozone
Is UV-C absorbed
completely absorbed by ozone and diatomic oxygen
Formation of ozone
- UV splits molecule of diatomic oxygen
- Two monatomic oxygen atoms released
3.Monatomic oxygen reacts with diatomic to form triatomic (ozone)
Destruction of ozone
1.UV splits an ozone molecule
2. Releases monatomic and diatomic oxygen
Why are CFCs ideal for their uses?
-boiling points close enough to ambient temperatures that the gases can be liquefied with easily achievable pressures
-ability to dissolve grease and oils
-Non flammable
-Non toxic
What is the Rowland Molina hypothesis
-Persistence of CFCs
-Dissociation by Uv and release of chlorine
-Reactions of chlorine and oxygen
-Other halogens
