the atmosphere Flashcards
why does the composition of the atmosphere only change over long timescales?
natural processes are in a state of balance, maintaining the average composition of earth
how is biologically damaging radiation in ‘solar wind’ prevented from reaching earth?
by the upper atmosphere
what are the three forms of oxygen?
monatomic (O)
diatomic(o2)
triatomic(o3)
how do naturally occurring gases increase temp on earth?
-warm atmosphere emits infrared energy,absorbed by earths surface
-warm atmosphere reduces heat loss by conduction from land to oceans
what does atmospheric pressure do?
controls the ease with which water molecules can evaporate and escape from the water surface
what is the ionosphere?
ionized part of the upper atmosphere of earth
what is the mesosphere?
third layer of atmosphere, directly above stratosphere and directly below thermosphere
what is the stratosphere?
layer of earths atmosphere above the troposphere, extending to 50km above earths surface
what is the troposphere?
lowest region of atmosphere, extending from earths surface to height of around 6-10km
what are wavelengths of EM radiation mainly?
UV, visible light, near infrared
what is the structure of the atmosphere?
-exosphere
-thermosphere
mesosphere
-ozone layer
-stratosphere
-troposphere
-earths surface
what is infrared used in?
tv remotes and optical fibres
what is ultraviolet used for?
sunbeds,nightclubs,detect counterfeit bank notes
what is radiation transmitted?
EM waves able to pass through atmosphere and reach earths surface. visible light passes through atmosphere. shorter wavelength, higher the energy transfer
how is radiation converted?
heat-
*heats the air, causes it to radiate energy to space and back toward earths surface
chemical energy-
*photoynthesis in plants converts solar energy into chemical energy using electrons and protons from water
what is the natural greenhouse effect?
-atmospheric processes that warm up the troposphere
-visible light passes through atmosphere easily & absorbed by earths surface
-warm surface emits infrared radiation that cant pass through atmosphere as easily as its absorbed by gases in atmosphere
what are greenhouse gases?
any gases that are better at absorbing infrared than the average for the atmosphere
how are human activities increasing carbon dioxide?
-combustion of fossil fuels and wood
-ploughing of soils
-drainage of marshes and bogs
how are human activities increasing methane?
-anaerobic respiration by microbes in padi fields
-landfill sites
-intestines of livestock
how are human activities increasing oxides of nitrogen?
-oxygen+nitrogen from air react at high temps in water laces such as vehicle engines and power stations
-then released into atmosphere in exhaust gases
how are human activities increasing chlorofluorocarbons?
-used as aerosol propellants
-fire extinguishers
-refrigerants
-solvents
-expanded foam plastics
how are human activities increasing tropospheric ozone?
produced by photochemical breakdown of NO2 and subsequent reactions with oxygen
name the greenhouse gases.
-water vapour
-carbon dioxide
-methane
-nitrous oxide
-hydrofluorocarbons
-perfluorocarbons
sulphur hexafloride
how does greenhouse effect cause changes in climate processes?
-amount,timing,duration,location
-changes in proportions of rain and snow
-wind patterns changes direction,velocity
how has precipitation changed?
-warmer atmosphere can hold moisture
-globally water vapour increases by 7% for every degree centigrade of warming
-total volume precipitation likely to increase by 1-2% per degree of warming
how have air conditions changed?
-jet streams are strong winds that blow from west to east in troposphere
-caused by differences in air temperature and pressure from equator and polar regions
-winds blow to equalise the pressures
how does melting ice affect sea levels?
-ice floating on seas surface doesnt cause sea level to rise
-ice on land will cause sea level to rise as water flowing into sea increases its volume
what are some properties of water affecting sea level rise?
-warmer atmosphere=more seawater expanding causing sea levels to rise
-water has high specific heat capacity so takes longer to heat up
-only surface seawater is warmed with direct contact with atmosphere
-cold deep water only heats up when slow ocean currents bring it to surface
what are ocean currents?
-movement regulates earths climate and transport carbon, heat and nutrients
what is the thermohaline circulations?
deep ocean currents are driven by differences in waters density, which is controlled by temperature and salinity
what is the gulf stream?
-wind-driven current, brings warm water northward along u.s. coast
-affect temperatures and weather patterns in all countries
what are ice shelves?
thick floating platforms of ice attached to the coastline
what is snow cover?
seasonal accumulation of snow on the ground
what is permafrost?
permanently frozen ground
what is sea ice?
frozen seawater
what are icebergs?
chunks of ice broken from glaciers
what are ice sheets?
thick ice covering land
what are glaciers?
larger masses of ice,flow under their own weight
what is the cryosphere?
parts of the earth where water is found in a frozen solid form
what is amount and duration of snow cover reducing?
-higher temps reduce amount of snow and ice, & length of time it stays on ground before melting
-less snow or ice reduces the albedo of earths surface so less sunlight is reflected away and more is absorbed
why are we seeing changes in extent and speed of movement of land ice?
-snow on land may become compacted onto ice, then flows downhill forming glacier
-may reach sea before melting forming icebergs
-warmer temps may cause front end of glacier to melt faster than it is moving forward so ice front retreats up valley
-meltwater from surface of glacier may flow down through cracks in ice, making it move quicker
-retreating + extending glaciers are evidence of warming temps
why are we seeing a loss of ice shelves?
-as sea levels rise,land ice doesnt need to move so far before floating off into sea
-ice sheets that are grounded may float and break up earlier as sea rises
-ice shelves dont directly cause sea rise as theyre floating and already displaced seawater
why are we seeing a change in thickness and area?
-area of ice that forms on sea surface in arctic and antarctic winters increases at temp drops
-area of ice that forms around antarctica have increased, due to increased freshwater flowing off land
-ice has high albedo and reflects most sunlight, if ice melts more sunlight would be absorbed causing increase in temp
define the albedo effect?
the ability of surfaces to reflect sunlight (heat from the sun) light surfaces=high albedo
what causes the magnetosphere?
it is generated by the molten of molten iron in earths surface
how did oxygen levels increasing provide protection from UV radiation?
ozone layer
why did CO2 levels decrease once life began on earth?
photosynthesising organisms absorb the carbon dioxide
what gas was most abundant in the early atmosphere?
carbon dioxide
what is the greenhouse effect?
when the suns energy reaches the earths atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases
why are ocean currents important on earth?
act like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics
how does the melting ice affect the north atlantic conveyor?
more freshwater-> becomes less dense-> currents slow down
what 2 factors lead to sea level rise?
-land ice melting
-thermal expansion of sea water
name 3 ways of monitoring climate
-satellites
-ice cores
-computer models
why is historical data not always accurate?
-not collected very widely
-not accurate technology available
why is climate change data uncertain?
-lack of historical data
*atmospheric composition
*temperature
*weather patterns
-limited reliability of proxy data
-lack of understanding of natural processes that control weather
*ocean currents and their interconnections
-natural changes & fluctuations that mask changes caused by anthropogenic actions
-time delay between cause and effect
what is a summary of interconnected systems?
interactions between systems make it difficult to accurately monitor changes + predict effects
- e.g. in UK, changes in jet streams may rise temperatures
what is a summary of lack of historical data?
unreliable data due to lack of sophisticated equipment and data collection on global scale
what is a summary of time scales + delay?
cause + effect time delay
-e.g. temp increase takes longer for oceans to heat up
what is a summary for natural fluctuations?
-all climate factors fluctuate due to solar output
-difficult to determine if caused by humans
-global climate has never been consistent
what is negative feedback?
-works against any movement away from a stable point and brings a system back into equilibrium
-reduces size of original change
-helps to re-establish original equilibrium
what is positive feedback?
-accelerates any movement away from a stable point
-increases size of original image
what is a tipping point?
human actions that cause climate change and causes changes in natural processes such that the original human actions no longer need to continue for climate change to continue increasing
positive feedback mechanisms examples?
-ocean acidification
-reduced albedo
-melting methane hydrate
-increased forest & peat fires
-rapid decomposition of dead organic matter in soil
what is carbon footprint?
volume of carbon dioxide released into atmosphere as result of the activities of a individual, organisation, or community
what is sustainable development?
meeting needs of current generations without compromising ability of future generations to meet their needs
what is flood control in climate change?
•flooding by rising water levels can be reduced by building higher river banks / coastal defences
•if water in river rise above level of surrounding land, would be necessary to pump rainwater from land up to river or sea
what is coastal erosion control in climate change?
•coastal erosion rates rise as waves strike the upper shore for longer in each tidal cycle
•variety of sea walls & wave screens are used to protect coasts
what is managed retreat in climate change?
•some areas so expensive that flood control measures used, even if expensive
•other areas, cost of flood prevention may be bigger than value of what needs protection, or may be ineffective
what is permeable drainage control in urban drainage control in climate change?
•permeable urban surfaces-replacing impermeable concrete & tarmac with permeable surfaces, such as gravel or soil, reduces flooding in urban area. slowing runoff reduces extremes in river flow + helps prevent flooding downstream
what is river flow management in urban drainage control in climate change?
•tributaries flowing into river will increase water level. retaining water in tributary or slowing flow of water from land may reduce flooding around main river.
•runoff from rural land into rivers after rain can be delayed by constructing low soil dams or increasing afforestation
•larger dams can be used to regulate river flow, storing water in times of heavy flow & releasing it to maintain river flow in dry weather
what is raised building in urban drainage control in climate change?
•raised buildings on stilts protects against flooding up to the height of the stilts
what is floating house in urban drainage control in climate change?
•in low lying areas where flooding is common, constructing houses on tethered floating platforms would protect from flooding.
•in the netherlands and the river deltas of bandladesh and india
