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