The Atmosphere Flashcards
What is the atmosphere?
Thin layer of gases surrounding the Earth, held in place by gravity
Why is the atmosphere essential to life on earth?
provides life support systems
- absorption of EM radiation from Sun
- gas resources for natural processes
- heat distribution
- delays escape of infrared energy
- creates ocean currents
- water vapour transport
What is the composition of gases in the atmosphere?
Nitrogen 78%
Oxygen 21%
Carbon dioxide 0.04%
Rare gases 1%
Methane 0.00017%
Water Vapour up to 4%
Ozone 0.000007%
What are the four ‘building block’ gases in the atmosphere?
Carbon
Nitrogen
Oxygen
Hydrogen
What are greenhouse gases?
Gases that are better at absorbing infrared than the average for the atmosphere
How does the greenhouse effect work?
- Visible light passes easily through the atmosphere
- It gets absorbed the the Earth’s surface, warming it up
- Warm Earth’s surface emits infrared radiation
- Infrared cannot pass through the atmosphere as easily because it is absorbed by the greenhouse gases.
- They reemit. The cycle continues.
What are the factors controlling the natural greenhouse effect?
Solar Emissions
Greenhouse Gases
How do solar emissions affect the natural greenhouse effect?
- they are increasing very slowly
- there is a short term 11 year cycle of varying solar output
What is the natural source of:
a) nitrogen
b) methane
c) water vapour
d) oxygen
e) ozone
a) bacteria in soils
b) bacteria in soils
c) evaporation
d) photosynthetic organisms
e) stratosphere only
What is the anthropogenic source of:
a) oxygen
b) water vapour
a) hospitals and welding (possibly)
b) evaporation from power station cooling towers
How is water vapour affected by climate change?
- more released by humans does not increase max humidity unless temp increases because it will precipitate
- climate change causes temps to increase = max humidity increases
- concentration is balanced by evapotranspiration and condensation. Both controlled by temp. Changing temp changes concentration
What are the anthropogenic sources of CO2?
Burning fossil fuels and wood
Ploughing soil
Draining marshes/bogs
What are the anthropogenic sources of methane?
Anaerobic respiration by microbes in padi fields/intestines of livestock/landfill sites
Creation of fossil fuels
Release from coal mines
Leaks from natural gas fields/pipelines
What are the anthropogenic sources of nitrous oxides?
Reaction of oxygen and nitrogen at high temps (engines and power stations)
Then released by exhausts
Fertilisers
What are the anthropogenic sources of CFCs?
Aerosol propellants
Coolants in fridges
Fire extinguishers
Expanding foam plastics
Solvents
What is the anthropogenic source of tropospheric ozone?
Nitrogen dioxide breaking down with light then reacting with oxygen
What are the relative effects per molecule of:
a) CO2
b) Methane
c) Nitrous oxides
d) CFCs
e) Tropospheric ozon
a) 1
b) 25
c) 160
d) 25,000
e) 2,000
What is the importance to life of:
a) methane
b) water vapour
c) nitrogen
d) carbon dioxide
e) oxygen
f) ozone
a) source of energy for chemoautotrophs
b) hydrological cycle and insulation as a GG
c) synthesis of proteins
d) insulation as a GG and reactant for photosynthesis. synthesises lipids, carbs and proteins
e) respiration
f) absorbs harmful UV dangerous to life
What maintains the average composition of the atmosphere?
- natural processes are in balance: change only happens over a very long time
What natural processes are important to the stability of the composition of the atmosphere?
Photosynthesis
Respiration
- roughly balance each other out but rates vary over different timescales causing gas fluctuations around their mean concentration
How does the CO2 concentration change:
a) daily
b) annually
a) Early hours = more as it is dark so respiration outweighs photosynthesis
Middle of day = less as the increased light allows photosynthesis.
Later = more, gets darker…
b) January-April = respiration outweighs photosynthesis so concentrations are high
April-August = photosynthesis levels high so concentration decreases
August-December = respiration outweighs photosynthesis so concentrations are high
What is the importance of atmospheric processes being connected?
If one process is changed, other processes can change
- it means human actions can trigger a chain reaction of altering processes as a direct response to the first change
- not possible to accurately predict the impact on specific processes yet though as there is a lot to be discovered.
What are the layers of the atmosphere in ascending order?
Troposphere
Stratosphere
Mesosphere
Thermosphere
What is the structure of the atmosphere in relation to distance from the Earth?
Majority of atmosphere is near the ground
- 80% of gases are in the troposphere which is within 10km of surface
gradually gets thinner up to about 10,000km
- considered the upper limit of the atmosphere
What is the troposphere?
- lowest part of atmosphere
- contains most of our weather
- turbulent
What is the stratosphere?
- layer after troposphere, separated by the tropopause
- still some weather
- used by high flying jets
- naturally contains ozone
What is the mesosphere?
- layer after stratosphere, separated by the stratopause
- hardly any gases, water vapour or particles to absorb solar radiation
What is the thermosphere?
- layer after the mesosphere, separated by mesopause
- contains ions
- reflects radio signals back and forth between the ground, enabling transmission of radio signals
- absorbs some solar radiation
What is the importance of the sun?
makes life possible
- provides energy required for life
- provides heat for a stable environment
- light for photosynthesis
What is the composition of the sun?
70% hydrogen
28% helium
2% other
Characteristics of the sun (8)
- contains 99.8% of mass of solar system
- surface temp roughly 6000 degrees
- core temp 15.6 million degrees
- surface pressure 0.1 atm
- core pressure 250 billion atm
- core = 25% interior radius
- nuclear fusion happens in core
- rotates every 25.4 days
What can happen to UV in the atmosphere?
Scattering
Absorbed
Reflected
What is scattering?
light is distributed randomly (scattered) by particles in the atmosphere
- the amount of scattering depends on wavelength of light and size of particles
What is reflection?
when the light is bounced back
What is absorption?
When EM radiation is converted into heat energy
How does UV react in the stratosphere?
- biologically damaging UV is stopped by the upper atmosphere.
- most passing through the upper atmosphere is prevented from getting to Earth by oxygen in the stratosphere. This continually creates and destroys ozone in a DYNAMIC EQUILIBRIUM
- there is O, O2 and O3 in the atmosphere. (monoatomic, diatomic and triatomic oxygen)
- O2 bond is broken by high energy UV radiation (photolysis) to form two O
- other O2 can react with O to form O3
- O3 bond is broken by high energy UV radiation (photolysis) to form O2 and O
- etc etc etc.
What is dynamic equilibrium?
The changes over time being brought back to a stable level by natural processes occurring
How does the atmosphere delay the escape of infrared energy?
- much of incoming visible light is absorbed, converted to heat and re-emitted as infrared energy
- naturally occurring gases in atmosphere absorb this infrared, convert it to heat and increase temp of atmosphere
- this raises Earth’s temp in two ways:
- warm atmosphere emits energy which is absorbed by Earth’s surface
- warm atmosphere reduces heat loss by conduction from land and oceans
What is the Earth’s energy budget?
The balance between the energy that the Earth receives from the sun and the energy that it loses back to space
Why is the atmosphere important in the Earth’s energy budget?
without the atmosphere and GE, due to GG, Earth would have an average temp of -19 degrees. This would make life very difficult if not impossible
- current average temp is 15 degrees
How does energy get reflected back out from the Earth?
What are the percentage reflection for:
a) fresh snow
b) open ocean
c) fresh asphalt
d) forests
e) green grass
f) desert
Albedo
a) 80
b) 6
c) 4
d) 15
e) 25
f) 40
How does the atmosphere distribute heat?
- most energy from Sun absorbed by Earth’s surface is absorbed in tropical regions.
- warm surface heats atmosphere above
- warm winds carry heat to higher latitudes e.g. south-westerly winds that bring warm air to UK from Caribbean Sea
How does the atmosphere create ocean currents?
- wind blows over sea
- creates currents that distribute heat by carrying warm water from tropical areas to higher latitudes e.g. North Atlantic Conveyor
- currents can also distribute dissolved nutrients
How does the atmosphere transport water vapour?
Winds carry water vapour to areas that would normally get little or no precipitation
How do gases in the atmosphere support life?
Needed for building biological molecules used by living organisms
Lipids - carbon, oxygen, hydrogen
Carbs - carbon, oxygen, hydrogen
Proteins - carbon, oxygen, hydrogen, nitrogen
How does absorption of EM radiation support life?
- biologically damaging solar wind prevented from reaching Earth by the upper atmosphere
- most UV that gets through upper atmosphere stopped by ozone in stratosphere
- too much radiation would kill cells
How does delaying escape of IR energy support life?
atmo gases absorb IR, convert to heat, increase temp of atmo
Raises temp in 2 ways:
- warm atmo emits infrared, then absorbed by Earth’s surface
- warm atmo reduces heat loss by conduction from land/oceans
Warmth is good for enzyme and chemical reactions needed for life
How does heat distribution support life?
The energy that is absorbed at the Earth’s surface from the sun is mostly absorbed at tropical regions
- warm surface heats atmo above
- heat distributed to higher latitudes by warm winds e.g. south westerly winds bringing heat to UK from Caribbean Sea
What are the methods to control global climate change?
- Control of GG
- Carbon Storage
- Geoengineering
Which GG do we need to control?
Carbon dioxide
methane
oxides of nitrogen
tropospheric ozone
chlorofluorocarbons
What are the control methods for carbon dioxide?
- reduction in ff use e.g. through energy conservation
- increase in renewable energy resources that don’t emit carbon e.g. wind turbines
- carbon sequestration e.g. afforestation, storing C02 from power stations in underground geological structures
What are the control methods for methane?
- reduction in livestock production
- decrease volume of waste sent to landfill e.g. increase in recycling
- improved recovery of gas from coal mines and oil and gas facilities
What are the control methods for oxides of nitrogen?
- reduce use of internal combustion engines e.g. use public transport
- install catalytic converters in vehicle exhausts to remove harmful gases and convert them into oxygen and nitrogen (CO/hydrocarbons are broken down/converted into CO2 and water)
- add urea to power station effluent/diesel exhaust engines to reduce NOx concentrations and convert exhaust gases into nitrogen and steam
What are the control methods for tropospheric ozone?
controls and processes which reduce NOx emissions also reduce the formation of ozone in troposphere:
- reduce use of internal combustion engines e.g. use public transport
- install catalytic converters in vehicle exhausts to remove harmful gases and convert them into oxygen and nitrogen (CO/hydrocarbons are broken down/converted into CO2 and water)
- add urea to power station effluent/diesel exhaust engines to reduce NOx concentrations and convert exhaust gases into nitrogen and steam
What are the control methods for chlorofluorocarbons?
- alternative material use in manufacture and appliance operation
e.g.
- HFCs and HCFCs in fridges
- alcohols as solvents in cleaning electronic equipment - Use alternative operational processes
e.g.
- pump and spray (cleaners and aerosols)
- roll on/stick deodorant instead of aerosol
What methods are used for carbon storage?
- carbon sequestration
- Carbon Capture and Storage (CCS)
How does carbon sequestration work?
planting more trees sequesters carbon in wood through photosynthesis
How does CCS work?
DEVELOPMENTAL TECH:
may remove CO2 produce by industrial processes e.g. fossil fuel power stations
Main stages:
1. Capture of CO2/removal of carbon from the fuel
2. Transport by road tanker, ship, or pipeline
3. CO2 storage in depleted oilfields, gas fields, aquifers, or its use in secondary oil recovery
What is geoengineering and how can it control CC?
involves largely untried tech that might control natural processes to reduce the anthropogenic GE
e.g.
- painting roofs white to increase albedo/sunlight reflection
- adding nutrients to the sea to stimulate plankton growth (shells of dead animals would take carbon to the sea bed)
- putting solar shades in orbit to reduce sunlight reaching Earth
Some strategies could have unpredictable consequences that could cause environmental damage
