Topic 7 Flashcards
Atmosphere
1.Nitrogen (N2)
78.0
Growth of plants.
2.Oxygen (O2)
20.95
Produced by photosynthesis.
Used in respiration.
Water Vapour (H2O)
0.2-4
Source for precipitation.
Provides most of the natural greenhouse gases.
Vital for existence of life.
Argon (Ar) and other inert gases
0.93
Can create an inert atmosphere that protects materials from reacting with oxygen or other gases.
Carbon Dioxide (CO2)
0.03
Used by plants in photosynthesis. Greenhouse gas.
Structure of atmosphere
The atmospheric pressure decreases as the height increases in all layers of the atmosphere.
1- Troposphere:
Temperature decreases with height as conduction and convection of heat from the Earth’s surface decrease.
The top of this layer is called the tropopause, where temperatures remain fairly constant.
This is the upper limit to the Earth’s weather and climate.
2- Stratosphere:
This layer contains the ozone layer, and the ozone layer is formed by the concentration of ozone that absorbs the incoming ultraviolet radiation from the Sun.
o Temperature increases slightly with height. This is called temperature inversion. The top of this layer is called the stratopause.
Ozone layer: ozone layer is part of the stratosphere which
absorbs most of the sun UV radiation
contains high concentration of ozone gas (O3).
3- Mesosphere:
。 Temperature falls rapidly as there’s no dust, water vapor or ozone to absorb the short-wave radiation.
The upper limit of this layer is called the Mesopause
Stratosphere
This layer also acts as a shield against incoming
meteorites.
4- Thermosphere:
。 Temperatures rise rapidly because of the
absorption of ultraviolet radiation by atomic oxygen.
• The upper limit of this layer is called the thermopause.
Examples of greenhouse gases
Natural: water vapor, carbon dioxide, methane, and nitrous oxides.
Artificial: Chlorofluorocarbons (CFCs).
Natural effect of greenhouse gas
The Earth receives incoming short-
wave radiation from the Sun. This
radiation is absorbed by the Earth’s
surface.
As the Earth’s surface warms, outgoing long-wave radiation (infrared
radiation) is emitted back into the
atmosphere.
Greenhouse gases in the troposphere absorb some of this radiation and deflect it back to the Earth’s surface.
Ozone layer depletion
Ozone layer protects the Earth from the Sun’s harmful UV radiation.
It is formed when oxygen (O2) filters from the top of the troposphere and reacts under the influence of ultraviolet radiation to form ozone (O3).
It is continually formed, destroyed and replaced naturally, creating a dynamic balance
that is disturbed by human activities.
When CFCs reach the stratosphere, the ultraviolet radiation breaks them down,
releasing chlorine.
Chlorine reacts with ozone in a destructive
process, breaking down the ozone molecules to
chlorine monoxide and oxygen, depleting the layer and forming a hole. This hole allows harmful radiation to enter the Earth’s atmosphere.
Managing atmospheric pollution
Reduction of carbon footprint:
Carbon footprint: the amount of greenhouse gases mainly carbon dioxide released into
the atmosphere by a particular human activity.
Reduced use of fossil fuels:
o Increased use of renewable energy.
Low Sulphur coal can be used.
•Energy efficiency:
Using energy efficient appliances and turning off appliances when not in use.
Insulation.
. Carbon capture and storage: Waste carbon dioxide from power stations can be transported via pipelines to storage sites. Can be made naturally by afforestation.
Transport policies:
O Creation of cycle lanes, bus lanes, metro systems and trams.
O Electric or hybrid cars can be encouraged.
o Biofuels can be used.
O Vehicles can be banned from certain parts of the city by walking and cycling.
o Public transport and residential parking can be made free.
International agreement and policies:
o Atmospheric pollution is an international problem as there are no boundaries in the atmosphere so CFCs that used in many countries can travel to others, so an international cooperation is required.
o However, international agreements are difficult to get all countries to agree as some countries are larger polluters than others and some countries can’t afford the technology or have access to renewable energy resources.
CFC replacement:
Reduction in the use of CFCs.
Hydrochlorofluorocarbons (HCFCs) can be used as an alternative.
Safe disposal of items containing CFCs
• Catalytic converters:
o Catalytic converters in vehicles reduce Sulphur dioxide emissions.
o They also convert nitrogen dioxide and carbon monoxide to carbon dioxide and nitrogen.
o Low-Sulphur vehicle fuels can also be used.
O
• Flue-gas desulfurization (FGD)
o Scrubbers can be used to remove 95% of Sulphur dioxide emissions.
o Lining chimneys with lime also reduces the emissions.
• Taxation:
o Higher road tax to decrease car ownership.
Reforestation and Afforestation:
o Reforestation: replanting an area with trees. 。
Afforestation: planting trees in a barren land.
Acidic rain
• Acid rain: precipitation with a pH value of less than 7
O Burning of fossil fuels in factories and power stations
release Sulphur dioxide and nitrogen oxides.
O Vehicle emissions add further nitrogen oxides.
O When these gases mix and react with the
water vapor in the atmosphere, they form weak
solutions of nitric and sulphuric acids.
o They are carried by winds.
o They eventually fall to Earth as acid rain.
Reasons for the difficulty of reducing air pollution:
- Difficult to pass legislation. 2. May impact the economy.
- Not popular with the public.
- Needs international agreement as pollution may be produced by neighboring countries yet
it passes international boundaries. - The technology that reduces air pollution is expensive.
- Countries with great population density.
- Abundance of fossil fuels.
All about Smog
• Smog:
o Source of smog:
Burning of fossil fuels in industry, homes, and vehicles.
o The reaction:
1- The atmospheric pollutants are released in the air when
fuels are burned.
2- These gases and particulates react with sunlight and its heat in the atmosphere to form also it’s Caused due to smog.
o Conditions that help smog formation: 1- Temperature inversion layer 2- Urban areas 3- High pressure. 4- Lack of air flow.
Volatile Organic Compounds (VOCs) {from industrial processes}: They are chemicals that easily enter the atmosphere as gases mainly from evaporation.
Examples:
1- Hydrocarbons (like methane)
2- Ammonium Nitrate
3- Carbon Monoxide (from incomplete combustion).
Vehicle emissions: emissions from vehicles show a variety of negative effects
and environment.
Examples:
1- Hydrocarbons (HC)
2- Carbon Monoxide (CO)
3- Oxides of Nitrogen (NOx)
4- Sulphur Oxides (SOX)
5- Volatile Organic Compounds (VOCs)
Safwatem
。 Temperature inversion: a weather condition when the air temperature increases
with altitude, rather than decreases.
During the day, the surfaces are heated.
On calm (no wind) nights in winter, the Earth surface cools very quickly and holds cold air near the ground.
Cold air is denser and unable to rise.
Steep-sided valleys and mountains increase the strength of inversion layer. aldar
This layer of warm air is the inversion layer which traps the pollutants under it increasing the formation of fog thus increasing the formation of smog.
Increase of carbon dioxide is due to
- Burning of fossil fuels in vehicles and factories
- Deforestation
- Increased respiration
- Increased energy demand
Increase of Methane is due to
- Mining
- Decomposition of wastes in landfill sites
- Increased food demand so increased rice and cattle farming
- Deforestation
- Melting of permafrost
Cfcs due to
- Aerosol spray
- Refrigeration
- Air conditioning
- Fire extinguishers
Nitrogen dioxide due to
- Vehicle exhaust
- Chemical exhaust
Tropospheric ozone is due to
Chemical reactions involving nitrogen dioxide and unburnt fuel vapors
Impact of smog
- Breathing difficulties.
- Respiratory diseases, like asthma, bronchitis & COPD.
- Irritation of eyes and throat.
- Fine particles carried into lungs, leading to lung cancer
. 5. Reduced photosynthesis.
