7 The atmosphere and human activities Flashcards
the structure of the atmosphere (the silly monkey talk)
troposphere, stratosphere, mesosphere, thermosphere
Troposphere characteristics
Lowest and thinnest layer it is 16 km at equator, 8 km at poles
• 90% of the atmosphere’s mass
• Temperature decreases with altitude 6°C per kilometer at the top of troposphere averages -50°C
• It is where weather occurs
• The boundary between the troposphere, and the stratosphere is called the tropopause
Stratosphere characteristics
• It extends from 10 km to 50 km above the ground
• It is less dense (less water vapor)
• Temperature increases with altitude
• There is almost no weather occurrence
• It contains high level of ozone layer
• Upper boundary is called stratopause
Mesosphere characteristics
• Extends to almost 80 km high
• Gases are less dense.
• Temperature decreases as altitude increases.
• Gases in this layer absorb very little UV radiation.
Thermosphere characteristics
• Above the mesosphere and extends to almost 600 km high
• Temperature increases with altitude
• Readily absorbs solar radiation
• Temperature can go as high as 1,500 °C
• Reflects radio waves.
Composition of atmosphere
Nitrogen 78%
Oxygen 21%
Argon 0.9%
Water vapour 0.2%
Carbon dioxide 0.04%
What is the ozone layer?
The Ozone layer or ozone shield is a region of Earth’s stratosphere that absorbs most of the Sun’s ultraviolet
radiation. It contains high concentrations of ozone (03) in relation to other parts of the atmosphere, although still small in relation to other
gases in the stratosphere.
The natural greenhouse effect
- a process that helps keep the Earth’s surface and atmosphere warm.
The Earth receives incoming short-wave radiation from the Sun.
a) Half of this radiation is absorbed by the Earth’s surface.
b) Around 20% is absorbed by the atmosphere.
c) Around 30% is reflected by clouds and the Earth’s surface, back into space.
• As the Earth’s surface warms, outgoing long-wave
Some solar radiation is reflected by the Earth and the atmosphere.
radiation (infrared radiation) is emitted back into the atmosphere.
• Greenhouse gases absorb some of this radiation and deflect it back to the Earth’s surface.
The more the concentration of the greenhouse gases, the more effectively they return radiation back to Earth.
Natural greenhouse gases
water vapour, carbon dioxide, ozone, methane and nitrous oxides.
Artificial greenhouse gas
Chlorofluorocarbons (CFCs).
the causes of atmospheric pollution
- smog
- acid rain
- ozone layer depletion
- enhanced greenhouse effect
What is Smog?
Smog is basically derived from the merging of two words; smoke and fog
Smog is a yellowish or blackish fog formed mainly by a mixture of pollutants in the atmosphere which consists of fine particles and ground level ozone.
How Smog is formed?
Burning of fossil fuels in industry, homes and vehicles provides particles like smoke and dust for fog to form around.
Type of smogs
Photochemical smog: Involves chemical reactions induced by sunlight on certain pollutants.
These reactions convert them into harmful substances, like ground-level or tropospheric ozone (‘bad’ ozone).
Volatile Organic Compounds (VOCs):
Chemicals that easily enter the atmosphere as gases, mainly from evaporation.
Examples: hydrocarbons (like methane), ammonium nitrate, carbon monoxide (incomplete combustion),
What happens during temperature inversion
The time that smog takes to form depends directly on the temperature. Temperature inversions are situations when warm air does not rise instead stays near the ground. During situations of temperature inversions if the wind is calm, smog may get trapped and remain over a place for recorded, for days.
Process of temperature inversion
Temperature inversion: a weather condition when the air temperature increases with altitude, rather than decreasing.
• During the day, the surfaces is heated due to longwave radiation.
• On calm and clear nights, the Earth surface cools very quickly, emitting radiation, cooling the air above it.
• At higher altitude, the air doesn’t cool as quickly, so this air becomes warmer than the air below it.
• This layer of warm air is the inversion layer, that disrupts the regular convection currents.
• The concentration of smog (pollutants) increases, often in valleys surrounded by steep-sided hills.
Impact of smog:
effects on human health
• leads to bronchial diseases
• leads to constant asthmatic attack
• irritation to the eye and reduce visibility
• leads to pulmonary diseases such as lunas cancer
• leads to low reduction in vitamin D which can lead to rickets.
Effects of acid rain
acidification of bodies of water,
effects on fish populations,
damage to crops and vegetation,
damage to buildings
Causes of acid rain
sulfur dioxide and oxides of nitrogen
Ozone layer depletion
o Ozone layer protects the Earth from the Sun’s harmful radiation.
o It is formed when oxygen (02) filters from the top of the troposphere and reacts under the influence of ultraviolet radiation to form ozone (03).
o 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 oxygen 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.
Impact of ozone depletion
• Higher levels of ultraviore radiation cause sun burn, skin cancers, retina damage and cataracts;
Extra ultraviolet radiation limits the reproduction of phytoplankton, affecting the entire food webs;
• Changes in biochemical composition of some plant leaves make them less attractive as food.
Enhanced Greenhouse effect
• created by addition of greenhouse gases to the atmosphere through human activities.
• More heat retained in the atmosphere.
• Increased temperature of the Earth’s surface, leading to global warming and climate change.
Impact of enhanced greenhouse effect
• climate change:
melting of ice sheets, glaciers and permafrost;
• rise of sea-level
• flooding and loss of land
• forced migration
the strategies used by individuals, governments and the international community to reduce the effects of atmospheric
pollution
• reduction of carbon footprint
• reduced use of fossil fuels
• energy efficiency
• carbon capture and storage
• transport policies
• international agreement and policies
• CFC replacement
• catalytic converters
• flue-gas desulfurisation
• taxation
• reforestation and afforestation
• reduction of carbon footprint
a measure of the impact of our activities on the environment.
Reduced use of fossil fuels:
Increased use of renewable energy.
Energy efficiency:
Using energy efficient appliances.
Carbon capture and storage:
Waste carbon dioxide from power stations can be transported via pipelines to storage sites.
Transport policies:
a) Creation of cycle lanes, bus lanes, metro systems and trams;
b) Electric or hybrid cars can be encouraged;
c)
Biofuels can be used;
d)
Vehicles can be banned from certain parts of city by pedestrianisation;
e) Public transport and residential parking can be made free.
CFC replacement:
Reduction in the use of CFCs;
Hydrochlorofluorocarbons (HCFCs) can be used as an alternative
Taxation:,
Higher road tax to decrease car ownership.
Catalytic converters:
Catalytic converters in vehicles reduce sulfur dioxide emissions; They also convert nitrogen dioxide and carbon monoxide to carbon dioxide and nitrogen;
• Flue-gas desulfurisation:
Scrubbers can be used to remove 95% of sulfur dioxide emissions; Lining chimneys with lime also reduce the emissions.
Reforestation and afforestation:
• Reforestation: replanting an area with trees;
• Afforestation: planting trees in a barren land.
Reasons why acid rain, global warming affects everyone
• gases can be moved over long distances/the atmosphere is not a barrier
• wind moves gases over long distance
• gases produce in one country can affect other country
pollutants that form smog
pollutants that form smog
● VOCs
● sulphur oxides
● carbon monoxide
● ozone
