Structure of Atmosphere
Which layer contains almost all weather activity?
Troposphere – lowest layer (0–12 km). Contains ~75 % of atmospheric mass and almost all water vapour; where clouds form and rainfall, storms, and winds occur. Temperature falls ≈ 6.5 °C per km.
What is the natural greenhouse effect?
A natural process where greenhouse gases (CO₂, CH₄, water vapour, N₂O) absorb and re-emit infrared radiation, keeping Earth about 33 °C warmer (~15 °C average) – essential for life.
What does “smog” mean?
Smog = Smoke + Fog – a haze of pollutants (ozone, NOₓ, VOCs, soot) trapped near the ground, common in cities with stagnant air and sunlight.
Which parts of the body are affected by smog?
Eyes & lungs – causes irritation, asthma, bronchitis, reduces lung function, increases mortality.
What is Carbon Capture & Storage (CCS)?
Capturing CO₂ from power-station flue gases and injecting it into deep geological formations (e.g. saline aquifers, old oil fields) to prevent atmospheric release.
Which layer contains the ozone layer, and what is its function?
Stratosphere (12–50 km) houses the ozone layer (≈ 20–30 km) which absorbs harmful ultraviolet-B and ultraviolet-C radiation, protecting living organisms from DNA damage.
Name three major greenhouse gases.
Carbon dioxide (CO₂): fossil-fuel combustion. Methane (CH₄): livestock, landfills, rice fields. Water vapour: natural feedback. Nitrous oxide (N₂O): fertilisers, transport.
Which two gases cause acid rain?
Sulfur dioxide (SO₂) from coal burning and nitrogen oxides (NOₓ) from vehicles react with water to form H₂SO₄ & HNO₃, lowering rain pH < 5.6.
Give one effect of UV exposure on health.
Prolonged exposure damages skin cells, skin cancer, premature ageing, and cataracts.
Name one key international agreement.
Montreal Protocol (1987): phased out CFCs → ozone recovery. Paris Agreement (2015): limit global warming < 2 °C through national emission targets.
Why does temperature increase with height in the stratosphere?
Ozone molecules absorb UV energy, converting it to heat. This causes a temperature inversion – temperatures rise from about –60 °C to 0 °C near the stratopause.
What is the enhanced greenhouse effect?
Human-driven increase in greenhouse gas concentrations (esp. CO₂) trapping extra heat which leads to global warming, rising sea levels, and climate instability.
How does temperature inversion worsen smog?
A warm air layer above cooler surface air prevents vertical mixing, so pollutants accumulate near ground level leads to thick, photochemical smog (e.g. Los Angeles, Delhi).
How does acid rain damage buildings?
Dissolves calcium carbonate in limestone & marble, erosion of monuments; rusts iron and steel; increases maintenance costs.
Why is afforestation effective for climate mitigation?
Trees absorb CO₂ during photosynthesis; create carbon sinks; also reduce local temperatures and erosion – low-cost, long-term solution.
Compare the troposphere and mesosphere in temperature change.
Troposphere: temperature decreases because it’s heated from the surface. Mesosphere: temperature also decreases (≈ –90 °C at top) because there’s almost no ozone to absorb radiation.
Explain two causes of rising CO₂.
(1) Combustion of coal, oil, gas for electricity & transport. (2) Deforestation removes carbon sinks, releasing stored carbon via decay/burning.
Describe two effects of acid rain on nature.
(1) Lowers pH of lakes results in fish eggs fail, species die. (2) Leaches nutrients (Ca, Mg) from soils results in forest decline, crop loss.
Explain how climate change increases extreme weather.
Warmer atmosphere holds more moisture leads to intense rainfall & floods; shifting pressure belts results in heatwaves and droughts.
Human activities intensify the ozone depletion. Give reasons why
CFCs, HCFCs used in spray cans, air conditioners, and refrigerators rise to the stratosphere. UV radiation breaks them down, releasing chlorine and bromine atoms, which react with ozone (O₃), splitting it into oxygen gas (O₂).
Explain how the composition and layering of the atmosphere make life possible.
The mixture of 78 % N₂, 21 % O₂, 1 % other gases supports respiration and plant photosynthesis. Ozone filters UV, greenhouse gases regulate temperature, and vertical layering keeps energy and gases cycling safely.
“Climate change is the greatest environmental challenge of the 21st century.” Discuss.
It’s global and long-term: intensifies droughts, floods, storms, sea-level rise, disease spread, and food insecurity. Because greenhouse gases mix globally, it demands international action (e.g. Paris Agreement 2015).
Evaluate effectiveness of policies reducing air pollution.
Highly effective in HICs: Clean Air Acts, catalytic converters, low-sulphur fuels cut emissions 70 – 90 %. Less effective globally: rapid industrialisation in LICs offsets progress.
Evaluate socio-economic impacts of atmospheric pollution.
Health-care costs rise; worker absenteeism; reduced agricultural yield; tourism loss in polluted cities; long-term GDP drag > 2 % in some regions.
“International agreements are essential for solving atmospheric problems.” Discuss.
The atmosphere is global → pollution crosses borders. Montreal Protocol = success model. Paris Agreement = progress but unequal commitment & financing gaps hinder results. Cooperation is vital but enforcement varies