Chemistry of the Atmosphere

What is the main gas in Earth’s atmosphere?

Nitrogen (about 78%)

What is the second most abundant gas in the atmosphere?

Oxygen (about 21%)

Name two minor gases in the atmosphere.

Argon, carbon dioxide

Name one trace gas in the atmosphere.

Neon, helium, krypton, methane

What is the current concentration of CO₂ in the atmosphere?

About 0.04%

How has Earth’s atmosphere changed over time?

Evolved from volcanic gases to oxygen-rich by photosynthesis

What was the early atmosphere mainly composed of?

Carbon dioxide, water vapour, ammonia, methane

What produced the first oxygen on Earth?

Photosynthetic bacteria and plants

What evidence is there for early atmosphere?

Volcanic activity, gas analysis, rock layers

What process removes CO₂ from the atmosphere?

Photosynthesis, dissolving into oceans

How did oceans affect the atmosphere?

Dissolved CO₂, allowed marine life to form shells

How did limestone form?

Marine organisms absorbed CO₂, shells turned to limestone

How does photosynthesis affect the atmosphere?

Removes CO₂, adds oxygen

How did oxygen levels increase historically?

Photosynthesis by plants and algae

What is the greenhouse effect?

Heating of Earth caused by gases trapping infrared radiation

Name three greenhouse gases.

CO₂, methane, water vapour

What human activities increase greenhouse gases?

Burning fossil fuels, deforestation, farming cattle/rice

How does increased CO₂ cause global warming?

Traps heat in Earth's atmosphere

What is global warming?

Increase in average temperature of Earth's atmosphere/sea

How does methane enter the atmosphere?

Animal farming, decay, rice fields, landfill sites

What is climate change?

Long-term shift in global or regional climate patterns

What problems result from global warming?

Extreme weather, melting ice, sea level rise

What is carbon footprint?

Total CO₂ and greenhouse gases emitted by person/product/process

How can carbon footprint be reduced?

Use renewable energy, improve efficiency, change lifestyles

What is combustion?

Burning fuels, produces CO₂ and water (hydrocarbons)

What is complete combustion?

Fuel burns with sufficient oxygen, forms only CO₂, H₂O

What is incomplete combustion?

Limited oxygen, makes CO, soot (carbon), and less energy

Why is carbon monoxide dangerous?

Colourless, odourless, toxic – reduces blood oxygen

What gas causes acid rain?

Sulfur dioxide (SO₂)

How does sulfur dioxide form?

Burning coal/oil containing sulfur impurities

How does nitrogen oxide (NOₓ) form?

High temperature in engines causes N₂ and O₂ to react

What are effects of acid rain?

Damages trees, buildings, harms aquatic life

What causes particulate pollution?

Incomplete combustion, produces soot

What damage do particulates cause?

Respiratory problems, global dimming

What is global dimming?

Reduction in sunlight due to particles in the air

How can air pollution be reduced?

Use cleaner fuels, catalytic converters, renewable energy

What is a pollutant?

A substance harmful to environment or health

What is smog?

Air pollution from particulate matter, nitrogen oxides, sunlight

How is oxygen made industrially?

Fractional distillation of liquid air

What is the role of trees in atmosphere?

Absorb CO₂, produce oxygen

How does deforestation affect atmosphere?

Increases CO₂, reduces oxygen production

What is sequestration?

Trapping carbon via trees, oceans, underground storage

How do greenhouse gases naturally regulate temperature?

Allow life by trapping warmth

What is the Keeling Curve?

Graph showing rising atmospheric CO₂ since 1958

What are ice cores used for?

Show past atmospheres by comparing trapped gases in ice layers

How do fossil fuels form?

Dead organisms compressed over millions of years

Name three fossil fuels.

Coal, oil, natural gas

What is the primary source of atmospheric CO₂?

Burning fossil fuels

What is anthropogenic mean?

Caused by humans (e.g., climate change)

What is stratosphere?

Atmospheric layer above the troposphere

What is ozone layer?

Protective layer filtering out harmful UV radiation

How is ozone formed?

O₂ absorbs UV and forms O₃

What damages ozone layer?

Chlorofluorocarbons (CFCs)

Why are CFCs banned?

They destroy ozone, increase UV risk

What is weathering?

Breakdown of rocks, contributes CO₂ to atmosphere

What are sinks of carbon dioxide?

Oceans, forests, soil, rocks

What is a catalytic converter?

Device in cars removing NOₓ, CO, hydrocarbons from exhaust

What is renewable energy?

Energy from natural sources that replenish quickly (e.g., solar, wind)

How does energy use affect atmosphere?

Non-renewable causes more pollution, CO₂ emissions

How is natural gas cleaner than coal?

Produces less CO₂ and particulates when burned

What is the correlation between CO₂ and temperature?

Generally, as CO₂ increases, temperature rises

What is methane’s effect compared to CO₂?

Methane traps more heat per molecule

Why is monitoring atmospheric CO₂ important?

Track climate change and pollution

What is the main challenge in reducing greenhouse gases?

Economic cost, technology transition, lifestyle changes

What is geoengineering?

Deliberate modification of environment to combat climate change

Why is water vapour not measured for carbon footprint?

Quickly cycles through the atmosphere

What is ocean acidification?

CO₂ dissolves in oceans forming carbonic acid, hurts marine life

Name a practical to test for carbon dioxide.

Bubble gas through limewater; turns milky/cloudy

How is air sampled for analysis?

Air collected and analysed by spectral or chemical methods

Why are ice cores reliable for past atmospheric data?

Trapped air bubbles show gas composition over time

How does temperature rise affect sea levels?

Melts ice caps, water expands, sea level rises

What is a climate model?

Scientific simulation of future climate trends

How do clouds affect atmospheric temperature?

Trap heat, reflect sunlight

What is acid deposition?

Fall of acids from atmosphere, wet or dry forms

What is photochemical smog?

Pollution formed under sunlight by NOₓ and hydrocarbons

What is peer review in climate science?

Scientists check each other's work for accuracy

How are pollutants tracked globally?

Monitoring stations, satellites, atmospheric models

What is adaptation (to climate change)?

Adjusting human practices to cope with changes

What is mitigation (in climate science)?

Action to reduce/stop the magnitude of climate change

What is the role of international agreements?

Coordinate efforts to cut emissions, e.g., Paris Agreement

How does volcanic activity change atmosphere?

Releases gases, particulates, affects climate temporarily

What is hydrogen sulfide?

Gas released by volcanoes, toxic, forms acid rain

How is air quality measured?

Concentration of pollutants, particulates, gases

What is greenhouse gas potential?

Measure of effect compared to CO₂ over set time

Name a recent improvement in monitoring air pollution.

Satellite remote sensing

Why is recycling important for atmosphere?

Reduces need for new materials, lowers emissions

What is urban heat island effect?

Cities are warmer due to human activities, less vegetation

What is carbon capture and storage?

Technology to remove CO₂ from emissions and store underground

What's an example of positive feedback in climate change?

Warming melts ice, less reflection, faster warming

Why does sea ice loss matter?

Reduces Earth's ability to reflect sunlight, increases warming

How does ocean currents affect global climate?

Redistribute heat energy across the planet

How do aerosols impact atmosphere?

Can cool by reflecting sun or warm by trapping heat

What is the main human cause of rising methane?

Cattle farming, rice paddies, landfill

How can personal choices affect atmospheric pollution?

Lower fossil fuel use, energy efficiency, diet change

What is the link between population growth and CO₂?

More people, more energy use, higher emissions